Janus particles, methods and uses thereof

Abstract

A Janus particle, comprising a particle core, the particle core comprising at least a first surface functionalized with a functional group and a second surface functionalized with a metal particle.

Description

JANUS PARTICLES. METHODS AND USES THEREOFFIELD

[0001] The present disclosure relates generally to Janus particles for contaminant removal and / or biological monitoring.BACKGROUND

[0002] Magnetic Janus particles have two or more chemistries onto the opposite sides of the particle, combining magnetic properties with selective configurations [1 ,2], Distinct compartments with different functionalities and magnetic responsive characteristic offer unique multi-functionality, making magnetic Janus particles an attractive candidate for various applications such as emulsion stabilization [2], sensing [3], drug delivery [4], display device [5], imaging [6] and so on. Magnetization in the Janus particle is usually generated from magnetic surface patch, magnetic core, or magnetically responsive hemisphere [7- 9], Emulsion polymerization [7], physical vapor deposition (PVD)

[0010] , and microfluidic dropgeneration technique

[0011] are some common methodologies to fabricate magnetic Janus particles. Despite various techniques applied for magnetic Janus particles fabrication, significant limitations such as extreme experimental conditions, expensive and specialized setups and principles of the technique, hurdle to combining different types of materials, scalability of the production, controlling size of the particles as well as particles uniformity. Therefore, new processes are required to overcome the aforementioned limitations and expand the potential application of magnetic Janus particles [11-14],SUMMARY

[0003] In one or more embodiments of the present disclosure, there is provided:1 . A Janus particle, comprising a particle core, the particle core comprising at least a first surface functionalized with a functional group and a second surface functionalized with a metal particle.2. The Janus particle of embodiment 1 , wherein the core comprises SiO2, TiO2, AI2O3, Fe2O3, ZrO2, SnO2, ZnO, SrTiO3, Ta2O5, or a combination thereof.3. The Janus particle of embodiment 1 or 2, wherein the core comprises SiO2, TiO2, AI2O3, or a combination thereof.4. The Janus particle of any preceding embodiment, wherein the core comprises SiO2.5. The Janus particle of any preceding embodiment, wherein the functional group functionalizing the first surface comprises an amine group, an alkylamine group, a hydroxyl group, a hydroxyalkyl group, a thiol group, an alkylthiol group, a carboxyl group, a sulfonic group, or a combination thereof.6. The Janus particle of any preceding embodiment, wherein the functional group comprises an amine group, an alkylamine group, a hydroxyl group, a hydroxyalkyl group, a thiol group, an alkylthiol group, or a combination thereof.7. The Janus particle of any preceding embodiment, wherein the functional group comprises an amine group, an alkylamine group, or a combination thereof.8. The Janus particle of any preceding embodiment, wherein the metal particle functionalizing the second surface comprises Fe, Cu, Ni, Au, Ag, Pd, Pt, Co, an oxide thereof, or a combination thereof.9. The Janus particle of any preceding embodiment, wherein the metal particle functionalizing the second surface comprises Fe, Cu, Ni, an oxide thereof, or a combination thereof.10. The Janus particle of any preceding embodiment, wherein the metal particle functionalizing the second surface comprises Fe, an oxide thereof, or a combination thereof.11. The Janus particle of any preceding embodiment, wherein the metal particle functionalizing the second surface is magnetic, paramagnetic, or a combination thereof.12. The Janus particle of any preceding embodiment, wherein the first surface comprises about 10% to about 35%, or about 15% to about 30%, or about 20% to about 25%, or about 25% of the surface of the core particle.13. The Janus particle of any preceding embodiment, wherein the second surface comprises about 65% to about 90%, or about 70% to about 85%, or about 75% to about 80%, or about 75% of the surface of the core particle.14. The Janus particle of any preceding embodiment, wherein the Janus particle comprises a SiO2core and a first surface functionalized with amine groups and a second surface functionalized with FeO4magnetite particles.15. A method of forming a Janus particle, the method comprising providing a particle core surface functionalized with a functional group; preparing a Pickering emulsion, the emulsion comprising the particle core immobilized at an interface of a wax-aqueous solution emulsion; functionalizing an exposed surface of the immobilized particle core with metal particles via electroless deposition to form the Janus particle; and isolating the Janus particle, the Janus particle comprising the particle core having a surface functionalized with the functional group and a second surface functionalized with the metal particle.16. The method of embodiment 15, wherein preparing the Pickering emulsion comprises providing a mixture comprising an aqueous solution of wax and the particle core, heating the mixture to at least the melting point of the wax, forming a melted wax-aqueous emulsion stabilized by the particle core, cooling the emulsion to at least the freezing point of the wax, and immobilizing the particle core at the interface of the wax-aqueous emulsion.17. The method of embodiment 15 or 16, wherein functionalizing an exposed surface of the immobilized nanoparticle core with metal particles comprises forming metal particles on the surface of the particle core, or depositing metal particles on the surface of the nanoparticle core via electroless deposition.18. Use of the Janus particle of any one of embodiments 1-14, or of the Janus particle made by the method of any one of embodiments 15-17 for simultaneous removal of at least two contaminants from an aqueous solution.19. The use of embodiment 18, wherein the contaminants comprise a heavy metal, an organic compound, or a combination thereof.20. A method of simultaneously removing at least two contaminants from an aqueous solution, the method comprising providing a Janus particle into the aqueous solution comprising the at least two contaminants, the Janus particle comprising a first surface functionalized with a functional group and a second surface functionalized with a metal particle; and removing a first contaminant from the aqueous solution via the functional group functionalizing the first surface of the Janus particle, and removing a secondcontaminant from the aqueous solution via the metal particle functionalizing the second surface of the Janus particle.21 . The method of embodiment 20, wherein the first contaminant comprises a heavy metal, and the second contaminant comprises an organic compound.22. The method of embodiment 20 or 21 , wherein removing the first contaminant comprises adsorbing the contaminant with the functional group functionalizing the first surface of the Janus particle.23. The method of any preceding embodiment, wherein removing the second contaminant comprises catalyzing degradation of the contaminant with the metal particle functionalizing the second surface of the Janus particle.24. The method of any preceding embodiment, wherein the functional group comprises an amine group, an alkylamine group, a hydroxyl group, a hydroxyalkyl group, a thiol group, an alkylthiol group, a carboxyl group, a sulfonic group, or a combination thereof.25. The method of any preceding embodiment, wherein metal particle comprises Fe, Cu, Ni, Au, Ag, Pd, Pt, Co, an oxide thereof, or a combination thereof.26. The method of any preceding embodiment, wherein the heavy metal is Cr, and the organic compound comprises phenol.27. Use of the Janus particle of any one of embodiments 1-14, or of the Janus particle made by the method of any one of embodiments 15-17 for extraction of biological material from an aqueous solution.28. The use of embodiment 27, wherein the biological material comprises DNA, RNA, viruses, or a combination thereof.29. The use of embodiment 27 or 28, wherein the aqueous solution comprises wastewater.30. A method of extracting biological material from an aqueous solution, the method comprising providing a Janus particle into the aqueous solution comprising biological material, the Janus particle comprising a first surface functionalized with a functional group and a second surface functionalized with a metal particle; and removing a component of the biological material from the aqueous solution via the functional group functionalizingsurface of the Janus particle and / or via the metal particle functionalizing the second surface of the Janus particle.31. The method of embodiment 30, wherein the aqueous solution is an acidic aqueous solution.32. The method of embodiment 30 or 31 , wherein functional group of the first surface is protonated; and / or the metal particle of the second surface is protonated.33. The method of any preceding embodiment, wherein the biological material is negatively charged.34. The method of any preceding embodiment, wherein the biological material comprises DNA, RNA, viruses, or a combination thereof.35. The method of any preceding embodiment, wherein the aqueous solution comprises wastewater.36. The method of any preceding embodiment, wherein the functional group comprises an amine group, an alkylamine group, a hydroxyl group, a hydroxyalkyl group, a thiol group, an alkylthiol group, a carboxyl group, a sulfonic group, or a combination thereof.37. The method of any preceding embodiment, wherein metal particle comprises Fe, Cu, Ni, Au, Ag, Pd, Pt, Co, an oxide thereof, or a combination thereof.38. A biological material isolation kit, comprising the Janus particle of any one of embodiments 1-14, or of the Janus particle made by the method of any one of embodiments 15-17; and instructions for use thereof.39. A biological material isolation kit, comprising the Janus particle of any one of embodiments 1-14, or of the Janus particle made by the method of any one of embodiments 15-17; and instructions for using the kit in accordance with the method of any one of embodiments 30 to 37.40. The kit of any preceding embodiment, wherein the biological material comprises DNA, RNA, viruses, or a combination thereof.BRIEF DESCRIPTION OF THE FIGURES

[0004] Embodiments of the present disclosure will now be described, by way of example only, with reference to the attached Figures.

[0005] FIG. 1 depicts SEM image of: (a) Wax colloidosome after Pickering emulsion and before surface modification, (b) Layer of SiO2@NH2 particles on wax sphere before surface modification, (c) Wax colloidosome after surface modification, (d) Layer of SiO2@NH2&Fe3O4Janus particles on surface of wax sphere, (e) SiO2@NH2homogeneous particle, (f) SiO2@Fe3O4homogeneous particle, (g) SiO2@NH2&Fe3O4Janus particle.

[0006] FIG. 2 depicts (a) FTIR spectra of SiO2@NH2and SiO2@Fe3O4homogenous particles and SiO2@NH2&Fe3O4Janus particle, (b) XRD pattern of SiO2@NH2and SiO2@Fe3O4homogenous particles and SiO2@NH2&Fe3O4Janus particle, (c) Magnetization curves of SiO2@Fe3O4homogenous particle and SiO2@NH2&Fe3O4Janus particle at room temperature. Inset shows value of coercivity, (d) Zeta potential of SiO2@Fe3O4and SiO2@NH2homogeneous particles and SiO2@NH2&Fe3O4Janus particle.

[0007] FIG. 3 depicts removal efficiency of chromium and phenol using SiO2@Fe3O4and SiO2@NH2homogeneous particles and SiO2@NH2&Fe3O4Janus particle as a function of: (a, b) pH at reaction condition of [Cr(VI)]=10 ppm, [phenol]=10 ppm, [PS]= 5 mM, particle dosage=3 g / l, 25 °C, 6 hr.

[0008] FIG. 4 depicts (a) Chromium (VI) adsorption kinetics model using SiO2@NH2homogeneous particle and SiO2@NH2&Fe3O4Janus particle, (b) phenol degradation kinetics model using SiO2@Fe3O4homogeneous particle and SiO2@NH2&Fe3O4Janus particle, (c) SiO2@NH2and SiO2@Fe3O4homogeneous particles and SiO2@NH2&Fe3O4Janus particle regeneration after five cycles of chromium (VI) removal, (d) SiO2@NH2 and SiO2@Fe3O4homogeneous particles (HP) and SiO2@NH2&Fe3O4Janus particle (JP) regeneration after five cycles phenol removal. Adsorption / Degradation Condition: [Cr(VI)]=10 ppm, [phenol]=10 ppm, pH 4, [PS]= 5 mM, particle dosage=3 g / l, 25 °C.

[0009] FIG. 5 depicts (a) DNA separation efficiency of SiO2@NH2&Fe3O4Janus particles, (b) Schematic of DNA adsorption mechanism on the surface of SiO2@NH2&Fe3O4Janus particles at pH 3. (c) DNA and RNA purification using commercial beads / Janus particles at step 1 : virus enrichment and step 2: nucleic acid purification (the purification concentrations of step 1 :beads and step 2:beads for DNA was normalized to 100%). (d) SARS-CoV-2 extraction performance of SiO2@NH2&Fe3O4Janus particles at step 1 and step 2 of a commercial DNA extraction kit with three iterations (see text and Materials and Methods section).

[0010] FIG. 6 depicts comparison of SiO2@NH2&Fe3O4Janus particle (legend entry “Magnetic Janus P”) with : (a) other adsorbents for chromium (VI) removal [15-18], (b) other reported metal catalysts for phenol removal [19-22], (Co: Initial concentration of the contaminant (ppm), q: Adsorption capacity (mg / g), E: Removal efficiency (%), m: Catalyst dosage (g / l), Coxidant: Oxidant Concentration (mM))

[0011] FIG. 7 depicts procedure for SiO2@NH2&Fe3O4Janus particle fabrication.

[0012] FIG. 8 depicts removal mechanism of chromium (VI) and phenol from water.

[0013] Fig. 9. depicts removal efficiency of chromium and phenol using SiO2@Fe3O4and SiO2@NH2homogeneous particles and SiO2@NH2&Fe3O4Janus particle as a function of: (a, b) Initial concentration of contaminants at reaction condition of pH 4, [PS]= 5 mM, particle dosage=3 g / l, 25 °C, 6 hr. (c, d) Particle dosage at reaction condition of [Cr(VI)]=10 ppm, [phenol]=10 ppm, pH 4, [PS]= 5 mM, 25 °C, 6 hrDETAILED DESCRIPTION

[0014] Unless defined otherwise, all technical and scientific terms used herein have the meaning as commonly understood in the art.

[0015] As used in the specification and claims, the singular forms "a", "an" and "the" include plural references unless the context dictates otherwise.

[0016] Generally, the present disclosure describes a Janus particle, comprising a particle core, the particle core comprising at least a first surface functionalized with a functional group and a second surface functionalized with a metal particle.

[0017] Magnetic Janus particle is a class of multi-functional material which has two or more chemistries on opposite sides of the particle, combining magnetic properties with selective configurations [2,23], Distinct surface regions with different properties and magnetic responsive characteristics can offer unique multi-functionality making magnetic Janus particles an attractive candidate for various applications such as emulsion stabilization [2], sensing [3], drug delivery [4], display device [5], imaging [6] and others. However, fabrication remains a significant challenge to substitute magnetic Janus particles for conventional homogenous magnetic particles, commercially [1],

[0018] Magnetization of Janus particles is usually generated from a magnetic surface patch and / or a magnetically responsive hemisphere or a magnetic core [7-9], Emulsion polymerization [7], physical vapor deposition (PVD)

[0010] , and microfluidic dropgeneration techniques

[0011] are some common methodologies for magnetic Janus particles fabrication in any of the aforementioned configurations. The various techniques applied formagnetic Janus particles fabrication have limitations, such as extreme experimental conditions, expensive and specialized setups, and principles of the technique. These create hurdles with respect to modularity in combining different types of materials, scaling up the production, controlling the size of the particles as well as achieving the particles’ size uniformity. Therefore, new processes are required to overcome these limitations and expand more exploration and potential applications of magnetic Janus particles [11-14], The approach described herein to eliminate these issues led to development of a method by the combination of Pickering emulsion and electroless deposition techniques.

[0019] Pickering emulsion

[0024] is considered a relatively facile, flexible, scalable and viable route for Janus particles synthesis. In this technique, trapped particles at an interface of wax-water emulsion are immobilized upon liquid-to-solid wax transition. Surface modification techniques are then applied to the unshielded surface of the immobilized particles to provide a Janus particle

[0025] , This technique was recently introduced to fabricate metal Janus particles by use of a polymer backbone which can bind both the surface of support particles and metal nanoparticles. For instance, TiO2nanoparticles were self-assembled on the surface of SiO2microparticles via acrylamide to generate a Janus swimming device

[0012] , Swimming devices include various types of micro-size colloidal particles which can undergo translational, rotational and propulsion motions in a fluid, where these motions may be driven by diffusophoresis, thermophoresis, electrophoresis, magnetophoresis, etc. [26-29], However, surface modification of support particles in this method was limited by the maximum solubility of the polymer in the reaction solution and size of as-prepared metal nanoparticles. A uniform layer of metal nanoparticles was not achievable in this technique

[0012] , Similarly, platinum (Pt) was also immobilized on one face of silica microparticles via seed and growth technique after covering the other face of the microparticles in the wax spheres using Pickering emulsion. Metallic nanoparticles were attached to the surface of supporting microparticles via electrostatic adhesion. In this technique, a uniform layer of metal nanoparticles with superparamagnetic properties is not achievable due to the inherent aggregation characteristics of the particles

[0030] ,

[0020] However, to date no study has focused on incorporating electroless deposition technique to Pickering emulsion for magnetic Janus particle fabrication. The electroless technique is an easy way to grow a nano-structured metal layer on a surface. The metal oxide film is deposited on a support surface by reduction chemical reaction and forms a chemically attached shell on the surface, which has the potential to be generalized to various types and sizes particles and metal oxides [31-33], This technique was used by Bailey et. al.

[0034] to asymmetrically form a Pt cap on the surface of SiO2microparticles.However, Pickering emulsion was used for (3-Aminopropyl)triethoxysilane (APTES) polymerization of one face of the microparticles, and metal deposition was implemented on the same face, after releasing microparticles from wax spheres, subsequently

[0034] , Here, we combined the electroless deposition technique with Pickering emulsion to deposit a thin layer of iron oxide on the exposed surface of amine-functionalized silica particles via controllable and versatile reactions to generate dual-surface functionalized magnetic Janus particles.

[0021] Described herein is a synthesis technique for fabrication of dual surface functionalized amine / magnetite Janus particles via a combination of the Pickering emulsion method and electroless deposition technique. For example, as described herein, the technique of electroless deposition was coupled with Pickering emulsion to deposit a thin layer of iron oxide on an exposed surface of SiO2@NH2particles via controllable and versatile reactions (Figure 7). Focusing on simplicity and scalability for commercial production, a dual surface functionalized amine / magnetite Janus particle (SiO2@NH2&Fe3O4) was fabricated and applied to water treatment process and biological monitoring applications.

[0022] Electroless deposition is an autocatalytic process to reduce metal ions such as iron, nickel, silver, etc. on a surface covered by catalytic metals such as palladium, platinum, etc. For example, an iron oxide layer which may be formed on a catalytic layer (which remains under said iron layer), can itself be autocatalytic for a next layer of metal oxide deposition. In an example of electroless deposition mechanism as described herein was based on a mixture of iron nitrate solution and reducing agent, which were used to initiate iron oxide layer formation on the surface.Surface multi-functionality of the magnetic Janus particles was examined in targeting dual compounds removal from a Chromium (Vl)Zphenol model. Despite many studies focusing on phenol degradation and also adsorbents for chromium (VI) separation, described herein is a study in which dual surface functionality of Janus particles has been used for simultaneous removal of chromium and phenol from water. For example, described herein are advantages of using magnetic Janus particle surface functionalities in two wastewaters- related applications. Specifically, simultaneous dual compound removal from a chromium (Vl) / phenol model was targeted. Chromium (VI) with the combination of organic copollutants (e.g., phenol) usually originates from industries such as leather, wood preservation, car manufacturing, petroleum refining, and agricultural activities; and can enter groundwater source, lake, river and soil as a contaminant

[0022] , Despite many studies on phenol degradation and chromium (VI) adsorption as two separate processes

[0023] -

[0027] ,described herein is a multi-functional platform for the removal of chromium and phenol from water, simultaneously. The SiO2@NH2&Fe3O4Janus particle capability at simultaneous chromium (Vl)Zphenol removal from water was compared to amine-functionalized SiO2@NH2and magnetite-functionalized SiO2@Fe3O4homogeneous particles to distinguish the distinct functionalities of the Janus particle two faces and as a proof-of- concept for removal ability of each face.

[0023] Nucleic acids (NAs) such as deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are biomaterials underlying the storage and transfer of biological information in all biological entities. Solid-phase extraction (SPE) methods are a platform for purification and isolation of biological macromolecules such as NAs, carried out with commercial purification kits based on magnetic beads

[0035] , Described herein, synthesized amine / magnetite Janus particles were tested as an alternative for magnetic beads in NAs purification. The intrinsic functional groups present on said magnetic Janus particle tend to be suitable for NA (nucleic acid) separation from wastewaters, within a large range of pH. The Janus particles described herein with surface binding properties were used in a purified DNA model and as an alternative for commercial beads in magnetic-based kits for virus and nucleic acids purification. For example, biological monitoring solution for SARS-CoV-2 coronavirus isolation and purification from municipal wastewaters was investigated.

[0024] Herein described is an alternative manufacturing methodology integrated to functionalize the surface of SiO2particles with magnetite and amine patches (Fig. 7). Pickering emulsion was combined with electroless deposition technique to form dual surface-functionalized Janus particles. Focusing on surface dual functionality, a new type of Janus particle was fabricated that not only benefited from low density of silica and magnetic responsive characteristic, but also was designed with two functional groups on distinct parts of the surface for use in water treatment process and / or biological monitoring. The herein described Janus particles combine the possibility of contaminants adsorption and degradation via a single particle. The herein described Janus particle benefits from favourable surface chemistry for electrostatic extraction of NAs. For example, use of the herein described SiO2@NH2&Fe3O4Janus particle was successful in the simultaneous removal of chromium (VI) and phenol from aqueous solution, owing to its dual surface functionality. Furthermore, SiO2@NH2&Fe3O4Janus particle was tested for NAs separation through particle surface binding properties in a purified DNA model, to be considered as an alternative for commercial beads in magnetic-based kits for viruses and nucleic acids, in particular SARS-CoV-2 coronavirus isolation and purification from wastewater sample.

[0025] Generally, the present disclosure provides a new generation of magnetic Janus particle with two surface functionalities on opposite sides of the particle. In an example described herein, an amine / magnetite Janus particle was fabricated through combination of Pickering emulsion and electroless deposition technique. In another example, an amine / magnetite Janus particle was used for simultaneous removal of two contaminants from water and genetic material recovery from wastewater sample.

[0026] In an embodiment of the Janus particle, the core particle is a particle that - prior to functionalization with the functional group and / or metal particle - comprises nucleophilic groups on at least the first surface, at least the second surface, or the entirety of its surface. In an example, the nucleophilic group comprises a hydroxyl group.

[0027] In an embodiment of the Janus particle, the core particle comprises a size ranging between nanometers to micrometers, and may be any one size or any range of sizes between nanometers to micrometers.

[0028] In an embodiment of the Janus particle, the core particle may be a density suitable for the material it is made of, and its size.

[0029] In an embodiment of the Janus particle, the functional group is a functional group with a high affinity for transition metals and / or is a functional group that may act as a coordinating ligand for coordinating to transition metals. In an example, the transition metals comprise coinage metals or platinum group metals.

[0030] In an embodiment of the Janus particle, the metal particle may comprise a transition metal suitable for forming metal particles, an oxide of such a transition metal, a combination of one or more of such transition metals or their oxides, or a combination thereof.

[0031] In one or more examples of the present disclosure generally provides:1. A Janus particle, comprising a particle core, the particle core comprising at least a first surface functionalized with a functional group and a second surface functionalized with a metal particle.2. The Janus particle of example 1 , wherein the core comprises SiO2, TiO2, AI2O3, Fe2O3, ZrO2, SnO2, ZnO, SrTiO3, Ta2O5, or a combination thereof.3. The Janus particle of example 1 or 2, wherein the core comprises SiO2, TiO2, AI2O3, or a combination thereof.4. The Janus particle of any preceding example, wherein the core comprises SiO2.5. The Janus particle of any preceding example, wherein the functional group functionalizing the first surface comprises an amine group, an alkylamine group, a hydroxyl group, a hydroxyalkyl group, a thiol group, an alkylthiol group, a carboxyl group, a sulfonic group, or a combination thereof.6. The Janus particle of any preceding example, wherein the functional group comprises an amine group, an alkylamine group, a hydroxyl group, a hydroxyalkyl group, a thiol group, an alkylthiol group, or a combination thereof.7. The Janus particle of any preceding example, wherein the functional group comprises an amine group, an alkylamine group, or a combination thereof.8. The Janus particle of any preceding example, wherein the metal particle functionalizing the second surface comprises Fe, Cu, Ni, Au, Ag, Pd, Pt, Co, an oxide thereof, or a combination thereof.9. The Janus particle of any preceding example, wherein the metal particle functionalizing the second surface comprises Fe, Cu, Ni, an oxide thereof, or a combination thereof.10. The Janus particle of any preceding example, wherein the metal particle functionalizing the second surface comprises Fe, an oxide thereof, or a combination thereof.11 . The Janus particle of any preceding example, wherein the metal particle functionalizing the second surface is magnetic, paramagnetic, or a combination thereof.12. The Janus particle of any preceding example, wherein the first surface comprises about 10% to about 35%, or about 15% to about 30%, or about 20% to about 25%, or about 25% of the surface of the core particle.13. The Janus particle of any preceding example, wherein the second surface comprises about 65% to about 90%, or about 70% to about 85%, or about 75% to about 80%, or about 75% of the surface of the core particle.14. The Janus particle of any preceding example, wherein the Janus particle comprises a SiO2core and a first surface functionalized with amine groups and a second surface functionalized with FeO4magnetite particles.15. A method of forming a Janus particle, the method comprising providing a particle core surface functionalized with a functional group; preparing a Pickering emulsion, the emulsion comprising the particle core immobilized at an interface of a wax-aqueous solution emulsion; functionalizing an exposed surface of the immobilized particle core with metal particles via electroless deposition to form the Janus particle; and isolating the Janus particle, the Janus particle comprising the particle core having a surface functionalized with the functional group and a second surface functionalized with the metal particle.16. The method of example 15, wherein preparing the Pickering emulsion comprises providing a mixture comprising an aqueous solution of wax and the particle core, heating the mixture to at least the melting point of the wax, forming a melted wax-aqueous emulsion stabilized by the particle core, cooling the emulsion to at least the freezing point of the wax, and immobilizing the particle core at the interface of the wax-aqueous emulsion.17. The method of example 15 or 16, wherein functionalizing an exposed surface of the immobilized nanoparticle core with metal particles comprises forming metal particles on the surface of the particle core, or depositing metal particles on the surface of the nanoparticle core via electroless deposition.18. Use of the Janus particle of any one of examples 1-14, or of the Janus particle made by the method of any one of examples 15-17 for simultaneous removal of at least two contaminants from an aqueous solution.19. The use of example 18, wherein the contaminants comprise a heavy metal, an organic compound, or a combination thereof.20. A method of simultaneously removing at least two contaminants from an aqueous solution, the method comprising providing a Janus particle into the aqueous solution comprising the at least two contaminants, the Janus particle comprising a first surface functionalized with a functional group and a second surface functionalized with a metal particle; and removing a first contaminant from the aqueous solution via the functional group functionalizing the first surface of the Janus particle, and removing a second contaminant from the aqueous solution via the metal particle functionalizing the second surface of the Janus particle.21. The method of example 20, wherein the first contaminant comprises a heavy metal, and the second contaminant comprises an organic compound.22. The method of example 20 or 21 , wherein removing the first contaminant comprises adsorbing the contaminant with the functional group functionalizing the first surface of the Janus particle.23. The method of any preceding example, wherein removing the second contaminant comprises catalyzing degradation of the contaminant with the metal particle functionalizing the second surface of the Janus particle.24. The method of any preceding example, wherein the functional group comprises an amine group, an alkylamine group, a hydroxyl group, a hydroxyalkyl group, a thiol group, an alkylthiol group, a carboxyl group, a sulfonic group, or a combination thereof.25. The method of any preceding example, wherein metal particle comprises Fe, Cu, Ni, Au, Ag, Pd, Pt, Co, an oxide thereof, or a combination thereof.26. The method of any preceding example, wherein the heavy metal is Cr, and the organic compound comprises phenol.27. Use of the Janus particle of any one of examples 1-14, or of the Janus particle made by the method of any one of examples 15-17 for extraction of biological material from an aqueous solution.28. The use of example 27, wherein the biological material comprises DNA, RNA, viruses, or a combination thereof.29. The use of example 27 or 28, wherein the aqueous solution comprises wastewater.30. A method of extracting biological material from an aqueous solution, the method comprising providing a Janus particle into the aqueous solution comprising biological material, the Janus particle comprising a first surface functionalized with a functional group and a second surface functionalized with a metal particle; and removing a component of the biological material from the aqueous solution via the functional group functionalizing surface of the Janus particle and / or via the metal particle functionalizing the second surface of the Janus particle.31 . The method of example 30, wherein the aqueous solution is an acidic aqueous solution.32. The method of example 30 or 31 , wherein functional group of the first surface is protonated; and / or the metal particle of the second surface is protonated.33. The method of any preceding example, wherein the biological material is negatively charged.34. The method of any preceding example, wherein the biological material comprises DNA, RNA, viruses, or a combination thereof.35. The method of any preceding example, wherein the aqueous solution comprises wastewater.36. The method of any preceding example, wherein the functional group comprises an amine group, an alkylamine group, a hydroxyl group, a hydroxyalkyl group, a thiol group, an alkylthiol group, a carboxyl group, a sulfonic group, or a combination thereof.37. The method of any preceding example, wherein metal particle comprises Fe, Cu, Ni, Au, Ag, Pd, Pt, Co, an oxide thereof, or a combination thereof.38. A biological material isolation kit, comprising the Janus particle of any one of examples 1-14, or of the Janus particle made by the method of any one of examples 15- 17; and instructions for use thereof.39. A biological material isolation kit, comprising the Janus particle of any one of examples 1-14, or of the Janus particle made by the method of any one of examples 15- 17; and instructions for using the kit in accordance with the method of any one of examples 30 to 37.40. The kit of any preceding example, wherein the biological material comprises DNA, RNA, viruses, or a combination thereof.

[0032] To gain a better understanding of the invention described herein, the following examples are set forth. It should be understood that these examples are for illustrative purposes only. Therefore, they should not limit the scope of this invention in anyway.

[0033] EXAMPLES

[0034] Example 1 - Magnetic Janus Particle for Compounds Removal from Aqueous Solutions

[0035] Magnetic particles have been widely applied to many adsorption and removal processes. Nevertheless, a dual surface functionality of magnetic Janus particles has not been explored for selective multi-compound removal applications. This is due to limitations of current fabrication methodologies - such as lack of scalability, extreme experimental conditions, and the need for complex setups. It is demonstrated here that a combination of Pickering emulsion and electroless deposition techniques is an approach to fabricating magnetic Janus particles with selective dual surface chemistries. Dual surface functionalized SiO2@NH2&Fe3O4Janus particles were synthesized with this technique. Multifunctional SiO2@NH2&Fe3O4Janus particles benefit from the low density of an inorganic silica core, an amine-functionalized face, as well as an iron oxide decorated face on the opposite side of the surface. The amine-functionalized silica particle was asymmetrically surface modified with magnetite nanoparticles by embedding the silica particles within wax spheres, thereby masking a part of the surface. SiO2@NH2&Fe3O4Janus particles were tested in a chromium (Vl) / phenol model and compared to corresponding homogeneous amine (SiO2@NH2) and magnetite (SiO2@Fe3O4) surface- functionalized particles to examine magnetic Janus particle dual surface functionality in multi-compound removal process. The dual-functionalized surface of the Janus particle enabled the simultaneous removal of two components from an aqueous solution through chromium adsorption via the amine face and phenol degradation via advanced oxidation process (AOP) through the magnetite face of the particle.

[0036] SiO2@NH2&Fe3O4Janus particle was also tested for DNA separation. The results implied that SiO2@NH2&Fe3O4Janus particles can be used as an effective adsorbent for genomic DNA due to its surface functionality. SiO2@NH2&Fe3O4Janus particles also replaced commercial magnetic beads commonly used in virus and DNA / RNA purification kits. Magnetic Janus particle was validated as a potential adsorbent for negatively-charged vesicles (e.g. lipid enveloped viruses) and nucleic acids (DNA and RNA) purification, and therefore incorporated into methods aiming to purify these biomolecules from complex matrices such as wastewater.

[0037] Results & Discussion

[0038] Characterization Results

[0039] Fig. 1a-d depict paraffin wax spheres after a Pickering emulsion process. In this process, particles dispersed in water were irreversibly adsorbed at the interface of a liquid paraffin droplet at a temperature above the paraffin wax’s melting point. The adsorbed particles were immobilized after droplets solidified when the emulsion was cooled to room temperature. As shown in Fig. 1a, colloidosomes - wax microcapsules whose surfaces are composed of colloidal particles - with mean diameter of 32.7 pm were produced using a monolayer of amine-functionalized silica particles (SiO2@NH2) as a stabilizer. Silica particles show spherical structure with core diameter of 620±20 nm in Fig. 1 b. The three- phase mean contact angle between paraffin, particle and water was 115°. Considering average diameter of SiO2particles and average immersion depth of particles in paraffin wax, one fourth of particles surface area was trapped in wax and protected from subsequent steps of particle surface modification. SEM images of corresponding wax spheres after surface modification via electroless deposition, Fig. 1c and d, reveal a layer of magnetic nanoparticles was formed on the unmasked surface of particles.

[0040] Fig. 1e-g show the morphology of SiO2@NH2and SiO2@Fe3O4homogeneous particles and SiO2@NH2&Fe3O4Janus particles. In Fig. 1e, silica particles were only surface-grafted with (3-Aminopropyl) triethoxysilane (APTES). Particles still had a smooth surface after amine functionalization step. Applying electroless deposition directly to SiO2@NH2homogeneous particles yielded SiO2@Fe3O4homogeneous particles (Fig. 1f). SiO2@Fe3O4colloids were uniformly coated with magnetite nanoparticles with an average size of 25 nm, indicating core / shell structure with rough surface generated by closed-pack iron oxide nanoparticles. Fig. 1g shows a SiO2@NH2&Fe3O4Janus particle structure. One face of the particle was modified with Fe3O4nanoparticles, while the other face was untouched because of paraffin wax. Fe3O4nanoparticles distribution on Janus particles was less in some parts of the particle which may be attributed to the packed monolayer of silica particles blocking part of the surface of adjacent particles. This prevented uniform surface modification compared to homogeneous SiO2@Fe3O4particles. Acorn-like anisotropic particle with one fourth amine-functionalized dome and three-fourths Fe3O4dome was in agreement with visualized average particles penetration depth in wax sphere during Pickering emulsion (Fig. 1 b).

[0041] Surface functional groups of SiO2@NH2and SiO2@Fe3O4homogenous particles and SiO2@NH2&Fe3O4Janus particle were analyzed via FTIR spectra presented in Fig. 2a. The strong peaks at 800 cnr1and 1050 cnr1corresponded to Si-O-Si and Si- OH, respectively and appeared in all three samples

[0036] , Two smooth absorption peaks at 1630 cnr1and 3400 cnr1were related to amine groups in SiO2@NH2and SiO2@Fe3O4homogenous particles and the SiO2@NH2&Fe3O4Janus particle. These two peaks overlapped with the peak corresponding to the hydroxyl groups which exist in all three samples [37-39], In FTIR spectra of SiO2@Fe3O4homogeneous particle and SiO2@NH2&Fe3O4Janus particle, a strong peak was observed in the adsorption band around 570 and 630 cm1. This peak was related to Fe3O4nanoparticles, which appeared at 576 cm1due to the Fe-0 bond of iron-oxide [40,41],

[0042] XRD patterns of SiO2@Fe3O4and SiO2@NH2homogeneous particles and SiO2@NH2&Fe3O4Janus particle are shown in Fig. 2b. X-ray diffraction was used to identify the crystalline network of iron oxide nanoparticles attached to the surface of the silica particle in SiO2@Fe3O4homogeneous and SiO2@NH2&Fe3O4Janus particles. XRD pattern of the SiO2@NH2homogeneous particle suggested the amorphous phase of the SiO2particle from the presence of a sharp 29 peak at 23°

[0042] , A similar peak existed in SiO2@Fe3O4homogeneous and SiO2@NH2&Fe3O4Janus particles patterns with less intensity, which was attributed to the SiO2core of particles. However, this peak was sharper in SiO2@NH2&Fe3O4Janus particle comparing to SiO2@Fe3O4homogeneous particle due to nonmagnetic patch of the particle. It was also evident that broad diffraction peaks at 29 values of 30.32°, 35.70°, 43.32°, 53.68°, 57.35°, 63.01 °, 71.54° and 74.61 ° in SiO2@Fe3O4homogeneous and SiO2@NH2&Fe3O4Janus particles could be assigned to the (2 2 0), (3 1 1), (4 0 0), (4 2 2), (5 1 1), (4 4 0), (6 2 0) and (5 3 3) planes of magnetite Fe3O4(JCPDS card no. 19-0629) [43,44], The XRD-based crystalline size of magnetite nanoparticles was 20 and 23 nm for SiO2@Fe3O4homogeneous and SiO2@NH2&Fe3O4Janus particles, respectively. The result was in agreement with iron oxide size approximation obtained from SEM images analysis.

[0043] The magnetization responsiveness originated from Fe3O4nanoparticles assembly on the surface of silica particles in SiO2@Fe3O4homogeneous particle and SiO2@NH2&Fe3O4Janus particle was analyzed by maximum saturation magnetization measurements through room-temperature hysteresis loop for both types of particles. As shown in Fig. 2c, the saturation magnetization of SiO2@Fe3O4homogeneous particle and SiO2@NH2&Fe3O4Janus particle was 23.1 emu g1and 5.8 emu g1, respectively. Although 75% of the SiO2@NH2&Fe3O4Janus particle surface was modified with the magnetite layer from Fig, 1 g, the saturation magnetization of SiO2@Fe3O4homogeneous particles is about four times more than Janus particles. This can be attributed to differences in the surface coverage of both particles with magnetite nanoparticles. As can be seen in Fig. 1f, the surface coverage of homogeneous particles is significantly higher than Janus particles. In addition, the iron oxide nanoparticles formed multi-layers at some locations in the case ofthe SiO2@Fe3O4homogeneous particles. As shown in the inset graph, the coercivity in both particles was -30 Oe, which was very close to zero and indicated that both SiO2@NH2&Fe3O4Janus and SiO2@Fe3O4homogeneous magnetic particles had superparamagnetic properties. Saturation magnetization of the SiO2@NH2&Fe3O4Janus particle was similar to the values reported for other Janus-type particles. For example, the maximum saturation magnetization of Fe3O4@PS / PGMA magnetic Janus particle, which was synthesized by ternary phase separation of PS (polystyrene), PGMA (poly(glycidyl methacrylate) and Fe3O4NPs was measured at 3.47 emu g1

[0045] , Saturation magnetization of polymeric-based magnetic Janus particle which was produced via microfluidic synthesis technique was 1.2 emu g1

[0046] , Magnetization properties are generally due to the metal component of a particle. As such, surface properties can be set aside when comparing saturation magnetization of different particles, as differences in surface properties between particles does not impact saturation magnetization analysis. Therefore, comparisons of particle saturation magnetization can reasonably be made between the herein described Janus particles and previously reported magnetic Janus particles.

[0044] Zeta potential is an important parameter for applications which are based on surface charge properties of particles. In Fig. 2d, zeta potential of SiO2@Fe3O4and SiO2@NH2homogeneous particles and SiO2@NH2&Fe3O4Janus particle was measured at pH range varied between 3 to 12 at room temperature. Zeta potential of SiO2@NH2homogeneous particle changed from 72 mV to -70 mV when pH increased from acidic to basic ranges. Terminal amine groups attached to the surface of SiO2@NH2particle are protonated and form -NHt at acidic pH. Isoelectric point (IEP) of SiO2@NH2homogeneous particle was around pH 9. The zeta potential curve for synthesized SiO2@Fe3O4particle suggested that surface charge of particles was positive in acidic pH and changed to negative at IEP equal to 4. Surface functional group on SiO2@Fe3O4particle were protonated and generated FeOH^ which was responsible for positive surface charge of particles at acidic pH. This was also in fair agreement with the IEP values available in literature for similar particles

[0047] , The IEP value for SiO2@NH2&Fe3O4Janus particle was shifted to pH 6. In acidic pH, due to high density of H+, two sides of the particle generated -NH and FeOH which contributed to positive charge of particle.

[0045] Contaminant Removal Results

[0046] SiO2@NH2and SiO2@Fe3O4homogeneous particles andSiO2@NH2&Fe3O4Janus particle were tested for simultaneous removal of phenol and chromium (VI) from aqueous solution through two different mechanisms. Chromium (VI) separation from aqueous solution is pH sensitive adsorption process due to electrostaticattraction and repulsion of chromium ions on charged surface at acidic and basic pH

[0048] , SiO2@NH2homogeneous and SiO2@NH2&Fe3O4Janus particles were used to adsorb Cr (VI) from water taking advantage of their amine-functionalized total and partial modified- surfaces, respectively. Removal efficiency and adsorption capacity were affected by surface charge of adsorbent and the degree of ionization of the chromium (VI), which depended strongly on pH.

[0047] Phenol as an organic pollutant was degraded and mineralized by advance oxidation process (AOP). In this technique for heterogeneous reduction of pollutants, magnetite was used and recommended as a catalyst for activation of PS (persulfate) as the oxidant

[0019] , Herein, SiO2@Fe3O4homogeneous and SiO2@NH2&Fe3O4magnetic Janus particles were used as catalyst for degradation of phenol due to immobilized magnetite nanoparticles on their surfaces. However, the Pd nanoparticles which were immobilized on the surface of SiO2@Fe3O4homogeneous and SiO2@NH2&Fe3O4Janus particles may also contribute to phenol degradation as a catalyst to some extent

[0049] , Without wishing to be bound by theory, Eq. 1 to Eq. 8 outline a possible mechanism of phenol degradation with iron oxide attached to the surface of particles. Persulfate is activated by of Fe2+through Eq. 1 and Eq. 2 and produces strong oxidizing S04“ • andOH’ radicals

[0050] ,S20 - + Fe2+-> SCJ-' + SO - + Fe3+Eq. (1)OH’ + Phenol -> H2O + Production Eq. (7)S04’ + Phenol -> H2O + S04~ + H++ Production Eq. (8)

[0048] Phenol molecules react with S04’ and OH’ radicals (Eq. 7 and 8) and break into smaller molecules through chain reactions and form degradation production [51-54], Therefore, as shown in Fig. 8, simultaneous removal of chromium (VI) and phenol from aqueous solution occurs via two different mechanisms on two opposite sides of SiO2@NH2&Fe3O4Janus particle.

[0049] pH Effect

[0050] Fig. 3a, b shows removal efficiency of chromium and phenol as pH range varied between 3 to 7. Performance of SiO2@Fe3O4and SiO2@NH2homogeneous particles and SiO2@NH2&Fe3O4Janus particle for chromium adsorption was shown in Fig.3a. pH plays an important role in adsorption of chromium (VI). Dichromate (Cr2O72~) is the major chemical species of chromium (VI) at acidic pH range (0.7<pH<6.5) [55,56], The result showed minimum chromium separation was obtained in SiO2@Fe3O4sample which was 30 % at pH 3, and decreased gradually as pH rose to 7. The higher removal efficiency of SiO2@Fe3O4particles at pH 3 was attributed to the relative positive surface charge of magnetite (FeOH2+) at pH 3, generating electrostatic attraction force with negative-charged Cr2072~ ions. At the isoelectric point of SiO2@Fe3O4particle (pH 4), overall net charge of the SiO2@Fe3O4particles was neutral and electrostatic attraction between chromium ions and particles surface was minimized. Maximum chromium separation was obtained by SiO2@NH2homogeneous particles (98%). At acidic pH, amine functional groups on the surface of SiO2@NH2particle are protonated and Cr2072~ ions adsorption to -NH2is facilitated through electrostatic attractions. However, chromium separation first decreased slightly as pH rose from 3 to 4, and then dropped significantly as pH exceeded 4. When pH increased, amine groups were deprotonated gradually and less amount of Cr2072~ ions were adsorbed to the surface of SiO2@NH2particles. Given that isoelectric point of SiO2@NH2particles was at pH 9, it was expected that at alkaline pH, chromium separation would reach the minimum values due to anion repulsion. Removal efficiency of SiO2@NH2&Fe3O4Janus particle was also maximum (81%) at pH 3 due to its inherent positive surface charge at acidic pH. As pH reached the isoelectric point of SiO2@NH2&Fe3O4Janus particle (pH 6.2), both sides of the particle were deprotonated and removal efficiency decreased consequently due to electrostatic repulsion between particle surface and chromium ions. Although pH 3 was beneficial for chromium adsorption, it was decided to go forward with pH 4 in order to minimize Cr2072~ ions adsorption on magnetite side of the SiO2@NH2&Fe3O4Janus particle considering magnetite is neutral at pH 4 based on its isoelectric point.

[0051] Fig. 3b shows phenol degradation efficiency in contact with SiO2@Fe3O4and SiO2@NH2homogeneous particles and SiO2@NH2&Fe3O4Janus particle at pH range between 3 to 7. Without a metal catalyst on the SiO2@NH2particle, less than 8% of phenol was degraded by PS after 60 min, suggesting that free radicals were not formed without transition metal Fe2+as catalyst. The results of phenol degradation indicated phenol removal was almost 100% within SiO2@Fe3O4and SiO2@NH2&Fe3O4Janus system at pH 3, whereas degradation efficiency decreased to 70% and 50% when pH increased to 7. This was attributed to repulsive electrostatic force generated between PS (F20 “) and particles’ negative surface charge at high pH, which was avoiding activation of PS in contact with the catalyst

[0050] , Furthermore, despite SO^' being a dominant species in acidicenvironment, OH’ was considered to be a major active group in the aqueous solution at alkaline pH due to the reaction presented at Eq. 9. Therefore, excess amount of OH’ radicals may scavenge SO^’ through Eq. 10, and reduce phenol degradation in alkaline condition

[0019] ,

[0052] Phenol and chromium (VI) removal process via SiO2@Fe3O4and SiO2@NH2homogeneous particles and SiO2@NH2&Fe3O4Janus particle was further optimized considering effect of the initial concentration of pollutants and particle dosage and results are shown in Fig. 9a, b and Fig. 9 c,d.

[0053] Concentration Effect

[0054] At Fig. 9a, b, the removal performance of SiO2@Fe3O4and SiO2@NH2homogeneous particles and SiO2@NH2&Fe3O4Janus particle was tested at different concentrations of chromium (VI) and phenol. Fig. 9a shows chromium adsorption efficiency on the surface of particles at 10 ppm, 20 ppm, 50 ppm and 100 ppm initial concentration of chromium (VI). Maximum adsorption efficiency was obtained at 10 ppm initial concentration of chromium (VI) with all three types of particles. As initial concentration of chromium increased from 10 ppm to 100 ppm, removal efficiency of SiO2@NH2particle and SiO2@NH2&Fe3O4Janus particle dropped from 95% to 66% and 75% to 30%, respectively. This was attributed to limited amine adsorption sites of particles which were saturated with chromium ions and at higher initial concentration, excess amount of chromium ions remained in the solution. Lower adsorption efficiency of SiO2@NH2&Fe3O4Janus particle comparing to SiO2@NH2particle was due to dual surface functionality of Janus particle. At constant dose of adsorbent, SiO2@NH2particle provided more amine adsorption sites compared to SiO2@NH2&Fe3O4Janus particle. Adsorption efficiency of SiO2@Fe3O4particles was not significant at 10 ppm chromium initial concentration, nevertheless it decreased to zero at higher chromium initial concentration. This slight change in adsorption efficiency of SiO2@Fe3O4particles with initial chromium concentration indicated that still limited positive-charge ( eOH2+) sites existed on the surface of particles at pH 4, which were saturated at low concentration of chromium and adsorption efficiency decreased with increase of initial adsorbate concentration, as a consequence.

[0055] Phenol degradation efficiency of SiO2@Fe3O4and SiO2@NH2homogeneous particles and SiO2@NH2&Fe3O4Janus particle were also tested at different initial concentration of phenol varying from 10 ppm to 100 ppm. As shown in Fig. 9b, almost 100% removal was observed at 10 ppm to 50 ppm initial concentrations of phenol in bothSiO2@Fe3O4and SiO2@NH2&Fe3O4systems. However, degradation removal efficiency of SiO2@Fe3O4homogenous particle decreased to 75% as initial concentration of phenol increased from 50 ppm to 100 ppm. Similarly, SiO2@NH2&Fe3O4Janus particle degradation performance decreased to 42% as the concentration increased to 100 ppm. At constant concentration of peroxide, produced oxidizing S04’ radicals would be constant and with increase of initial concentration of phenol, S04’ radicals are consumed and phenol degradation efficiency is reduced.

[0056] Particle Dosage

[0057] The removal efficiency of phenol and chromium at various dosages of particles ranging from 3 g / l to 15 g / l was investigated. The effect of SiO2@Fe3O4and SiO2@NH2homogeneous particles and SiO2@NH2&Fe3O4Janus particle dosage on chromium (VI) adsorption is shown in Fig. 9c, d. Among the three types of particles, removal efficiency of chromium (VI) remained unchanged (98%) when SiO2@NH2particle dosage increased from 3 g / l to 15 g / l. Removal efficiency of SiO2@NH2system indicated that low dosage of SiO2@NH2particle provided sufficient active site for chromium adsorption. Removal efficiency in SiO2@Fe3O4system was low at all doses of particles, however a slight increase at higher dosages of particles was attributed to increase of positive-charge ( eOH2+) sites which may have existed in pH 4. Removal efficiency of SiO2@NH2&Fe3O4Janus particle increased from 75% to 98% when particles dose increased from 3 g / l to 8 g / l and then remained constant at higher doses. At higher concentration of Janus particle more surface area with amine active sites was provided for chromium adsorption and removal efficiency increased, as a consequence.

[0058] Phenol removal efficiency at different dosages of particles is shown in Fig. 9d. The results demonstrated that phenol degradation efficiency stayed constant for all three types of particles. Both SiO2@Fe3O4homogeneous particle and SiO2@NH2&Fe3O4Janus particle were able to activate PS and produce enough S04-’ for phenol degradation at low concentration of particles. However, SiO2@NH2particle was not capable of phenol removal even at high concentration of particles.

[0059] Kinetics

[0060] Fig. 4a shows chromium adsorption and phenol degradation kinetics in three systems using SiO2@Fe3O4and SiO2@NH2homogeneous particles and SiO2@NH2&Fe3O4Janus particle. Given the low chromium and phenol removal efficiencies of SiO2@Fe3O4and SiO2@NH2systems, respectively, chromium adsorption kinetics was studied for SiO2@NH2homogeneous particle and SiO2@NH2&Fe3O4Janus particle andphenol degradation kinetics was studied for SiO2@Fe3O4homogeneous particle and SiO2@NH2&Fe3O4Janus particle.

[0061] As shown in Fig. 4a, semi-empirical Fleming adsorption kinetics model (Eq. 11) fits the chromium (VI) adsorption on both the SiO2@NH2homogeneous particle and SiO2@NH2&Fe3O4Janus particle [18,57], qt= kCotnEq. (11) where qtis adsorption capacity (mg / g), k is kinetic constant (min-1), Co is the initial concentration of sorbate (mg / l), t is time (min), and n is empirical constant. Regression coefficient R2> 0.98 and R2> 0.95 were obtained for SiO2@NH2homogeneous particle and SiO2@NH2&Fe3O4Janus particle as chromium (VI) adsorbents, respectively. In this model, rate of adsorption from medium to solid-liquid boundary was based on single pseudo mass transfer coefficient and an equilibrium was obtained between chromium (VI) ions in solution and surface of particles

[0058] , The adsorption kinetics constant (k) for SiO2@NH2and SiO2@NH2&Fe3O4systems was obtained 0.11 L. g-1.min025and 0.041 Lg Trnin041, respectively. The empirical constant (n) was obtained 0.25 and 0.41 for SiO2@NH2and SiO2@NH2&Fe3O4particles, respectively. The value of n depends on the adsorbent saturation to approach equilibrium

[0059] , SiO2@NH2&Fe3O4Janus particles with lower active sites for chromium adsorption approach equilibrium faster than SiO2@NH2homogeneous particles.

[0062] Phenol degradation kinetics with Fe3O4supported on silica in SiO2@Fe3O4and SiO2@NH2&Fe3O4systems was studied in Fig. 4b. The catalytic activity of SiO2@Fe3O4homogeneous particle and SiO2@NH2&Fe3O4Janus particle were studied through phenol degradation kinetics. Pseudo-first-order (PFO) kinetic model (Eq. 12) was employed to estimate kinetics parameter of phenol degradation reaction

[0060] ,Ct= Coe~ktEq. (12) where Ct(mg / l) and Co (mg / l) are the concentration of contaminant at time t and 0, respectively, and k is the pseudo first-order reaction rate constant (min-1). PFO kinetic model presented a high regression coefficient (R2> 0.98) for both system, indicating this model well described the systems. The reaction rate constant (k) for SiO2@Fe3O4and SiO2@NH2&Fe3O4systems was estimated 0.3 min'1and 0.22 min1, respectively. Thus, both particles exhibited superior catalytic performance for persulfate activation. However, degradation rate of phenol via SiO2@Fe3O4was higher than SiO2@NH2&Fe3O4. This may be attributed to higher SiO2@Fe3O4surface coverage with magnetite nanoparticles which provides more catalytic active site for PS activation.

[0063] Regeneration and Durability

[0064] Reusability and durability of SiO2@Fe3O4and SiO2@NH2homogeneous particles and SiO2@NH2&Fe3O4Janus particle at simultaneous removal of phenol and chromium (VI) was tested through five consecutive cycles of removal / regeneration. Between each cycle, particles were dispersed in NaOH (0.01 M), separated and redispersed in deionized water and washed twice, and then applied to the next cycle. Chromium and phenol concentration was measured after each removal / regeneration cycle and removal efficiencies are shown in Fig 4c, d. The efficiency of chromium removal after five cycles was still around 80% and 60% via SiO2@NH2homogeneous particle and SiO2@NH2&Fe3O4Janus particle, respectively (Fig. 4c). Reduction in chromium removal after the five cycles was considered due to incomplete desorption of chromium (VI) ions from amine functional groups in 0.01 M NaOH. Using larger NaOH solution concentration would desorb more chromium (VI), but would also leach e2+from the particles surface. In alkaline solution, OH~ neutralized H+from -NHt and increases the number of negatively charged functional groups of the surface. In the alkaline environment, CrO42~ is also the major chemical species of chromium in the solution. Therefore, NaOH solution can be used as an eluent to generate electrostatic repulsion between the surface of the particles and chromium ions and desorb the chromium ions from the surface of the particles [61-63], The degradation efficiency of phenol in both SiO2@Fe3O4and SiO2@NH2&Fe3O4systems remained constant (100%) in all five cycles (Fig. 4d). This indicated that the exposure to NaOH solution did not leach appreciable Fe2+from the particles. Thus both SiO2@Fe3O4and SiO2@NH2&Fe3O4have reusability as the catalyst for phenol degradation.

[0065] DNA Separation

[0066] Adsorption properties of SiO2@NH2&Fe3O4Janus particle were investigated using DNA as a nucleic acid model.

[0067] Adsorption efficiency at 5 ng / pl initial concentration of DNA solution at several values of pH are shown in Fig. 5a. Removal efficiency increased with the presence of the particles, indicating that the SiO2@NH2&Fe3O4Janus particle had potential for DNA purification. Removal efficiency was above 99% at pH 3 and reduced to 25% as pH increased to 7.5.

[0068] Fig. 5b demonstrates the mechanism of DNA detection and separation, and bindings with functional groups at the surface of SiO2@NH2&Fe3O4Janus particles. Electrostatic interaction between positive charged functional groups on the surface of particles and highly negative charged DNA molecules are considered to be responsible for nucleic acid separation [63,64], At acidic pH 3, the positively charged groups of -NHt couple with NA molecules in the solution via electrostatic interaction. FeOH^ positive's -charged sites of the magnetite side also contribute to adsorption (Fig. 2d) at pH 3. As pH increase to 4, the magnetite side of the particle is almost neutral, while amine side is still positive. At higher pH up to 7.5, OH~ neutralizes H+, and the number of negatively charged functional groups of the surface increases. Repulsive force between DNA molecules and negative sites of the particle surface reduces separation efficiency.

[0069] The SiO2@NH2&Fe3O4Janus particle capability for the separation of a lipid- enveloped virus as well as NA (DNA and RNA) was also validated within a complex sample such as wastewater. The SiO2@NH2&Fe3O4Janus particles were used to replace commercial magnetic beads in an extraction kit, either in the virus enrichment step (where the particles bind to negatively charged molecules or vesicles such as viruses) or in the nucleic acid purification step. The results were then compared to the control system in which commercial beads were used in both steps. As shown in Fig. 5c, DNA recovery obtained using SiO2@NH2&Fe3O4Janus particles in either step 1 or 2 was lower than commercial beads while RNA recovery using SiO2@NH2&Fe3O4Janus particles in step 1 or step 2 was higher than the values obtained in the control system. This result demonstrates that, overall, the SiO2@NH2&Fe3O4Janus particles performed as well as commercial beads in nucleic acid recovery in both steps.

[0070] The recovered nucleic acids were then tested for SARS-CoV-2 RNA concentration, and the results are shown in Fig. 5d. When the SiO2@NH2&Fe3O4Janus particles were replaced for the virus enrichment (stepl), a modest recovery of SARS-CoV-2 RNA was obtained as compared with the commercial beads in step 1 , suggesting the potential of Janus particles for this application. When Janus particles were compared to 1 pm commercial beads with optimized silica-like surface chemistry and high specific surface area to capture NA in step 2, the SiO2@NH2&Fe3O4Janus particles performed as well as the commercial beads to recover SARS-CoV-2 RNA.

[0071]

[0072] Recovered nucleic acid was then tested for SARS-CoV-2 RNA concentration and results are shown in Fig. 5b. When the SiO2@NH2&Fe3O4Janus particle was replaced for the virus enrichment particle, a modest recovery of SARS-CoV-2 RNA was obtained as compared with the commercial beads in step 1 , suggesting the potential of Janus particle for this application. When Janus particle was compared to 1 pmcommercial Dynabeads™ MyOne™ SILANE bead with optimized silica-like surface chemistry and high specific surface area to capture NA in step 2, the SiO2@NH2&Fe3O4performed as well as the commercial beads to recover SARS-CoV-2 RNA.

[0073] General Discussion of Herein Described Fabrication Method

[0074] SiO2@NH2&Fe3O4 Janus particle was synthesized via a combination of Pickering emulsion with phase change (liquid droplets solidify) and electroless deposition technique. Compared to physical vapour deposition (PVD), which is a common approach for magnetic Janus particles fabrication, the herein described Pickering emulsion method tends not to require extreme experimental conditions, such as vacuum or specific gas atmosphere. In addition, surface modification of Janus particles in Pickering emulsion occurs in the bulk of solution, unlike PVD which requires a monolayer of particles. Therefore, Janus particle synthesis via Pickering emulsion may be a scalable and simple methodology which may be applicable to large-quantity production of Janus particles

[0010] , Janus particle size can be determined by selecting an appropriate core particle in the Pickering emulsion route, while particle size is an outcome of the fabrication in some common Janus particle fabrication techniques, such as microfluidic

[0011] , Furthermore, Pickering emulsion in combination with various surface modification methods can broaden the material range that can be used to build Janus particles with multi-functionality, while in some Janus particle synthesizing methods, such as emulsion polymerization and microfluidic, at least one part of particle needs to be made of polymeric materials. Pickering emulsion tends to be a simple technique that does not require any complex setup such as microfluidic channels or evaporator system [7,14],

[0075] Electroless deposition technique was chosen for surface modification of particles with magnetic material following the Pickering emulsion step. Compared to direct self-assembly of as-prepared metal nanoparticles on surface of support particles via polymer chains

[0065] , herein, wax spheres were immersed in solution of metal salt and reducing agent. Therefore, it may be applied to different types of metal and various nanorange core particles. Moreover, surface chemistry of particles may be controlled or tuned by reaction time and salt concentration manipulation. Further, an almost uniform layer of metal can be attached on the surface of particles via electroless deposition technique. It is more difficult to reach a uniform magnetic shell with direct as-prepared metal nanoparticles self-assembly on the surface because of the inherent metal particles properties such as high-density and magnetization, which result in particles aggregation and settlement during synthesizing

[0065] ,

[0076] In previous studies on water treatment process with colloidal particles, only one compound removal at a time was targeted. Herein, advanced morphology of Janus particles coupled with responsive materials such as metal oxides allowed for multiple components simultaneous removal from aqueous solution. SiO2@NH2&Fe3O4Janus particle was a great catalyst for phenol degradation via AOP mechanism and an effective adsorbent of chromium ions via adsorption technique; both processes occur simultaneously within water being treated. SiO2@NH2&Fe3O4Janus particle applicability was compared with previously reported catalysts and adsorbents in Table 1 and 2; and Fig. 6.

[0077] Chromium (VI) adsorption has been studied with different types of surface functionalized particles. In literature studies of Cr absorption, maximum adsorption efficiency could be achieved at acidic pH, which is in agreement with the results obtained and described herein. Chromium (VI) adsorption capacity and removal efficiency of select nano-absorbents with various surface modification at similar initial concentration of contaminant is summarized in Table 1 below, and Fig. 6a, and compared with the Janus particles described herein. Given that one fourth of the SiO2@NH2&Fe3O4Janus particles described herein were covered with chromium adsorbent, not only it was found that the Janus particle showed good potential for chromium (VI) removal from aqueous solution compared to other adsorbents, but it was also found that the adsorption capacity ofSiO2@NH2&Fe3O4Janus particle was in good agreement with the values reported for other amine functionalized adsorbents, as demonstrated in Table 1 , and Fig. 6a.

[0078] Table. 1. Comparison of other adsorbents for chromium (VI) removal withSiO2@NH2&Fe3O4Janus particle.Adsorption Capacity RemovalAdsorbent (mg / g) Efficiency (%)Manganese Ferrite (MnFe2O4) 0.4 67Bismuth Activated Carbons 2.5 50

[0016] Activated Carbon 2.5 100

[0017] Catecholamine Coated 10 97

[0018] Maghemite NPThisSiO2@NH2&Fe3O4JP 1.2Study

[0079] Similarly, studies of catalytic degradation of phenol via various systems made of metal oxide nanoparticles or metal compounds-coated supports was also considered relative to the herein described Janus particle. Maximum degradation efficiency was compared and summarized in Table 2, and Fig. 6b. In comparison to various metal catalysts, as well as other magnetite-based catalysts used for phenol degradation via AOP, it was found that the SiO2@NH2&Fe3O4Janus particle exhibited a great efficiency forphenol removal from aqueous solution, as shown in Table 2. This therefore indicates that SiO2@NH2&Fe3O4is a multi-functional platform capable of removing chromium (VI) and phenol from aqueous solution, simultaneously.

[0080] Table. 2. Comparison of other reported metal catalysts for phenol removal with SiO2@NH2&Fe3O4Janus particle. . x x- Removal „ *Catalyst Concentrations Ref.Efficiency (%)[phenol] = 25 ppm Mn2O3- truncated Crystal [Catalyst] = 0.4 g / l 50

[0020] [Oxidant] = 2 g / l[phenol] = 10 pM rGO-Ag0 / Fe3O4nanohybrid [Catalyst] = 0.1 g / l 45

[0019] [Oxidant] = 1 mM[phenol] = 25 ppm Nanostructured CeVO4[Catalyst] = 1 g / l 100

[0021] [Oxidant] = 6 mM[phenol] = 20 ppm FesO GO Nanocomposite [Catalyst] = 1 g / l 80

[0022] [Oxidant] = 10 mM[phenol] = 20 ppmSiO2@NH2&Fe3O4JP [Catalyst] = 3 g / l 100[Oxidant] = 5 mM

[0081] Therefore, despite the lower chromium removal efficiency and adsorption capacity of the SiO2@NH2&Fe3O4Janus particles compared to SiO2@NH2homogeneous particles, SiO2@NH2&Fe3O4Janus particles are a new multifunctional platform capable of simultaneously removing of chromium (VI) and phenol from aqueous solution. In addition, SiO2@NH2&Fe3O4Janus particles also benefit from magnetic responsiveness. One of the challenges of the colloidal particles in water treatment is their removal from water at the end of the process. In the case of using the mixture of both homogeneous particles (SiO2@NH2and SiO2@Fe3O4) in this application, further arrangements are required to collect the SiO2@NH2particles from water. However, the magnetic properties of SiO2@NH2&Fe3O4Janus particles are considered a potential solution for collecting the particles in wastewater treatment applications. Therefore, in wastewater treatment applications with multiple contaminants, Janus particles are a more advantageous design for selective multi-compound removal.

[0082] DNA adsorption efficiency of SiO2@NH2&Fe3O4Janus particle was compared with other magnetic particles surface-modified with different functional groups,as summarized in Table 3. In comparison with other magnetic particles, SiO2@NH2&Fe3O4Janus particle demonstrated high DNA separation efficiency.

[0083] Table. 3. Adsorption efficiency of SiO2@NH2&Fe3O4Janus particle in comparison with other reported magnetic beads used for DNA separation.Adsorbent Removal Efficiency (%) Ref.PDA@Fe3O4composite 90

[0066] Magnetic PGMA microspheres 91

[0067] Multi-amino group modified MNPs 80

[0068] SiO2@NH2&Fe3O4JP 99 This Study

[0084] Commercial magnetic-based kits for viruses and nucleic acids purification tend to be sensitive to conditions such as viral concentration in the sample, and experience high-cost of the magnetic beads, and large-scale laboratory infrastructures. These limitations, as well as demand for supply chain are barriers for more research development. Therefore, magnetic particles that can be fabricated via a simple and fast approach is in demand to separate biomolecules with high yield and purity [69-71], Pickering emulsion / electroless deposition can be a cheap and simple experimental methodology for magnetic Janus particle fabrication. Further, the herein described SiO2@NH2&Fe3O4Janus particle may be a tool for quantitative purification and recovery of chemical and biological signatures from complex systems, such as wastewater. SiO2@NH2&Fe3O4Janus particles appear to perform as well as commercial magnetic beads in a simple experimental setup for virus and nucleic acid purification from wastewater systems due to its surface functionality and magnetic property.

[0085] Non-binding Conclusions

[0086] Described herein are multifunctional magnetic Janus particles with superparamagnetic properties fabricated via Pickering emulsion followed by electroless deposition technique. Superparamagnetism is a form of magnetism which can appear in small ferromagnetic or ferrimagnetic nanoparticles. Through this property, particles may be more easily recovered and collected from the effluent, such as wastewater, via application of an external magnetic field. In this process, a part of the particles were masked in the wax spheres, while the uncovered part was surface-modified with metal oxide nanoparticles. SiO2@NH2&Fe3O4magnetic Janus particle was used for simultaneous removal of chromium (VI) and phenol from aqueous solution, and the dual surface functionality of the particle was tested in comparison with SiO2@Fe3O4and SiO2@NH2homogeneous particles. The herein described SiO2@NH2&Fe3O4Janus particle offered an amine face and a magnetite face. In the described multi-compound removal processes, chromium (VI)adsorption took place on the amine face of the particle and phenol degradation occurred due to catalytic face (magnetite) of the particle. At 10 ppm concentration of both contaminants, SiO2@NH2&Fe3O4Janus particle was able to remove 75% of chromium (VI) and 100% of phenol. Although SiO2@Fe3O4particles exhibited higher degradation efficiency at high concentrations of phenol compared to the SiO2@NH2&Fe3O4Janus particle, chromium (VI) removal efficiency remained low in this system. Similarly, SiO2@NH2particle exhibited higher chromium (VI) adsorption efficiency compared to the SiO2@NH2&Fe3O4Janus particle at all concentrations of chromium (VI). However, phenol degradation in this system was almost zero. SiO2@NH2&Fe3O4Janus particle was also tested for DNA and RNA separation. The results showed that up to 99% of DNA was removed from solution in acidic pH. Results also showed that when Janus particle was used in lieu of commercial beads to purify NA from a complex matrix (e.g. Wastewater), and in particular the RNA of the SARS-CoV-2 coronavirus that caused the COVID-19 global pandemic, the SiO2@NH2&Fe3O4Janus particle performance was equal, highlighting the application of this particle for wastewater-based surveillance.

[0087] Also reported herein is a scalable and tunable approach for fabrication of multifunctional magnetic Janus particles with superparamagnetic properties, which may have potential in wastewater related applications. A Pickering emulsion with droplet phase change followed by electroless deposition was used to generate and attach metal nanoparticles to the surface of amine-functionalized silica colloids. This protocol may offer a flexible platform that may open a processing route for scalable fabrication of a wide range of metal oxide nanoparticles on the surface of various types of supporting particles. Herein, SiO2@NH2&Fe3O4Janus particles were successfully synthesized implementing this protocol with trapping amine-functionalized silica particles in wax sphere and initiating iron oxide electroless deposition reaction on the unshielded face of the particles. It was shown that selective multi-functional surface of magnetic Janus particles potentially can be used for removal of two or more components from aqueous solution. Therefore, dual surface functionality of fabricated magnetic Janus particles was tested in a water sample with mixture of phenol and chromium (VI). Magnetic Janus particles performed well in adsorption of chromium on their amine face and degradation of phenol on their magnetite face. SiO2@NH2&Fe3O4Janus particle was also tested as a replacement for expensive magnetic beads used in DNA and RNA separation from water model with pure DNA as well as real wastewater sample. Results showed that the SiO2@NH2&Fe3O4Janus particle performance was equal to commercial magnetic beads, highlighting the application of this particle for wastewater-based surveillance.

[0088] Materials and Method

[0089] SiO2@NH2was fabricated by grafting APTES on the surface of silica particles and SiO2@Fe3O4core / shell was fabricated via electroless deposition technique. SiO2@NH2&Fe3O4Janus particle was also synthesized via a combination of Pickering emulsion to make Janus particles, and electroless deposition technique to modify a patch of particle surface. Silica was selected as the body material of SiO2@NH2and SiO2@Fe3O4homogeneous particles and SiO2@NH2&Fe3O4Janus particle due to flexibility of fabrication method in size and monodispersity of particles. Low-density of the silica support with robust attached magnetite nanoparticles is also very useful in the development of suspensionbased applications compared to conventional homogeneous magnetite-made particles.

[0090] Materials

[0091] Absolute ethanol (99%), methanol (99%), tetraethyl orthosilicate (TEOS),(3-Ami nopropyl) triethoxysilane (APTES), sodium tetrachloropalladate (II) (Na2PdCI4), sodium chloride (NaCI), dimethylamine borane (DMAB), iron (III) nitrate (Fe(NO3)3, paraffin wax of mp>65°, dichloromethane (CH2CI2) 99%, potassium persulfate (K2S2O8), phenol (C6H5OH), potassium dichromate (K2Cr2O7), sodium hydroxide (NaOH), sodium acetate (C2H3NaO2), acetic acid (CH3COOH), HEPES (C8H18N2O4S) and hydrochloric acid (HCI) were purchased from Sigma Aldrich. Ammonia solution (NH4OH) 28-30%, and MES (C6HI3NO4S) buffer solution (1 .0 M) at pH 5 and pH 6 were purchased from fisher scientific. All chemical reagents in this work were of analytical grade and used without further purification.

[0092] Particles Preparation

[0093] SIO2Particle

[0094] Silica particle was used as the support core for SiO2@NH2and SiO2@Fe3O4homogeneous particles and SiO2@NH2&Fe3O4Janus particle production. Stober technique is an ammonia-catalyzed hydrolysis-condensation technique

[0072] which was implemented herein for uniform and monodisperse silica particle fabrication. In this process, 8 ml TEOS was added dropwise to the reaction beaker containing solution of 200 ml ethanol, 16 ml water, and 12 ml ammonia solution, while the solution was stirred at room temperature. The mixture was further aged for 24 hr. Relative monodispersed silica particles were formed after 24 hr. Silica particles were collected by centrifugation and washed with ethanol three times and dried in the oven at 80 °C over night and stored for further use.

[0095] SiO2-NH2Homogeneous Particle (SIO2-NH2)

[0096] The amine functionalized particles were prepared via hydrolysis and polymerization of APTES on the surface of silica particle. Silica particles were dispersedwithin 0.1 M solution of APTES following previously published protocol

[0073] , Silica particles were added to methanol first and sonicated for 3 min to ensure particles are well-dispersed in the methanol. APTES was then added dropwise to the suspension and left on stirrer over night at room temperature. Suspension of surface-functionalized silica particle was centrifuged and particles were redispersed in methanol three times to remove excess unattached polymers. Modified particles were dried in the oven over night and stored for further use.

[0097] SIO2@Fe3O4Homogeneous Particle (SiO2@Fe3O4)

[0098] SiO2@Fe3O4particle was synthesized via previously published protocol

[0074] , Briefly, catalyst solution was prepared by dissolving 12 mg NaPdCI4in solution of NaCI (1 M) and 10 ml MES buffer (0.1 M) at pH 5 and left for 20 hr to form palladium oligomers. SiO2-NH2particles were then dispersed in the catalyst solution and palladium oligomers were attached to the surface of particles under vigorous agitation. Particles were centrifuged and washed three times in water and dried in oven. Catalyzed-particles were then dispersed in mixture of 0.01 M hydrated iron (III) nitrate and 0.03 M dimethylamineborane at 40 °C and SiO2@Fe3O4particles were collected by applying a permanent magnet after 2 hr. Modified particles were washed several times with deionized water and dried in oven over night and stored for further use.

[0099] SIO2@NH2&Fe3O4Janus Particle (SIO2@NH2&Fe3O4)

[0100] SiO2@NH2&Fe3O4Janus particle was synthesized via a combination of Pickering emulsion technique and electroless deposition. Pickering emulsion was prepared following previous protocols

[0075] , SiO2-NH2particles were well dispersed in 50 ml deionized water using ultrasonic vibration for 3 min. 2 g of paraffin wax was then added to the suspension and the mixture was heated up to 80°C using oil bath until the wax completely melted down. Subsequently, the mixture was submitted to vigorous stirring by PRO Scientific PRO250 homogenizer operating at 14000 rpm for 1 min. The emulsion of wax in water was then cooled down to room temperature to solidify the wax droplets. Upon cooling the mixture, SiO2-NH2particles were trapped at interface of wax spheres. The Pickering emulsion was then filtered and rinsed with deionized water to remove unattached or weakly attached particles. SiO2@NH2&Fe3O4Janus particle fabrication process was followed by adding the wax spheres covered by SiO2-NH2particles into palladium catalyst solution for 30 min. Wax spheres were then collected from reaction solution by filtration and rinsed with deionized water. Surface modification of unprotected face of particle was completed by adding catalyzed spheres to a mixture of 0.01 M hydrated iron (III) nitrate and 0.03 M dimethylamineborane at 40 °C for 2 hr. The wax spheres were then collected by applyingpermanent magnet, filtered and rinsed with deionized water to remove unreacted species and dissolved in dichloromethane to remove wax. SiO2@NH2&Fe3O4Janus particles were then released and centrifuged. This process was repeated three times until complete removal of wax. SiO2@NH2&Fe3O4Janus particles were then dried in oven over night and stored for further use.

[0101] Characterization

[0102] Particles structure, size and morphology of wax spheres were studied using FEI Quanta 250 FEG Field Emission Scanning Electron Microscope (SEM) and Image J software. Particles and wax spheres were diluted in water and a droplet of the suspensions was dried on carbon tape of the sample holder at room temperature. Agilent Cary 630 Fourier-Transform Infrared (FTIR) spectrometer was used between 4000 and 400 cnr1to identify surface functional groups of modified particles and compare SiO2, SiO2@NH2and SiO2@Fe3O4homogeneous particles and SiO2@NH2&Fe3O4Janus particle. X-ray Powder Diffraction (XRD) spectra was obtained for SiO2@NH2, SiO2@Fe3O4homogeneous particles and SiO2@NH2&Fe3O4Janus particle to identify the structural properties of iron oxide nanoparticles attached to the surface of silica particle. The XRD analysis was performed using a Bruker D8 Advance (ECO) powder X-ray diffractometer operating at the reflection mode with Cu Ka radiation (k = 0.1542 nm). The powder X-ray diffraction pattern (XRD) was between 29 = 10-80° with a step size of 0.04° and a dwell time of 6 s / step. Peaks on the spectrum of SiO2@Fe3O4homogeneous particle and SiO2@NH2&Fe3O4Janus particle in comparison with SiO2@NH2homogeneous particle were assigned to ironoxide. Crystallite size of magnetite in both SiO2@Fe3O4homogeneous and SiO2@NH2&Fe3O4Janus particles were calculated by Scherrer equation (Eq. 13) as follow:D = - Bc^os-ft Eq “. ( '13) ’ where D is the diameter of crystallite, K is a constant, A is wavelength of X-ray radiation (Cu-Ka=0.1542 nm), p is Bragg angle (in radian) and B is the full width at half maximum (FWHM) of the intense and broad peaks in radian

[0076] , The magnetic properties of magnetic-types particles were investigated using VSM analysis through hysteresis loop for SiO2@NH2&Fe3O4Janus particle and SiO2@Fe3O4homogeneous particle. Magnetic response curve was obtained at room temperature using a Superconducting Quantum Interference Vibrating Sample Magnetometer (SQUID VSM). Sample magnetization was recorded as the uniform isothermal magnetic field varied from -30 to 30 kOe. The zeta potential of SiO2@NH2and SiO2@Fe3O4homogeneous particles and SiO2@NH2&Fe3O4Janus particle was measured and analyzed using a Zetasizer Nano ZS Size Analyzer from Malvern Panalytical with the particles concentration of 0.3 mg / l in dilute suspension.

[0103] Chromium (VI) and Phenol Removal Tests

[0104] Chromium (VI) and phenol 500 mg / l stock solutions was prepared by dissolving potassium dichromate (K2Cr2O / ) and phenol in deionized water. HCI (0.1 M) and NaOH (0.1) solutions were used to adjust acidic and basic pH. Batch separation was studied via removal tests conducted by adding measured amount of SiO2@NH2and SiO2@Fe3O4homogeneous particles and SiO2@NH2&Fe3O4Janus particle to 10 ml solutions which were diluted to different concentrations varying from 10 mg / l to 100 mg / l in 15 ml falcon tubes. Potassium persulfate was then added to the falcon tubes to initiate catalytic reaction. The solutions were shaken at room temperature for specified time. To avoid photo degradation, tubes were thoroughly covered by aluminium foil. At the end of each test, SiO2@Fe3O4homogeneous particle and SiO2@NH2&Fe3O4Janus particle were removed by applying external magnetic field and SiO2@NH2was separated from the solution by high-speed centrifuge at 4000 rpm for 10 min. Supernatants were then tested by Agilent 8900 ICPQQQ with SPS4 Autosampler and Shimadzu QP2010 GCMS to measure residual concentration of chromium (VI) and phenol, respectively. The removal efficiency of chromium and phenol was calculated according to Eq. 14:£.=o2£txi00 Eq. (14)Co where E is removal efficiency (%), Co is initial concentration of contaminant (mg / l) and Ctis final concentration (mg / l) of contaminant at time t.Adsorption capacity of particles was also determined through Eq. 15 as follow:where Ceis equilibrium concentration of chromium (VI) in the solution (mg / l), u is volume of the solution (I) and m is the weight of adsorbent (g).

[0105] Particles reusability was determined through five consecutive removal cycles. Particles were first dispersed in 10 ml solution of contaminants. The solution was shaken for 24 hr. Particles were then removed and dispersed in 10 ml solution of NaOH (0.05 M) for 24 h, washed with deionized water and redispersed in solution of contaminants for the next cycle. After each removal step, supernatants were tested to measure remain concentration of chromium (VI) and phenol.

[0106] DNA separation test

[0107] A 500 ml culture of E.coli DH10B (Invitrogen™) were grown in LB (Luria broth) overnight at 37°C. Culture was centrifuged at 4000 x g for 20 minutes at 4°C and thesupernatant was discarded. DNA was extracted from the pellet using the DNeasy PowerLyzer Microbial Kit (Qiagen) following manufacturer’s instructions.

[0108] DNA adsorption test was conducted in batch system. HCI (0.1 M) solution, acetate (0.1 M), HEPES ((4-(2-hydroxyethyl)-1 -piperazineethanesulfonic acid); 0.1 M) and MES (2-(N-morpholino)ethanesulfonic acid; 1 .0 M) buffer solutions were used to adjust pH at 3.5, 4.8, 6 and 7.5, respectively. For each pH, 100 pl solution of DNA was mixed with 400 pl of buffer at each tube. Particles were then added to the solution. Samples were briefly vortexed and incubated for 10 min and placed on a magnet to separate particles from suspension. After 5 min, 10 pl of each sample was taken for concentration measurements with Qubit HS dsDNA assay. The removal efficiency of DNA was then calculated through Eq. 14.

[0109] MagMAX™ Wastewater Ultra Nucleic Acid Isolation Kit (Applied Biosystems™, Waltham, MA, USA) is a technology commonly used for efficient nucleic acid (NA) extraction and recovery from wastewater samples. For nucleic acid extraction and purification from wastewater, ISCO portable auto-samplers are programmed to collect 24-hour composite wastewater samples. The samples are collected by the City of Calgary Water Utility Services staff using a standard protocol

[0077] , Nucleic acid extraction is carried out from 10 ml of wastewater following the manufacturer’s instructions. The commercial magnetic beads provided by the kit are resuspended in nuclease-free water and sonicated for 15 minutes. The kit contains two steps where it uses the magnetic beads: (Step 1 : Virus Enrichment) Dynabeads™ bind negatively charged vesicles and molecules such as viruses in the wastewater sample and (Step 2: Nucleic Acid Purification) the beads bind DNA / RNA in the sample obtained from Step 1 . In this work, using commercial magnetic beads at two steps of nucleic acid recovery is defined as the control experiment.

[0110] To test the capability of SiO2@NH2&Fe3O4 Janus particles to remove nucleic acid from a real wastewater sample, the particles were substituted for magnetic beads provided by the kit in the neutral environment of the wastewater sample. The magnetic beads were replaced by an equivalent volume of SiO2@NH2&Fe3O4 Janus particles in either Step 1 (Virus Enrichment) or Step 2 (Nucleic Acid Purification) while completing the other step with the commercial magnetic beads. Therefore, the ability of SiO2@NH2&Fe3O4 Janus particles to bind nucleic acids in negatively charged vesicles and viruses present in wastewater and also nucleic acids present in enriched sample were investigated. Samples were processed in triplicate and nucleic acids were eluted in 100 pl of nuclease-free water.

[0111] To compare the total yield of nucleic acids using each protocol, 5 pl of the eluted DNA and RNA were quantified with a Qubit Fluorometer with the Qubit HS dsDNAand Qubit HS RNA kits (Invitrogen™, Waltham, MA, USA). Furthermore, to quantify the concentration of SARS-CoV-2 coronavirus, the virus responsible for the COVID-19 global pandemic which has been readily detected in wastewater around the world, RT-qPCR of the nucleocapsid gene (N1) of the virus was performed.

[0112] Example 2 - Magnetic Janus Particle for Wastewater Applications

[0113] Magnetic particles may be applied to adsorption and removal processes. Among different types of magnetic colloids, Janus magnetic particles offer possibilities for effective removal of several components from an aqueous solution. Nevertheless, integrating different types of material into a single structure requires design features without major complex steps to address limitations of current methodologies. Herein, a new process is described for dual-surface functionalized magnetic Janus particle fabrication. The primary silica particles with surface-attached amine groups were further modified by iron oxide nanoparticles, asymmetrically, exploiting Pickering emulsion and electroless deposition technique. The surface dual functionality of the particle was designed for its versatility and used in wastewater related applications, as described herein. As also described herein, it is shown that the Janus particle design can simultaneously remove chromium (VI) and phenol from an aqueous solution. The fabricated magnetic-responsive Janus particle was also an effective adsorbent for genomic DNA and showed comparable or better performances to commercial magnetic beads currently available in the market. Thus, described herein is platform for designing magnetic Janus particles with multifunctional surface for wastewater treatment applications. For example, see Example 1 and Example 2 as follows.

[0114] Phenol Degradation Mechanism

[0115] Eq. S1 to Eq. S8 are recommended as mechanism of phenol degradation in presence of iron oxide. Persulfate is activated by of Fe2+through Eq. S1 and Eq. S2 and produces strong oxidizing S04-’ and OH’ radicals

[0050] ,S2O - + Fe2+SO4 ’ + SO - + Fe3+Eq. (S1)Phenol molecules react with S04“ ’ and OH’ radicals (Eq. S7 and S8) and break into smaller molecules through chain reactions and form degradation productions [51-54],

[0116] Pollutants Initial Concentration Effect

[0117] In Fig. 9a, b, the removal performance of SiO2@Fe3O4and SiO2@NH2homogeneous particles (HP) and SiO2@NH2&Fe3O4Janus particle (JP) was tested at different concentrations of chromium (VI) and phenol. Fig. 9a shows chromium adsorption efficiency on the surface of particles at 10 ppm, 20 ppm, 50 ppm and 100 ppm initial concentration of chromium (VI). Maximum adsorption efficiency was obtained at 10 ppm initial concentration of chromium (VI) with all three types of the particles. As the initial concentration of chromium increased from 10 ppm to 100 ppm, the removal efficiency of SiO2@NH2particle and SiO2@NH2&Fe3O4Janus particle dropped from 95% to 66% and 75% to 30%, respectively. This can be attributed to limited amine adsorption sites of particles which are saturated with chromium ions - and at higher initial concentrations, the excess amount of chromium ions that remain in the solution. The lower adsorption efficiency of SiO2@NH2&Fe3O4Janus particle compared to SiO2@NH2particle is considered due to the dual surface functionality of Janus particle. At constant dose of adsorbent, SiO2@NH2particle provides more amine adsorption site compared to SiO2@NH2&Fe3O4Janus particle. The adsorption efficiency of the SiO2@Fe3O4particle was not considered significant at 10 ppm chromium initial concentration: nevertheless, it decreased to zero at higher chromium initial concentration. This slight change in adsorption efficiency of SiO2@Fe3O4particle with initial chromium concentration suggests limited positive-charge ( eOH2+) sites exist on the surface of particles at pH 4, which are saturated at low concentrations of chromium and adsorption efficiency decreases with increase of initial adsorbate concentration, as consequent.

[0118] Phenol degradation efficiency of SiO2@Fe3O4and SiO2@NH2homogeneous particles and SiO2@NH2&Fe3O4Janus particle was also tested at different initial concentrations of phenol varying from 10 ppm to 100 ppm. As shown in Fig. 9b, almost 100% removal was observed at 10 ppm to 50 ppm initial concentrations of phenol in both SiO2@Fe3O4and SiO2@NH2&Fe3O4systems. The degradation removal efficiency of SiO2@Fe3O4homogenous particle decreased to 75% as the initial concentration of phenol increased from 50 ppm to 100 ppm. Similarly, SiO2@NH2&Fe3O4Janus particle degradation performance decreased to 42% as the concentration increased to 100 ppm. At the constant concentration of peroxide, produced oxidizing SO^’ radicals would be constant and with the increase of initial concentration of phenol, S04-’ radicals are consumed and phenol degradation efficiency is reduced.

[0119] Particle Dosage Effect

[0120] The removal efficiency of phenol and chromium at various dosages of particles ranging from 3 g / l to 15 g / l was investigated in Fig. 9c, d. The effect of SiO2@Fe3O4and SiO2@NH2homogeneous particles and SiO2@NH2&Fe3O4Janus particle dosage on chromium (VI) adsorption is shown in Fig. 9c. Among the three types of particles, the removal efficiency of chromium (VI) remained unchanged (98%) when SiO2@NH2particle dosage increased from 3 g / l to 15 g / l. The removal efficiency of the SiO2@NH2system suggested that low dosage of SiO2@NH2particle provides sufficient active sites for chromium adsorption. Removal efficiency in the SiO2@Fe3O4system was low at all doses of particles; however, a slight increase at higher dosages of particles can be attributed to the increase of positive-charge ( eOH2+) sites which may exist in pH 4. The removal efficiency of SiO2@NH2&Fe3O4Janus particle increased from 75% to 98% when the particles dose increased from 3 g / l to 8 g / l and then remained constant at higher doses. At higher concentrations of Janus particle more surface area with amine active sites is provided for chromium adsorption and removal efficiency increases, as consequence.

[0121] Phenol removal efficiency at different dosages of particles is shown in Fig. 9d. The results demonstrate that phenol degradation efficiency stayed constant for all three types of particles. Both SiO2@Fe3O4homogeneous particle and SiO2@NH2&Fe3O4Janus particle can activate PS and produce enough SO^’ for phenol degradation at low concentrations of particles. However, the SiO2@NH2particle is not capable of phenol removal even at high concentrations of particles.

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[0077] N. Acosta, M.A. Bautista, J. Hollman, J. McCalder, A.B. Beaudet, L. Man, B.J.Waddell, J. Chen, C. Li, D. Kuzma, S. Bhatnagar, J. Leal, J. Meddings, J. Hu, J.L. Cabaj, N.J. Ruecker, C. Naugler, D.R. Pillai, G. Achari, M.C. Ryan, J.M. Conly, K. Frankowski, C.R. Hubert, M.D. Parkins, A multicenter study investigating SARS- CoV-2 in tertiary-care hospital wastewater, viral burden correlates with increasing hospitalized cases as well as hospital-associated transmissions and outbreaks, Water Res. 201 (2021) 117369-117379. https: / / doi.Org / 10.1016 / j.watres.2021.117369.The embodiments described herein are intended to be examples only. Alterations, modifications, and / or variations can be effected to the particular embodiments by those of skill in the art. The scope of the claims should not be limited by the particular embodiments set forth herein, but should be construed in a manner consistent with the specification as a whole.

[0123] The aspects, embodiments, and / or examples of the present disclosure being thus described, it should be recognized that said aspects, embodiments, and / or examples may be varied in ways that do not depart from the spirit and scope of the present disclosure, and that said variations are intended to be included within the scope of the following claims.

[0124] All publications, patents and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication patent, or patent application was specifically and individually indicated to be incorporated by reference.

Claims

WHAT IS CLAIMED IS:1 . A Janus particle, comprising a particle core, the particle core comprising at least a first surface functionalized with a functional group and a second surface functionalized with a metal particle.

2. The Janus particle of claim 1 , wherein the core comprises SiO2, TiO2, AI2O3, Fe2O3, ZrO2, SnO2, ZnO, SrTiO3, Ta2O5, or a combination thereof.

3. The Janus particle of claim 1 or 2, wherein the core comprises SiO2, TiO2, AI2O3, or a combination thereof.

4. The Janus particle of any preceding claim, wherein the core comprises SiO2.

5. The Janus particle of any preceding claim, wherein the functional group functionalizing the first surface comprises an amine group, an alkylamine group, a hydroxyl group, a hydroxyalkyl group, a thiol group, an alkylthiol group, a carboxyl group, a sulfonic group, or a combination thereof.

6. The Janus particle of any preceding claim, wherein the functional group comprises an amine group, an alkylamine group, a hydroxyl group, a hydroxyalkyl group, a thiol group, an alkylthiol group, or a combination thereof.

7. The Janus particle of any preceding claim, wherein the functional group comprises an amine group, an alkylamine group, or a combination thereof.

8. The Janus particle of any preceding claim, wherein the metal particle functionalizing the second surface comprises Fe, Cu, Ni, Au, Ag, Pd, Pt, Co, an oxide thereof, or a combination thereof.

9. The Janus particle of any preceding claim, wherein the metal particle functionalizing the second surface comprises Fe, Cu, Ni, an oxide thereof, or a combination thereof.

10. The Janus particle of any preceding claim, wherein the metal particle functionalizing the second surface comprises Fe, an oxide thereof, or a combination thereof.

11. The Janus particle of any preceding claim, wherein the metal particle functionalizing the second surface is magnetic, paramagnetic, or a combination thereof.

12. The Janus particle of any preceding claim, wherein the first surface comprises about 10% to about 35%, or about 15% to about 30%, or about 20% to about 25%, or about 25% of the surface of the core particle.

13. The Janus particle of any preceding claim, wherein the second surface comprises about 65% to about 90%, or about 70% to about 85%, or about 75% to about 80%, or about 75% of the surface of the core particle.

14. The Janus particle of any preceding claim, wherein the Janus particle comprises a SiO2core and a first surface functionalized with amine groups and a second surface functionalized with FeO4magnetite particles.

15. A method of forming a Janus particle, the method comprising providing a particle core surface functionalized with a functional group; preparing a Pickering emulsion, the emulsion comprising the particle core immobilized at an interface of a wax-aqueous solution emulsion; functionalizing an exposed surface of the immobilized particle core with metal particles via electroless deposition to form the Janus particle; and isolating the Janus particle, the Janus particle comprising the particle core having a surface functionalized with the functional group and a second surface functionalized with the metal particle.

16. The method of claim 15, wherein preparing the Pickering emulsion comprises providing a mixture comprising an aqueous solution of wax and the particle core, heating the mixture to at least the melting point of the wax, forming a melted wax-aqueous emulsion stabilized by the particle core, cooling the emulsion to at least the freezing point of the wax, and immobilizing the particle core at the interface of the wax-aqueous emulsion.

17. The method of claim 15 or 16, wherein functionalizing an exposed surface of the immobilized nanoparticle core with metal particles comprises forming metal particles on the surface of the particle core, or depositing metal particles on the surface of the nanoparticle core via electroless deposition.

18. Use of the Janus particle of any one of claims 1-14, or of the Janus particle made by the method of any one of claims 15-17 for simultaneous removal of at least two contaminants from an aqueous solution.

19. The use of claim 18, wherein the contaminants comprise a heavy metal, an organic compound, or a combination thereof.

20. A method of simultaneously removing at least two contaminants from an aqueous solution, the method comprising providing a Janus particle into the aqueous solution comprising the at least two contaminants, the Janus particle comprising a first surface functionalized with a functional group and a second surface functionalized with a metal particle; and removing a first contaminant from the aqueous solution via the functional group functionalizing the first surface of the Janus particle, and removing a second contaminant from the aqueous solution via the metal particle functionalizing the second surface of the Janus particle.

21. The method of claim 20, wherein the first contaminant comprises a heavy metal, and the second contaminant comprises an organic compound.

22. The method of claim 20 or 21 , wherein removing the first contaminant comprises adsorbing the contaminant with the functional group functionalizing the first surface of the Janus particle.

23. The method of any preceding claim, wherein removing the second contaminant comprises catalyzing degradation of the contaminant with the metal particle functionalizing the second surface of the Janus particle.

24. The method of any preceding claim, wherein the functional group comprises an amine group, an alkylamine group, a hydroxyl group, a hydroxyalkyl group, a thiol group, an alkylthiol group, a carboxyl group, a sulfonic group, or a combination thereof.

25. The method of any preceding claim, wherein metal particle comprises Fe, Cu, Ni, Au, Ag, Pd, Pt, Co, an oxide thereof, or a combination thereof.

26. The method of any preceding claim, wherein the heavy metal is Cr, and the organic compound comprises phenol.

27. Use of the Janus particle of any one of claims 1-14, or of the Janus particle made by the method of any one of claims 15-17 for extraction of biological material from an aqueous solution.

28. The use of claim 27, wherein the biological material comprises DNA, RNA, viruses, or a combination thereof.

29. The use of claim 27 or 28, wherein the aqueous solution comprises wastewater.

30. A method of extracting biological material from an aqueous solution, the method comprising providing a Janus particle into the aqueous solution comprising biological material, the Janus particle comprising a first surface functionalized with a functional group and a second surface functionalized with a metal particle; and removing a component of the biological material from the aqueous solution via the functional group functionalizing surface of the Janus particle and / or via the metal particle functionalizing the second surface of the Janus particle.31 . The method of claim 30, wherein the aqueous solution is an acidic aqueous solution.

32. The method of claim 30 or 31 , wherein functional group ofthe first surface is protonated; and / or the metal particle of the second surface is protonated.

33. The method of any preceding claim, wherein the biological material is negatively charged.

34. The method of any preceding claim, wherein the biological material comprises DNA, RNA, viruses, or a combination thereof.

35. The method of any preceding claim, wherein the aqueous solution comprises wastewater.

36. The method of any preceding claim, wherein the functional group comprises an amine group, an alkylamine group, a hydroxyl group, a hydroxyalkyl group, a thiol group, an alkylthiol group, a carboxyl group, a sulfonic group, or a combination thereof.

37. The method of any preceding claim, wherein metal particle comprises Fe, Cu, Ni, Au, Ag, Pd, Pt, Co, an oxide thereof, or a combination thereof.

38. A biological material isolation kit, comprising the Janus particle of any one of claims 1- 14, or of the Janus particle made by the method of any one of claims 15-17; and instructions for use thereof.

39. A biological material isolation kit, comprising the Janus particle of any one of claims 1- 14, or of the Janus particle made by the method of any one of claims 15-17; and instructions for using the kit in accordance with the method of any one of claims 30 to 37.

40. The kit of any preceding claim, wherein the biological material comprises DNA, RNA, viruses, or a combination thereof.

Images