A method for synthesizing toxic-free spherical-shaped bioglass nanoparticles by a microfluidic device

Abstract

The present invention discloses a method for synthesizing toxic-free spherical-shaped bioglass nanoparticles (BGNs) by a microfluidic device. More particularly, the present invention relates to the fabrication and working of the microfluidic device. The synthesized BGNs exhibit size in nanometre scale range. Hence, the method of synthesis of BGNs does not require any reagent, apparently increasing the reproducibility significantly. Furthermore, the BGNs exhibit a large specific surface area and a large surface-to-volume ratio thereby applicable in biomedical applications such as drug delivery and tissue regeneration.

Description

[0001] A METHOD FOR SYNTHESIZING TOXIC-FREE SPHERICAL- SHAPED BIOGLASS NANOPARTICLES BY A MICROFLUIDIC DEVICE

[0002] FIELD OF INVENTION:

[0003] [1] The present invention is in the field of microfluidics. More particularly, the present invention relates to a method for synthesizing toxic-free spherical-shaped nano-bioglass by a microfluidic device. The toxic-free spherical-shaped nano-bioglass are synthesized in the form of bioglass nanoparticles (BGNs) having high reproducibility, biocompatibility and good morphology. The method for preparing said BGNs is time-efficient and cost-efficient.

[0004] BACKGROUND OF INVENTION:

[0005] [2] Nano-bioglass, also known as bioglass nanoparticles (BGNs) are a synthetic biomaterial that were developed in the late 1990’s with a prime focus on hard tissue regeneration. They are generally amorphous in nature and are available as powders, coatings and 3D scaffolds. The nanoparticles are superior to the bioglass particles due to their small size, large specific surface area and large surface-to-volume ratio thereby having applicability in biomedical applications such as drug delivery, tissue regeneration etc.

[0006] [3] Bioglass nanoparticles (BGNs) are generally synthesized by sol gel method or melt quenching method. In melt quenching technique of synthesizing BGNs, the particles produced are irregular, inhomogeneous in size distribution and require sophisticated equipment for the production process, while in sol gel procedure, the nano-bioglass particles are size and morphology controlled. In this case, nano-bioglass is produced in the form of powder, fibers or 3D porous scaffolds. In a typical sol gel synthesis process, tetraethyl orthosilicate (TEOS) is employed as a precursor for silica dissolved in ethanol and water, undergoing hydrolysis and then condensation in the presence of a basic medium, i.e., ammonium hydroxide. Metal ion precursors like calcium nitrate and triethyl phosphate are added at different time intervals to maintain the mono-dispersity of the silica nanoparticles. The resulting nanoparticles are then dried overnight and calcined to form BGNs. Moreover, apart from metal precursors, surfactants like cetrimonium bromide (CTAB) are also added to shape the bioglass nanoparticles. [4] However, the metal precursors added interact with cationic surfactants and cause loss of ordered mesoporosity. Additionally, removal of the template significantly affects the internal structure of BGNs. Lately, various templates have been used for bioglass nanoparticles such as CTAB, P123 (soft templates) or hard templates such as polymer spheres, natural grains and DNA. However, the particle formation was seen outside the template whose removal lead to aggregation. Along with these challenges, the particle size produced is generally more than 100 nm whereas the accepted size for nanoparticles is between 1-100 nm in order to be applicable in drug delivery efficiently. Even though there has been enough evidence to appreciate the production of BGNs, several challenges remain, especially in the precise control of size, composition and crystalline nature.

[0007] [5] Microfluidics has acquired ultimate importance over the last years, due to their accuracy in manipulating and monitoring the fluids on micrometric scale channels. Microfluidics provide a controlled environment for synthesis of nanoparticles and have several advantages over batch synthesis. They have high reproducibility, are cost efficient, have good control over particle size and mixing time and apparently reduce the synthesis time drastically. Single phase microfluidic system has a continuous laminar flow through single or multiple inlets where formation of particle occurs, providing a homogenous environment for the reaction to take place. The different geometries of the microfluidic device are used to control the mixing of reagents resulting in desirable shape and size of the nanoparticles. Therefore, they are used to synthesize bioglass particles with desirable shape and geometry.

[0008] [6] For instance, reference is made to CN116077467A which discloses a microfluidic device comprising at least more than one cell membrane channel, and when the number of the cell membrane channels is two or more than two, the cell membrane channels converge in front of a cell membrane mixing channel and converge into the cell membrane mixing channel. The citation further provides a method for synthesizing the drug-loaded nanoparticles coated with the composite biological membrane in one step but this does not provide any details for synthesising a nanoparticle.

[0009] [7] Further reference is made to CN110560186A which discloses a method for synthesizing biofilm nanoparticles by a micro-fluidic chip and the micro-fluidic chip thereof. The method comprises steps as follows: introducing a biofilm solution into a biofilm channel, introducing an organic solution containing polymers into a polymer channel, mixing the organic solution and the biofilm solution and entering of the mixed solution after mixing in a first fixing channel followed by introducing a PBS (phosphate buffer solution) into a PBS channel, and mixing the PBS with the mixed solution and the solution obtained after mixing is output into a second mixing channel, and the polymers in the mixed solution are extruded into a biofilm under the actions of pressure and ultrasonic waves. However, the biofilm nanoparticles synthesized have used polymer solutions which are coated with biofilms by ultrasound water bath sonicator making it a time-consuming process.

[0010] [8] Reference is further made to IN202241013384 which discloses a method to synthesize toxic-free star shaped gold nanostructures by a microfluidic device. The present invention further provides a method for preparing a microfluidic device. The citation further provides a method to deliver biomolecules to the cells using light pulses mediated by Au NS. Nevertheless, the invention is more cost effective in nature and the gold nanoparticles are collected through a controlled temperature output and requires multiple centrifugation process.

[0011] [9] Reference is further made to CN204912776U which discloses a micro-fluidic preparation of nanometre gold solution including at least two syringe pumps, an infusion pipeline, a micro-fluidic chip, a temperature control device and a finished product storage tank. The micro-fluidic chip is the little access structure of glass matrix sculpture, the microchannel includes a Y type blender, a static mixer and a microtubule way and the syringe pump passing through the infusion pipeline is connected to Y type blender entry. The temperature control device is located at the micro-fluidic chip bottom and the microchannel export is passed through the infusion pipeline connecting into the article storage tank. Nevertheless, the synthesis of the nanometre gold solution has a complex set up along with a microfluidic chip.

[0012]

[0010] The precursors used for bioglass nanoparticles production are numerous, making the synthesis a tedious and time-consuming process. Other than this, most studies go through hurdles in producing nanoparticles of bioglass as the particles produced are submicron in size which is more than 100 nm. Furthermore, there is a lack of homogeneity in the shape and size distribution of bioglass nanoparticles when synthesized by batch process.

[0013]

[0011] In a conventional batch reactor method, only concentrations of the parameters are modified during mixing that results in unequal size distribution of BGNs synthesized. In conventional batch reactor, the only parameter that is capable of being changed is the stirring of reagents during synthesis. Since microfluidic devices are viewed microscopically, the formation and reagent mixing are clearly visualised, making it easier to change the parameters accordingly. Another maj or disadvantage is that the BGNs synthesis takes several hours to days whereas in a microfluidic device, BGNs are synthesized in only a few seconds.

[0014]

[0012] Thus, it is very important under this circumstance to develop a method for synthesizing toxic-free spherical-shaped bioglass nanoparticles by a microfluidic approach that is applicable in drug delivery and tissue regeneration.

[0015]

[0013] Accordingly, there is a dire need in the state of art to provide a method for the synthesis of toxic-free spherical-shaped bioglass nanoparticles by a microfluidic device with good biocompatibility, high reproducibility and enhanced morphology.

[0016] OBJECTS OF THE INVENTION:

[0017]

[0014] The principle object of the present invention is to provide a method for synthesizing toxic-free spherical nano-bioglass or bioglass nanoparticles (BGNs) by a microfluidic device.

[0018]

[0015] Another object of the present invention is to provide a method of fabrication of the microfluidic device to synthesize toxic-free spherical-shaped bioglass nanoparticles.

[0019]

[0016] Yet another object of the present invention is to provide toxic-free spherical -shaped bioglass nanoparticles having biocompatibility, good morphology and high reproducibility.

[0020]

[0017] Yet another object of the present invention is to provide the synthesis of toxic-free spherical-shaped bioglass nanoparticles by the microfluidic device in only a few seconds.

[0021]

[0018] Yet another object of the present invention is to provide toxic-free spherical -shaped bioglass nanoparticles that are applicable in drug delivery and tissue regeneration.

[0022] SUMMARY OF INVENTION:

[0023]

[0019] In one aspect, the present invention provides a method for synthesizing toxic-free spherical-shaped bioglass nanoparticles, comprising of the following steps: (a) mixing metallic precursors such as tetraethyl orthosilicate (TEOS), ethanol and triethyl phosphate in a ratio of 1 : 0.8: 0.1 to obtain solution A; (b) mixing ammonium hydroxide, ethanol, deionized water and calcium chloride in a ratio of 1 : 0.5: 0.03: 0.3 to obtain solution B; (c) subjecting said solution A of step (a) and said solution B of step (b) to ultra-sonication for a range of time period from 8 to 12 seconds; (d) hydrolyzing TEOS of said solution A of step (a) with ammonium hydroxide of said solution B of step (b) to obtain silica particles followed by incorporating said solutions A and B of steps (a) and (b) into the plurality of inlets of the microfluidic device to obtain bioglass nanoparticles (BGNs); (e) collecting said bio-glass nanoparticles of step (d) synthesized in the outlet of the microfluidic device and subjecting said particles to centrifugation in a range of 7830 to 7850 rpm for a time period in a range of 5 - 7 minutes to obtain centrifuged BGNs; and (f) drying said centrifuged BGNs of step (e) in a hot air oven at 45°C overnight to obtain pure BGNs.

[0024]

[0020] In another aspect, the present invention provides a microfluidic device for synthesising toxic-free spherical-shaped bioglass nanoparticles (BGNs) as described herein, wherein said microfluidic device comprises of: a plurality of inlets, a plurality of rows of serpentine, a spiral and an outlet.

[0025] BRIEF DESCRIPTION OF THE DRAWINGS:

[0026]

[0021] The accompanying drawings constitute a part of the description and are used to provide further understanding of the present invention. Such accompanying drawings illustrate the embodiments of the present invention, which are used to describe the principles of the present invention together with the description.

[0027]

[0022] Figure 1 illustrates a pictorial representation of the AutoCAD design of the microfluidic device (scale bar- 0.1mm) representing the microfluidic device in part (a); and representing the enlarged designs in developing the microfluidic device along with their dimensions in parts (b) to (d), in accordance with an implementation of the present invention.

[0028]

[0023] Figure 2 illustrates details of fabrication of microfluidic device depicting the steps in fabrication of microfluidic device by photolithography technique, in accordance with an implementation of the present invention.

[0024] Figure 3 illustrates the different geometries present in design obtained through the photolithography technique, in accordance with an implementation of the present invention.

[0029]

[0025] Figure 4 illustrates the final image of the device bonded on a glass substrate, in accordance with an implementation of the present invention.

[0030]

[0026] Figure 5 illustrates the transmission electron microscopy (TEM) images and X-Ray diffraction analysis (XRD) results of the three trails performed, in accordance with an implementation of the present invention.

[0031]

[0027] Figure 6 illustrates the TEM images of optimized BGNs with a focus of single particle in part (i); and a monodispersed layer with homogenous size (less than 300 nm) and shape in part (ii), in accordance with an implementation of the present invention.

[0032]

[0028] Figure 7 illustrates the XRD data in part (a); and the FTIR analysis in part (b), in accordance with an implementation of the present invention.

[0033]

[0029] Figure 8 illustrates the SEM images of bioactivity test, in accordance with an implementation of the present invention.

[0034] DETAILED DESCRIPTION OF THE INVENTION:

[0035]

[0030] While the invention is susceptible to various modifications and alternative forms, specific embodiment thereof will be described in detail below. It should be understood, however that it is not intended to limit the invention to the particular forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternative falling within the scope of the invention as defined by the appended claims.

[0036]

[0031] Although one or more features and / or elements may be described herein in the context of only a single embodiment, or alternatively in the context of more than one embodiment, or further alternatively in the context of all embodiments, the features and / or elements may instead be provided separately or in any appropriate combination or not at all. Conversely, any features and / or elements described in the context of separate embodiments may alternatively be realized as existing together in the context of a single embodiment.

[0032] The terminology used herein is for the purpose of describing particular various embodiments only and is not intended to be limiting of various embodiments. As used herein, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0037]

[0033] As discussed in the background section of the present invention, the existing methods for synthesizing bioglass nanoparticles (BGNs) reported in the prior art majorly comprise of gold nanoparticles which are cost inefficient and further the method for synthesizing said nanoparticles is time consuming and inefficient.

[0038]

[0034] Therefore, to overcome the existing problems in the art, the present invention provides a method for synthesizing toxic-free spherical -shaped bioglass nanoparticles (BGNs), by a microfluidic device. The present invention provides homogeneity in the shape and size distribution of bioglass nanoparticles. Moreover, the flow rate of precursors plays a major role in their time of mixing and thus production of scalable and controlled morphology and size of BGNs. Another important feature of the present invention is that the method for synthesising BGNs by a microfluidic device takes only a few seconds.

[0039]

[0035] The present invention provides a method for synthesizing toxic-free spherical-shaped bioglass nanoparticles by a microfluidic device, having good morphology, enhanced biocompatibility and high reproducibility.

[0040]

[0036] Overall, the method for synthesizing toxic-free spherical shaped bioglass nanoparticles by a microfluidic device of the present invention is different and technically advance over the conventional method(s) in view of the following advantageous: a) Biomedical applications: The present invention allows the synthesis of toxic- free spherical-shaped bioglass nanoparticles by a microfluidic device having small size, larger specific surface area and larger surface to volume ratio, thereby being applicable in a number of biomedical applications such as drug delivery and tissue regeneration. b) Minimal time for synthesis: The present invention provides a time-efficient method for synthesizing toxic-free spherical-shaped bioglass nanoparticles by microfluidic approach in only a few seconds, thereby saving a lot of time and energy. c) High reproducibility of bioglass nanoparticles: The present invention provides the synthesis of toxic-free spherical-shaped bioglass nanoparticles without any need of reagents, thereby increasing the reproducibility of the bioglass nanoparticles with microfluidic approach. d) Monodispersed nature of the bioglass nanoparticles: In chemical synthesis of bioglass, calcination process (heating the sample up to 600°C for 3 hours) takes place to prevent particle aggregation but the particles produced using the microfluidic device were monodispersed even without the calcination process.

[0041]

[0037] In an embodiment of the present invention, there is provided a method for synthesizing toxic-free spherical-shaped bioglass nanoparticles (BGNs) by a microfluidic device, comprising of the following steps: (a) mixing metallic precursors such as tetraethyl orthosilicate (TEOS), ethanol and tri ethyl phosphate in a ratio of 1 : 0.8: 0.1 to obtain solution A; (b) mixing ammonium hydroxide, ethanol, deionized water and calcium chloride in a ratio of 1 : 0.5: 0.03: 0.3 to obtain solution B; (c) subjecting said solution A of step (a) and said solution B of step (b) to ultra- sonication for a range of time period from 8 to 12 seconds; (d) hydrolyzing TEOS of said solution A of step (a) with ammonium hydroxide of said solution B of step (b) to obtain silica particles followed by incorporating said solutions A and B of steps (a) and (b) into the plurality of inlets of the microfluidic device to obtain bio-glass nanoparticles (BGNs); (e) collecting said bio-glass nanoparticles of step (d) synthesized in the outlet of the microfluidic device and subjecting said particles to centrifugation in a range of 7830 to 7850 rpm for a time period in a range of 5 - 7 minutes to obtain centrifuged BGNs; and (f) drying said centrifuged BGNs of step (e) in a hot air oven at 45°C overnight to obtain pure BGNs.

[0042]

[0038] In another embodiment of the present invention, there is provided a method for synthesizing toxic-free spherical-shaped bioglass nanoparticles as described herein, wherein said toxic-free spherical shaped bioglass nanoparticles exhibit a diameter in a range of 200 nm to 280 nm.

[0039] In another embodiment of the present invention, there is provided a method for synthesizing toxic-free spherical shaped bioglass nanoparticles as described herein, wherein said solution A exhibits a flow rate ranging from 120 to 250 pL / min and solution B exhibits a flow rate ranging from 325 to 450 pL / min.

[0043]

[0040] In another embodiment of the present invention, there is provided a method for synthesizing toxic-free spherical-shaped bioglass nanoparticles as described herein, wherein said toxic-free spherical-shaped bioglass nanoparticles are applied in drug delivery and tissue regeneration.

[0044]

[0041] In an embodiment of the present invention, there is provided said microfluidic device for synthesizing toxic-free spherical-shaped bioglass nanoparticles (BGNs) as described herein, comprising a plurality of inlets; a plurality of rows of serpentine; a spiral; and an outlet.

[0045]

[0042] In another embodiment of the present invention, there is provided a microfluidic device as described herein, wherein said plurality of inlets having a diameter in a range of 2 mm to 2.5 mm, seed a precursor and a surfactant.

[0046]

[0043] In another embodiment of the present invention, there is provided a microfluidic device as described herein, wherein said plurality of rows of serpentine possess a diameter in a range of 0.1 mm to 0.2 mm and length in a range of 57 mm to 59 mm.

[0047]

[0044] In another embodiment of the present invention, there is provided a microfluidic device as described herein, wherein said spiral is turned four times with a width ranging from 2 mm to 2.5 mm between each turn.

[0048]

[0045] In another embodiment of the present invention, there is provided a microfluidic device as described herein, wherein said outlet is attached to said spiral with a diameter in a range of 2 mm to 2.5 mm.

[0049]

[0046] The present invention is illustrated hereunder in greater detail in relation to non-limiting exemplary embodiments as per the following examples:

[0050] EXAMPLES

[0047] The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and the description of how to make and use the present invention, and are not intended to limit the scope of what the inventors regard as their invention nor are they intended to represent that the experiments below are all and only experiments performed. The methodology of preparing few of the preferred embodiments shall become clearer with working examples provided below.

[0051] CHEMICALS AND INSTRUMENTS USED:

[0052]

[0048] The following chemicals and instruments were used in the present invention:

[0053] 1. Metallic precursors like calcium chloride and triethyl phosphate, TEOS, ammonium hydroxide and ethanol are procured from chemical vendors, Sigma Aldrich and Merck Chemicals.

[0054] 2. Conning 15 ml centrifuge tubes and Thermo Fischer centrifugation equipment was used to centrifuge the obtained output from the microfluidic device.

[0055] 3. Hot air oven was used to dry the centrifuged particles overnight at a temperature of 45°C.

[0056] Example 1: Synthesis of Bioglass nanoparticles (BGNs)

[0057]

[0049] The synthesis of BGNs is described as follows. The chemical synthesis was converted into microfluidic technology by converting the concentration and volume requirements into the flow rate. The maximum allowable flow rate and the ratio of flow rates between the inlets was estimated before the experiment to avoid the leakage problem. BGNs synthesis used a sol gel technique that uses ammonium hydroxide to create a basic medium for hydrolysis of TEOS into silica particles. Over time, the silica nanoparticles formed undergo condensation and the incorporation of other metallic precursors, i.e., calcium chloride and tri ethyl phosphate was done. The device has two inlets hence two solutions were prepared. Solution A consists of tetraethyl orthosilicate (TEOS), ethanol and triethyl phosphate in a ratio of 1 :0.8:0.1 and solution B consisted of ammonium hydroxide, ethanol, deionized water and calcium chloride in a ratio of 1 :0.5 :0.03 :0.3 and then both were subjected to ultra- sonication at room temperature for 10 seconds before seeding into the inlets. Figure 4 represents an AutoCAD design of the device with their inlets and the outlet represented by respective seeding solutions. BGNs produced were collected in outlet and subjected to centrifugation at 7830 rpm for 5 minutes. The particles were then dried in a hot air oven at 45°C overnight.

[0058] Example 2: Fabrication of the device

[0059]

[0050] The design for the device was made using AutoCAD software 2019 version. A multiple row of serpentine was chosen in order to enhance the mixing process followed by a single spiral design to mix the two solutions that were later collected via the outlet attached to the end of spiral. Two inlets were provided, where one was used to seed solution A and the other inlet for Solution B. The dimension was chosen assuming a laminar flow of the fluid inside the device. Inlets and the outlet have a dimension of 2mm diameter, 4 turned spiral possess a width of 2mm between each turn. There were 20 rows of serpentine and has outer diameter of 0.2mm and inner diameter of 0.1mm. Each row has a length of 58.4mm as seen in Figure 1.

[0060]

[0051] The microfluidic device was fabricated by lithography technique. The steps are as shown in Figure 2. First, a silicon wafer was piranha cleaned and SU-8 photoresist (2035 series) was spin coated at optimized parameters to obtain the desirable height. Prebaking was done for 17 minutes after the spin coating followed by exposure of the wafer to UV by a chromium mask (designed by AutoCAD). Post exposure baking was then done for 5 minutes. A SU-8 pattern on the wafer was developed by an appropriate developer and cleaned well with acetone and isopropyl alcohol as shown in Figure 3. Later, polydimethylsiloxane (PDMS) was mixed and poured over the pattern and kept for curing at 60°C for 5 hours to obtain the desired inlets, outlet and micro channels. Finally, the PDMS layer was pulled out from the SU-8 structure and bonded on a glass substrate after plasma oxygen treatment.

[0061] Example 3: Optimisation of bioglass nanoparticles (BGNs)

[0062]

[0052] The flow rates of both inlets were altered until monodispersed BGNs were obtained. Figure 5 depicts the Transmission Electron microscopic Images (TEM) and X-ray diffractions (XRD) results of the trails performed. The XRD results showed prominent peaks consistently between 23° to 30° indicating the formation of calcium silicates. These results infer a good reproducibility and repeatability of the experiments. Transmission electron microscopy (TEM) analysis

[0063]

[0053] Figure 6 illustrates that TEM analysis reveals that synthesized BGNs are well-defined spherical spheres with a diameter of less than 300 nm and have formed a monodisperse layer. From the X-ray diffraction analysis seen in part (a) of Figure 7, peaks at 23.5 and 29.6 that are closer to crystalline calcium silicate values are obtained.

[0064] Fourier Transform Infrared

[0065]

[0054] Part (b) of Figure 7 depicts that the FTIR spectra indicated wavenumbers at 478 (P-0 bond in phosphorous oxide), 709-801-1092 (Si-0 bond formation), 1385, 1464 (C-H bond), 1640 (C-N bonds), 2848-3452 (O-H bonds), 2992 (C-H in CH2 bond) which represented different bands present in the synthesized BGNs.

[0066]

[0055] To analyse the surface topography of the particles obtained a SEM analysis was done. About Img of the powdered sample was sputtered coated with gold using the sputtering system and SEM analysis was done. Part (i) of Figure 8 shows the 1-micron size image of the particles synthesised where a homogenous size of particles is appreciated along with an elemental analysis profiling that indicated the presence of silicon, (30%), phosphorous (1%) and calcium (0.5%) depicting the composition of bioglass particles. An in-vitro bioactivity test was performed by immersing the particles in stimulated body fluid (SBF- a chemical which mimics the human blood plasma) for 7 days. An increase in phosphorus and oxide indicated formation of appetite layer and the decrease in silica and calcium indicated that the particles are biodegradable in nature. The change in the surface indicates that the particles are toxic free and biocompatible in nature.

[0067]

[0056] Parts (i) and (ii) of Figure 8 shows the topographical analysis of the particles through SEM before and after immersing in stimulated body fluid (SBF).

[0068] ADVANTAGES OF PRESENT INVENTION:

[0057] The present invention provides a method of synthesizing toxic-free spherical-shaped bioglass nanoparticles by a microfluidic device for drug delivery and tissue regeneration.

[0069]

[0058] The advantages of the method of synthesizing toxic-free spherical-shaped bioglass nanoparticles by a microfluidic device of the present invention are:

[0070] (i) The microfluidic device provides a controlled environment for the synthesis of nanoparticles that possesses high reproducibility, good control over particle size and mixing time, is cost-efficient and reduces the synthesis time drastically.

[0071] (ii) Since microfluidic devices are viewed microscopically, visualisation of the formation and reagent mixing in detail and tuning of the parameters accordingly becomes easy. Another major advantage is that generally BGNs synthesis takes several hours to days, whereas in a microfluidic device, the synthesis is done in a few seconds.

[0072] (iii)In the chemical synthesis of bioglass, calcination (heating the sample up to 600°C for 3 hours) is done to prevent particle aggregation but the particles produced using the microfluidic device of the present invention are monodispersed even without the calcination process.

[0073] (iv)In a conventional batch reactor, the only parameter that is tuneable is the stirring of reagents during synthesis. Since microfluidic device of the present invention provide a microscopic view, it becomes possible to visualize the formation and reagent mixing in detail and easy to tune the parameters accordingly.

[0074] (v) The microfluidic device of the present invention has good control over the kinetics of the chemical reactions by varying the flow rates and concentrations of the precursors utilized in the synthesis of bioglass nanoparticles (BGNs).

Claims

WE CLAIM:

1. A method for synthesizing toxic-free spherical-shaped bioglass nanoparticles by a microfluidic device, comprising of the following steps:(a) mixing metallic precursors such as tetraethyl orthosilicate (TEOS), ethanol and tri ethyl phosphate in a ratio of 1 : 0.8: 0.1 to obtain solution A;(b) mixing ammonium hydroxide, ethanol, deionized water and calcium chloride in a ratio of 1 : 0.5: 0.03: 0.3 to obtain solution B;(c) subjecting said solution A of step (a) and said solution B of step (b) to ultrasonication for a range of time period from 8 to 12 seconds;(d) hydrolyzing TEOS of said solution A of step (a) with ammonium hydroxide of said solution B of step (b) to obtain silica particles followed by incorporating said solutions A and B of steps (a) and (b) into the plurality of inlets of the microfluidic device to obtain bio-glass nanoparticles (BGNs);(e) collecting said bio-glass nanoparticles of step (d) synthesized in the outlet of the microfluidic device and subjecting said particles to centrifugation in a range of 7830 to 7850 rpm for a time period in a range of 5 - 7 minutes to obtain centrifuged BGNs; and(f) drying said centrifuged BGNs of step (e) in a hot air oven at 45°C overnight to obtain pure BGNs.

2. The method for synthesizing toxic-free spherical shaped bioglass nanoparticles as claimed in claim 1, wherein said toxic-free spherical shaped bioglass nanoparticles exhibit a diameter in a range of 200 nm to 280 nm.

3. The method for synthesizing toxic-free spherical shaped bioglass nanoparticles as claimed in claim 1, wherein said solution A exhibits a flow rate ranging from 120 to 250 pL / min and solution B exhibits a flow rate ranging from 325 to 450 pL / min.

4. The method for synthesizing toxic-free spherical-shaped bioglass nanoparticles as claimed in claim 1, wherein said toxic-free spherical-shaped bioglass nanoparticles are applied in drug delivery and tissue regeneration.

5. A microfluidic device for synthesizing toxic-free spherical -shaped bioglass nanoparticles (BGNs) as claimed in claim 1, comprises of:(i) a plurality of inlets;(ii) a plurality of rows of serpentine;(iii)a spiral; and(iv)an outlet.

6. The microfluidic device for synthesizing toxic-free spherical-shaped bioglass nanoparticles as claimed in claim 4, wherein said plurality of inlets having a diameter in a range of 2 mm to 2.5 mm, seed a precursor and a surfactant.

7. The microfluidic device for synthesizing toxic-free spherical-shaped bioglass nanoparticles as claimed in claim 4, wherein said plurality of rows of serpentine possess two different diameters of outer and inner in a range of 0.1 mm to 0.2 mm and length in a range of 57 mm to 59 mm.

8. The microfluidic device for synthesizing toxic-free spherical-shaped bioglass nanoparticles as claimed in claim 4, wherein said spiral is turned four times with a width ranging from 2 mm to 2.5 mm between each turn.

9. The microfluidic device for synthesizing toxic-free spherical-shaped bioglass nanoparticles as claimed in claim 4, wherein said outlet is attached to said spiral with a diameter in a range of 2 mm to 2.5 mm.

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