Three-dimensional porous matrices for detecting and / or determining analytes and method for obtaining same

Abstract

The present invention belongs to the field of the detection and / or determination of analytes of interest, for example, in the environmental, industrial, agri-food or health fields. In particular, the present invention relates to a three-dimensional porous polydimethylsiloxane (PDMS) matrix comprising tetraethyl orthosilicate (TEOS) and zeolite, which is capable of retaining different sensing reagents in a precise manner therein, so that said three-dimensional matrix can function as a sensor or multisensor of a wide variety of analytes.

Description

[0001] DESCRIPTION THREE-DIMENSIONAL POROUS MATRICES FOR THE DETECTION AND / OR DETERMINATION OF ANALYTES AND OBTAINING METHOD THEREIN The present invention belongs to the field of detection and / or determination of analytes of interest, for example, in the environmental, industrial, agri-food or health fields. In particular, the present invention relates to a porous three-dimensional matrix of polydimethylsiloxane (PDMS) comprising tetraethylorthosilicate (TEOS) and zeolite, which is capable of retaining different sensor reagents within it in a precise manner, such that said three-dimensional matrix can act as a sensor or multisensor for a wide variety of analytes. BACKGROUND OF THE INVENTION In recent years, three-dimensional porous materials with polymers as a base that have a three-dimensional morphology, for example, sponge morphology, have been studied and developed [Shin, JH; Heo, JH; Jeon, S.; Park, JH; Kim, S.; Kang, HWBio-Inspired Hollow PDMS Sponge for Enhanced Oil–Water Separation. J Hazard Mater 2019, 365, 494–501]. Different methods have been proposed for the synthesis of these polydimethylsiloxane (PDMS) based sponges such as the sugar or salt tempering method [Wang, J.; Guo, J.; Si, P.; Cai, W.; Wang, Y.; Wu, G. Polydopamine-Based Synthesis of an In(OH)3- PDMS Sponge for Ammonia Detection by Switching Surface Wettability. RSC Adv 2016, 6, 4329–4334], emulsion tempering [Tebboth, M.; Jiang, Q.; Kogelbauer , A. ; Bismarck, A. Inflatable Elastomeric Macroporous Polymers Synthesized from Medium Internal Phase Emulsion Templates. ACS Appl Mater Interfaces 2015, 7, 19243–19250], nickel foam, colloidal crystals, gas foaming, phase separation, PDMS bead formation [Li, N.; Li, T.; Lei, X.; Fu, B.; Liao, W.; Qiu, J. Preparation and Characterization of Porous PDMS Beads for Oil and Organic Solvent Sorption.Polym Eng Sci 2014, 54, 2965–2969], PDMS emulsion with paraffin oil, sponge formation with polyurethane, sponge formation with citric acid, or sponge formation by UV radiation. Most of these materials are applicable for the absorption of oils given their high hydrophobic capacity, acting as absorbent decontaminants. Some sponges have also been developed as portable devices for use in soft robotics, as piezoresistive sensors for motion detection and tracking or health monitoring, and as flexible and ultrasensitive capacitive pressure sensors in the field of electronics. Furthermore, hydrophilic sponges made of PDMS-polyvinyl alcohol or polyacrylic acid have been developed for use in continuous transport in microfluidic systems.This type of material is also applicable in the field of biology as a medium for endothelial cell culture, immunoassays, peptide or protein coating, or localized drug delivery. Some developed sponges have photocatalytic multifunction capabilities, thermal insulation, and the ability to reduce ice-surface adhesion. Furthermore, there are various reagents that, through different types of interactions or chemical reactions with different analytes, are capable of detecting or even determining the concentration of said different analytes, such as the reagent 1,2-napthoquinone-4-sulfonate (NQS), capable of detecting / determining the presence or concentration of ammonia or amines through colorimetric changes.Other reagents capable of detecting / determining the presence of other analytes include, for example, nitroprusside, which can detect ammonium along with thymol, or N-(1-naphthyl)ethylenediamine dichlorohydrate (NEDD), which can detect nitrites and nitrates. However, these reagents have the disadvantage of not being stable in solution, which is a challenge for determining these analytes.There are also colorimetric sensors in the state of the art for the determination of chemical species such as amines in situ in the air, which comprise a PDMS matrix in which a reagent is embedded that is capable of detecting said amines, by immersing the PDMS matrix in a solution comprising said dissolved reagent, this reagent being 1,2-napthtoquinone-4-sulfonate (NQS), such as those described in patents ES2519891A1 (EP3001184B1), and in patent ES2619356B1 which particularly describes a passive calorimetric sensor for the detection and / or determination of ammonia or aliphatic amines in gases comprising a polydimethylsiloxane (PDMS) matrix having embedded 1,2-naphthoquinone-4-sulfonate (NQS) and tetraethylorthosilicate (TEOS)).However, these state-of-the-art colorimetric sensors have certain drawbacks, since achieving low detection and quantification limits requires a long exposure time to the gas in question, making them not optimal for performing timely tests to control and monitor these atmospheric pollutants. Therefore, there is a need in the field to provide sensor devices that, in addition to being compact and having mechanical integrity, exhibit high sensitivity in the detection / determination of said analytes in short periods of time. DESCRIPTION OF THE INVENTION The authors of the present invention provide a porous three-dimensional matrix of polydimethylsiloxane (PDMS) polymer that has been doped with tetraorthoethylsilicate (TEOS) and zeolite. Therefore, it is a PDMS matrix comprising TEOS and zeolite (Z@TEOS@PDMS, where "Z" refers to zeolite).This is a material that is preferably a sponge-like material. The synthesis of this new material comprises a method in which, in addition to adding PDMS, TEOS and zeolite, sugar (sieved or unsieved) is also used, for example, by the sugar annealing method or a similar method, such that although said sugar is used during the synthesis of the Z@TEOS@PDMS sponge, said sugar is not part of the new Z@TEOS@PDMS material (porous three-dimensional matrix) finally obtained after the synthesis. This Z@TEOS@PDMS material can also embed / retain different types of reagents in the three-dimensional matrix, or release previously embedded reagents from the matrix, for example, sensor reagents capable of detecting and / or determining an analyte, which allows the use of Z@TEOS@PDMS as a sensor to detect and / or determine analytes.If they are provided with a matrix in which to capture them, such as that of the present invention, the drawback of not being stable in solution by NQS, nitroprusside or N- (1-naphthyl) ethylenediamine dichlorohydrate (NEDD) disappears, so they are stable over time and this drawback does not exist. Therefore, a first aspect of the present invention relates to a porous three-dimensional matrix of polydimethylsiloxane (PDMS), between 40% and 60%, preferably 60% (hereinafter matrix of the invention or Z@TEOS@PDMS), characterized in that it comprises ^ tetraethylorthosilicate (TEOS) between 40% and 60%, preferably 40%; and ^ zeolite between 0.5% and 1%, preferably 1%, where the three-dimensional matrix has a porosity of between 55-80% with respect to the total volume of the matrix, preferably a porosity of 60-75%, even more preferably 66±6%, with pore sizes between 20-360 μm, preferably 85-295 μm, even more preferably 200 μm.It is preferably formed by the sugar tempering method, a modified sugar tempering method, or a similar method. Preferably, the three-dimensional matrix has dimensions between 7 and 15 mm in diameter and a thickness between 1.5 and 2 mm. This thickness is sufficient to retain the reagents and analytes being studied. A smaller thickness would make the material less robust, leading to breakage much sooner. Furthermore, it would not optimally load the reagents, causing the sensitivity of the assays to decrease. "Porosity" is defined according to the invention as the volumetric fraction of pores in the material, and can be located either on the surface of the sponge or within it.The technique used to measure the % porosity (by volume) in this invention has been optical microscopy (using a Nikon ECLIPSE E200 device, with a 10x magnification lens, along with the calculation of the weight of the sponge loaded and unloaded with reagent in solution, as specified in equation 1 below). Although other techniques could also be used to measure porosity such as scanning electron microscopy (SEM) or transmission electron microscopy (TEM). The "pore size" is defined according to the invention as the geometric distribution of the pores in the material, with "macropores" being defined in this invention as those pores that have widths greater than 50 nm. The technique used to measure the pore size in this invention has been optical microscopy (using a Nikon ECLIPSE E200 device, with a 10x magnification lens, in addition to the calculation specified in equation 2).Although other techniques such as scanning electron microscopy (SEM) or transmission electron microscopy (TEM) could also be used to measure porosity, both porosity and pore size have been calculated from equations 1 and 2. In the present invention, the "sugar tempering method" consists of forming a mixture of sugar and the PDMS-containing synthesis material, such that upon gelling the entire mixture and subsequently removing the sugar from it, pores are formed in the material, giving it a sponge-like morphology. The resulting Z@TEOS@PDMS material has a high porosity that allows for the absorption of a wide variety of reagents. In fact, its porosity ranges between 55-80% by volume relative to the total volume of the porous three-dimensional matrix, preferably 60-75%, and even more preferably 66±6%. This gives it high porosity, very light weight, low density, and high elasticity. All of these characteristics derived from the porosity of the material are also useful for using this material as a sensor for the detection and / or determination of analytes.The sizes of said pores are between 20-360 μm, preferably 85-295 μm, even more preferably 200 μm. It has been observed that these pore sizes 85-295 μm, optimize both the quantity and the homogeneous distribution of the reagent to be retained and / or released, thereby optimizing the detection and / or determination of analytes. The porous three-dimensional matrix Z@TEOS@PDMS according to the invention can have any geometry or size, although preferably its size is between 7-15 mm in diameter, and / or 1.5-2 mm in thickness. This size at the millimeter level can be measured using different techniques, for example, using a caliper with a precision of up to 0.05 mm or a millimeter ruler. Depending on the intended use of the sponge (releasing reagents or capturing the analyte), the size of the sponge can be modified, optimizing its use to obtain the best possible detection and quantification limits.For example, regarding reagent release, depending on the volume of solution to be analyzed, the amount of reagent embedded in one sponge size or another would be sufficient. In the cases studied, a sponge size of 7 mm in diameter is sufficient to analyze at least 2 mL of solution. If larger volumes are to be analyzed, the sponge size may need to be larger. PDMS provides the three-dimensional Z@TEOS@PDMS matrix with high elasticity and malleability, high chemical and thermal stability, biocompatibility, chemical resistance, zero toxicity, and transparency, in addition to high permeability to gases, vapors, and liquids.Furthermore, the combination of the 3 components of the three-dimensional matrix of the invention (PDMS, TEOS, and zeolite) in the Z@TEOS@PDMS matrix provides a series of advantages that are mentioned below: The addition of tetraethylorthosilicate (TEOS) confers a certain hydrophilic character to the PDMS polymer matrix, which is inherently hydrophobic. With the addition of TEOS, the dispersion of the zeolite in the sponge is facilitated, improving the pore size distribution of the porous matrix; and therefore the loading of the sensor reagents in the Z@TEOS@PDMS sponge in a more homogeneous manner, avoiding the loss of reagent. It also improves the mechanical properties of the Z@TEOS@PDMS matrix and reduces the gelation time, that is, the time it takes to obtain the solid matrix of Z@TEOS@PDMS with the sugar from the liquid mixture of the compounds that confer it, by means of the synthesis method that will be explained later.Zeolite is a crystalline aluminosilicate with a porous structure containing channels and cavities of molecular size and well-defined interconnections, which allow the transfer of molecules into its interior. When zeolite is added together with the PDMS polymer, the transfer of these molecules (reactant) into the Z@TEOS@PDMS three-dimensional matrix is ​​also achieved, especially if the zeolite particles are homogeneously dispersed in the matrix (which is in turn promoted by the presence of TEOS as indicated above), thus facilitating the retention and release of these molecules by the three-dimensional matrix.Furthermore, the addition of zeolite to the Z@TEOS@PDMS also allows the reagent used to be retained / embedded and dispersed more homogeneously within the sponge, further preventing reagent loss once it has been loaded into the matrix (for example, the sponge can be loaded by immersing it in a solution containing the reagent(s). Furthermore, the addition of zeolite provides the Z@TEOS@PDMS matrix with properties such as adsorption and ion exchange capacity, which improves the matrix's interaction with molecules such as sensor reagents and analytes. By providing the matrix with zeolite, a Z@TEOS@PDMS matrix is ​​also achieved with structures that improve the matrix's ability to retain and / or release different reagents.Additionally, the addition of zeolite also improves the mechanical properties of the three-dimensional Z@TEOS@PDMS matrix, giving robustness to the sponge, and increasing the sensitivity of the three-dimensional Z@TEOS@PDMS matrix as a sensor by increasing its surface area / volume ratio. Furthermore, the addition of zeolite also favors the synthesis of the matrix by promoting its gelation (solidification of the Z@TEOS@PDMS sponge-like material after synthesizing it from a liquid mixture of its components). In summary, a better distribution is achieved in terms of homogeneity and pore size of the synthesized porous three-dimensional Z@TEOS@PDMS matrix, as well as in the loading and distribution of sensor reagents in the matrix, with the addition of zeolite (and TEOS) to the PDMS. In a preferred embodiment of this first aspect, the zeolite comprised in the matrix of the invention has a particle size of less than 20 μm, according to the manufacturer's specifications.This size of less than 20 μm aids in greater and more homogeneous dispersion of the zeolite in the matrix, leading to a more homogeneous distribution of the retained reagents in the resulting Z@TEOS@PDMS material. In another preferred embodiment of this first aspect, the zeolite comprised in the matrix of the invention is present at a concentration of between 0.5% and 1% by weight based on the weight of the PDMS and TEOS mixture. This provides the advantage of achieving gelation of the material, since without the zeolite, a solid material is not obtained. Furthermore, it allows for a more homogeneous distribution of the retained reagents inside the sponge, providing better responses in the analysis of analytes captured in the sponge itself or improved release of these reagents into the test solution.It has been observed that percentages of zeolite less than 1% provide the material with less robust characteristics, with less thickness and a greater likelihood of breakage, decreasing its capacity to retain and / or release reagents and analytes within it. Furthermore, it has been studied that the use of a percentage greater than 1% of zeolite in the synthesis does not present structural changes with respect to the use of 1%. In another preferred embodiment, the zeolite has a particle size less than 20 μm. In another preferred embodiment, the zeolite is present at a concentration of 1% by weight based on the weight of the mixture of PDMS and TEOS. In fact, in a preferred embodiment, the zeolite has a size of less than 20 μm and is added at a concentration of 1% by weight based on the weight of the mixture of PDMS and TEOS.In another preferred embodiment of this first aspect, the PDMS in the matrix of the invention is present at a concentration of 40-60% by weight relative to the amount of TEOS, preferably at a concentration of 60% by weight and the TEOS at a concentration of 40% by weight. This provides the porous three-dimensional matrix Z@TEOS@PDMS with greater robustness and a greater loading capacity of the matrix with the sensor reagent. Therefore, a particular non-limiting example of the invention according to this embodiment would be the porous three-dimensional matrix comprising 60% PDMS and 40% TEOS (and 1% zeolite relative to the weight of the mixture of PDMS and TEOS). In another preferred embodiment of this first aspect, the matrix of the invention has a thickness of between 1.5 and 2 mm. In this way, optimal retention of the reagents for the assays studied in this invention is guaranteed.A smaller thickness would result in a less robust material, and its reagent retention capacity would be lower. Furthermore, for the tests studied in this invention, it has not been necessary to use a material with a greater thickness to obtain good results. In another preferred embodiment of this first aspect, the matrix of the invention has a size between 7 mm and 15 mm in diameter. This way, a sponge size that is sufficiently small (7 mm) is obtained to be able to perform tests with reduced sample volumes (up to 2 mL) in the release of reagents, or lower detection limits are obtained in the analysis in atmosphere with a larger sponge size (15 mm). In another preferred embodiment of this first aspect, the matrix does not comprise imidazole and / or imidazolate, and / or does not comprise zeolites with imidazole and / or imidazolate.A second aspect of the invention relates to a method for obtaining the matrix of the invention comprising the steps of: a) mixing TEOS and zeolite; b) adding PDMS to the mixture of section a) with stirring until a homogeneous mixture is obtained; c) adding a PDMS curing agent to the mixture of section b) with stirring until a homogeneous mixture is obtained; d) adding sieved sugar of size between 300 and 400 µm to the mixture c) and homogenizing by stirring; e) pouring the mixture obtained in section d) into a mold and allowing it to gel, where the gelation is preferably carried out by a heating step at 30-50 ° C for 10-24 hours, preferably at 40 ° C, preferably for 12 hours.f) removing the resulting solid from the mold and drying it, preferably by heating it at 70-90 °C for 20-30 minutes, preferably at 90 °C, preferably for 30 minutes; and g) removing the sugar from the resulting solid, preferably by immersing it in stirring water; thereby obtaining the porous three-dimensional matrix Z@TEOS@PDMS. The addition of sugar in step d) has the advantage of allowing the gelation of the PDMS-TEOS-ZEOLITE synthesis with sugar particles (preferably granulated and sieved), since by mixing the sugar during the synthesis and allowing it to gel, the sugar particles become embedded in the mold during the synthesis, taking the shape of the mold, allowing the pores to form in the material, thus giving the resulting matrix a sponge-like morphology when the sugar is removed and allowing the sample to gel with the new composition of the invention.The addition of granulated and sieved sugar allows not only the production of sponges in the shape of the mold used for the synthesis, but also a more homogeneous distribution of pores with sizes within an acceptable range for good performance in the retention and / or release of reagents and analytes. The gelation in step e) allows the production of a solid intermediate material, and can be carried out by heating between 30-50 °C, for a time between 10-24 hours, preferably at 40 °C, preferably for 12 hours, which provides the advantage that the gelation is carried out entirely at a temperature at which the material does not degrade and in a minimum time so that the solvent, such as TEOS, evaporates almost completely and the material remains solid and dry.Gelling according to the invention refers to obtaining the PDMS synthesis mixture with the sugar particles in a solid state by applying heat, at least at a temperature between 30-50 ° C, preferably 40 ° C, for a time between 10-24 hours, preferably 12 hours. This step is necessary to obtain a solid from which the sugar will subsequently be removed to obtain the sponge. If this gelation step is not carried out, a solid is not obtained, but rather a "paste" with which the final sponge structure is not obtained. The drying of step f) after extracting the solid intermediate material from the mold, provides the advantage of obtaining the dry or practically dry solid material with the shape of the mold of step e), a shape that is stable after drying.During this stage, any remaining liquid components, such as TEOS, that could negatively interfere with sponge formation during the sugar elimination stage, are eliminated, ensuring the formation of this sponge-like structure. This stage is preferably carried out by heating between 70-90°C, preferably 90°C, for 20-30 minutes, preferably 30 minutes. This has the advantage of eliminating any remaining TEOS, which could hinder sponge formation during the sugar elimination stage. If the material is not completely dry when the sugar elimination stage begins, the sponge-like structure will not form properly.If this drying step is carried out at a temperature of 90°C for 30 minutes with the material outside the mold, so that all areas of the mold are in contact with the heat of the oven, the material is completely dried, eliminating any liquid that may remain in the material that could prevent the formation of the sponge in subsequent stages. Furthermore, this step is carried out for a maximum of 30 minutes to prevent any degradation of the material. The sugar in step g) can be removed by..., although it is preferably done by immersing the solid in an aqueous solution, for example, water, which provides the advantage of being a non-toxic solvent, with a high boiling point that allows heating without easily evaporating and in which sugar is highly soluble, even at room temperature.This immersion can also optionally be carried out at a temperature between 40-50 °C, preferably at 50 °C, for a time between 10-20 minutes, preferably 10 minutes. This facilitates the removal of the sugar by dissolution. The solvent for dissolving the sugar can be any in which it is soluble, carrying out the dissolution at the temperature at which said solvent dissolves the sugar, the solvent being preferably water. This step g) can be carried out as many times as necessary, for example 3 times, until the sugar is completely dissolved. The mixing or stirring according to the invention comprises any process known for this purpose in the state of the art, for example, mixing by magnetic stirring or by ultrasound.The combination of all these steps allows the generation of the new three-dimensional matrix Z@TEOS@PDMS with high porosity and a controllable pore size, which is also capable of retaining and / or releasing reagents, for example, sensor reagents that make the Z@TEOS@PDMS sponge a sensor with high speed and sensitivity for sensing analytes. It is also worth mentioning that the addition of species comprising imidazole or imidazolate to the mixture, when synthesizing the Z@TEOS@PDMS matrices, presents problems when gelling the Z@TEOS@PDMS material, so preferably the zeolites to be added according to the invention are zeolites that do not comprise imidazole or imidazolate, whereby imidazolate zeolites, for example ZIF type zeolites such as ZIF-67, are less preferred according to the invention.Furthermore, imidazole and / or imidazolate are not soluble in TEOS, so the mixture does not dissolve well and a homogeneous mixture is not achieved during the synthesis of the Z@TEOS@PDMS matrix. In a preferred embodiment, the method for obtaining the Z@TEOS@PDMS matrix does not comprise the addition of imidazole and / or imidazolate, and / or does not comprise the addition of zeolites with imidazole and / or imidazolate, in any of its steps. In a preferred embodiment of this second aspect, the zeolite has a particle size of less than 20 μm. In another preferred embodiment of this second aspect, the zeolite is added in a concentration of up to 1% by weight in the mixture resulting from step a). In another preferred embodiment of this second aspect, the PDMS is added in a concentration of 40-60%, preferably 60% by weight, on the total mixture after step b).In another preferred embodiment of this second aspect, the PDMS is prepared from two components, a base selected from silicone elastomers (such as polydimethylsiloxanes or polyvinylmethylsiloxanes) and a curing agent selected from curing agents suitable for curing said silicone elastomer(s). Some non-limiting examples of said curing agents are catalysts such as tin octoate (STO) or dibutyltin dilaurate (DBT) as component B, which is the standard curing agent. Even more preferably, the PDMS used as a polymer matrix is ​​manufactured from a Sylgard 184 silicone elastomer kit containing the base as component A, and the curing agent as component B. Preferably, the base and the curing agent are mixed in a 10:1 ratio by mass.In the present invention, polydimethylsiloxane (PDMS) is preferably used as the silicone elastomer, as it is a hydrophobic, crosslinked silicone elastomer that provides stability, is optically transparent, inert, non-flammable, and non-toxic. The order of addition for the formation of the polymer is to homogenize the mixture with PDMS and, once the homogeneous synthesis mixture is obtained, a curing agent is added to obtain the polymer. If the PDMS is polymerized before obtaining the synthesis mixture, it would be difficult to obtain a homogeneous polymer with TEOS and zeolite, and subsequently with sugar, which would prevent the formation of the sponge as described in this invention. The sugar added in step c) is preferably a pre-sieved sugar, such that the particle size and particle size distribution of the sugar can be controlled.This has an effect on the resulting Z@TEOS@PDMS matrix, since it allows controlling both the % porosity, as well as homogenizing and / or controlling the pore size. In another preferred embodiment of this second aspect, the sugar added in step c), either sieved or unsieved, has a particle size between 200 and 600 μm. In fact, the use of a small particle size of sugar (around 300 and 400 μm) provides more compact and homogeneous pores with each other. This improves the retention of the reagent inside the sponge, providing more homogeneous and reproducible reagent retention and detection and / or determination of the analyte, either for the response of the sensor reagent retained in the Z@TEOS@PDMS sponge-type device itself, or for the subsequent release of said sensor reagent into the medium.This homogeneous response increases reproducibility by manufacturing different sponges and retaining different reagents in them, since each different sponge retains a similar or identical amount of reagent. In fact, the best relationship between sensitivity and reproducibility and homogeneity of response is obtained with the use of a sieved sugar particle size between 300 and 400 μm, which allows obtaining high porosities of the Z@TEOS@PDMS sponge, for example, a porosity of 66 ± 6% by volume with respect to the total volume of the sponge, porosity calculated from equation 1, which optimizes the homogeneity and amount of reagent retained by the Z@TEOS@PDMS sponge, as well as the release of reagents from the sponge to the medium, where appropriate, thereby improving both the speed and sensitivity in the detection and / or determination of analytes in the medium to be measured with the Z@TEOS@PDMS sponge.On the contrary, it has been surprisingly observed that a smaller sugar particle size (less than 200 μm) makes the synthesis of the Z@TEOS@PDMS sponge difficult, since the sugar powder as a template forms a paste that does not favor the formation of sponge since it forms a compact solid mass. In another preferred embodiment of this second aspect, the sugar added in step c) has a 7:3 weight ratio with respect to the rest of the components of the mixture that form part of the three-dimensional matrix resulting after step g). This 7:3 ratio ensures that in the synthesis mixture (with sugar) the sugar does not notably predominate over the PDMS synthesis, thus achieving a balance in the proportions. If the proportion of sugar is too high with respect to the PDMS synthesis, this prevents the formation of a robust structure because the sugar particles do not allow a good bonding of the polymer with each other.On the other hand, if the amount of PDMS significantly predominates over the sugar particles during the synthesis, pore formation is low, resulting in a solid mass with hardly any porosity. The material or matrix of the invention is useful for use as a sensor for the detection and / or determination of analytes, by retaining and optionally releasing reagents previously retained in the Z@TEOS@PDMS material, in greater quantities and in a more homogeneous manner. This, together with its low weight, density, robustness, and high elasticity, makes the Z@TEOS@PDMS a good portable device for retaining reagents as well as for the analysis and / or detection of analytes, for example at the point of need. Therefore, a third aspect of the present invention relates to a sensor for detecting and / or determining analytes, comprising the matrix of the invention and at least one sensor reagent capable of detecting and / or determining an analyte embedded in the three-dimensional matrix.According to the present invention, the term "reagent" or "sensor reagent" refers to any compound capable of interacting or reacting with an analyte, such that, based on said interaction or reaction, it is possible to quantify and / or determine the presence and / or concentration of said analyte. Preferably, it is selected from 1,2-naphthoquinone-4-sulfonate (NQS), salicylate (SL), nitroprusside (NP), sulfanilamide (SA), N-(1-naphthyl)ethylenediamine dichlorohydrate (NEDD), urease, Fast Blue B (FBB), 4-amino antipyrine (4-AAP), and any combination thereof. More preferably, the combination of two or more reagents provides the advantage of being able to detect and / or determine different types of analytes at different concentrations in the same medium and with the same sensor.Some of these reagents are more stable under certain storage conditions, such as 4-amino antipyrine or urease, which are more stable than Fast Blue B, which can degrade more easily. The invention also contemplates as a reagent any compound that reacts to form a colorimetric reaction, such as the Folin-Ciocalteu (FC) compound for the determination of phenols. Furthermore, species that comprise amino groups in their structure, such as imidazole or imidazolate, being secondary amines, react with the NQS sensor reagent, thus impairing its function as a sensor reagent, for example, to detect ammonia or ammonium, which is why its use is less preferred according to the invention. Another amine that also reacts with the sensor reagent, thus impairing its sensor function, is polydopamine (PDA), which is why its use is also less preferred.In fact, the three-dimensional Z@TEOS@PDMS matrix, which combines TEOS and zeolite in the PDMS matrix, allows rapid diffusion, in just a few seconds, of both the analyte and the reagent retained / embedded in the Z@TEOS@PDMS matrix, or released by the Z@TEOS@PDMS matrix. Therefore, when this matrix is ​​used as a sensor, it presents high sensing speed and sensitivity to the analytes to be detected and / or determined in different media, for example, in aqueous solution. This gives the sponge loaded with the reagents characteristics similar to those obtained when these reagents are used in solution, which is not the case with these same reagents embedded in other types of sensors with a polymeric matrix.Furthermore, these reagents embedded in the sponge can be stable under certain storage conditions, such as storage at a temperature of 4°C in the case of urease or -20°C in the case of the other reagents studied in this invention, which is not possible when they are in solution since these reagents degrade easily. In fact, thanks to the combination of these 3 compounds, the Z@TEOS@PDMS matrix presents a highly improved absorbance (for example, to ammonia) with respect to other analyte sensors in the state of the art, as will be observed by way of example in Figure 3, which will be explained later. Another advantage of the use of this porous matrix as a sensor is that by allowing both the retention and subsequent release of different reagents, it allows high adaptability to the use of different sensor reagents for the detection / determination of a high amount of analytes in a wide variety of media.Furthermore, it indicates that it is applicable to a large number of colorimetric reagents, regardless of the analyte they determine, their composition, or the medium in which they are found. A fourth aspect of the present invention relates to contacting the matrix with a solution containing the reagents to be retained / embedded in the matrix.More specifically, the fourth aspect of the present invention relates to a method for obtaining a sensor described according to the third aspect of the present invention; which comprises obtaining a matrix according to steps (a) to (g) of the method described according to the second aspect of the present invention, which additionally incorporates the following steps: h) immersing the porous three-dimensional matrix obtained in step g) in a solution of at least one sensor reagent, that is, in a solution containing a sensor compound to detect the analyte, such that said sensor compound is incorporated into the three-dimensional matrix or sponge; i) removing the excess solution absorbed from the matrix after its immersion in section (h) by using an absorbent material, preferably using paper, cotton cloth and / or cotton gauze, more preferably paper, thus obtaining the sensor with the reagent incorporated.This step i) is only necessary for sensors that are going to capture the analyte inside, but, however, it is not necessary for sensors that release the reagents into the solution. The absorbent material is not limited, although it is preferably paper, AA, BB... In a preferred embodiment of the fourth aspect, the solution of step (h) comprises at least one reagent selected from 1,2-naphthoquinone-4-sulfonate (NQS), salicylate (SL), nitroprusside (NP), sulfanilamide (SA), N-(1-naphthyl)ethylenediamine dichlorohydrate (NEDD), urease, Fast Blue B (FBB), 4-amino antipyrine (4-AAP), or any combination thereof. A fifth aspect of the present invention relates to the use of the matrix of the invention for the manufacture of a sensor to detect and / or determine analytes. A sixth aspect of the present invention relates to the use of the sensor of the invention for the detection and / or determination of analytes.In a preferred embodiment of the use of the sensor of the invention, the analyte is selected from ammonium, ammonia, phenols, urea, cannabidiol (CBD), 3,5-dihydroxyhydrocinnamic acid (DHCA), nitrites, nitrates, or combinations thereof. In another preferred embodiment, the analyte is found in gaseous media, solid media, or aqueous media, preferably biological matrices, air, and food. A seventh aspect of the present invention is the method for estimating analytes in a gaseous, aqueous, or solid medium, which comprises I. contacting the sensor described above with the medium comprising the analyte to be detected and / or determined; II. waiting a time between 5 and 80 minutes (depending on the assay); and III. observing a change in the color of the embedded sensor reagent and / or the solution.In fact, by using the sensor of the invention, the present invention provides a simple, rapid and low-cost method for estimating different analytes in media such as atmospheres or aqueous media, by using the Z@TEOS@PDMS material with at least one embedded sensor reagent as a sensor, by bringing the sensor (Z@TEOS@PDMS porous matrix with the retained / embedded sensor reagent) into contact with the medium comprising the analyte to be detected and / or determined, and / or by releasing (optionally, where appropriate) the reagents embedded in the Z@TEOS@PDMS matrix into the medium, the matrix and the medium being in contact. This makes it possible to detect and / or determine analytes in the medium, for example, by a color change of the Z@TEOS@PDMS material comprising the embedded sensor reagent, and / or a color change of the solution in which the sensor reagent previously embedded in the Z@TEOS@PDMS matrix is ​​optionally released.The sensor of the invention can be used to detect and / or determine a wide variety of analytes, depending on the sensor reagent used, in different concentrations, with high sensitivity and quickly. According to the invention, "analyte" is understood to mean any chemical or biological compound present in a medium whose presence and concentration in said medium is of interest to determine, for example, through its interaction or reaction with the "sensor reagent." Preferably, the analyte is selected from ammonium, ammonia, phenols, urea, cannabidiol (CBD), 3,5-dihydroxyhydrocinnamic acid (DHCA), nitrites, nitrates, or combinations thereof. Examples of some phenols to be determined are resorcinol or acid phenols such as 3,4,5-trihydroxybenzoic acid. The analytes to be detected can be found in any type of medium: gaseous, solid, liquid (such as aqueous), or combinations thereof.In fact, in another preferred embodiment, the analyte is found in solid media such as biological matrices, foods, soils, vegetation, etc.; liquid media such as aqueous solutions or matrices, saliva, urine, alcoholic beverages, plant and fruit juice, etc.; and gaseous media such as air, atmospheres of animal or industrial environments, breath, etc.; or combinations thereof such as an aqueous biological matrix. The aforementioned sensor reagents retained in the Z@TEOS@PDMS matrix result in a sensor device that is useful, for example, for estimating the presence of ammonia (NH3) in atmospheres, or of ammonium (NH4. +) in saliva, nitrite (NO2-) and nitrate (NO3-) in water, cannabinoid compounds in plants and drugs, phenols and ammonium in water. The detection and / or determination of ammonium, urea (CO(NH₂)₂) and / or 3,5-dihydroxyhydrocinnamic acid (DHCA) can be carried out in biological matrices such as saliva and urine. The detection and / or determination of ammonia can be carried out in large volume atmospheres or media, for example, those dedicated to livestock and other animal husbandry and industries, as well as in small volume atmospheres or media such as food or liquid samples in a confined atmosphere. On the other hand, the determination of ammonium, phenols, cannabidiol, nitrite and nitrate can be carried out in liquid samples.The detection and / or release of the analyte with the Z@TEOS@PDMS sponge can also be performed by the release of the reagents previously embedded / retained in it, for example by the release of sodium salicylate (SL) and nitroprusside (NP) to detect ammonium in solution, of amino antipyrine (4-AAP) to detect phenol (Ph) or bisphenol-A (BPh-A), of urease together with sodium salicylate (SL) and nitroprusside (NP) to determine urea and / or ammonium in solution, of Fast Blue B (FBB) to detect 3,5-dihydroxyhydrocinnamic acid (DHCA) and / or cannabidiol, of sulfanilamide (SA) and N-1-naphthyl-ethylenediamine dichlorohydrate (NEDD) to determine nitrites and nitrates, etc.These reagents are released into a test solution containing the analytes to be detected and / or determined. This solution is where the reaction with the reagent occurs, allowing the detection of the different analytes in solution based on a color change in the solution detected with the naked eye in a qualitative analysis. This can also be quantified using different methods such as diffuse reflectance spectrophotometry using laboratory equipment, or miniaturized portable methods using a smartphone. These are colorimetric reagents, and therefore, the detection of the analyte is determined from a color change in the solution or in the sensor itself.The advantage of releasing the reagents previously embedded in the sponge is that when the reagents are released, the sponge is capable of re-retaining and optionally re-releasing new analyte-sensing reagents, so that the Z@TEOS@PDMS sponge can be reused, for example, as a sensor for the detection and / or determination of new analytes in new media after loading it with new sensor reagents. In a preferred embodiment of the analyte estimation method, the observation of the color change in step III is carried out by UV-Vis absorbance measurements, diffuse reflectance, or by means of an app or software, preferably SPECTROFREE.The quantitative determination of the analyte to be detected and / or determined present in the medium can be carried out by UV-Vis absorbance measurements, diffuse reflectance measurements, or using a SPECTROFREE app developed by the research group of the present invention through the image generated on the smartphone. The results show that these sponge-type devices are reproducible, cost-effective, stable over time under low-temperature conditions, and, in the case of dissolution tests, reusable.Furthermore, they allow simple and rapid detection of analytes with the option of developing the assay at the point of need, that is, at the specific time or situation in which an individual or entity requires or desires a particular resource, product or service to fulfill a specific purpose or address a particular problem or need, such as environmental analysis of ammonia, nitrates, nitrites and / or phenols, among others, as well as tests in biological matrices such as ammonium in saliva, among others, which require in-situ testing, quickly and simply. In summary, the ability of these Z@TEOS@PDMS sponges to retain and / or release different sensor reagents in a precise and homogeneous manner makes them potential analyte sensing devices that present high sensitivity, as well as a low detection time in the detection of the analyte of interest, as can be seen in Table 2.For example, detection limits as small as 0.01 mg NH4 are obtained. + / mL for the determination of ammonium in saliva, 0.01 ppm for the detection of nitrites in water, or 0.04 ppm for the determination of DHCA in urine. Regarding analysis times, the range is between 80 and 5 minutes, which includes the entire analysis process for these analytes, allowing times as low as 5 minutes, for example, in the determination of nitrites and nitrates in water, DHCA in urine, or CBD in water. An eighth aspect of the invention is a computer program adapted to implement the method for detecting and / or determining analytes described above. Throughout the description and claims, the word "comprises" and its variants are not intended to exclude other technical features, additives, components, or steps. For those skilled in the art, other objects, advantages, and characteristics of the invention will become apparent partly from the description and partly from the practice of the invention.The following examples and figures are provided by way of illustration, and are not intended to be limiting of the present invention. BRIEF DESCRIPTION OF THE FIGURES To complement the description and in order to aid in a better understanding of the features of the invention, in accordance with preferred embodiments, figures are attached as an integral part of said description, in which the following is represented for illustrative and non-limiting purposes: Figure 1.- Shows the molds for the design of the absorbent base material and the different Z@TEOS@PDMS sponges obtained. The small mold is for obtaining 7 mm diameter sponges, while the large mold is for obtaining 15 mm diameter sponges.The synthesis process is also shown according to steps e) corresponding to heating in an oven for 12 hours at 40ºC, f) corresponding to heating in an oven for 30 minutes at 90ºC, and g) corresponding to the sugar elimination stage. The graph shown was made by UV / Vis spectrometry, where the absorbance of sucrose in water was determined during the sugar elimination stage (stage g). The absorbance of sucrose in the three sugar elimination stages is shown at a wavelength of 270 nm, where it is observed that in the second and third stages, no absorbance signal is obtained at this wavelength, therefore, almost all the sugar is eliminated. Figure 2.- It shows images obtained by optical microscopy of unloaded Z@TEOS@PDMS sponges found in the first row, loaded Z@TEOS@PDMS@NQS sponges observed in the second row in lighter gray color being yellowish in the original color image, and in the third row their colorimetric responses to 34.8 mg NH3 / m. 3(50 ppmv) of ammonia with a darker gray coloration being brownish in the original coloration, with proportions of 40:60 and 60:40 of PDMS-TEOS in that, with zeolite, and using a sugar size of 300-400 μm to form the previous template on which the mixture of PDMS, TEOS, and zeolite is poured; sugar template that is subsequently removed by dissolving it. Figure 3.- Shows the response of other PDMS-TEOS-NQS-NPsSiO2 and PDMS-TEOS-NQS-IL-NPsSiO2 sensors with formulations of previous patents, compared to the Z@TEOS@PDMS@NQS sensor of the present invention with a sugar size in its synthesis of between 300-400 μm and a ratio of 60:40 PDMS- TEOS. Test carried out in the 2L static dilution bottle for 20 minutes with an ammonia concentration of 34.8mg / m3, equivalent to 50ppmv. Figure 4.- Shows diffuse reflectance spectra obtained for the Z@TEOS@PDMS@NQS sponges of: A) at different ammonia concentrations (0 – 34.8 mg / m 3, equivalent to 0 – 50ppmv) in the 2 L static dilution bottle for 20 minutes; of: B) and C) its stability with the storage time in the freezer, so that it is observed how the sensor is stable under these storage conditions by presenting a similar absorbance for the same concentration after at least two months, a) corresponding to the same day, b) one week, e) one month, f) one and a half months, g) two months; and of: D) of 7 mm diameter Z@TEOS@PDMS@NQS sponges in the static dilution bottle for 10 minutes. Figures A and D represent the increase in absorbance with increasing NH3 concentration. Figure 5.- Shows the diffuse reflectance spectra obtained for the 7 mm diameter Z@TEOS@PDMS@NQS sponges at: A) at different ammonia concentrations (0 – 417 mg / m3, equivalent to 0 – 0.22 mg / mL of saliva sample) in a 50 mL bag, for 10 minutes; B) its stability with the storage time in a freezer, a) corresponding to the same day, b) one week, c) two weeks, d) three weeks, e) one month, f) one and a half months, g) two months; and C) at different ammonium concentrations (0 - 20 ppm) in the 24-well plate for 60 minutes. Figure 6.- Shows the results obtained with the “SPECTROFREE” software application, for the 15 mm Z@TEOS@PDMS@NQS sponge (A) and the 7 mm one (B) for a sample. In this application, it is observed how with only a blank and a standard, the concentration of the sample can be obtained. “Blank Avg” is the measurement of the blank in the three color coordinates red (R), green (G) and blue (B). “Std Avg” is the measurement of the pattern in each of the three coordinates. “Spl Avg” is the measurement of the sample in each of the three coordinates.“K” is the slope obtained from the known concentration of the standard for each coordinate by subtracting the blank (R=K. R C Std .; G=K G C Std ; B= K B C Std “C Sample” is the sample concentration estimated from the K of the pattern for each coordinate and the measurements of the R, G, and B coordinates after subtracting the blank. Looking at the two images above, we conclude that the sample has a concentration of 14.98 mg NH3 / m 3 , as indicated in “C Sample” of the corresponding red color, obtained from a blank and a standard of 14 mg NH3 / m 3 In the two lower images the sample concentration of 0.16 mg NH4 is obtained. + / mL, corresponding to “C Sample” of the red color coordinate, from a blank and a standard of 0.147 mg NH4 + / mL. Figure 7.- Shows UV-Vis spectra obtained for the sponges A) Z@TEOS@PDMS@SL@NP of 7 mm diameter at different ammonium concentrations (0–1 ppm) in an eppendorf for 10 minutes; B) Z@TEOS@PDMS@SA@NEDD of 7 mm diameter at different nitrite concentrations (0–1.25 ppm) in an eppendorf for 5 minutes; C) Z@TEOS@PDMS@PDMS@SA@NEDD of 7 mm diameter at different nitrate concentrations (0 – 25 ppm) reduced to nitrite with zinc nanoparticles (ZnNPs) in an eppendorf for 5 minutes; D) Diffuse reflectance spectra obtained for the 7 mm diameter Z@TEOS@PDMS@NQS sponges at different ammonium concentrations (0 – 2.3 ppm) obtained from the hydrolysis of urea and determined in the 24-well plate for 60 minutes and E) UV-Vis spectra obtained for the 7 mm diameter Z@TEOS@PDMS@SL@NP sponges at different ammonium concentrations (0 – 0.26 ppm) obtained from urea hydrolysis and determined in an Eppendorf for 10 minutes. Figure 8 shows UV-Vis spectra obtained for 7 mm diameter Z@TEOS@PDMS@FBB sponges at different concentrations of A) DHCA (0 – 2 ppm) and B) CBD (0 – 20 ppm), both A) and B) determined in an Eppendorf for 5 minutes; and of Z@TEOS@PDMS@AAP sponges at different concentrations of C) phenol (0 – 2 ppm) and D) bisphenol A (0 – 5 ppm), both C) and D) determined in an Eppendorf for 10 minutes. Figure 9.- Shows the results obtained with the SPECTROFREE application for the 7 mm Z@TEOS@PDMS@AAP sponge, for two samples A) and B) comprising an aqueous phenol solution of 0.5 ppm and 1 ppm respectively. “Blank Avg” is the measurement of the blank in the three color coordinates red (R), green (G) and blue (B). “Std Avg” is the measurement of the pattern in the three coordinates. “Spl Avg” is the measurement of the sample in the three coordinates.“K” is the slope obtained from the known concentration of the standard. “C Sample” is the concentration of the sample obtained from that of the standard. If we observe the two upper images, it is concluded that the sample has a concentration of 0.54 ppm of phenol, as indicated in “C Sample” of the corresponding green color, obtained from a blank and a standard of 0.5 ppm of phenol. In the two lower images, the sample concentration of 0.98 ppm of phenol is obtained, corresponding to “C Sample” of the green color coordinate, from a blank and a standard of 1 ppm of phenol. EXAMPLES The invention will now be illustrated by means of tests carried out by the inventors, which demonstrate the effectiveness of the product of the invention. 1. Experimental procedures 1.1.Reagents Elastomer Base (PDMS) (Sylgard 184); tetraethylorthosilicate (TEOS) (Sigma Aldrich); zeolite (Sigma Aldrich); 1,2-naphthoquinone-4-sulfonate (NQS) (Sigma Aldrich); ammonium chloride (NH4Cl) (Probus); 2M NaOH solution (VWR Chemicals); 2M bicarbonate buffer solution pH = 11.3 (Merk Eurolab), sulfanilamide (SA) (Guinama); N-1-naphthyl-ethylenediamine dichlorohydrate (NEDD) (Fluka); zinc nanoparticles (ZnNPs) (Sigma Aldrich); sodium nitrite (Merk Eurolab); potassium nitrate (Merk Eurolab); 330mM citric acid solution (VWR Prolabo); ethanol (VWR Chemicals); Sodium salicylate (SL) (Sigma Aldrich); sodium nitroprusside (NP) (Probus); 1M NaOH solution – 0.6% NaOCl (VWR Chemicals); 0.2M phosphate buffer solution, pH = 7.2 (PanReac); urea (VWR Chemicals); urease (Sigma Aldrich); Fast Blue B (FBB) (Sigma Aldrich); cannabidiol (CBD) (Sigma Aldrich); 3,5-dihydroxyhydrocinnamic acid (DHCA) (Sigma Aldrich); 4-amino antipyrine (4-AAP) (Sigma Aldrich); potassium ferrocyanide (K3Fe(CN)6) (Probus); phenol (Ph) (Sigma Aldrich); bisphenol A (BPh-A) (Sigma Aldrich). 1.2. Instrumentation Cary 60 UV-Vis spectrophotometer, with “VideoBarrelino” video accessory and differential refractory optical fiber: reflectance spectra recordings in the range 200-1000 nm; oven (Pol-Eko Aparatura); Ultrasonic Cleaner (LBX instruments); DTS-2 microplate thermostatic shaker (Elmi); Redmi Note 8 smartphone. 1.3. Sensor Design Figure 1 shows the synthesis scheme of Z@TEOS@PDMS sponges. It is carried out based on the sugar annealing method for the formation of sponges with modifications. First, zeolite (0.038 g x) is mixed with tetraethylorthosilicate (TEOS, 1.4g x) and a dispersion is formed under ultrasound for a few seconds. Next, the polydimethylsiloxane polymer matrix (PDMS, 2g x) is added and stirred for 45–60 minutes, depending on the viscosity of the synthesis. The curing agent (0.2g x) is added and homogenized for 15 minutes. Sifted sugar with a particle size between 400 and 300μm is added in a 3:7 ratio (synthesis:sugar) with respect to the synthesis mass (3.438g). For the largest sponge, 0.4g of the mixture is weighed into a mold (an 8-well plate) (Figure 1). When the smaller sponge is synthesized, 0.12g of the mixture is weighed into another mold (a plate of up to 25 wells). In both cases, the gel is left to set for 12 hours in an oven at 40°C, then removed from the mold and dried for 30 minutes at 90°C. For each gram weighed, 7 to 8 large sponges and up to 30 small ones are obtained.Next, to remove the sugar, 2 mL of water is added to each of the 24 wells of a plate and shaken at 50 ° C for 10 minutes, performing this step up to 3 times with each sponge. Z@TEOS@PDMS sponges of 15 mm diameter and 7 mm diameter sponges are obtained, both with a thickness between 1.5-2 mm. To obtain the Z@TEOS@PDMS@NQS sponges with the sensor reagent retained in them, 5 large or 12 small ones are immersed in an aqueous solution of 10,000 ppm of NQS for approximately 30 minutes. They are then carefully dried with a paper towel to remove excess solution from the sponge and stored at a temperature of -20 ° C until use. To obtain the Z@TEOS@PDMS@SL@NP sponges, they are immersed in a 50:50 ethanol-water solution of 10000ppm salicylate (SL) and 5000ppm nitroprusside (NP) for 30 minutes and stored at a temperature of -20ºC until use.In the case of Z@TEOS@PDMS@SA@NEDD sponges, the sponges are immersed for 30 minutes in a 50:50 ethanol-water solution of 15000ppm of sulfanilamide (SA) and 5000ppm of N-1-naphthyl-ethylenediamine dichlorohydrate (NEDD) and stored at a temperature of -20ºC until use. To obtain Z@TEOS@PDMS@U sponges, they are immersed in a solution of 8000ppm of urease in 0.2M phosphate buffer and pH = 7.2 for 30 minutes and stored at a temperature of 3ºC until use. In the case of obtaining Z@TEOS@PDMS@FBB, the sponges are immersed in a 2500ppm solution of Fast Blue B (FBB) in water for 30 minutes and stored at a temperature of -20ºC; and to obtain Z@TEOS@PDMS@AAP, the sponges are immersed for 30 minutes in an aqueous solution of 10000ppm of the reagent 4-amino antipyrine (4-AAP) and stored at a temperature of -20ºC until use. 1.4 Determination of ammonia in a Z@TEOS@PDMS@NQS atmosphere 1.4.1 Standard generation Ammonia standards were prepared using 2L static dilution bottles. A known concentration of ammonium in water (100μL) was added, followed by a volume of NaOH (200μL) for complete volatilization of the ammonium to ammonia. 1.4.2 Sponge response The response was measured using two different sponge sizes. The static dilution bottle with the sponge suspended was used. An NH4 solution was introduced into the confined atmosphere. + with basifying solution to generate NH3. NH3 concentrations of 3.5, 7, 10.4, 14, 24.3 and 34.8 mg / m3 have been studied. 3, corresponding to 5, 10, 15, 20, 35 and 50 ppmv of NH3 respectively, for the static dilution bottle of 2L air volume. 1.5 Determination of ammonium in saliva Z@TEOS@PDMS@NQS 1.5.1 Generation of standards For the preparation of ammonia standards, hermetically sealed bags with the sponge adhered to the wall were used. A known concentration of ammonium in water (100μL) followed by bicarbonate buffer (100μL) was added, for air volumes of 50mL in the bag, in order to achieve complete volatilization of ammonium into ammonia. 1.5.2 Sponge response The response measurement was performed in a sealed bag with the sponge adhered to one of the walls. A solution of NH4 was introduced into the confined atmosphere + with basifying solution to generate NH3. Concentrations of 0.018, 0.037, 0.074, 0.147 and 0.221 mgNH4 have been studied. + / mL of saliva sample, corresponding to 34.8, 70, 139, 278 and 417 mg / m 3of air, and 50, 100, 200, 400 and 600 ppmv of NH3 respectively, for the sealed bag of 50 mL volume of air. 1.6 Determination of ammonium in aqueous media Z@TEOS@PDMS@NQS 1.6.1 Generation of standards For the preparation of ammonium standards, 24-well plates of 2 mL volume were used. A known concentration of ammonium in water was added followed by a volume of NaOH (200 μL) up to a volume of 1 mL in each completely sealed well, in order to achieve complete volatilization of ammonium into ammonia. 1.6.2 Sponge response The response measurement was performed with the sponge attached to the lid of the completely sealed 24-well plate. To generate the ammonia atmosphere, a basifying solution of NaOH was introduced along with the NH4 standards. + NH4 concentrations have been studied +1.7 Determination of ammonium in aqueous media Z@TEOS@PDMS@SL@NP 1.7.1 Generation of standards For the preparation of ammonium standards, Eppendorf tubes were used. A known concentration of ammonium in water was added, the sponge loaded with the reagents, and then a volume of 1M NaOH – 0.6% NaOCl (40μL) was added for the formation of indophenol. 1.7.2 Sponge response For the measurement of the response, NH4 concentrations have been studied +of 0.1, 0.2, 0.4, 0.5 and 1 ppm in a total volume of 1 mL of solution. 1.8 Determination of nitrites and nitrates in aqueous media Z@TEOS@PDMS@SA@NEDD 1.8.1 Generation of standards Eppendorf tubes were used to prepare nitrite standards. A known concentration of NO2- in water was added, the sponge loaded with the reagents and then a volume of 330 mM citric acid (500 μL) for the formation of the chromophore that produces the color change. Eppendorf tubes were used to prepare nitrate standards. A known concentration of NO3- in water was added together with zinc nanoparticles immobilized on nylon by filtration for its reduction to nitrites, the sponge loaded with the corresponding reagents was added, and then a volume of 330mM citric acid (500μL) was added for the formation of the chromophore that produces the color change. 1.8.2 Sponge response To measure the response, NO2- concentrations of 0.025, 0.05, 0.25, 0.5 and 1.25 ppm in a total volume of 2 mL and NO3- concentrations of 1.5, 3, 5, 10, 15, 20 and 25 ppm in a total volume of 2 mL. 1.9 Determination of urea in urine by Z@TEOS@PDMS@U and Z@TEOS@PDMS@NQS 1.9.1 Generation of standards For the hydrolysis of urea into ammonium, a sponge loaded with urease is introduced into an Eppendorf tube with 12.5 and 15 ppm of urea in 0.2 M phosphate buffer and pH = 7.2 and left to incubate for 20 minutes in a water bath at 37 ° C. For the preparation of ammonium standards, 24-well plates of 2 mL volume were used. A theoretical concentration of ammonium from the hydrolysis of urea with urease was added, followed by a volume of NaOH (200 μL) up to a volume of 1 mL with water in each completely sealed well, in order to achieve complete volatilization of ammonium into ammonia. 1.9.2 Sponge Response The response measurement was performed with the sponge attached to the lid of the completely sealed 24-well plate. To generate the ammonia atmosphere, a basifying solution of NaOH was introduced along with the NH4 standards. +. The hydrolysis of 12.5 and 15 ppm of urea with the urease sponge has been studied, obtaining, theoretically, 0.75, 1.90, 3.75 and 7.43 ppm of ammonium from which a hydrolysis yield is obtained. 1.10 Determination of urea in urine by Z@TEOS@PDMS@U and Z@TEOS@PDMS@SL@NP 1.10.1 Generation of standards For the hydrolysis of urea in ammonium, a sponge loaded with urease is introduced into an Eppendorf tube with 5 and 15 ppm of urea in 0.2M phosphate buffer and pH = 7.2, and left to incubate for 20 minutes in a water bath at 37 ° C. For the preparation of ammonium standards, Eppendorf tubes were used. A theoretical concentration of ammonium was added from the previously urease-catalyzed hydrolysis of urea and then a volume of 1M NaOH – 1% NaOCl (300μL) for the formation of indophenol. 1.10.2 Sponge response To measure the response, the hydrolysis of 5 and 15 ppm of urea with the urease sponge has been studied, theoretically obtaining 0.05, 0.09, 0.23 and 0.35 ppm of ammonium from which a hydrolysis yield is obtained. 1.11 Determination of cannabidiol (CBD) by Z@TEOS@PDMS@FBB 1.11.1 Generation of standards Eppendorf tubes were used to prepare CBD standards. A known concentration of CBD in water was added and the sponge loaded with the reagent for the formation of the chromophore that produces the color change. 1.11.2 Sponge response To measure the response, CBD concentrations of 2, 5, 10, 15 and 20 ppm in a total volume of 1 mL of solution have been studied. 1.12 Determination of 3,5-dihydroxyhydrocinnamic acid (DHCA) in urine using Z@TEOS@PDMS@FBB 1.12.1 Generation of standards Eppendorf tubes were used to prepare DHCA standards.A known concentration of DHCA in ethanol and the sponge loaded with the reagent were added for the formation of the chromophore that produces the color change. 1.12.2 Sponge response To measure the response, DHCA concentrations of 0.05, 0.1, 0.5, 1 and 2 ppm in a total volume of 1 mL of solution were studied. 1.13 Determination of phenols in aqueous matrices using Z@TEOS@PDMS@AAP 1.13.1 Generation of standards Eppendorf tubes were used to prepare standards for the studied phenols. A known concentration of phenol in water, a volume of 0.5M phosphate buffer pH = 8 (50 μL) and the sponge loaded with the reagent were added. To form the complex that produces the color change, a volume of 15% K3Fe(CN)6 in water (50 μL) was added. 1.13.2 Sponge response To measure the response, phenol concentrations between 0.05 and 2 ppm, and bisphenol A concentrations between 0.05 and 5 ppm have been studied in a total volume of 2 mL of solution.Results In this example, the use of three-dimensional sponge-shaped polymeric membranes doped with different reagents was evaluated in such a way that they allow the retention and / or release of these reagents for the estimation of NH3 in NH4 atmospheres. +, urea, phenols, CBD, DHCA, NO2- and NO3- in aqueous media and biological matrices. The polymeric matrix is ​​composed of PDMS, TEOS and zeolite and after the removal of the sugar template the reagent is loaded by immersion. 2.1 Study of the elimination of sugar in the sponges Figure 1 shows the sucrose spectra in the process of sugar removal from the sponges observing the absorbance at a wavelength of 270nm. In the first 10-minute cycle, spectrum corresponding to the continuous line, most of the sugar present in the device is eliminated, obtaining a lower response in the two cycles that follow in this process, being the dashed line spectra, and dashed line with points, respectively. 2.2 Study of the sponge response with different percentage of PDMS Figure 2 shows optical microscopy images obtained from the different unloaded white Z@TEOS@PDMS sponges loaded with NQS, and their response to 50ppmv of ammonia with proportions of 40:60 and 60:40 of PDMS-TEOS with zeolite and the optimized sugar particle size, in the static dilution bottle for 20 min. 2.3 Study of ammonia patterns for Z@TEOS@PDMS@NQS Table 1 shows the percentage of ammonium volatilization in ammonia in different tests; studying the volume, test time and ammonia concentration used. The determination of ammonium in the solution residue after the test is obtained by the method of using thymol with nitroprusside, observing the absorbance signal at a wavelength of 690 nm. The deviation is obtained from the expression ^̅^ ± K. S / √^^, where in this expression ^̅^ refers to the average of the values ​​obtained, K s refers to the value of the expanded uncertainty, and n refers to the number of samples; considering a value of K s=2, corresponding to the expanded uncertainty, which corresponds to a coverage probability of approximately 95%. The volatilization percentages of ammonium in ammonia under the test conditions studied are satisfactory. There are no significant differences between the use of the static dilution bottle and the hermetically sealed bag, and either test vessel can be chosen as required. The values ​​are similar between different test times, ranging from 1 to 8 hours, ensuring that most of the ammonium present in ammonia is volatilized into the confined atmosphere over time. Furthermore, the volatilization percentage is similar regardless of the ammonia concentration used for the test. Table 1.Percentage of ammonium volatilization in ammonia in different tests studying the type of container, static dilution bottle or bag, the test time from 1 to 8 hours and the ammonia concentration of 10, 20 and 50 ppmv of ammonia, where V. aire refers to the volume of the atmosphere of the container where the test is performed (bottle or bag), time (h) refers to the test time, and [NH3] refers to the concentration of ammonia in said atmosphere resulting from the volatilization of ammonium (NH4 +) initially present in the test medium. Study of ammonium release in different test vessels VAir (L) Time (h) [NH3] ppmv % volatilization of NH4+Dilution bottle 2 1 50 95.5 ± 1.5 static Hermetic bag 2 1 50 97.5 ± 0.5 Study of ammonium release at different test times VAir (L) Time (h) [NH3] ppmv % volatilization of NH4+Dilution bottle 2 1 50 95.5 ± 1.5 static Dilution bottle 2 5 50 94.2 ± 0.5 static Dilution bottle 2 8 50 94.5 ± 1.0 static Study of ammonium release at different concentrations V aire (L) Time (h) [NH3] ppmv % volatilization of NH4 +Dilution bottle 2 1 - 8 10 92.6 ± 1.7 static Dilution bottle 2 1 - 8 20 95.4 ± 0.7 static Dilution bottle 2 1 - 8 50 95.1 ± 0.9 static 2.4 Study of the Z@TEOS@PDMS@NQS sponge response Figure 3 shows a very high sponge response (i.e., a high absorbance of 0.94, indicating a high sensitivity for ammonia) compared to that achieved with alternative sensors with formulations from previous patents such as PDMS-TEOS- NQS-NPsSiO2 and PDMS-TEOS-NQS-IL-NPsSiO2, at a test time of 20 minutes with an ammonia concentration of 34.8 mg / m 3in the 2L static dilution bottle, equivalent to 50ppmv of ammonia. Figure 4A shows the diffuse reflectance spectra of the synthesized 15mm diameter sponges. It is observed how the device response increases with the ammonia concentration generated in the atmosphere over a 20-minute test time. The analytical parameters are indicated in Table 2. Increasing the test time would decrease the detection and quantification limits. The chosen time is adequate to obtain a good linear relationship at desired concentrations for the determination of NH3 in farm and industrial atmospheres. Figure 4B represents the response obtained at a certain concentration of white sensors stored in the freezer for at least two months, obtaining a similar absorbance in each case, therefore, it is stable during that period of time. Figure C represents the absorbance of three sensors, reacted with 3.5mgNH3 / m3, 14mgNH3 / m3 and another of 34.8mgNH3 / m3, stored in the freezer for at least two months. It is observed that the response does not vary significantly, therefore, they are stable. The same occurs with the 7 mm sponge according to Figure 4C. Figure 4D shows the spectra corresponding to a calibration obtained after 10 minutes of exposure to the NH3 atmosphere, and Table 2 the analytical parameters. Figures A and D represent the increase in absorbance with increasing NH3 concentration. Figure 5A shows the diffuse reflectance spectra of 7 mm sponges confined in a bag for testing the analyte ammonium in saliva. A similar behavior to that reflected in the previous section is observed, maintaining the test time, but reducing the volume of air in the confined atmosphere and the ammonium concentrations used, from 0 to 0.22 mg NH4. + / mL of sample. Table 2 indicates the estimated analytical parameters. Figure 5B shows the stability of different sponge blanks stored at -20°C (in a freezer) for at least two months. The response of these blanks is studied in the bag for 10 minutes at a concentration of 0.15 mg of NH4. + / mL of sample, equivalent to 278 mg of NH3 / m 3, and 400 ppmv of ammonia. There are no significant variations in the response of different sponges. It is observed that at low temperatures, the sponges are preserved for at least two months, obtaining a similar response in the different blanks stored for different times under these conditions. Figure 5C shows the results for the assay in 24-well microplates and Table 2 the analytical parameters. Figure 6 shows the results obtained with the SPECTROFREE software application, for the 15 mm sponge (A) and the 7 mm sponge (B). With this sponge, an LOD for ammonia in an atmosphere of 2.4 mg NH3 / m is obtained. 3 in 10 min of passive sampling, which corresponds to rapid analyte detection in just a few minutes, with high sensitivity and zero energy cost. Furthermore, the use of Z@TEOS@PDMS sponges with a diameter of up to 15 mm allows the determination of 2.1 to 34.8 mg of NH3 / m 3in a time of 20 minutes (equivalent to 3 and 50 ppmv of NH3 respectively), while sponges of 7 mm diameter can determine from 7.3 to 34.8 mg of NH3 / m 3, (equivalent to 10.5 and 50 ppmv of NH3, respectively), under the same confined atmosphere volume conditions. Visually, the Z@TEOS@PDMS@NQS sponge that retains the NQS reagent adopts an orange color, and upon contact with atmospheric ammonia, it changes from orange to brown depending on the ammonia concentration. Furthermore, this Z@TEOS@PDMS sponge can be used to measure ammonia atmospheres in all types of habitats (e.g., animal habitats or poultry breeding habitats). In fact, in habitats dedicated to poultry or other livestock breeding, the limit is 20 ppmv of NH3, while in occupational environments, the environmental limit values ​​(ELVs) for daily (DDE) and short-term (STE) exposure are 20 and 50 ppmv of NH3.Additionally, when the Z@TEOS@PDMS@NQS sponge is used to detect ammonium in saliva, by releasing ammonia from saliva ammonium in a confined air volume, a LOD of 0.01 mg NH4 is achieved. + / mL of saliva in 10 min. In fact, with the use of 7 mm diameter Z@TEOS@PDMS@NQS sponges, a confined volume of 60 to 417 mg of NH3 / m can be determined. 3 (equivalent to 86 and 600 ppmv of ammonia, and to 0.03 and 0.22 mg NH4 + / mL of saliva), in a time of 10 minutes. This in turn allows to relate the ammonium content in saliva with different diseases. 2.5 Study of the response of the Z@TEOS@PDMS@SL@NP sponge Figure 7A shows the UV-Vis spectra of 7 mm diameter sponges loaded with salicylate and nitroprusside. It is observed how the response of the device increases with the concentration of ammonium in the solution in a time of 10 minutes of testing. The analytical parameters are shown in Table 2. The response of different tests carried out with reused sponges (n=20), with sponges loaded with reagents and stored at a temperature of -20ºC (in a freezer) for at least two weeks, and sponges that have been loaded with reagents just before use fit the sensitivity shown in Table 2. Table 2. Test conditions, linearity, linear range and detection limits, and quantification of the optimized sponge with different reagents.1 15 mm sponge; t(min) refers to the test time; 2 Ammonium from the hydrolysis of urea; (a) mg NH3 / m 3 ; (b) mg NH4 + / mL, (c) mg / L.

[0002] D O7L . 4 1 0 7 5 0 1 00 . 2 . 0 . 0 . 0 . 0 4 5 . 2 5 0 4 0 5 6 3 2 1 40 . 0 . 0 . 0 . 1 . 0 . 0 l a e n i l either l 8 2 5 . 8 . 2 . 2 . 2 a 4 3 6 2 v r 3 4 3 0 11 . . and – – – 0 t 1 – – 5 2 0 2 0 2 5 522 – – – 2 – – n 3 I. 3 3 2 . 07 . – 1 02 . 0 0 . – 7 1 1 – 7 2 01 . 0 . 0 . 0 5 . 0 . 12 7 9 9 9 8 . 9 . 9 . 99 9 9 9 7 8 9 9 9 . 9 . 9 9 9 9 9 9 9 9R 0 0 0 0 0 . 0 . 0 . . . 0 . . 0 . d 0 0 0 0 a d i 6 l 0 7 1 ± ± ± ± ± 8 9 6 a 4 0 . 0 . 20 5 0 0 e 0 n . 0 0 0 0 i 0 0 0 . 0 . . 0 ± 0 . 0 0 0 . 0L S a ± ± ± 8 40 8 6 ± 88 2 1 1 00 1 73 9 0 5 3 4 2 8 ± 1 ± ± ± 4 00 a. 00 . 00 . 0 0 . 0 0 . 7 00 0 0 . 0 . . 0 . 0 0 . 0 . 0 0 . 0 . 0 0 . 3 3 8 5 0 0 0 0 0 0 0 0 0 0 . 00 . 00 . 00 . 02 0 ± 0 . 5 4 ± ± 705 1 0±0 . 0 1 . 0 1 25 8 3 0 0 . 00 0 0 0 0 . 00 . 5 0 0 0 . . 0 . 0 . 0 0 0 0 4 3± ± ± ± ± ± ±Sb 6 2 5 3 ± 0 6 4 9 0 7 5 ± 4 4 6 7 5 1 ± 0 1b ). 0 a ( 0 ). 0 a ( 0 0 7 0 5 6 6 .0 ). b ( 3 0 ) .4 c ( 0 ). 9 c ( 0 6 4 0 0 8 0 8 4 8 3 1 0 0 2 1 5 . ). c ( 0 ). c ( 00 0 . . 0 . 0 . 0 . 00 0 0 ) c ( ) c ( ) c ( ) c ( . . 0 00 0 ) c ( ) c ( nó n i c ó i u l c i u l i s s L L d d o l l i L L m L o l l L L L m 2 m 2 L L L c m o o l 1 2 m i m m = = , f , 2 c m f , f o o 1 , 1 , 1 , V V 2 2 p l r r r p ll fr f r f r f f o , , m 0 4 i c o o o i o o o r o r o y a a l a c i a l a c 5 2 o p d n d n d 4 n 2 c o p d n d n d n d n d n s l e t t á l e i t t á a s l a c / L e p e p e p a c / L e p e p e e e n o t o t o a l p E p p a E l P 1 p p p p p E B s e B se BP m 1E m EE p TO p TO p E a a o r i e r d f e s e f ó s a vi a u a u a a a n a n a n a a a M m ó l t m a g t SA g u A g u i A g A r i HE r i HE r u u u HE g A g A g AAA , t n i 0 0 0 0 0 0 0 0 0m2 1 1 6 1 5 5 8 3 5 5 1 1L AAL @ NNNSSUNUS @ @ @ @ S @ @ @ @ @ @ @ SSSSMSSS @ @ @ MMMM a jD M M M S S S S S S M M S D D D D D D D M M D M D M M P P P P P P n P o S P D S P S P P P D D D D D D D P P P D P P @B B B @B @A A A @A p @ S s S Q N @ S Q @ S Q @ S Q N P E P E @ @ @N @N @ + S @ S S Q @ + N S @ S F S F S - @ O O O4S - O4E O E O O O S S @ S @ O O O S E E E E T E E E O E O O E E E O E T T T T @ T T T T ET ET T T T T @ Z @ Z @ @ Z @ @ @ @ @ @ Z Z 1 Z Z Z @ Z @ Z @ Z Z Z Z @ Z l on o t i - l 3 + 2 - + A o e f a H4O O 3 4 C D H B n e s i n N H N N N H 2 N D C F B A- lTable 2 shows the test conditions for the different analytes, such as test time, the medium in which the analyte was found, and the volume of air or solution used, as well as the material. Furthermore, the sensitivity of each analyte for the reagent used is obtained, along with the linear range and the detection limit. It is concluded that favorable results are obtained for all the analytes studied, with test times between 10 and 80 minutes, with sample volumes of no more than 2 mL and very favorable regression coefficients, indicating that this sponge-like material is suitable for this type of retention and / or release tests of reagents and analytes such as those studied in Table 2 in different media. The Z@TEOS@PDMS@SL@NP matrix can provide an LOD as low as 0.05 mg / L of ammonium in 10 min, indicating high sensitivity in a short time.In fact, with Z@TEOS@PDMS@SL@NP sponges with a diameter of 7 mm, 0.15 to 1 ppm of ammonium can be determined in aqueous matrices in 10 minutes by releasing these reagents into the solution, producing a color change from yellow to green in the presence of the analyte. 2.6 Study of the response of the Z@TEOS@PDMS@SA@NEDD sponge Figure 7B shows the UV-Vis spectra of 7 mm diameter sponges loaded with Griess reagents, i.e., sulfanilamide (SA) and N-1-naphthyl- ethylenediamine dichlorohydrate (NEDD), for the determination of nitrites. It is observed how the response of the device increases with the concentration of nitrites in the solution in a 5-minute test time. The analytical parameters are indicated in Table 2.The response of different tests carried out with reused sponges (n=20), with sponges loaded with reagents and stored at a temperature of -20ºC for at least two weeks, and with sponges that have been loaded with reagents just before use, fit the equation shown in Table 2. Figure 7C shows the UV-Vis spectra of the synthesized sponges of 7 mm diameter and loaded with Griess reagents, that is, sulfanilamide (SA) and N-1-naphthyl-ethylenediamine dichlorohydrate (NEDD), for the determination of nitrates. It is observed how the response of the device increases with the concentration of nitrates in the solution in a 5-minute test time. Nitrates are reduced to nitrites for their determination with zinc nanoparticles immobilized on nylon.By using sulfanilamide (SA) and N-1-naphthyl-ethylenediamine dichlorohydrate (NEDD) previously embedded in the Z@TEOS@PDMS matrix, a Z@TEOS@PDMS@SA@NEDD matrix with LODs of 0.007 mg / L and 0.4 mg / L in 5 minutes, respectively, for nitrite and nitrate can be obtained. Furthermore, with 7 mm diameter Z@TEOS@PDMS@SA@NEDD sponges, 0.02 to 1.25 ppm of nitrite and 1.14 to 25 ppm of nitrate can be determined in aqueous matrices in 5 minutes. The determination of nitrates is carried out from their reduction to nitrites with zinc nanoparticles immobilized on nylon45. Visually, during the determination of nitrite and nitrate after reduction to nitrite, the solution changes color from colorless to pink with the formation of a chromophore containing azo groups. 2.7 Study of the response of the Z@TEOS@PDMS@U sponge The catalytic action of the urease, which is loaded in the synthesized sponge, is studied under the test conditions, determining the ammonium obtained from the hydrolyzed urea from the NQS-doped sponges and the sponges with the Berthelot method, that is, using sponges doped with sodium salicylate (SL) and sodium nitroprusside (NP). Figure 7D shows the diffuse reflectance spectra of 7 mm diameter sponges loaded with the NQS derivatizing reagent for the determination of hydrolyzed urea into ammonium by the catalytic action of the urease present in the sponge. It is observed how the response of the device increases with the concentration of ammonium from urea in the solution over a 60-minute test time. The analytical parameters are given in Table 2.Figure 7E shows the UV-Vis spectra of 7 mm diameter sponges loaded with salicylate and nitroprusside for the determination of urea hydrolyzed into ammonium by the catalytic action of the urease present in the sponge. It is observed how the response of the device increases with the concentration of urea in the solution over a 10-minute test time. The analytical parameters are given in Table 2. In summary, this allows the estimation of urea using the matrix of the invention that comprises the retained / embedded urease enzyme (U), which hydrolyzes urea into ammonium. Visually, when the urease is released into the solution by diffusion, and this catalyzes the hydrolysis of urea into ammonium, the solution changes color from colorless to pink.Subsequently, the ammonium in the urine is estimated using the matrix with an embedded ammonium sensor reagent NQS, obtaining the Z@TEOS@PDMS@NQS sponge capable of detecting and / or determining the ammonium present in urine at concentrations from 0.7 to 4.6 ppm of ammonium. Alternatively, the sponge with NP can also be used to determine the ammonium, obtaining in this case the @TEOS@PDMS@NP sponge, with which ammonium concentrations of 0.1 to 1 ppm can be measured. With this, the determined ammonium can be related to the amount of urea initially present, as well as estimating the yield of the urea hydrolysis reaction to ammonium. 2.8 Study of the response of the Z@TEOS@PDMS@FBB sponge The UV-Vis spectra of the 7 mm diameter sponges loaded with Fast Blue B for DHCA are shown in Figure 8A. It is observed how the response of the device increases with the concentration of DHCA in the solution in a 5-minute test time.Table 2 indicates the analytical parameters obtained. Figure 8B shows the UV-Vis spectra of the 7 mm sponges loaded with Fast Blue B for CBD. It is observed how the device response increases with the CBD concentration in the solution over a 5-minute test time. Table 2 indicates the analytical parameters. The Z@TEOS@PDMS@FBB sponge can therefore be used as a sensor for the determination of 3,5-dihydroxyhydrocinnamic acid (DHCA), which is a gluten biomarker, and cannabidiol (CBD); with the use of Fast Blue B (FBB) salt retained in the matrix, obtaining the Z@TEOS@PDMS@FBB matrix with LODs of 0.04 and 1.6 mg / L in 5 min for DHCA and CBD, respectively. In fact, with Z@TEOS@PDMS@FBB sponges with a diameter size of 7 mm, concentrations of 5 to 20 ppm of CBD can be measured in aqueous matrices within 5 minutes, and 0.1-2 ppm of DHCA in biological matrices within 5 minutes.Visually, when the FBB salt is released into the solution by diffusion, said FBB salt reacts with DHCA and CBD with the formation of a chromophore with azo groups from the diazonium salt, generating a color change from yellow to red. 2.9 Study of the response of the Z@TEOS@PDMS@AAP sponge Figures 8C and 8D show the UV-Vis spectra of 7 mm sponges loaded with 4-AAP. It is observed how the response of the device increases with the concentration of phenol and bisphenol A in the solution in a 10-minute test time and Table 2 the analytical parameters. Figure 9 shows the results obtained with the SPECTROFREE software application for the sponge and two sample concentrations. With the Z@TEOS@PDMS@4-AAP sponge for the determination of phenols such as phenol or bisphenol-A in aqueous solution, by diffusing 4-AAP into the solution, a LOD of up to 0.23 ppm of phenol and 0.41 ppm of bisphenol-A can be achieved in 10 min.In fact, 7 mm diameter Z@TEOS@PDMS@4-AAP sponges can determine 0.68–2 ppm of phenol and 1.24–5 ppm of bisphenol-A in 10 minutes. Visually, this reaction of 4-AAP with phenols forms a colored complex. All these assays allow the determination of analytes such as ammonia, ammonium, nitrites, nitrates, cannabidiol, and phenols, among others, with great speed, high sensitivity, good regression coefficients, and favorable detection and quantification limits, indicating that this material is suitable for the retention and / or release of reagents and analytes by diffusion. The use of this sponge-type sensor improves the results of other types of PDMS-based sensors, whose release of reagents through dissolution or diffusion of analytes into the sensor is slower, and in some cases, not 100% of the embedded reagents are released.Furthermore, the sponge format offers the same advantages as reagents in solution, in terms of effectiveness, but by avoiding their degradation, they are properly preserved, which does not occur in solution.

Claims

CLAIMS 1. Porous three-dimensional matrix of polydimethylsiloxane (PDMS), between 40% and 60% by weight, characterized in that it comprises ^ Tetraethylorthosilicate (TEOS) between 40% and 60% by weight, and ^ zeolite between 0.5% and 1% by weight on the weight of the mixture of PDMS and TEOS, where the three-dimensional matrix has a porosity of between 55-80% with respect to the total volume of the matrix, with pore sizes between 20-360 μm.

2. Matrix according to claim 1, wherein the zeolite has a particle size of less than 20 μm.

3. Matrix according to any of claims 1 or 2, wherein the zeolite is in a concentration of 1% by weight on the weight of the mixture of PDMS and TEOS.

4. The matrix according to any one of claims 1 to 3, wherein the PDMS is at a concentration of 60% by weight and the TEOS is at a concentration of 40% by weight.

5. The matrix according to any one of claims 1 to 4, wherein the matrix has a thickness of between 1.5 and 2 mm. 6.Three-dimensional matrix according to any one of claims 1 to 5, wherein the matrix has a size between 7 mm and 15 mm in diameter.

7. Method for obtaining a porous three-dimensional matrix described according to claims 1 to 6, comprising the steps of: a) mixing TEOS and zeolite; b) adding PDMS to the mixture of section a) under stirring until a homogeneous mixture is obtained; c) adding a PDMS curing agent to the mixture of section b) under stirring until a homogeneous mixture is obtained; d) adding sieved sugar with a particle size between 300 and 400 µm to the mixture c) and homogenizing by stirring; e) pouring the mixture obtained in section d) into a mold and allowing it to gel, where the gelation is preferably carried out by a heating step at 30-50 °C for 10-24 hours, preferably at 40 °C for 12 hours; f) removing the resulting solid from the mold and drying it, where the drying is preferably carried out by a heating step at 70-90 °C for 20-30 minutes, preferably at 90 °C for 30 minutes; and g) removing the sugar from the resulting solid, preferably by immersing the solid in water with stirring.

8. The method according to claim 7, wherein the zeolite has a particle size of less than 20 µm.

9. Method according to claim 7 or 8, wherein the zeolite is added in a concentration of up to 1% by weight of the total mixture obtained after performing step a). 10.Method according to any one of claims 7 to 9, wherein the PDMS is added in a concentration of 60% by weight of the total mixture obtained after step b).

11. Method according to any one of claims 7 to 10, wherein the PDMS is prepared from two components, a base selected from silicone elastomers and a curing agent selected from curing agents suitable for curing said silicone elastomer(s).

12. Method according to any one of claims 7 to 11, wherein the sugar added in step c) has a particle size between 300 and 400 μm.

13. Method according to any one of claims 7 to 12, wherein the sugar added in step c) has a 7:3 weight ratio with respect to the rest of the components of the mixture that form part of the three-dimensional matrix resulting after step g).

14. Sensor for detecting and / or determining analytes comprising the matrix.

15. A sensor according to claim 14, wherein the sensor reagent is selected from 1,2-naphthoquinone-4-sulfonate (NQS), salicylate (SL), nitroprusside (NP), sulfanilamide (SA), N-(1-naphthyl)ethylenediamine dichlorohydrate (NEDD), urease, Fast Blue B (FBB), 4-amino antipyrine (4-AAP), and any combination thereof.Method for obtaining a sensor described according to any of claims 14 to 15; comprising obtaining a matrix according to steps (a) to (g) of the method described according to any of claims 7 to 13 and the following steps: h) immersing the porous three-dimensional matrix obtained in step g) in a solution of at least one sensor reagent; i) removing the excess solution absorbed from the matrix after its immersion in section (h) by means of an absorbent material, preferably paper, cotton cloth and / or cotton gauze, more preferably paper, thus obtaining the sensor with the reagent incorporated. 17.Method according to claim 16, wherein the solution of step (h) comprises at least one reagent selected from 1,2-naphthoquinone-4-sulfonate (NQS), salicylate (SL), nitroprusside (NP), sulfanilamide (SA), N-(1-naphthyl)ethylenediamine dichlorohydrate (NEDD), urease, Fast Blue B (FBB), 4-amino antipyrine (4-AAP), and any combination thereof.

18. Use of the porous three-dimensional matrix according to any one of claims 1 to 6 for the manufacture of a sensor for detecting and / or determining analytes.

19. Use of the sensor described according to claims 14 or 15 for the detection and / or determination of analytes.

20. Use of the sensor according to claim 19, wherein the analyte is selected from. among ammonium, ammonia, phenols, urea, cannabidiol (CBD), 3,5-dihydroxyhydrocinnamic acid (DHCA), nitrites, nitrates, or combinations thereof.

21. Use of the sensor according to any of claims 19 or 20, wherein the analyte is found in gaseous media, solid media or aqueous media, preferably biological matrices, air and food.

22. A method for estimating analytes in a gaseous, aqueous or solid medium characterized in that it comprises I. contacting the sensor described according to claims 14 or 15 with the medium comprising the analyte to be detected and / or determined; II. waiting a time between 5 and 80 minutes; and III. observing a change in the color of the embedded sensor reagent and / or the solution.

23. The method of claim 22, wherein the observation of the color change in stage III is carried out by UV-Vis absorbance measurements, diffuse reflectance measurements, or by means of an app or software. 24.A computer program adapted to implement the method of either claim 22 or 23.

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