A layered nanocomposite of laccase, chitosan, and Fe3O4 nanoparticles-reduced graphene oxide for the nanomolar electrochemical detection of bisphenol A.

A hybrid conjugate of reduced graphene oxide/ferrous-ferric oxide nanoparticles (rGO-Fe3O4 NPs) is characterized and assembled with chitosan and laccase to form a layered functional superstructure. After its characterization by field-effect scanning electron microscopy, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), the nanocomposite has been deposited on glassy carbon for the enzyme-mediated electrochemical determination of the endocrine disruptor bisphenol A (BPA). Proof-of-concept assays conducted by using CV, EIS, and square wave voltammetry reveal that the enzymatic biosensor provides linear response in a wide range of BPA concentrations (6-228 ppb), very high sensitivities, and excellent durability (over 1-month storage). Using amperometric detection, remarkable sensitivities (2080 µA µM-1 cm-2) and detection limits (18 nM) are attained. Applications to real samples of bottled water proved feasible with recoveries in the range 107-124%. Graphical abstract Reduced graphene oxide conjugated with magnetite nanoparticles (rGO-Fe3O4) was assembled with laccase (wine-colored dots) and chitosan for the electrochemical determination of bisphenol A. The enzymatic biosensor exhibited excellent linearity (6-228 ppb) and stability. Best sensitivity (2080 µA µM-1 cm-2, detection limit 18 nM) was obtained by amperometry.

Cationic imprinting of Pb(II) within composite networks based on bovine or fish chondroitin sulfate.

Imprinting chondroitin sulfate (CS)/silica composites with Pb(II) and Cu(II) cations was explored with CS of bovine and different fish species origin. The process was based on the assumption that particular arrangements of the linear CS chains in aqueous solution, induced so as to accommodate cross complexation with the cations, would be embodied into a tridimensional matrix created through an organoalkoxysilane sol-gel scheme. The presence of Cu(II) in the synthesis of the composites did not result in the production of significantly stronger Cu(II)-oriented binding arrangements, and therefore, the imprinting was not successful. Inversely, for Pb(II), the materials obtained exhibited a "memory" effect for the Pb(II) ions, expressed in the observation of stronger (13%-44%) binding as compared to the nonimprinted counterparts, and increased selectivity (1.5-2 folds) against Cd(II). The imprinting features observed were dependent on the CS source. However, it was not possible to identify, among a set of their properties (carboxylate and sulfate abundance, percent of disulfated units, 4S/6S ratio, and molecular weight), any that correlated directly with the observed imprinting features. The augmented selectivity provided by the cation-imprinting process may be advantageous in areas such as analytical separation, remediation, purification, sensing, and others, particularly in those cases where a certain cation is of special interest within a mixture of them.

Electrochemical immunosensor for point-of-care detection of soybean Gly m TI allergen in foods.

Soybean is a legume with high technological functionality, commonly used by the food industry as an ingredient in different products. However, soybean is an allergenic food whose undeclared presence in processed foods may represent a public health risk. In this work, it was developed an efficient electrochemical immunosensor, targeting the soybean trypsin inhibitor (Gly m TI) allergen using commercial anti-Gly m TI IgG, aiming at detecting/quantifying minute amounts of soybean in different food formulations. For this purpose, model mixtures of different foods (sausages, cooked-hams, biscuits) were prepared to contain known amounts of soybean protein isolate (100,000-0.1 mg kg-1) and submitted to specific thermal treatments (autoclaving, oven-cooking, baking). The electrochemical immunosensor allowed quantifying down to 0.1 mg kg-1 of soybean in the three food matrices, raw and processed (0.0012 mg of Gly m TI/kg of matrix). Accordingly, the immunosensor is suitable for detecting traces of soybean in raw, processed, and complex foods, thus protecting 99 % of soybean-allergic patients.

Boosting Supercapacitor Efficiency with Amorphous Biomass-Derived C@TiO2 Composites.

Carbon materials are readily available and are essential in energy storage. One of the routes used to enhance their surface area and activity is the decoration of carbons with semiconductors, such as amorphous TiO2, for application in energy storage devices.

Plasmonic genosensor for detecting hazelnut Cor a 14-encoding gene for food allergen monitoring.

A plasmonic nanostructure was constructed as a biorecognition element coupled to an optical sensing platform in sandwich format, targeting the hazelnut Cor a 14 allergen-encoding gene. The analytical performance of the genosensor presented a linear dynamic range between 100 amol L-1 and 1 nmol L-1, a limit of detection (LOD) < 19.9 amol L-1, and a sensitivity of 13.4 ± 0.6 m°. The genosensor was successfully hybridized with hazelnut PCR products, tested with model foods, and further validated by real-time PCR. It reached a LOD <0.001% (10 mg kg-1) of hazelnut in wheat material (corresponding to 1.6 mg kg-1 of protein) and a sensitivity of -17.2 ± 0.5 m° for a linear range of 0.001%-1%. Herein, a new genosensing approach is proposed as a highly sensitive and specific alternative tool with potential application in monitoring hazelnut as an allergenic food, protecting the health of sensitized/allergic individuals.

Chitins from Seafood Waste as Sustainable Porous Carbon Precursors for the Development of Eco-Friendly Supercapacitors.

Carbon materials derived from marine waste have been drawing attention for supercapacitor applications. In this work, chitins from squid and prawn marine wastes were used as carbon precursors for further application as electrodes for energy storage devices. Chitins were obtained through a deproteinization method based on enzymatic hydrolysis as an alternative to chemical hydrolysis as commonly presented in the literature. The obtained porous carbons were characterized using a BET surface area analyzer to determine the specific surface area and pore size, as well as scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), Raman spectroscopy, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), to characterize their morphology, composition, and structure. The electrochemical characterization was performed using a glassy carbon (GC) electrode modified with marine waste-based porous carbons as the working electrode through cyclic voltammetry and galvanostatic charge/discharge using ethaline, a choline chloride-based deep eutectic solvent (DES), as an eco-friendly and sustainable electrolyte. Squid and prawn chitin-based carbons presented a surface area of 149.3 m2 g-1 and 85.0 m2 g-1, pore volume of 0.053 cm3 g-1 and 0.029 cm3 g-1, and an associated specific capacitance of 20 and 15 F g-1 at 1 A g-1, respectively. Preliminary studies were performed to understand the effect of -OH groups on the chitin-based carbon surface with DES as an electrolyte, as well as the effect of aqueous electrolytes (1 mol L-1 sulphuric acid (H2SO4) and 1 mol L-1 potassium hydroxide (KOH)) on the capacitance and retention of the half-cell set up. It is provided, for the first time, the use of chitin-based carbon materials obtained through a one-step carbonization process combined with an eco-friendly DES electrolyte for potential application in energy storage devices.

Renewable Carbon Materials as Electrodes for High-Performance Supercapacitors: From Marine Biowaste to High Specific Surface Area Porous Biocarbons.

Waste, in particular, biowaste, can be a valuable source of novel carbon materials. Renewable carbon materials, such as biomass-derived carbons, have gained significant attention recently as potential electrode materials for various electrochemical devices, including batteries and supercapacitors. The importance of renewable carbon materials as electrodes can be attributed to their sustainability, low cost, high purity, high surface area, and tailored properties. Fish waste recovered from the fish processing industry can be used for energy applications and prioritizing the circular economy principles. Herein, a method is proposed to prepare a high surface area biocarbon from glycogen extracted from mussel cooking wastewater. The biocarbon materials were characterized using a Brunauer-Emmett-Teller surface area analyzer to determine the specific surface area and pore size and by scanning electron microscopy coupled with energy-dispersive X-ray analysis, Raman analysis, attenuated total reflectance Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. The electrochemical characterization was performed using a three-electrode system, utilizing a choline chloride-based deep eutectic solvent (DES) as an eco-friendly and sustainable electrolyte. Optimal time and temperature allowed the preparation of glycogen-based carbon materials, with a specific surface area of 1526 m2 g-1, a pore volume of 0.38 cm3 g-1, and an associated specific capacitance of 657 F g-1 at a current density of 1 A g-1, at 30 °C. The optimal material was scaled up to a two-electrode supercapacitor using a DES-based solid-state electrolyte (SSE@DES). This prototype delivered a maximum capacitance of 703 F g-1 at a 1 A g-1 of current density, showing 75% capacitance retention over 1000 cycles, delivering the highest energy density of 0.335 W h kg-1 and power density of 1341 W kg-1. Marine waste can be a sustainable source for producing nanoporous carbon materials to be incorporated as electrode materials in energy storage devices.

Molecularly imprinted polymer as a synthetic antibody for the biorecognition of hazelnut Cor a 14-allergen.

Artificial receptors that mimic their natural biological counterparts have several advantages, such as lower production costs and increased shelf-life stability/versatility, while overcoming the ethical issues related to raising antibodies in animals. In this work, the proposed tailor-made molecularly imprinted polymer (MIP)-allergen receptors aimed at substituting or even transcending the performance of biological antibodies. For this purpose, a MIP was proposed as an artificial antibody for the recognition of hazelnut Cor a 14-allergen. The target protein was grafted onto the conducting polypyrrole receptor film using gold screen-printed electrodes (Au-SPE). The electrochemical assessment presented a linear response for the dynamic range of 100 fg mL-1-1 µg mL-1 and a LOD of 24.5 fg mL-1, as determined by square wave voltammetry from the calibration curves prepared with standards diluted in phosphate buffer. Surface plasmon resonance (SPR) was used as a secondary transducer to evaluate the performance of the Cor a 14-MIP sensor, enabling a linear dynamic range of 100 fg mL-1- 0.1 µg mL-1 and a LOD of 18.1 fg mL-1. The selectivity of the tailored-made Cor a 14-MIP was tested against potentially cross-reactive plant/animal species based on the rebinding affinity (Freundlich isotherm-KF) of homologues/similar proteins, being further compared with custom-made polyclonal anti-Cor a 14 IgG immunosensor. Results evidenced that the MIP mimics the biorecognition of biological antibodies, presenting higher selectivity (only minor cross-reactivity towards walnut and Brazil nut 2S albumins) than the Cor a 14/anti-Cor a 14 IgG immunosensor. The application of electrochemical Cor a 14-MIP sensor to model mixtures of hazelnut in pasta enabled quantifying hazelnut down to 1 mg kg-1 (corresponding to 0.16 mg kg-1 of hazelnut protein in the matrix). To the best of our knowledge, Cor a 14-MIP is the first sensor based on an artificial/synthetic biorecognition platform for the specific detection of hazelnut allergens, while presenting high-performance parameters with demonstrated application in food safety management.

Sustainable Preparation of Nanoporous Carbons via Dry Ball Milling: Electrochemical Studies Using Nanocarbon Composite Electrodes and a Deep Eutectic Solvent as Electrolyte.

The urgent need to reduce the consumption of fossil fuels drives the demand for renewable energy and has been attracting the interest of the scientific community to develop materials with improved energy storage properties. We propose a sustainable route to produce nanoporous carbon materials with a high-surface area from commercial graphite using a dry ball-milling procedure through a systematic study of the effects of dry ball-milling conditions on the properties of the modified carbons. The microstructure and morphology of the dry ball-milled graphite/carbon composites are characterized by BET (Brunauer-Emmett-Teller) analysis, SEM (scanning electron microscopy), ATR-FTIR (attenuated total reflectance-Fourier transform infrared spectroscopy) and Raman spectroscopy. As both the electrode and electrolyte play a significant role in any electrochemical energy storage device, the gravimetric capacitance was measured for ball-milled material/glassy carbon (GC) composite electrodes in contact with a deep eutectic solvent (DES) containing choline chloride and ethylene glycol as hydrogen bond donor (HBD) in a 1:2 molar ratio. Electrochemical stability was tracked by measuring charge/discharge curves. Carbons with different specific surface areas were tested and the relationship between the calculated capacitance and the surface treatment method was established. A five-fold increase in gravimetric capacitance, 25.27 F·g-1 (G40) against 5.45 F·g-1, was found for commercial graphene in contact with DES. Optimal milling time to achieve a higher surface area was also established.

Electrochemical and optical biosensing platforms for the immunorecognition of hazelnut Cor a 14 allergen.

Two immunosensors were advanced to target hazelnut Cor a 14 based on electrochemical and optical transduction. Both approaches were developed with two types of custom-made antibodies, namely anti-Cor a 14 IgG (rabbit) and anti-Cor a 14 IgY (hen's egg) targeting the Cor a 14 allergen. Antibody immobilisation was performed via EDC/NHS onto disposable screen-printed electrodes. The detection limit (LOD) of the electrochemical immunoassay for Cor a 14 was 5-times lower than the optical, being down to 0.05 fg mL-1 with a dynamic range of 0.1 fg mL-1 to 0.01 ng mL-1. Antibody selectivity was verified against non-target 2S albumins (potential cross-reactive plant species). Anti-Cor a 14 IgY exhibited the best specificity, presenting minor cross-reactivity with peanut/walnut. Preliminary results of the application of anti-Cor a 14 IgY electrochemical immunosensor to incurred foods established a LOD of 1 mg kg-1 of hazelnut in wheat (0.16 mg kg-1 hazelnut protein).

Characterization of Carbon Nanomaterials Dispersions: Can Metal Decoration of MWCNTs Improve Their Physicochemical Properties?

A suitable dispersion of carbon materials (e.g., carbon nanotubes (CNTs)) in an appropriate dispersant media, is a prerequisite for many technological applications (e.g., additive purposes, functionalization, mechanical reinforced materials for electrolytes and electrodes for energy storage applications, etc.). Deep eutectic solvents (DES) have been considered as a promising "green" alternative, providing a versatile replacement to volatile organic solvents due to their unique physical-chemical properties, being recognized as low-volatility fluids with great dispersant ability. The present work aims to contribute to appraise the effect of the presence of MWCNTs and Ag-functionalized MWCNTs on the physicochemical properties (viscosity, density, conductivity, surface tension and refractive index) of glyceline (choline chloride and glycerol, 1:2), a Type III DES. To benefit from possible synergetic effects, AgMWCNTs were prepared through pulse reverse electrodeposition of Ag nanoparticles into MWCNTs. Pristine MWCNTs were used as reference material and water as reference dispersant media for comparison purposes. The effect of temperature (20 to 60 °C) and concentration on the physicochemical properties of the carbon dispersions (0.2-1.0 mg cm-3) were assessed. In all assessed physicochemical properties, AgMWCNTs outperformed pristine MWCNTs dispersions. A paradoxical effect was found in the viscosity trend in glyceline media, in which a marked decrease in the viscosity was found for the MWCNTs and AgMWCNTs materials at lower temperatures. All physicochemical parameters were statistically analyzed using a two-way analysis of variance (ANOVA), at a 5% level of significance.

Ordering and Nonideality of Air-Ionic Liquid Interfaces in Surface Second Harmonic Generation.

The air-ionic liquid interface for a series of ionic liquids involving imidazolium cations [Cnmim] with different alkyl chain lengths (n = 2, 4, 6, 8, 10, and 12) and the same [NTf2] imide anion has been studied by polarization-resolved second harmonic generation (SHG). An increase as a function of the alkyl chain length of the orientational parameter reveals the increasing ordering of the air-pure ionic liquid interfaces although it is not possible to disentangle the change in mean tilt angle from a change in the tilt angle probability distribution width. Besides, the study of the air-mixed ([C12mim])x([C2mim])1-x[NTf2] ionic liquid interface clearly demonstrates the interfacial nonideality of the mixed ionic liquids. The long alkyl chain cation perturbs the interface as seen from the orientational parameter and displaces the short alkyl chain one for bulk mixture contents as low as 10%. At higher long alkyl chain cation bulk mixture contents, the interface behaves close to a pure long alkyl chain ionic liquid.

Molecularly imprinted polymer SPE sensor for analysis of CA-125 on serum.

Considering the high incidence level and mortality rate of ovarian cancer, particularly among the European female population, the carbohydrate antigen 125 (CA-125) was selected as the protein target for this study for the development of a MIP-based biosensor. This work presents the development of molecular imprinting polymers (MIPs) on gold electrode surface for CA-125 biomarker recognition. The preparation of the CA-125 imprinting was obtained by electropolymerization of pyrrole (Py) monomer in a gold electrode using cyclic voltammetry (CV) in order to obtain highly selective materials with great molecular recognition capability. The quantification of CA-125 biomarker was made through the comparison of two methods: electrochemical (square wave voltammetry -SWV) and optical transduction (surface plasmon resonance -SPR). SWV has been widely used in biological molecules analysis since it is a fast and sensitive technique. In turn, SPR is a non-destructive optical technique that provides high-quality analytical data of CA-125 biomarker interactions with MIP. Several analytical parameters, such as sensitivity, linear response interval, and detection limit were determined to proceed to the performance evaluation of the electrochemical and optical transduction used in the development of the CA-125 biosensor. The biosensor based in the electrochemical transduction was the one that presented the best analytical parameters, yielding a good selectivity and a detection limit (LOD) of 0.01 U/mL, providing a linear concentration range between 0.01 and 500 U/mL. This electrochemical biosensor was selected for the study and it was successfully applied in the CA-125 analysis in artificial serum samples with recovery rates ranging from 91 to 105% with an average relative error of 5.8%.

Redox properties of the calcium chelator Fura-2 in mimetic biomembranes.

Fura-2 is one of the most commonly used fluorescent dyes to analyze the cytosolic Ca(2+) concentration ([Ca(2+)](i)) of living cells. Fura-2-dependent measurements of [Ca(2+)](i) are susceptible to changes of pH, reactive oxygen species concentration and membrane potential. Fura-2 is often loaded over the lipophilic cell membrane into the cytosol of a cell in its esterified form (Fura-2/AM) which is then cleaved by endogenous esterases. We have analyzed the electrochemical properties of Fura-2/AM and Fura-2 salt by cyclic voltammetry ("three-phase" and "thin-film" electrode methods). Using Fura-2/AM as a redox facilitator, we were able to mimic the transport of various ions across a lipophilic barrier. We show that Fura-2/AM in this biomimetic set-up can be reversibly oxidized in a single electrochemical step. Its redox reaction was highly proton sensitive in buffers with pH< or =6. At physiological pH of around 7.0, the oxidation of Fura-2/AM was coupled to an uptake of mono-anions across the liquid-liquid interface. The voltage-dependence of the redox cycle was sensitive to the free Ca(2+) concentration, either after de-esterification of Fura-2/AM, or when Fura-2 salt was used. The complex between Fura-2 and Ca(2+) ions is ionic (complexation occurs via the dissociated negative groups of Fura forms), while the redox transformations in Fura-2 occurs at the nitrogen atoms of the amino groups. Our results suggest that redox transformations of the Fura-2 forms do not affect the binding ability toward Ca(2+) ions and thus do not interfere with [Ca(2+)](i) measurements.

Voltammetric insights in the transfer of ionizable drugs across biomimetic membranes: recent achievements.

The latest results of voltammetric research on the ionic transfer process of ionisable drugs across bare and lipid-modified liquid-liquid interfaces are reviewed. In recent years, two voltammetric methods have been extensively applied to this purpose, i.e. the classical four electrode voltammetry at the interface between two immiscible electrolyte solutions, and the "three-phase electrode." Thus, a brief background of the methodologies and some successful examples of their application are highlighted in this work. Particular attention is given to the ionic transfer kinetics and to the electrochemical characterization of the drug-membrane interactions between the ionized drugs and lipid-modified interfaces. Future trends in this area are also mentioned in connection with high-throughput assessment of ADMET properties of drugs.

Measurement artifacts identified in the UV-vis spectroscopic study of adduct formation within the context of molecular imprinting of naproxen.

The ultraviolet-visible spectroscopy has been assessed as a technique for the evaluation of the strength of template-precursor adduct in the development of molecular imprints of the non-steroidal anti-inflammatory drug naproxen (NAP). The commonly employed approach relies on the collection of UV spectra of drug+precursor mixtures at different proportions, the spectra being recorded against blanks containing the same concentration of the precursor. The observation of either blue or red band-shifts and abatement of a major band are routinely attributed to template-precursor adduct formation. Following the described methodology, the precursors 1-(triethoxysilylpropyl)-3-(trimethoxysilylpropyl)-4,5-dihydroimidazolium iodide (AO-DHI(+)) and 4-(2-(trimethoxysilyl)ethyl)pyridine (PETMOS) provoked a blue-shift and band abatement effect on the NAP spectrum. Molecular dynamics simulations indicated a reasonable affinity between NAP and these precursors (coordination numbers 0.33 for AO-DHI(+) and 0.18 for PETMOS), hence showing that NAP-precursor complexation is in fact effective. However, time dependent density functional theory (TD-DFT) calculations of the spectra of both free and precursor-complexed NAP were identical, thus providing no theoretical basis for the complexation-induced effects observed. We realized that the intense spectral bands of AO-DHI(+) and PETMOS (at around 265 nm) superimpose partially with the NAP bands, and the apparent "blue-shifting" in the NAP spectra when mixed with AO-DHI+ and PETMOS was in this case a spurious effect of the intense background subtraction. Therefore, extreme care must be taken when interpreting other spectroscopic results obtained in a similar fashion.

Acylated-naproxen as the surface-active template in the preparation of micro- and nanospherical imprinted xerogels by emulsion techniques.

A strategy based on water-in-oil emulsion for the dispersion of a sol-gel mixture into small droplets was employed with the view of the production of naproxen-imprinted micro- and nanospheres. The procedure, aiming at a surface imprinting process, comprised the synthesis of a naproxen-derived surfactant. The imprinting process occurred at the interface of the emulsions or microemulsions, by the migration of the NAP-surfactant head into the sol-gel drops to leave surficial imprints due mainly to ion-pair interaction with a cationic group contained within the growing sol-gel network. The surface-imprinted microspheric particles exhibited a log-normal size distribution with geometric mean diameter of 3.1µm. A mesoporous texture was found from measurements of the specific surface area (206m(2)/g) and pore diameter (Dp 2nm). Evaluation of the microspheres as packed HPLC stationary phases resulted in the determination of the selectivity factor against ibuprofen (α=2.1), demonstrating the successful imprinting. Chromatographic efficiency, evaluated by the number of theoretical plates (222platescm(-3)), emerged as an outstanding feature among the set of all relatable formats produced before, an advantage intrinsic to the location of the imprinted sites on the surface. The material presented a capacity of 3.2µmolg(-1). Additionally, exploratory work conducted on their nanoscale counterparts resulted in the production of nanospheres in the size order of 10nm providing good indications of a successful imprinting process.

Electrochemical study of ion transfer of acetylcholine across the interface of water and a lipid-modified 1,2-dichloroethane.

The ion transfer of acetylcholine (AcH(+)) ions across the unmodified and phospholipid-modified water|1,2-dichloroethane (DCE) interface has been studied by means of square-wave and cyclic voltammetry, as well as by electrochemical impedance spectroscopy. After being transferred in the organic phase, the AcH(+) ions undergo chemical reactions with the phospholipids. The overall behavior of the experimental system studied in the presence of phospholipids has been compared with the theoretical results of an ECrev reaction. The kinetic parameters of the chemical interactions between AcH(+) and the phospholipids have been determined from the voltammetric and impedance measurements. Additional characterization of those interactions has been made by using the surface tension measurements.

Ultrathin phenyl-functionalized solid phase microextraction fiber coating developed by sol-gel deposition.

A new sol-gel application for the development of SPME fibers is described. Phenyltrimethoxysilane (PTMOS) and methyltrimethoxysilane (MTMOS) were the sol-gel precursors used at different proportions, together with different water contents, catalyst and reaction time. It was observed that obtaining a good film quality was determinant for a good extracting fiber performance. The film thickness ranged 0.2-1 microm and could not be increased by multi-coating processes. Apparently, a dense, non-porous microstructure was obtained. These coatings exhibited a strong hydrophobic character, as shown by the capability of extraction of long chain and apolar aromatic compounds, which, was comparable to that of the 100 microm polydimethylsiloxane (PDMS) and 65 microm carbowax-divinylbenzene (CW-DVB). The developed fiber has shown high thermal (350 degrees C) and organic solvent stability (ethanol, toluene and dichloromethane), thus bearing adequate characteristics to be associated to GC and potentialities that may also envisage suitability for HPLC. The new fibers may be useful for the microextraction of non-polar compounds, although at trace levels and in simple matrixes only, due to the susceptibility to competition.

Naproxen-imprinted xerogels in the micro- and nanospherical formsby emulsion technique.

Naproxen-imprinted xerogels in the microspherical and nanospherical forms were prepared by W/O emulsion and microemulsion, respectively. The work evolved from a sol­gel mixture previously reported for bulk synthesis. It was relatively simple to convert the original sol­gel mixture to one amenable to emulsion technique. The microspheres thus produced presented mean diameter of 3.7 µm, surface area ranging 220­340 m2/g, selectivity factor 4.3 (against ibuprofen) and imprinting factor 61. A superior capacity (9.4 µmol/g) was found, when comparing with imprints obtained from similar pre-gelification mixtures. However, slow mass transfer kinetics was deduced from column efficiency results. Concerning the nanospherical format, which constituted the first example of the production of molecularly imprinted xerogels in that format by microemulsion technique, adapting the sol­gel mixture was troublesome. In the end, nanoparticles with diameter in the order of 10 nm were finally obtained, exhibiting good indications of an efficient molecular imprinting process. Future refinements are necessary to solve serious aggregation issues, before moving to more accurate characterization of the binding characteristics or to real applications of the nanospheres.