Influence of Size and Shape of Silica Supports on the Sol⁻Gel Surface Molecularly Imprinted Polymers for Selective Adsorption of Gossypol

In silico design of magnetic, polymeric synthetic receptor targeting clumping factor A, for the specific capture and detection of Staphylococcus aureus

Rapid diagnosis of Staphylococcus aureus (S. aureus) is critical for both therapy and infection control programs. Currently available rapid bacterial detection methods such as polymerase chain reaction (PCR) requires expensive equipment and trained personnel, whereas, enzyme-linked immunosorbent assay (ELISA) requires antibodies and thus, suffer from limitations such as limited reagent stability. Herein, we used stable, cost-effective alternates to the antibodies known as synthetic antibodies i.e., molecularly imprinted polymers (MIPs). In this study, polymeric synthetic receptor commonly known as MIPs were layered onto magnetic nanoparticles, specifically designed for the detection of S. aureus through the binding interaction with its surface biomarker- clumping factor A (ClfA). This approach offers a low limit of detection (LOD) of 102 colony-forming units per mL (CFU/mL) and a wide linear detection range (103 to 108 CFU/mL) for S. aureus. Briefly, ClfA gene was cloned, expressed and protein was purified using Ni-NTA affinity chromatography and anion-exchange chromatography. Magnetic nanoparticles were initially synthesized and coated with silica, followed by introduction of aldehyde groups for immobilization through imine bonding. ClfA was then immobilized onto the functionalized nanoparticles, serving as a template for MIP synthesis. To determine a monomer combination with high binding capacity and specificity for ClfA, docking studies were performed using Autodock 4.2. The polymerization process employed selected monomer combination, yielding MIP tailored to recognize ClfA. The binding properties of the MIP were extensively investigated, demonstrating specificity and selectivity for ClfA over non-specific proteins. Furthermore, the clinical utility of the MIP was assessed by examining its binding with ClfA in serum samples. The present study contributes to the advancement of specific and efficient tools for the S. aureus diagnostics, based on a virulence biomarker, ClfA, emphasizing the potential applications of molecularly imprinted magnetic nanoparticles for the detection of microorganisms and their virulence.

Highly-Efficient Reusable [Silica@Iminophosphine-FeII] Hybrids for Hydrogen Production via Formic Acid and Formaldehyde Dehydrogenation

The use of hybrids, developed by grafting homogeneous catalysts onto supporting materials, has already demonstrated significant potential in various catalytic processes. These systems combine the advantages of homogeneous catalysts, such as high activity and selectivity, with those of solid supports, including enhanced recyclability. Catalytic hydrogen (H2) production via dehydrogenation of C1 organic molecules targeting its use in fuel cells is a contemporary scientific issue directly connected with climate crisis. Here, Iminophospine hybrid [SiO2@benzNP] and its reduced analogue [SiO2@benzNHP] were synthesized, covalently grafted on colloidal SiO2, fully characterized (FT-IR, RAMAN, TGA, ssNMR, BET), and used for in-situ synthesis of [SiO2@benzNP-FeII] and [SiO2@benzNHP-FeII] catalytic complexes for H2 production from formic acid (HCOOH) and formaldehyde (HCHO), at 80 °C. In HCOOH, both heterogenized catalysts exhibit high selectivity, producing H2 and CO2 in a 1 : 1 ratio, without CO contamination, making them ideal for fuel cell applications. [SiO₂@benzNHP-FeII] catalyst demonstrated superior performance in both substates. In HCOOH dehydrogenation, over 82,000 turnover number (TONs) were achieved and retained its efficiency for over five cycles, without any further metal addition. In HCHO dehydrogenation, it showed excellent efficiency as well, achieving 1.3 L of pure H2 with TONs exceeding 7,000, in 3 consecutive uses. Advanced spectroscopic analysis confirmed the stability and structural integrity of the catalysts, linking the Schiff base reduction and N-H groups to enhanced activity, durability and reusability. This study demonstrates the potential of hybrid materials with non-noble metals for cost-effective and sustainable H2 production, paving the way for scalable renewable energy solutions.

Functionalizing of magnetic nanoparticles as nano-architecture towards bioimaging and colorimetric recognition of MCF-7 cells: dual opto-sensing and fluorescence monitoring for early-stage diagnosis of breast cancer

Considering the high incidence of breast cancer, a sensitive and specific approach is crucial for its early diagnosis and follow-up treatment. Folate receptors (FR), which are highly expressed on the epithelial tissue such as breast cancer cells (e.g., MCF-7), have been used in cancer diagnosis and bioimaging. This study presents an innovative colorimetric and fluorescence bioimaging platform towards MCF-7 using folic acid (FA)-conjugated iron-oxide magnetite silica-based nanocomposite (Fe3O4@SiO2-3-aminopropyl)triethoxysilane (APTES-NH2)@cysteine (Cyt)-Cyt@FA). For identification of MCF-7, the polyvinylpyrrolidone (PVP)-capped-platinum (Pt) nanoparticle was utilized as a nanozyme to catalyze the reaction between 3,3',5,5'-tetramethylbenzidine (TMB) and H2O2 for visual detection of MCF-7 cells. Colorimetric changes are detectable by the naked eye and spectrophotometry at the wavelength of 450 nm, with a linear range of 50-5000 cells/mL and a detection limit of 30 cells/mL. The Fe3O4@SiO2-APTES-NH2@Cyt-Cyt@FA complex was modified with rhodamine B as a fluorescence bioimaging probe to monitor FR-overexpressed MCF-7 cells. The nanocomposite is biocompatible with a toxicity threshold of about 800 µg/mL. These methodologies facilitate bioimaging and colorimetric assays without sophisticated instrumentation, offering high specificity, sensitivity, repeatability, and stability, making them suitable as versatile methods for detecting and bioimaging cancer cells.

Determination of ovalbumin sensing response of protein-imprinted bilayered hydrogel strips via measurement of mechanically driven bending angles based on swelling-induced deformation

Novel detection method has been developed to explore changes in mechanical bending angles on a bilayer of polyethylene terephthalate (PET) and molecularly imprinted polymer (MIP). For an ovalbumin (OVA)-imprinted hydrogel layer, functional monomers were employed to achieve sufficient binding effect in the polymer matrix. The OVA amount added in the MIP precursor solution and the dimensions of OVA-imprinted hydrogel (MIH) strips were controlled to maximize the change in bending angles as an OVA sensing response within a valid detection range. The sensing behaviors were determined by monitoring the difference in the bending angles via protein adsorption based on the swelling-induced deformation of the OVA-extracted hydrogel (E-MIH) strip. The equilibrium adsorption capacity of the E-MIH strip was calculated via the Bradford protein assay. The detection limit, quantification limit, and imprinting factor were calculated. To compare the selectivity coefficients, the adsorption behaviors of three proteins were investigated. Finally, the reusability of the E-MIH strip was explored via repeated adsorption and extraction. Based on the results, the E-MIH strips demonstrated a promising protein sensing platform monitoring mechanical bending angles affected by swelling deformation.

Synthesis and characterization of zeolitic imidazolate frameworks nanocrystals and their application in adsorption and detoxification of gossypol in cottonseed oil

Three zeolitic imidazolate frameworks (ZIFs) materials including ZIF-8 (H₂O), ZIF-8 (methanol) and ZIF-L were synthesized and applied to the adsorption and detoxification of gossypol in cottonseed oil. The characterization results showed three ZIFs materials had good crystal structure, thermal stability and high specific surface area. The ZIFs materials had also good adsorption performance for gossypol and their adsorption processes can be described by the pseudo-second-order adsorption kinetic models. Adsorption isotherm analysis indicated that Langmuir model expressed a better conformity than Freundlich model, suggesting that the adsorption was the single-layer adsorption on a uniform site. Furthermore, the spiked experiment showed that the detoxification rate of ZIFs materials in vegetable oil was 72-86 %. A satisfied detoxification rate of 50-70 % was found in the detoxification experiment of real cottonseed oil samples. Therefore, these results demonstrate the great potential of using ZIFs materials as detoxification in cottonseed oil.

Selective Adsorption of Quercetin by the Sol-Gel Surface Molecularly Imprinted Polymer

Quercetin, as one of the most biologically active natural flavonoids, is widely found in various vegetables, fruits and Chinese herbs. In this work, molecularly imprinted polymer (MIP) was synthesized through surface molecular imprinting technology with sol-gel polymerization mechanism on SiO₂ at room temperature using quercetin as the template, SiO₂ as the supporter, 3-aminopropyltriethoxysilane (APTES) as the functional monomer, and tetraethoxysilane (TEOS) as the cross-linker. The prepared MIP was characterized via scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR) and nitrogen adsorption measurements to validate its surface morphology, structure and functionality. SEM images revealed that the morphology of MIP was rough and spherical with the particle size of 260 nm larger than that of the support SiO₂. In the FTIR spectra of MIP, the band around 1499 cm^-1 and 2932 cm^-1 were assigned to N-H and C-H groups, respectively. The results indicated that the imprinted polymer layers were grafted on the surface of SiO₂ and the MIP had been successfully prepared. Since the specific surface area and pore volume of MIP were markedly higher than those of NIP and SiO₂ and were 52.10 m² g^-1 and 0.150 cm³ g^-1, respectively, it was evident that the imprinting process created corresponding imprinted cavities and porosity. The MIP for adsorbing quercetin was evaluated by static adsorption experiment. The results indicated that the adsorption equilibrium could be reached within 90 min and the maximum adsorption capacity was as high as 35.70 mg/g. The mechanism for adsorption kinetics and isotherm of MIP for quercetin was proved to conform the pseudo-second-order kinetics model (R² = 0.9930) and the Freundlich isotherm model (R² = 0.9999), respectively, revealing that chemical adsorption and heterogeneous surface with multilayer adsorption dominated. In contrast to non-imprinted polymer (NIP), the MIP demonstrated high selectivity and specific recognition towards quercetin whose selectivity coefficients for quercetin relative to biochanin A were 1.61. Furthermore, the adsorption capacity of MIP can be maintaining above 90% after five regeneration cycles, indicating brilliant reusability and potential application for selective adsorption of quercetin.

A Fusion of Molecular Imprinting Technology and Siloxane Chemistry: A Way to Advanced Hybrid Nanomaterials

Molecular imprinting technology is a well-known strategy to synthesize materials with a predetermined specificity. For fifty years, the "classical" approach assumed the creation of "memory sites" in the organic polymer matrix by a template molecule that interacts with the functional monomer prior to the polymerization and template removal. However, the phenomenon of a material's "memory" provided by the "footprint" of the chemical entity was first observed on silica-based materials nearly a century ago. Through the years, molecular imprinting technology has attracted the attention of many scientists. Different forms of molecularly imprinted materials, even on the nanoscale, were elaborated, predominantly using organic polymers to induce the "memory". This field has expanded quickly in recent years, providing versatile tools for the separation or detection of numerous chemical compounds or even macromolecules. In this review, we would like to emphasize the role of the molecular imprinting process in the formation of highly specific siloxane-based nanomaterials. The distinct chemistry of siloxanes provides an opportunity for the facile functionalization of the surfaces of nanomaterials, enabling us to introduce additional properties and providing a way for vast applications such as detectors or separators. It also allows for catalyzing chemical reactions providing microreactors to facilitate organic synthesis. Finally, it determines the properties of siloxanes such as biocompatibility, which opens the way to applications in drug delivery and nanomedicine. Thus, a brief outlook on the chemistry of siloxanes prior to the discussion of the current state of the art of siloxane-based imprinted nanomaterials will be provided. Those aspects will be presented in the context of practical applications in various areas of chemistry and medicine. Finally, a brief outlook of future perspectives for the field will be pointed out.

Isolation of Phenolic Compounds from Raspberry Based on Molecular Imprinting Techniques and Investigation of Their Anti-Alzheimer's Disease Properties

Alzheimer's disease is the most common neurodegenerative disease, characterized by memory loss and cognitive dysfunction. Raspberry fruits contain polyphenols which have antioxidant and anti-inflammatory properties. In this study, we used molecular imprinting technology to efficiently isolate phenolic components from the raspberry ethyl acetate extracts. Six phenolic components (ellagic acid, tiliroside, kaempferol-3-o-rutoside, gallic acid, ferulic acid and vanillic acid) were identified by UPLC-Q-TOF-MS analysis. Molecular docking was used to predict the anti-inflammatory effects and anti-Alzheimer's potential of these isolated compounds, which showed a good binding ability to diseases and related proteins. However, the binding energy and docking fraction of ellagic acid, tiliroside, and kaempferol-3-o-rutoside were better than those of gallic acid, ferulic acid and vanillic acid. Additionally, by studying the effects of these six phenolic components on the LPS-induced secretion of inflammatory mediators in murine microglial (BV2) cells, it was further demonstrated that they were all capable of inhibiting the secretion of NO, IL-6, TNF-α, and IL-1β to a certain extent. However, ellagic acid, tiliroside, and kaempferol-3-o-rutoside have better inhibitory effects compared to others. The results obtained suggest that the phenolic components extracted from ethyl acetate extracts of raspberry by molecularly imprinted polymers have the potential to inhibit the progression of Alzheimer's disease.

Purification of Andrographolide Methanolic Extract Using Molecularly Imprinted Polymer Prepared by Precipitation Polymerization

Molecularly Imprinted Polymer (MIP) has a specific cavity in which the conformity of shape, size, and functionalities corresponds with its template molecule and has been widely used in separation processes. Therefore, this study aims to examine the application of MIP for the purification of andrographolide. The MIP was synthesized by precipitation polymerization using methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) as the functional monomer and cross-linker, andrographolide as a template, and acetonitrile:toluene (3:1) as porogen solvent. The results showed that the binding capacity of Synthesized MIP was 1.2486 mg/g, while the particle size was 295.5 nm with a polydispersity index of 0.064. Furthermore, the imprinting and selectivity factors were 1.148 and 12.37, respectively. The purification process by MIP increased the purity from 55.37 ± 0.69 to 94.94% ± 0.34, while the isolate characterization showed that purified andrographolide had a similar character compared to the standard.

The Effect of the Synthesis Method on Physicochemical Properties of Selective Granular Polymer Sorbents

Investigation of the effect of the polymer synthesis method on physicochemical properties of sorbents is one of the topical problems in the chemistry of macromolecular compounds that has high scientific and practical interest. Determination of the optimal synthesis method will make it possible to create sorbents with physicochemical properties that led to the realization of effective sorption. In this work, we investigated the effect of synthesis methods (Pickering emulsion polymerization and precipitation polymerization in solution) of granular polymers based on 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate on physicochemical and sorption properties. The synthesis by Pickering emulsion polymerization led to improvement of the n-propyl alcohol diffusion into the polymer network and to the formation of more homogeneous and structurally stable polymer networks. Creating selective polymer networks by Pickering emulsion polymerization compared to precipitation polymerization in solution led to an increase in porosity, creation of more segregated surface of granules, improvement of binding sites availability at the temperature of 37 °C, and formation of the homogeneous sorption surface with high affinity to target molecules at 25 °C and 37 °C. Selective polymers synthesized by both polymerization methods had the largest values of available sorption surfaces areas for target molecules at 37 °C.

Molecularly imprinted cryogel cartridges for the selective recognition of tyrosine

Molecularly imprinted polymers are used for creating a specific cavity and selective recognition sites for the structure of a target molecule in a polymeric structure. In this study, specific molecularly imprinted cryogel cartridges were synthesized using two distinct functional monomers to compare imprinting efficiency for the selective recognition of Tyrosine (Tyr). Tyr-imprinted cryogel cartridge (MIP1) was prepared using metal-chelate coordination for the imprinting process by free-radical bulk polymerization under frozen conditions, and Tyr-imprinted cryogel cartridge (MIP2) was prepared in the same way using hydrophobic effects for imprinting. After the characterization of the cryogel cartridges was carried out, the optimum adsorption conditions of both were determined according to the different parameters such as flow rate (0.5-2.5 ml/min), pH of the medium (4.0-8.0), initial Tyr concentration (0.1-3.0 mg/ml), and temperature (4-45°C). Selectivity experiments of Tyr-imprinted and non-imprinted cryogel cartridges were carried out by using phenylalanine, tryptophan, and cysteine. Besides, the eluted Tyr from MIP1 and MIP2 cryogel cartridge were applied to FPLC system. Also, the reusability experiments of Tyr-imprinted cryogel cartridges was observed no significant decrease in the adsorption capacity.

Controlled drug delivery for cancer cell treatment via magnetic doxorubicin imprinted silica nanoparticles

Magnetic doxorubicin imprinted silica nanoparticles for remotely triggered doxorubicin release upon applying an alternating magnetic field.

Dual roles of 3-aminopropyltriethoxysilane in preparing molecularly imprinted silica particles for specific recognition of target molecules

3-Aminopropyltriethoxysilane (APTES) is a silane widely used to supply amino groups for further modifications on various materials, but it is less studied as a catalyst to catalyze sol–gel silica polymerization. Here, by using APTES as the catalyst instead of the conventional basic catalysts, a novel strategy was developed to prepare silica-based molecularly imprinted polymers (MIPs). Meanwhile, APTES was employed as the functional monomer to create imprinted nanocavities for specific recognition of target molecules. The as-synthesized MIP exhibited ultra-high recognition capability due to the elimination of the detrimental effect on the imprinting performance caused by the additional catalysts. The preparation process, specificity, pH effect, binding capacity and affinity of the MIP were studied in detail. The MIP microparticles could be packed into a solid phase extraction column for removing the target molecule in water efficiently, and the molecule could easily be enriched by 40 times. The interaction of the functional monomer and template was studied by the calculation method, giving a more clear understanding of the recognition behaviours of the imprinted polymers. The strategy could be extended not only to prepare highly specific MIPs for other small phosphoric molecules, but also for biomolecules e.g. phosphorylated peptides or proteins.

A novel strategy was developed for preparing highly selective molecularly imprinted polymers using 3-aminopropyltriethoxysilane as both a functional monomer and catalyst.

A nanocomposite probe of polydopamine/molecularly imprinted polymer/quantum dots for trace sarafloxacin detection in chicken meat

A nanooptosensor based on the fluorescence quenching of a composite probe was fabricated for the detection of sarafloxacin. The components of the nanocomposite fluorescent probe were a high affinity material of polydopamine polymer (PDA), a selective material of molecularly imprinted polymer (MIP), and optically sensitive quantum dots (QDs). The developed nanocomposite fluorescent probe exhibited excellent selectivity and sensitivity for sarafloxacin. The molecularly imprinted polymer had an imprinting factor (IF) of 8.18 and produced a probe that quenched fluorescence more effectively than a non-imprinted polymer (NIP) probe. The emission intensity of the MIP probe was linearly quenched by sarafloxacin over a range of 0.10 to 15.0 μg L^-1 with a determination coefficient (R²) of 0.9966. The developed nanooptosensor had a limit of detection of 0.05 μg L^-1. The optosensor detected sarafloxacin in chicken meat samples with recoveries ranging from 82.8 to 99.1% with an RSD below 3%. The found concentrations in spiked samples were compared well with recoveries obtained by HPLC method of detection. This developed nanooptosensor is simple to operate and cost-effective and the analytical procedure is rapid. Graphical abstract.

Molecularly Imprinted Polymers for Gossypol via Sol⁻Gel, Bulk, and Surface Layer Imprinting-A Comparative Study

Three gossypol molecularly imprinted polymers (MIPs) were prepared by bulk polymerization (MIP1), surface layer imprinting using silica gel as the support (MIP2), and the sol-gel process (MIP3). The as-prepared MIPs were characterized by SEM and nitrogen adsorption-desorption techniques to study the morphology structure. The adsorption experiments exhibited that MIP1 had adsorption capacity as high as 564 mg·g-1. The MIP2 showed faster adsorption kinetics than MIP1 and MIP3. The adsorption equilibrium could be reached for gossypol in 40 min. A selectivity study showed that the adsorption capacity of MIPs for gossypol was about 1.9 times higher than that of the structurally-similar analogs ellagic acid and 6.6 times higher than that of the quercetin. It was found that the pseudo-second-order kinetic model and the Freundlich isotherm model were more applicable for the adsorption kinetics and adsorption isotherm of gossypol binding onto the MIP1 and MIP2, respectively. Results suggested that among those three, the MIP2 was a desirable sorbent for rapid adsorption and MIP1 was suitable for selective recognition of gossypol.