1,720,995 research outputs found
Molecular imprinting using biopolymers as building Blocks: Sustainable and biocompatible metamaterials for smart recognition and selective biointerfaces
Full text linkThe present review provides a comprehensive analysis of the development and application of molecularly imprinted polymers (MIPs) derived from natural biopolymers, covering literature from the early 1980s onward. The discussion is organized based on the chemical nature of the biopolymers utilized, covering glucans, chitosan, alginates, proteins, and nucleic acids. Each section offers a description of the respective biopolymer, reports synthetic approaches and applications, and attempt a critical evaluation of its effectiveness in molecular imprinting. The use of biopolymers in MIP technology is a promising approach for producing highly selective and sustainable recognition systems. The review underscores the potential of biopolymer-based MIPs in advancing molecular imprinting technology and their impactful contributions to future applications
Molecularly imprinted polymers electrochemical sensing: the effect of inhomogeneous binding sites on the measurements. a comparison between imprinted polyaniline versus nanoMIP-Doped polyaniline electrodes for the EIS detection of 17β-Estradiol
Full text linkMolecularly imprinted polymers (MIPs) are synthetic receptors made by template-assisted synthesis. MIPs might be ideal receptors for sensing devices, given the possibility to custom-design selectivity and affinity toward a targeted analyte and their robustness and ability to withstand harsh conditions. However, the synthesis of MIP is an inherently random process that produces a statistical distribution of binding sites, characterized by a variety of affinities. This is verified both for bulk MIP materials and for MIP's thin layers. In the present work, we aimed at assessing the effects of inhomogeneous versus homogeneous imprinted binding sites on electrochemical sensing measurements, and the possible implications on the sensor's performance. In the example of an Electrochemical Impedance Spectroscopy (EIS) sensor for the 17β-estradiol (E2) hormone, the scenario of inhomogeneous binding sites was studied by modifying electrodes with an E2-MIP polyaniline (PANI) thin layer, called the "Imprinted PANI layer". In contrast, the condition of discrete and uniform binding sites was epitomized by electrodes modified with a thin PANI layer purposedly doped with E2-MIP nanoparticles (nanoMIPs), which were referred to as "nanoMIP-doped PANI". The behaviors of the two EIS sensors were compared. Interestingly, the sensitivity of the nanoMIP-doped PANI was almost twice with respect to that of the imprinted PANI layer, strongly suggesting that the homogeneity of the binding sites has a fundamental role in the sensor's development. The nanoMIP-doped PANI sensor, which showed a response for E2 in the range 36.7 pM-36.7 nM and had a limit of detection of 2.86 pg/mL, was used to determine E2 in wastewater.Italian Ministry of Research and University doctoral program PON PNRR D.M.351ACS Sensor
On the Effect of Soft Molecularly Imprinted Nanoparticles Receptors Combined to Nanoplasmonic Probes for Biomedical Applications
Full text linkSoft, deformable, molecularly imprinted nanoparticles (nanoMIPs) were combined to nano-plasmonic sensor chips realized on poly (methyl methacrylate) (PMMA) substrates to develop highly sensitive bio/chemical sensors. NanoMIPs (d(mean) < 50 nm), which are tailor-made nanoreceptors prepared by a template assisted synthesis, were made selective to bind Bovine Serum Albumin (BSA), and were herein used to functionalize gold optical nanostructures placed on a PMMA substrate, this latter acting as a slab waveguide. We compared nanoMIP-functionalized non-optimized gold nanogratings based on periodic nano-stripes to optimized nanogratings with a deposited ultra-thin MIP layer (<100 nm). The sensors performances were tested by the detection of BSA using the same setup, in which both chips were considered as slab waveguides, with the periodic nano-stripes allocated in a longitudinal orientation with respect to the direction of the input light. Result demonstrated the nanoMIP-non optimized nanogratings showed superior performance with respect to the ultra-thin MIP-optimized nanogratings. The peculiar deformable character of the nano-MIPs enabled to significantly enhance the limit of detection (LOD) of the plasmonic bio/sensor, allowing the detection of the low femtomolar concentration of analyte (LOD similar to 3 fM), thus outpassing of four orders of magnitude the sensitivies achieved so far on optimized nano-patterned plasmonic platforms functionalized with ultra-thin MIP layers. Thus, deformable nanoMIPs onto non-optimized plasmonic probes permit to attain ultralow detections, down to the quasi-single molecule. As a general consideration, the combination of more plasmonic transducers to different kinds of MIP receptors is discussed as a mean to attain the detection range for the selected application field
Deformable molecularly imprinted nanogels permit sensitivity-gain in plasmonic sensing
No full textSoft molecularly imprinted nanogels (nanoMlPs), selective for human transferrin (HTR), were prepared via a template assisted synthesis. Owing to their soft matter, the nanoMIPs were observed to deform at binding to HTR: while no relevant changes were observed in the hydrodynamic sizes of HTR-free compared to HTR-loaded nanoMIPs, the HTR binding resulted in a significant increment of the nanoMIP stiffness, with the mean Young's modulus measured by AFM passing from 17 +/- 6 kPa to 56 +/- 18 kPa.When coupled to a plastic optical fibre (POF) plasmonic platform, the analyte-induced nanoMIP-deformations amplified the resonance shift, enabling to attain ultra-low sensitivities (LOD = 1.2 fM; linear dynamic range of concentrations from 1.2 fM to 1.8 pM). Therefore, soft molecularly imprinted nanogels that obey to analyte-induced deformation stand as a novel class of sensitivity-gain structures for plasmonic sensing
Spoon-shaped polymer waveguides to excite multiple plasmonic phenomena: A multisensor based on antibody and molecularly imprinted nanoparticles to detect albumin concentrations over eight orders of magnitude
Full text linkA polymeric multimode waveguide, characterized by a pioneering spoon-shaped geometry, was herein proposed for the first time to devise Surface Plasmon Resonance (SPR) biochemical sensors. The plasmon excitation was enabled by layering a gold nanofilm of ∼60 nm onto the spoon-waveguide. As a consequence of the waveguide's extra-ordinary geometry, two distinct sensing regions were identified: a planar one, located on the spoon's neck, and a concave one on the bowl, with angled surfaces. The bulk sensitivity (Sn) is correlated both to the way the light was launched in/collected from the sensor (parallel or orthogonal to the main axis of the waveguide) and to the sensing area interrogated (planar-neck or angled-bowl), indicating that the sensor's performance can be conveniently tuned, depending on the chosen measuring configuration. The SPR sensor's characterization showed Sn equal to 750 nm/RIU for the neck and to 950 nm/RIU for the bowl. To further inspect the peculiar sensing-features and assess the application niches, the spoon-shaped waveguide was functionalized with two kinds of receptors, both specific for human serum albumin (HSA): an antibody on the bowl region (high Sn); molecularly imprinted nanoparticles (nanoMIPs) on the neck region (low Sn). The experimental results showed a limit of detection (LOD) for the immune-sensor of 280 pM and an LOD for the nanoMIP-sensor of 4.16 fM. The overall response of the HSA multi-sensor encompassed eight orders of magnitude, suggesting that the spoon-shaped waveguide's provides multi-scale detection and holds potential to devise multi-analyte sensing platforms
A Thermal‐Reflow‐Based Low‐Temperature, High‐Pressure Sintering of Lyophilized Silk Fibroin for the Fast Fabrication of Biosubstrates
No full textSolid fibroin is a bulk nonporous material that can be prepared with two methods: a liquid–gel–solid transition from a fibroin solution or a sintering procedure starting from silk powder. Both methods have their own disadvantages: the first requires several weeks and the process is size dependent; the second requires high temperatures. To overcome these limitations, a low‐temperature sintering procedure based on a thermal‐reflow is proposed in this work to produce in fast‐fashion monoliths of solid fibroin. Thermal‐reflow is a well‐known mechanism that takes place when the glass transition temperature of the material is lower than the temperature used to process it. Water plays an important role decreasing the glass transition temperature down to 40 °C. For the first time, a thermal reflow is conducted on lyophilized silk fibroin at 40 °C, associating to the water addition a high‐pressure compression. To optimize the process, a full factorial design of experiment is used. The material is then studied in the crucial phases by digital scanning calorimetry, Fourier‐transform infrared spectroscopy, and scanning electron microscopy. Finally, a mechanical characterization and a preliminary in vitro test are conducted
Protein-based molecular imprinting: gelatin nanotraps for interleukin-6 sequestration in inflammation cell models
Full text link: Protein-derived biomaterials are currently underrated as building blocks in molecular imprinting, even though they offer several benefits, such as biocompatibility and safe biodegradability. Gelatin is a biopolymer that can be easily modified with pendant double bonds for polymerization, making it suitable for tissue engineering and biofabrication. In this study, we used gelatin methacryloyl (GelMA) as a building block combined with molecular imprinting technology to create an original class of bioinspired nanotraps specifically capable of sequestering the proinflammatory cytokine interleukin-6 (IL-6). The stability in solution, biocompatibility, and biodegradability of the nanotraps were assessed. The nanotraps were selective and specific for IL-6, showing nanomolar affinity and, when tested in vitro on an inflammation cell model, sequestered IL-6 with a dose-response relationship. Overall, our study shows that protein chemistry-driven molecular imprinting could become more widely used to devise biocompatible functional nanomaterials
Preparation and Statistical Characterization of Tunable Porous Sponge Scaffolds using UV Cross-linking of Methacrylate-Modified Silk Fibroin
No full textSilk fibroin sponges have been widely studied and reported in literature for tissue engineering applications. Several fabrication methods have been proposed during the years to cover most of the demands in terms of properties, which should be adapted to the considered tissue. Most of these procedures are based on the secondary structure transition of the protein to the stable β crystalline form. This transition, known as physical cross-linking, makes the sponge resistant to dissolution in water, and, in general, increases the sponge stiffness. In our work, we propose an alternative method to ensure the stability of the sponge based on chemical cross-linking of a methacrylated version of silk fibroin (Sil-MA) obtained via chemical modification. The Sil-MA water solution with the addition of a photoinitiator (LAP) allows the opening, under UV radiation, of a double carbon–carbon bond and radical polymerization. The incorporation of air bubbles (that serves as a template for the pores) was accomplished by a mixer; then, the foam was stabilized under UV light and the excess water was removed by freeze-drying. Because of the cytotoxicity of the photoinitiator (found when used at a high concentration), an additional washing step in water has been introduced to eliminate the residues and improve the cells’ viability. Fourier transform infrared (FTIR) analysis confirmed the functionalization of the protein. To evaluate the effect of the composition on the sponge properties, a 23 full factorial design of the experiment has been adopted. FTIR analysis revealed that the sponge composition did not affect the protein’s secondary structure. The analysis of images obtained by SEM allowed some statistical measures of the porosity curves to be studied and modeled. The same modeling procedure was applied to the dissolution test in a simulated body fluid, to the water absorption, and to the cell viability (tested by the MTT and LDH assays). An empirical model for each property was built, showing how by changing the composition it is possible to tune the sponge properties
Breath figures decorated silica-based ceramic surfaces with tunable geometry from UV cross-linkable polysiloxane precursor
No full textLittle has been published so far on the fabrication of porous ceramic films by using the Breath Figure method. In this work we explored the Breath Figure method to obtain ceramics with patterned surfaces. A UV cross-linkable polysiloxane was used to produce Breath Figures with tunable pore size. Pores formation, in terms of size and distribution on the polysiloxane films, were studied as a function of the concentration of the starting solution and time before UV irradiation. The polymeric breath figures were then pyrolyzed in controlled atmosphere to obtain, through the polymer-derived ceramic, PDCs, route the corresponding ceramic preserving the original porous surface. Pyrolysis under different gases, in particular air, nitrogen and ammonia, allows obtaining films of three different ceramic materials: silicon dioxide, SiO2, silicon oxycarbide, SiOC and silicon oxynitride, SiON respectively
Non-Specific Responsive Nanogels and Plasmonics to Design MathMaterial Sensing Interfaces: The Case of a Solvent Sensor
Full text linkThe combination of non-specific deformable nanogels and plasmonic optical probes provides an innovative solution for specific sensing using a generalistic recognition layer. Soft polyacrylamide nanogels that lack specific selectivity but are characterized by responsive behavior, i.e., shrinking and swelling dependent on the surrounding environment, were grafted to a gold plasmonic D-shaped plastic optical fiber (POF) probe. The nanogel–POF cyclically challenged with water or alcoholic solutions optically reported the reversible solvent-to-phase transitions of the nanomaterial, embodying a primary optical switch. Additionally, the non-specific nanogel–POF interface exhibited more degrees of freedom through which specific sensing was enabled. The real-time monitoring of the refractive index variations due to the time-related volume-to-phase transition effects of the nanogels enabled us to determine the environment’s characteristics and broadly classify solvents. Hence the nanogel–POF interface was a descriptor of mathematical functions for substance identification and classification processes. These results epitomize the concept of responsive non-specific nanomaterials to perform a multiparametric description of the environment, offering a specific set of features for the processing stage and particularly suitable for machine and deep learning. Thus, soft MathMaterial interfaces provide the ground to devise devices suitable for the next generation of smart intelligent sensing processes
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