Cholesterol recognition system by molecular imprinting on self-assembled monolayer

Two-Dimensional Estrone-Imprinted System on a Self-Assembled Monolayer

In this study, a thin poly (methyl methacrylate) coating was formed on a self-assembled monolayer formed on a gold plate after chemically binding estrone. Subsequently, the estrone molecules were hydrolyzed and extracted using a solvent to form a molecular-imprinted system. The estrone-imprinted gold plate was then used as a working electrode to measure the estrone recognition ability through electrochemical methods. The recognition ability of this working electrode was evaluated for similar compounds. The selectivity factors for the seven estrone analogs were measured, and these values ranged from 0.19 to 0.67. According to the experimental results, the estrone-imprinted system showed good differentiation of estrone from other estrone analogs. Comparing these selectivity factors with those of a previous study on a cholesterol-imprinted system, the relative molecular size difference between the target molecule and similar molecules had a significant impact on the selectivity factor.

Construction of nano-drug delivery and antitumor system of stimuli-responsive polypeptides

The size of the nanoparticles is moderate and the dispersion is well, which will not be recognized nonspecifically and clearance by the endothelial reticular system. In this study, stimuli-responsive polypeptides nano-delivery system has been constructed, which can realize the response to various stimuli in the tumor microenvironment. Tertiary amine groups are grafted to the side chain of polypeptides as the point of charge reversal and particle expansion. In addition, a new kind of liquid crystal monomer was prepared by substituting cholesterol-cysteamine, which can promote polymers to realize the transformation of spatial conformation by adjusting the ordered arrangement of macromolecules. The introduction of hydrophobic elements greatly enhanced the self-assembly performance of polypeptides, which could effectively improve the drug loading and encapsulation rate of nanoparticles. Nanoparticles could achieve targeted aggregation in tumor tissues, and there were no toxicity and side effects on normal bodies during treatment, with good safety in vivo.

Modern and Dedicated Methods for Producing Molecularly Imprinted Polymer Layers in Sensing Applications

Molecular imprinting (MI) is the most available and known method to produce artificial recognition sites, similar to antibodies, inside or at the surface of a polymeric material. For this reason, scholars all over the world have found MI appealing, thus developing, in this past period, various types of molecularly imprinted polymers (MIPs) that can be applied to a wide range of applications, including catalysis, separation sciences and monitoring/diagnostic devices for chemicals, biochemicals and pharmaceuticals. For instance, the advantages brought by the use of MIPs in the sensing and analytics field refer to higher selectivity, sensitivity and low detection limits, but also to higher chemical and thermal stability as well as reusability. In light of recent literature findings, this review presents both modern and dedicated methods applied to produce MIP layers that can be integrated with existent detection systems. In this respect, the following MI methods to produce sensing layers are presented and discussed: surface polymerization, electropolymerization, sol–gel derived techniques, phase inversionand deposition of electroactive pastes/inks that include MIP particles.

A highly-specific photoelectrochemical platform based on carbon nanodots and polymers functionalized organic-inorganic perovskite for cholesterol sensing

Herein, we reported the introduction of carbon nanodots (CNDs) and polyvinylidene fluoride (PVDF) as additives into perovskite CH₃NH₃PbI₃ through in situ synthesis to prepare PVDF-CH₃NH₃PbI₃@CNDs composite, which demonstrated improved water tolerance and mechanical stability. The application of PVDF-CH₃NH₃PbI₃@CNDs for photoelectrochemical sensing was then explored. A molecularly imprinted polymer (MIP) that could specifically recognize cholesterol (CHO) was anchored to PVDF-CH₃NH₃PbI₃@CNDs via a simple thermal polymerization process, followed by elution with hexane. A label-free and sensitive photoelectrochemical method for CHO detection was achieved by using the MIPs@PVDF-CH₃NH₃PbI₃@CNDs platform. The detection limit for CHO was 2.1 × 10^-14 mol/L, lower than most of the existing CHO detection methods. In our perception, this platform can be extended to numerous other analytes. This research result may provide a new understanding to improve the performance and broaden the application range of organic-inorganic perovskites.

A molecularly imprinted polymer undergoing a color change depending on the concentration of bisphenol A

A molecularly imprinted system is introduced here whose color gradually changes as the analyte becomes rebound. The MIP was prepared from an acryloyl-modified β-cyclodextrin (β-CD), acrylamide (AAm), and N,N'-methylenebisacrylamide (MBAA), and imprinted with bisphenol A (BPA). The sensing capability of the MIP was first tested by potentiometry. A spin-coated gold plate coated with the MIP was used as a working electrode; the electrode can differentiate BPA from phenol or p-cresol, which were used as analogs of BPA. Next, a color-responsive system was fabricated by forming a hydrogel membrane containing the modified β-CD, AAm, and MBAA. A vesicle solution was prepared from N-(2-aminoethyl)pentacosa-10,12-diynamide by sonication and incorporated into the hydrogel. The blue polydiacetylene was formed by UV photopolymerization. In the presence of BPA, this system undergoes a color change from blue to red that is proportional to the degree of BPA rebinding. The color change is due to the contraction of the gel membrane that rebinding causes. The method works to 0.5 mM BPA concentration range. The detection limits for BPA are 0.1 mM on visual assessment and 50 μM on spectrophotometric readout. Graphical AbstractA molecular imprinting system is described whose color changes from blue to red as it binds bisphenol A. The degree of rebinding can be measured by detecting the color change of polydiacetylene vesicle. CD: cyclodextrin, BPA: bisphenol A.

Probing a Reversible Cationic Switch on a Mixed Self-Assembled Monolayer Using Scanning Electrochemical Microscopy

Probing a switch on biomimic membrane surfaces would offer some references to the research on permeability of cytomembranes. In this work, a mixed 11-mercaptoundecanoic acid/1-undecanethiol self-assembled monolayer (MUA/UT SAM) was constructed as a model of a biomembrane. In this mixed SAM, the MUA molecules work as functional parts for the switch and the UT molecules work as diluents. The surface coverage, wetting property, and pK_a of this mixed SAM all have been well-inspected. The mixed SAM exhibits excellent switchable properties for cations, which is well-monitored by scanning electrochemical microscopy. When the pH of a solution is higher than the pK_a, protons would stimulate a shift of dissociation equilibrium of terminal carboxyl groups. The dissociated carboxylate ions would lead to a switch on the state of the SAM. Otherwise, the SAM shows an off state when the pH is lower than the pK_a. In addition, the repeatability, applicability, and the mechanism of the switch all have been well-evaluated.