Surface imprinted core–shell nanorod for selective extraction of glycoprotein

Fundamentals, Synthetic Strategies and Applications of Non-Covalently Imprinted Polymers

Molecular imprinting has emerged as an important and practical technology to create economical and stable synthetic mimics of antibodies and enzymes. It has already found a variety of important applications, such as affinity separation, chemical/biological sensing, disease diagnostics, proteomics, bioimaging, controlled drug release, and catalysis. In the past decade, significant breakthroughs have been made in non-covalently imprinted polymers, from their synthesis through to their applications. In terms of synthesis, quite a few versatile and facile imprinting approaches for preparing MIPs have been invented, which have effectively solved some key issues in molecular imprinting. Additionally, important applications in several areas, such as sensors, proteomics and bioimaging, have been well demonstrated. In this review, we critically and comprehensively survey key recent advances made in the preparation of non-covalently imprinted polymers and their important applications. We focus on the state-of-art of this technology from three different perspectives: fundamentals, synthetic strategies, and applications. We first provide a fundamental basis for molecular imprinting technologies that have been developed, which is extremely helpful for establishing a sound understanding of the challenges in molecular imprinting. Then, we discuss in particular the major breakthroughs within the last ten years (2014-2024), with emphasis on new imprinting approaches, what strengths the breakthroughs can provide, and which new applications the properties of the prepared non-covalently imprinted polymers are fit for.

Highly selective colorimetric determination of glutathione based on sandwich-structured nanoenzymes composed of gold nanoparticle-coated molecular imprinted metal-organic frameworks

A sandwich-structured composite nanoenzyme (NH2-MIL-101(Fe)@Au@MIP) was prepared using molecularly imprinted polymers, metal-organic frameworks, and gold nanoparticles and a highly selective glutathione (GSH) colorimetric sensor was constructed. The inner part of the composite nanoenzymes is a metal-organic framework loaded with gold nanoparticles (AuNPs), NH2-MIL-101(Fe)@Au, which has superior peroxidase-like activity compared with  NH2-MIL-101(Fe). This is due to the surface plasmon resonance effect of AuNPs. GSH can form strong Au-S bonds with AuNPs, which can significantly reduce the enzymatic activity of NH2-MIL-101(Fe)@Au, thereby changing the absorbance at 450 nm of the sensing system. The degree of change in absorbance is correlated with the concentration of GSH. In the outer part, the molecularly imprinted polymer with oxidized glutathione (GSSG) as a dummy template provided specific pores, which significantly improved the selectivity of the sensing system. The sensor showed good GSH sensing performance in the range 1 ~ 50 μM with a lower limit of detection (LOD) of 0.231 μM and good sensing performance in fetal bovine serum, indicating its high potential for clinical diagnostic applications.

Sequentially Controlled Recognition of Different Proteins Using Programmable Protein Imprinted Nanospheres

Although protein imprinted materials with multiple templates are developed to selectively separate different proteins, it is difficult to achieve the programmed adsorption and separation of different proteins using one material, because the available protein imprinted materials are constructed through irreversible crosslinking and their structures are unprogrammable and non-reconstructive. Herein, a novel nanosphere (MS@PTL-g-PNIPAM) is designed, which not only is temperature and pH responsive but also can dynamically reversibly crosslink/de-crosslink under ultraviolet light of different wavelengths. With the help of the dynamically reversible photo-crosslinking, the nanospheres can be repeatedly programmed into protein imprinted nanospheres toward different target proteins. Moreover, the prepared imprinted nanospheres can easily achieve the controlled rebinding and release of target proteins, benefiting from the introduced temperature- and pH-responsive moieties. As a consequence, this study realizes the specific separation of different target proteins from protein mixture and the real bovine blood sequentially by programming one material. It is resource saving, time saving, recyclable, and it will provide convenience for protein imprinted materials to use in the blood purification, drug delivery, and virus detection.

Research progress of sensors based on molecularly imprinted polymers in analytical and biomedical analysis

Molecularly imprinted polymers (MIPs) have had tremendous impact on biomimetic recognition due to their precise specificity and high affinity comparable to that of antibodies, which has shown the great advantages of easy preparation, good stability and low cost. The combination of MIPs with other analytical technologies can not only achieve rapid extraction and sensitive detection of target compounds, improving the level of analysis, but also achieve precise targeted delivery, in-vivo imaging and other applications. Among them, the recognition mechanism plays a vital role in chemical and biological sensing, while the improvement of the recognition element, such as the addition of new nanomaterials, can greatly improve the analytical performance of the sensor, especially in terms of selectivity. Currently, due to the need for rapid diagnosis and improved sensing properties (such as selectivity, stability, and cost-effectiveness), researchers are investigating new recognition elements and their combinations to improve the recognition capabilities of chemical sensing and bio-sensing. Therefore, this review mainly discusses the design strategies of optical sensors, electrochemical sensors and photoelectric sensors with molecular imprinting technology and their applications in environmental systems, food fields, drug detection and biology including bacteria and viruses.

Amino acid-immobilized copper ion-modified carbon-based adsorbent for selective adsorption of bovine hemoglobin

We prepared an amino acid-immobilized copper ion-modified carbon-based adsorbent (C@TA@P@A-Cu) for selective bovine hemoglobin (BHb) adsorption in biological samples. Carbon nanoparticles were used as the matrix, and copper ions were attached to the amino acid-modified carbon nanoparticles as metal chelate complexes via immobilized metal affinity. BSA, Lyz, OVA, and HRP were chosen as reference proteins for further study. Furthermore, the synthesis conditions of adsorbents, SPE conditions, selectivity, competitivity, reproducibility, and reusability were extensively investigated. The results showed that the maximum adsorption capacity of C@TA@P@A-Cu microspheres for BHb under optimal conditions was 673.0 mg g^-1. The addition of a TiO₂ layer with an increased specific surface area of the adsorbent and the addition of poly-l-lysine (PLL) inhibited the adsorbent's binding ability to non-BHb proteins, but chelated Cu²⁺ increased the adsorbent's specific binding ability to BHb. Furthermore, after six adsorption-desorption cycles, the adsorbent has satisfactory reusability with no significant change in adsorption capacity. Furthermore, C@TA@P@A-Cu was successfully used to identify BHb from real blood samples, as confirmed by SDS-PAGE, and it is expected to have potential applications in protein purification and disease diagnosis.

Synthesis of ferroferric oxide@silicon dioxide/cobalt-based zeolitic imidazole frameworks for the removal of doxorubicin hydrochloride from wastewater

Due to its low-cost, eco-friendliness and easy mode of separation biosynthesized magnetic ferroferric oxide (Fe₃O₄) can be successfully used for the removal of organic contaminants from wastewater. However, there are some challenges that to date have limited this compound's practical removal efficiency. Thus, in this study, a cobalt-based zeolitic imidazole frameworks (ZIF-67) coated biosynthesized ferroferric oxide@silicon dioxide (Fe₃O₄@SiO₂) magnetic composite (Fe₃O₄@SiO₂/ZIF-67) was prepared to address these issues and subsequently used to remove doxorubicin hydrochloride (DOX). Characterization results showed that the fabricated composite exhibited significant magnetic properties (16.1 emu·g^-1) with a size ranging between 50 and 250 nm. The amount of DOX adsorbed by the composite (90.7 mg·g^-1) was much higher than either of the component parts, which were only 35.7 and 82.5 mg·g^-1 for Fe₃O₄@SiO₂ and ZIF-67 respectively. This indicated enhanced DOX adsorption by Fe₃O₄@SiO₂/ZIF-67. The DOX adsorption best fit a pseudo-second order kinetic and Langmuir adsorption model. These studies suggested that the DOX adsorption mechanism involved a combination of electrostatic interactions, π-π stacking, hydrogen bonding and pore filling. Regeneration and application studies, exposing Fe₃O₄@SiO₂/ZIF-67 to real water samples, practically demonstrated that Fe₃O₄@SiO₂/ZIF-67 with propensity for magnetic separation and recycle is a promising nanomaterial for DOX removal.