Molecularly imprinted polymers (MIPs) are synthetic receptors with tailor-made recognition sites for target molecules. Their high affinity and selectivity, excellent stability, easy preparation, and low cost make them promising substitutes to biological receptors in many applications where molecular recognition is important. In particular, spherical MIP nanoparticles (or nanoMIPs) with diameters typically below 200 nm have drawn great attention because of their high surface-area-to-volume ratio, easy removal of templates, rapid binding kinetics, good dispersion and handling ability, undemanding functionalization and surface modification, and their high compatibility with various nanodevices and in vivo biomedical applications. Recent years have witnessed significant progress made in the preparation of advanced functional nanoMIPs, which has eventually led to the rapid expansion of the MIP applications from the traditional separation and catalysis fields to the burgeoning biomedical areas. Here, a comprehensive overview of key recent advances made in the preparation of nanoMIPs and their important biomedical applications (including immunoassays, drug delivery, bioimaging, and biomimetic nanomedicine) is presented. The pros and cons of each synthetic strategy for nanoMIPs and their biomedical applications are discussed and the present challenges and future perspectives of the biomedical applications of nanoMIPs are also highlighted.

Molecularly Imprinted Nanoparticles for Biomedical Applications.

Molecularly imprinted polymers (MIPs) receive extensive interest, owing to their structure predictability, recognition specificity, and application universality as well as robustness, simplicity, and inexpensiveness. Surface-enhanced Raman scattering (SERS) is regarded as an ideal optical detection candidate for its unique features of fingerprint recognition, nondestructive property, high sensitivity, and rapidity. Accordingly, MIP based SERS (MIP-SERS) sensors have attracted significant research interest for versatile applications especially in the field of chemo- and bioanalysis, showing excellent identification and detection performances. Herein, we comprehensively review the recent advances in MIP-SERS sensors construction and applications, including sensing principles and signal enhancement mechanisms, focusing on novel construction strategies and representative applications. First, the basic structure of the MIP-SERS sensors is briefly outlined. Second, novel imprinting strategies are highlighted, mainly including multifunctional monomer imprinting, dummy template imprinting, living/controlled radical polymerization, and stimuli-responsive imprinting. Third, typical application of MIP-SERS sensors in chemo/bioanalysis is summarized from both small and macromolecular aspects. Lastly, the challenges and perspectives of the MIP-SERS sensors are proposed, orienting sensitivity improvement and application expanding.

http://ir.yic.ac.cn/bitstream/133337/25064/1/Molecular-Imprinting-Based%20Surface-Enhanced%20Raman%20Scattering%20Sensors.pdf

Molecular-Imprinting-Based Surface-Enhanced Raman Scattering Sensors.

The electrochemical detection of mercury in aqueous solutions was studied at glassy carbon (GC) and indium–tin oxide (ITO) electrodes modified by gold nanoparticles (Au NPs). Two methods of modification were used: electrochemical reduction of HAuCl4 and electrostatic adsorption of Au NPs stabilized by citrate. We found that the Au NPs modified surfaces yielded higher sensitivity and sharper and more reproducible stripping peaks of Hg as compared with the bare electrodes. The effect of the modification by Au NPs on the stripping potential was examined. Interestingly, the stripping of Hg on GC and ITO modified by Au NPs occurred at the same potential as on bare GC and ITO, respectively. Only the full coverage of ITO by either electrochemically deposited Au for a long time or by vapor deposition, shifted the stripping potential more positive by ca. 0.4 V to that observed on a bare Au electrode. These and further experiments led us to conclude that the Au NPs served as nucleation sites for the deposition of H...

Electrochemical Detection of Low Concentrations of Mercury in Water Using Gold Nanoparticles

Nanomaterials and new biorecognition molecules based surface plasmon resonance biosensors for mycotoxin detection.

We report on the development of new optical sensors using molecularly imprinted polymers (MIPs) combined with different materials and explore the novel strategies followed in order to overcome some of the limitations found during the last decade in terms of performance. This review pretends to offer a general overview, mainly focused on the last 3 years, on how the new fabrication procedures enable the synthesis of hybrid materials enhancing not only the recognition ability of the polymer but the optical signal. Introduction describes MIPs as biomimetic recognition elements, their properties and applications, emphasizing on each step of the fabrication/recognition procedure. The state of the art is presented and the change in the publication trend between electrochemical and optical sensor devices is thoroughly discussed according to the new fabrication and micro/nano-structuring techniques paving the way for a new generation of MIP-based optical sensors. We want to offer the reader a different perspective based on the materials science in contrast to other overviews. Different substrates for anchoring MIPs are considered and distributed in different sections according to the dimensionality and the nature of the composite, highlighting the synergetic effect obtained as a result of merging both materials to achieve the final goal.

Molecularly Imprinted Polymer-Based Hybrid Materials for the Development of Optical Sensors

We report the first attempt of using molecularly imprinted polymers (MIPs) in the shape of nanoparticles that were doped with gold nanoparticles (AuNPs) for surface enhanced Raman scattering (SERS)-based sensing of molecular species. Specifically, AuNPs doped molecularly imprinted nano-spheres (AuNPs@nanoMIPs) were synthesized by one-pot precipitation polymerization using Sudan IV as the template for the SERS sensing. The AuNPs@nanoMIPs were characterized by various modes of scanning transmission electron microscopy (STEM) that showed the exact location of the AuNPs inside the MIP particles. The effects of Au concentration and solution stirring on the shape and the polydispersity of the particles were studied. Significant enhancement of the Raman signals was observed only when the MIP particles were doped with the AuNPs. The SERS signal improved significantly with increase in the Au concentration inside the AuNPs@nanoMIPs. Selectivity measurements of the Sudan IV imprinted AuNPs@nanoMIPs carried out with different Sudan derivatives showed high selectivity of the AuNPs-doped MIP particles.

Nanosphere molecularly imprinted polymers doped with gold nanoparticles for high selectivity molecular sensors

Molecularly imprinted polymer particles: Formation, characterization and application

We present a novel gas phase detection prototype based on assembling core-shell nanospheres made of a silver core and coated with a molecularly imprinted polymer (MIP) adsorbed onto an interdigitated array (IDA) electrode chemiresistor (CR). The core-shell nanospheres, AgNP@MIPs, were imprinted with linalool, a volatile terpene alcohol, as a model system. The thickness of the MIP layer was tuned to a few nanometers to enable the facile ingress and egress of the linalool, as well as to enhance the electrical transduction through the Ag core. The AgNP@MIPs were spread onto the IDA-CR modified with various positively charged polymers, by drop casting and dip-coating. The AgNP@MIPs were characterized by various techniques such as extra high-resolution scanning and tunnelling electron microscopy and X-ray diffraction. The MIP recognition event was transduced into a measurable increase in the resistance. The response to linalool exposure and removal was fast and the device was fully recovered and could be reused. Finally, the difference in the resistance change between imprinted and non-imprinted nanospheres was substantial.

Core–shell nanoparticles for gas phase detection based on silver nanospheres coated with a thin molecularly imprinted polymer adsorbed on a chemiresistor

Electrochemical determination of Hg(II) in aquatic solutions on bare and modified glassy carbon electrode (GCE) is reported Optimizing the parameters used for a bare GCE, such as the electrolyte solution, the potential and time of deposition, resulted in linear response over a large range of Hg(II) concentrations (4–160 ppb) using linear sweep anodic stripping voltammetry Modification of the electrode with 4,4′-disulfanediyldibenzenediazonium (DSBD) yielded a lowest detection limit of 1 ppb Two procedures for DSBD synthesis are described for the first time, and the product was characterized by microanalysis, FTIR and 1H-NMR The electrochemical attachment of DSBD to the electrode was studied and compared with the electrochemical behaviour of DSBD analogous molecules, ie 4-aminophenyl disulfide, p-aminothiophenol and phenyl disulfide

The synthesis and characterization of thiol-based aryl diazonium modified glassy carbon electrode for the voltammetric determination of low levels of Hg(II)

Adsorption of chiral molecules on heterogeneous catalysts is a simple approach for inducing an asymmetric environment to enable enantioselective reactivity. Although the concept of chiral induction is straightforward, its practical utilization is far from simple, and only a few examples toward the successful chiral induction by surface anchoring of asymmetric modifiers have been demonstrated so far. Elucidating the factors that lead to successful chiral induction is therefore a crucial step for understanding the mechanism by which chirality is transferred. Herein, we identify the adsorption geometry of OH-functionalized N-heterocyclic carbenes (NHCs), which are chemical analogues to chiral modifiers that successfully promoted α-arylation reactions once anchored on Pd nanoparticles. Polarized near-edge X-ray absorption fine structure (NEXAFS) measurements on Pd(111) revealed that NHCs that were associated with low enantioselectivity were characterized with a well-ordered structure, in which the imidazole ring was vertically positioned and the OH-functionalized side arms were flat-lying. OH-functionalized NHCs that were associated with high enantioselectivity revealed a disordered/flexible adsorption geometry, which potentially enabled better interaction between the OH group and the prochiral reactant.

Tehila Shahar

Papers

Nanosphere molecularly imprinted polymers doped with gold nanoparticles for high selectivity molecular sensors

Molecularly imprinted polymer particles: Formation, characterization and application

Core–shell nanoparticles for gas phase detection based on silver nanospheres coated with a thin molecularly imprinted polymer adsorbed on a chemiresistor

The synthesis and characterization of thiol-based aryl diazonium modified glassy carbon electrode for the voltammetric determination of low levels of Hg(II)

Influence of N-Substituents on the Adsorption Geometry of OH-Functionalized Chiral N-Heterocyclic Carbenes.