Molecularly imprinted polymers coupled to mass spectrometric detection for metallothionein sensing

Ag+-stabilized DNA triplex coupled with catalytic hairpin assembly and CRISPR/Cas12a amplifications for sensitive metallothionein assay

Metallothionein (MT) is a protein biomarker secreted by liver in response to the treatment for heavy metal toxicity and oncological diseases. On the basis of a new Ag+-stabilized DNA triplex probe (Ag+-SDTP), we establish a fluorescent biosensing system for high sensitivity detection of MT by combining catalytic hairpin assembly (CHA) and the CRISPR/Cas12a signal enhancements. The MT analyte complexes with Ag+ in Ag+-SDTP to disrupt the triplex structure and to release the ssDNA strands, which trigger subsequent CHA formation of many protospacer adjacent motif (PAM)-containing dsDNAs from two hairpins. Cas12a/crRNA further recognizes these PAM sequences to activate its trans-catalytic activity to cyclically cleave the fluorescently quenched ssDNA reporters to recovery drastically amplified fluorescence for detecting MT down to 0.34 nM within the dynamic range of 1∼800 nM. Moreover, the sensing method is able to selectively discriminate MT from other non-specific molecules and can realize low level detection of MT in diluted human serums, manifesting its potentiality for monitoring the disease-specific MT biomarker at trace levels.

The utility of molecularly imprinted polymers for mass spectrometric protein and proteomics analysis

Selective and efficient sample clean-up is important in mass spectrometric protein- and proteomics analyses from biological matrices. Molecularly imprinted polymers (MIPs), polymers prepared to have tailor-made cavities for capture of target analytes may by such represent an interesting alternative for selective clean-up. The present review aims to give an overview of the utility of MIPs for protein capture from biological matrices prior to mass spectrometry (MS) analysis. The application of MIPs in depletion of abundant proteins, in protein and proteotypic peptide capture as well as in capture of post-translational modifications (PTMs) is described and discussed. In addition, an overview of available MIP formats and their advantages and challenges is given, together with an overview of the mass spectrometric techniques used in protein analysis after MIP capture. Overall, the present literature demonstrates that for many applications MIPs for sample clean-up in mass spectrometric protein and proteomics analysis from biological matrices is still not fully matured. MIPs for proteotypic peptide capture is the most mature approach and a method for routine use may be available within the next few years.

Molecularly Imprinted Polymers Exhibit Low Cytotoxic and Inflammatory Properties in Macrophages In Vitro

Molecularly imprinted polymers (MIPs) against sialic acid (SA) have been developed as a detection tool to target cancer cells. Before proceeding to in vivo studies, a better knowledge of the overall effects of MIPs on the innate immune system is needed. The aim of this study thus was to exemplarily assess whether SA-MIPs lead to inflammatory and/or cytotoxic responses when administered to phagocytosing cells in the innate immune system. The response of monocytic/macrophage cell lines to two different reference particles, Alhydrogel and PLGA, was compared to their response to SA-MIPs. In vitro culture showed a cellular association of SA-MIPs and Alhydrogel, as analyzed by flow cytometry. The reference particle Alhydrogel induced secretion of IL-1β from the monocytic cell line THP-1, whereas almost no secretion was provoked for SA-MIPs. A reduced number of both THP-1 and RAW 264.7 cells were observed after incubation with SA-MIPs and this was not caused by cytotoxicity. Digital holographic cytometry showed that SA-MIP treatment affected cell division, with much fewer cells dividing. Thus, the reduced number of cells after SA-MIP treatment was not linked to SA-MIPs cytotoxicity. In conclusion, SA-MIPs have a low degree of inflammatory properties, are not cytotoxic, and can be applicable for future in vivo studies.

CdS quantum dots-based immunoassay combined with particle imprinted polymer technology and laser ablation ICP-MS as a versatile tool for protein detection

For the first time, the combination of molecularly imprinted polymer (MIP) technology with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is presented with focus on an optimization of the LA-ICP-MS parameters such as laser beam diameter, laser beam fluence, and scan speed using CdS quantum dots (QDs) as a template and dopamine as a functional monomer. A non-covalent imprinting approach was employed in this study due to the simplicity of preparation. Simple oxidative polymerization of the dopamine that creates the self-assembly monolayer seems to be an ideal choice. The QDs prepared by UV light irradiation synthesis were stabilized by using mercaptosuccinic acid. Formation of a complex of QD-antibody and QD-antibody-antigen was verified by using capillary electrophoresis with laser-induced fluorescence detection. QDs and antibody were connected together via an affinity peptide linker. LA-ICP-MS was employed as a proof-of-concept for detection method of two types of immunoassay: 1) antigen extracted from the sample by MIP and subsequently overlaid/immunoreacted by QD-labelled antibodies, 2) complex of antigen, antibody, and QD formed in the sample and subsequently extracted by MIP. The first approach provided higher sensitivity (MIP/NIP), however, the second demonstrated higher selectivity. A mixture of proteins with size in range 10–250 kDa was used as a model sample to demonstrate the capability of both approaches for detection of IgG in a complex sample.