Construction of DNA ligase-mimicking nanozymes via molecular imprinting.

Enzyme mimics are of significant importance due to their facile preparation, low cost and stability to rigorous environments. Molecularly imprinted polymers (MIPs) have been important synthetic mimics of enzymes. However, effective strategies for the rational design of enzyme-mimicking MIPs have still remained limited. Herein, we report a new strategy, termed affinity gathering-enhanced coupling and thermal cycling amplification (AGEC-TCA), for the rational design and engineering of molecularly imprinted mesoporous silica nanoparticles (MSNs) that are capable of ligating short ssDNA fragments. This strategy relied on enhancing the effective collision probability via binding substrates into highly favorable orientation by product-imprinted MSNs as well as product release via thermal cycling which enabled successive product amplification. Using modified and natural hexadeoxyribonucleotide as templates, the prepared product-imprinted MSNs exhibited a remarkably enhanced reaction speed (by up to 63-fold) as well as excellent sequence specificity towards substrate trideoxyribonucleotides. Thus, this strategy opened up a new avenue to access enzyme mimics via molecular imprinting.

Precision Imprinting of Glycopeptides for Facile Preparation of Glycan-Specific Artificial Antibodies.

Antibodies specific to glycans are essential in many areas for many important fields, including disease diagnostics, therapeutics, and fundamental researches. However, due to their low immunogenicity and poor availability, glycans pose serious challenges to antibody development. Although molecular imprinting has developed into important methodology for creating antibody mimics with low cost and better stability, glycan-specific molecularly imprinted polymers (MIPs) still remain rather rare. Herein, we report a new strategy, precision imprinting with alternative templates, for the facile preparation of glycan-specific MIPs. Glycopeptides with desirable peptide length immobilized on a boronate affinity substrate were first prepared as alternative templates through in situ dual enzymatic digestion. A thinlayer was then produced to cover the glycans to an appropriate thickness through precision imprinting. With glycoproteins containing only N-glycans as well as both N- and O-glycans as glycan source, this approach was proved to be widely applicable and efficient. The strategy is particularly significant for the recognition of O-glycans, because enzymes that can release O-glycans from O-linked glycoproteins are lacking. The MIPs exhibited excellent glycan specificity. Specific extraction of glycopeptides and glycoproteins containing certain glycans from complex samples was demonstrated. This strategy opened a new avenue for the facile preparation of glycan-specific MIPs, facilitating glycan-related applications and research.

Molecularly imprinted mesoporous silica nanoparticles for specific extraction and efficient identification of Amadori compounds.

Amadori compounds are an important family of chemical species with high values in the quality control and research of food and tobacco products as well as disease diagnosis. Since they are present in a large population with close structure and nature, recognition of specific Amadori compounds from complex sample matrices presents a challenging task. Particularly, few reagents or materials that can recognize specific Amadori compounds have been reported. In this study, we synthesized molecularly imprinted mesoporous silica nanoparticles (MIMSNs) that can highly specifically recognize and efficiently extract an Amadori compound of interest from complex samples. N-(1-deoxy-d-glucose-1-yl)tryptophan (Glc-Trp), a typical Amadori compound, was used as the template and target compound. The prepared MIMSNs exhibited excellent binding properties. The cross-reactivity was only 2.9-4.8% towards interfering analogs. The binding constant and binding capacity towards the target were 66 µM and 45 µmol/g, respectively. The imprinting approach showed outstanding imprinting effect, giving an imprinting factor of 119.4. Through combining MIMSNs-based extraction with electrospray ionization-mass spectrometry (ESI-MS) and capillary electrography (CE), a targeted analysis approach was established and demonstrated to be an efficient platform for identification and determination of Glc-Trp from cigarette sample.

Coupling of Phosphate-Imprinted Mesoporous Silica Nanoparticles-Based Selective Enrichment with Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry for Highly Efficient Analysis of Protein Phosphorylation.

Protein phosphorylation is a major post-translational modification and represents a ubiquitous mechanism for the cellular signaling of many different biological processes. Selective enrichment of phosphopeptides from the complex biological samples is a key step for the mass spectrometric (MS) analysis of protein phosphorylation. Herein, we present phosphate-imprinted mesoporous silica nanoparticles (MSNs) as an ideal sorbent for selective enrichment of phosphopeptides and an off-line combination with matrix-asisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) for highly efficient analysis of protein phosphorylation. The phosphate-imprinted MSNs were prepared according to a newly reported strategy called dual-template docking oriented molecular imprinting (DTD-OMI). The prepared molecularly imprinted mesoporous material exhibited several significant merits, such as excellent selectivity toward phosphopeptides, tolerance to interference, fast binding equilibrium, and large binding capacity, which made the molecularly imprinted mesoporous material an ideal sorbent for selective enrichment of phosphopeptides. Using ß-casein as a representative phosphoprotein, highly efficient phosphorylation analysis by the off-line platform was verified. Phosphorylation analysis of a nonfat milk sample was also well demonstrated. Because of their highly desirable properties, the phosphate-imprinted MSNs could find more applications in the analysis of protein phosphorylation.