Probing Low-Copy-Number Proteins in a Single Living Cell

Greenificated Molecularly Imprinted Materials for Advanced Applications

Molecular imprinting technology (MIT) produces artificial binding sites with precise complementarity to substrates and thereby is capable of exquisite molecular recognition. Over five decades of evolution, it is predicted that the resulting host imprinted materials will overtake natural receptors for research and application purposes, but in practice, this has not yet been realized due to the unsustainability of their life cycles (i.e., precursors, creation, use, recycling, and end-of-life). To address this issue, greenificated molecularly imprinted polymers (GMIPs) are a new class of plastic antibodies that have approached sustainability by following one or more of the greenification principles, while also demonstrating more far-reaching applications compared to their natural counterparts. In this review, the most recent developments in the delicate design and advanced application of GMIPs in six fast-growing and emerging fields are surveyed, namely biomedicine/therapy, catalysis, energy harvesting/storage, nanoparticle detection, gas sensing/adsorption, and environmental remediation. In addition, their distinct features are highlighted, and the optimal means to utilize these features for attaining incredibly far-reaching applications are discussed. Importantly, the obscure technical challenges of the greenificated MIT are revealed, and conceivable solutions are offered. Lastly, several perspectives on future research directions are proposed.

An Integrated Photoelectrochemical Nanotool for Intracellular Drug Delivery and Evaluation of Treatment Effect

With reduced background and high sensitivity, photoelectrochemistry (PEC) may be applied as an intracellular nanotool and open a new technological direction of single-cell study. Nevertheless, the present palette of single-cell tools lacks such a PEC-oriented solution. Here a dual-functional photocathodic single-cell nanotool capable of direct electroosmotic intracellular drug delivery and evaluation of oxidative stress is devised by engineering a target-specific organic molecule/NiO/Ni film at the tip of a nanopipette. Specifically, the organic molecule probe serves simultaneously as the biorecognition element and sensitizer to synergize with p-type NiO. Upon intracellular delivery at picoliter level, the oxidative stress effect will cause structural change of the organic probe, switching its optical absorption and altering the cathodic response. This work has revealed the potential of PEC single-cell nanotool and extended the boundary of current single-cell electroanalysis.

A microfluidic device enabling deterministic single cell trapping and release

Successful single-cell isolation is a pivotal technique for subsequent biological and chemical analysis of single cells. Although significant advances have been made in single-cell isolation and analysis techniques, most passive microfluidic devices cannot deterministically release trapped cells for further analysis. In this paper, we present a novel microfluidic device that can achieve high-efficiency cell trapping, which can then be released in a deterministic order. The device contains an array of trapping sites, a main channel, a trigger channel, and an air channel. Two types of capillary valves are configured along the channels. As these capillary valves can be automatically opened in a predefined pattern, the incoming cells can be spontaneously and sequentially trapped into separate trapping sites. After trapping, the individual trapped cells can be released from their sites in a last-trapped-first-released manner by applying pressure from the trigger channel to counteract against the pressure from the main channel. The theoretical model of the trapping and release flow field is established respectively to describe the conditions required for trapping and release. Experiments using MCF-7 cells demonstrated the capability of our device for deterministic single cell trapping and release. We envision that our method constitutes a useful sample preparation platform for single cell analysis.

Molecularly Imprinted Polymer-Based Smart Prodrug Delivery System for Specific Targeting, Prolonged Retention, and Tumor Microenvironment-Triggered Release

Prodrug and drug delivery systems are two effective strategies for improving the selectivity of chemotherapeutics. Molecularly imprinted polymers (MIPs) have emerged as promising carriers in targeted drug delivery for cancer treatment, but they have not yet been integrated with the prodrug strategy. Reported here is an MIP-based smart prodrug delivery system for specific targeting, prolonged retention time, and tumor microenvironment-triggered release. 5'-Deoxy-5-fluorocytidine (DFCR) and sialic acid (SA) were used as a prodrug and a marker for tumor targeting, respectively. Their co-imprinted nanoparticles were prepared as a smart carrier. Prodrug-loaded MIP specifically and sustainably accumulated at the tumor site and then gradually released. Unlike conventional prodrug designs, which often require in-liver bioconversion, this MIP-based prodrug delivery is liver-independent but tumor-dependent. Thus, this study opens new access to the development of smart prodrug delivery nanoplatforms.

Selective Binding of Dopamine and Epinephrine in Water by Molecularly Imprinted Fluorescent Receptors

Catecholamines play important roles in biology but their structural similarity makes it challenging to construct synthetic receptors with selective binding. A combination of covalent and noncovalent binding groups in the hydrophobic core of water-soluble nanoparticles enabled them to recognize dopamine and epinephrine with an association constant (Ka ) of 3-4×104  M-1 in water, an order of magnitude higher than those of previously reported synthetic hosts. In addition, minute structural changes among analogues were detected including the addition or removal of a single hydroxyl or methyl group.

Preparation of salbutamol imprinted magnetic nanoparticles via boronate affinity oriented surface imprinting for the selective analysis of trace salbutamol residues

Salbutamol (SAL) is one of the most widely abused feed additives in animal husbandry.

Ultrasensitive profiling of multiple biomarkers from single cells by signal amplification mass spectrometry

A signal amplification protocol based on mass spectrometry (MS) was developed to profile simultaneously multiple biomarkers from a single cell using various mass label (ML)-modified Au nanoparticles (AuNPs). The strategy with ultrahigh sensitivity and specificity has potential prospects in the deep exploration of molecular and cellular characterization.