Coordinated Axial Ligand and d-π Conjugated Network Makes the Difference: Engineered 2D Mn-Based Antioxidase Mimic for Enhancing Stem Cell Protection

Reactive oxygen species (ROS) refer to various partially reduced oxygen moieties that are naturally generated due to biochemical processes. Elevated formation of ROS leads to damage to biomolecules, resulting in oxidative stress and cell death. The increased level of ROS also affects therapeutics based on stem cell transplantation. Nanomaterials-based enzyme mimetics have attracted immense attention, but there are several challenges to be addressed in terms of selectivity, efficiency, and biocompatibility. This highlight focuses on a recent investigation by Cheng and coworkers, who engineered an Mn-superoxide dismutase (Mn-SOD)-inspired material with Mn-N5 sites having an axial ligand and 2D d-π-conjugated network. This engineering approach enhances antioxidase-like function and effectively rescues stem cells from ROS. In addition, it also protects osteogenesis-related gene transcription, ensuring survival rates and osteogenic differentiation of hMSCs under ROS environment. This versatile and robust artificial antioxidase holds promise for stem cell therapies and ROS-originated diseases.

A Single-Atom Nanozyme Cascade for Selective Tumor-Microenvironment-Responsive Nanocatalytic Therapy

The evolution of cancers to resist existing therapeutic strategies has constantly led researchers to design next-generation therapeutics. Research on nanomedicine holds significant potential in developing newer cancer therapeutics. Nanozymes bearing the properties of enzymes can be promising anticancer agents due to their tunable enzyme-like properties. In one such approach, a biocompatible cobalt-single-atom nanozyme (Co-SAs@NC) bearing catalase and oxidase-like activities that function in cascade at the tumor microenvironment has been reported recently. The current highlight discusses this investigation to unveil Co-SAs@NC's mechanism in tumor cell apoptosis through in vivo studies.

Delineating the Role of Tailored Gold Nanostructures at the Biointerface

Gold (Au) has emerged as a superior element, because of its widespread applications in electronic and medical fields. The desirable physical, chemical, optical, and inherent enzyme-like properties of Au are efficiently exploited for detection, diagnostic, and therapeutic purposes. Au offers a unique advantage of fabricating gold nanostructures (GNS) having exact physical, chemical, optical, and enzyme-like properties required for the specific biomedical application. In this Review, the emerging trend of GNS for various biomedical applications is highlighted. Some notable structural and chemical modifications achieved for the detection of biomolecules, pathogens, diagnosis of diseases, and therapeutic applications are discussed in brief. The limitations of GNS during biomedical usage are highlighted and the way forward to overcome these limitations are discussed.

All Ag Nanoparticles Are Not the Same: Covalent Interactions between Ag Nanoparticles and Nitrile Groups Help Combat Drug- and Ag-Resistant Bacteria

Antimicrobial resistance has long been viewed as a lethal threat to global health. Despite the availability of a wide range of antibacterial medicines all around the world, organisms have evolved a resistance mechanism to these therapies. As a result, a scenario has emerged requiring the development of effective antibacterial drugs/agents. In this article, we exclusively highlight a significant finding reported by Zbořil and associates (Adv. Sci. 2021, 2003090). The authors construct a covalently bounded silver-cyanographene (GCN/Ag) with the antibacterial activity of 30 fold higher than that of free Ag ions or typical Ag nanoparticles (AgNPs). Ascribed to the strong covalent bond between nitrile and Ag, an immense cytocompatibility is shown by the GCN/Ag towards healthy human cells with a minute leaching of Ag ions. Firm interactions between the microbial membrane and the GCN/Ag are confirmed by molecular dynamics simulations, which rule out the dependence of antibacterial activity upon the Ag ions alone. Thus, this study furnishes ample scope to unfold next-generation hybrid antimicrobial drugs to confront infections arising from drug and Ag-resistant bacterial strains.

Stepping towards benign alternatives: sustainable conversion of plastic waste into valuable products

The extensive use of plastic and the absence of efficient and sustainable methods for its degradation has raised critical concerns about its disposal and degradation. Furthermore, the escalated use of personal protective equipment (PPE) and masks during the ongoing COVID-19 pandemic has put us under tremendous pressure of generating huge amounts of plastic waste. Traditional plastic waste disintegration protocols, while effective, pose additional inevitable environmental risks. Owing to this, almost all the used plastic is directly discarded into the marine and terrestrial bodies, causing great harm to the flora and fauna. Plastic has even started entering the food chain in the form of micro- and nano-plastics, leading to deleterious effects. Considering the global need for finding sustainable ways to degrade plastic, several approaches have been developed. Herein we highlight and rationally compare the recent reports on the development of benign alternatives for the sustainable disintegration of plastic detritus into value-added products. Here we discuss, in depth, photoreforming of a variety of polymers to liquid fuels under natural conditions; enzyme-based deconstruction of polymeric materials via microorganisms and their engineered mutants into useful virgin monomers at ambient temperature; and pyrocatalytic degradation of polyethylene through efficient synthetic materials into valuable fuels and waxes. By critically analyzing the methods, we also provide our opinion on such sustainable techniques and discuss newer approaches related to bioinspired and biomimetic chemistry principles for the management of plastic waste.

A review on the role of transition metals in selenylation reactions

Organoselenium chemistry has emerged as a distinctive area of research with tremendous utility in the synthesis of biologically and pharmaceutically active molecules. Significant synthetic approaches have been made for the construction of C-Se bonds which find use in other organic transformations. This review focuses on the versatility of transition metal-mediated selenylation reactions, providing insights into various synthetic pathways and mechanistic details. Further, this review aims to offer a broad perspective for designing efficient and novel catalysts to incorporate organoselenium moiety into the inert C-H bonds.

A concise discussion on the potential spectral tools for the rapid COVID-19 detection

Developing robust methods to detect the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), a causative agent for the current global health pandemic, is an exciting area of research. Nevertheless, the currently used conventional reverse transcription-polymerase chain reaction (RT-PCR) technique in COVID-19 detection endures with some inevitable limitations. Consequently, the establishment of rapid diagnostic tools and quick isolation of infected patients is highly essential. Furthermore, the requirement of point-of-care testing is the need of the hour. Considering this, we have provided a brief review of the use of very recently reported robust spectral tools for rapid COVID-19 detection. The spectral tools include, colorimetric reverse transcription loop-mediated isothermal amplification (RT-LAMP) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), with the admittance of principal component analysis (PCA) and machine learning (ML) for meeting the high-throughput and fool-proof platforms for the detection of SARS-CoV-2, are reviewed. Recently, these techniques have been readily applied to screen a large number of suspected patients within a short period and they demonstrated higher sensitivity for the detection of COVID-19 patients from unaffected human subjects.