Fluorescent Neoglycoprotein Gold Nanoclusters: Synthesis and Applications in Plant Lectin Sensing and Cell Imaging

Protein-Templated Metal Nanoclusters: Molecular-like Hybrids for Biosensing, Diagnostics and Pharmaceutics

The use of proteins as biomolecular templates to synthesize atomically precise metal nanoclusters has been gaining traction due to their appealing properties such as photoluminescence, good colloidal- and photostability and biocompatibility. The synergistic effect of using a protein scaffold and metal nanoclusters makes it especially attractive for biomedical applications. Unlike other reviews, we focus on proteins in general as the protective ligand for various metal nanoclusters and highlight their applications in the biomedical field. We first introduce the approaches and underlined principles in synthesizing protein-templated metal nanoclusters and summarize some of the typical proteins that have been used thus far. Afterwards, we highlight the key physicochemical properties and the characterization techniques commonly used for the size, structure and optical properties of protein-templated metal nanoclusters. We feature two case studies to illustrate the importance of combining these characterization techniques to elucidate the formation process of protein-templated metal nanoclusters. Lastly, we highlight the promising applications of protein-templated metal nanoclusters in three areas-biosensing, diagnostics and therapeutics.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2017-2018

This review is the tenth update of the original article published in 1999 on the application of matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2018. Also included are papers that describe methods appropriate to glycan and glycoprotein analysis by MALDI, such as sample preparation techniques, even though the ionization method is not MALDI. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, new methods, matrices, derivatization, MALDI imaging, fragmentation and the use of arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Most of the applications are presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. The reported work shows increasing use of combined new techniques such as ion mobility and highlights the impact that MALDI imaging is having across a range of diciplines. MALDI is still an ideal technique for carbohydrate analysis and advancements in the technique and the range of applications continue steady progress.

Systemic Lectin-Glycan Interaction of Pathogenic Enteric Bacteria in the Gastrointestinal Tract

Microorganisms, such as bacteria, viruses, and fungi, and host cells, such as plants and animals, have carbohydrate chains and lectins that reciprocally recognize one another. In hosts, the defense system is activated upon non-self-pattern recognition of microbial pathogen-associated molecular patterns. These are present in Gram-negative and Gram-positive bacteria and fungi. Glycan-based PAMPs are bound to a class of lectins that are widely distributed among eukaryotes. The first step of bacterial infection in humans is the adhesion of the pathogen's lectin-like proteins to the outer membrane surfaces of host cells, which are composed of glycans. Microbes and hosts binding to each other specifically is of critical importance. The adhesion factors used between pathogens and hosts remain unknown; therefore, research is needed to identify these factors to prevent intestinal infection or treat it in its early stages. This review aims to present a vision for the prevention and treatment of infectious diseases by identifying the role of the host glycans in the immune response against pathogenic intestinal bacteria through studies on the lectin-glycan interaction.

Natural protein-templated fluorescent gold nanoclusters: Syntheses and applications

For the past decades, the synthesis of metal nanoclusters has been a great interest for research, for their unique physicochemical properties and great contributions to the catalytic, electrical and biomedical applications. Protein-templated gold nanoclusters (AuNCs) is a kind of fluorescent nanomaterials with good solubility, excellent stability, biocompatibility, decent quantum yields and active groups (-COOH, -NH₂) for facilitating modifications. Natural proteins are easily available, commercially affordable, diverse and multitudinous in animals, plants and foods, which provide a template pool for the exploration of AuNCs. This is one of the few reviews of specifically focusing on the natural protein-templated fluorescent AuNCs. The syntheses, properties and applications of different AuNCs were enumerated. Prospects were given on utilizing structure-modified proteins, bioactive enzymes, antibodies which should endow the AuNCs more favourable fluorescence performances and functional characteristics. The applications of AuNCs in analytical, biomedical and food sciences would be further heightened.

Gold-Nanocluster-Embedded Mucin Nanoparticles for Photodynamic Therapy and Bioimaging

Effective delivery of a photosensitizer with the ability to trace its eventual progress forms an important aspect in photodynamic therapy (PDT). Further, the delivery mechanism might require possessing the ability to traverse through the complex mucus barrier that offers retention of therapeutic molecules. In this work, gold nanocluster (Au NC)-embedded mucin nanoparticles were synthesized by a rapid green synthetic procedure for application as nanocarriers and to achieve image-guided PDT. The mucin-based nanocarrier exhibited excellent biocompatibility toward normal cells (HEK 293T). The photosensitizer methylene blue (MB) was loaded onto these Au NC-mucin nanoparticles (NPs). HeLa cancer cells were treated with MB-loaded Au NC-mucin nanoparticles under irradiation of 640 nm light. The cell viability assay revealed that the viability of HeLa cells was reduced to 50% after treatment with MB-loaded Au NC-mucin NPs under 640 nm irradiation. The luminescence exhibited by Au NCs in the nanocarrier was applied for tracking the delivery of MB inside the HeLa cells using confocal microscopy. The flow cytometry assays elucidated the mechanism of cell death.