Glycopolymer Decorated pH-Dependent Ratiometric Fluorescent Probe Based on Förster Resonance Energy Transfer for the Detection of Cancer Cells.

Development of fluorescent imaging probes is an important topic of research for the early diagnosis of cancer. Based on the difference between the cellular environment of tumor cells and normal cells, several "smart" fluorescent probes have been developed. In this work, a glycopolymer functionalized Förster resonance energy transfer (FRET) based fluorescent sensor is developed, which can monitor the pH change in cellular system. One-pot sequential reversible addition-fragmentation chain transfer (RAFT)polymerization technique is employed to synthesize fluorescent active triblock glycopolymer that can undergo FRET change on the variation of pH. A FRET pair, fluorescein o-acrylate (FA) and 7-amino-4-methylcoumarin (AMC) is linked via a pH-responsive polymer poly [2-(diisopropylamino)ethyl methacrylate] (PDPAEMA), which can undergo reversible swelling/deswelling under acidic/neutral condition. The presence of glycopolymer segment provides stability, water solubility, and specificity toward cancer cells. The cellular FRET experiments on cancer cells (MDA MB 231) and normal cells (3T3 fibroblast cells) demonstrate that the material is capable of distinguishing cells as a function of pH change.

Multifunctional Layer-by-Layer Coating Based on a New Amphiphilic Block Copolymer via RAFT-Mediated Polymerization-Induced Self-Assembly Process.

In this hi-tech world, the "smart coatings" have sparked significant attention among materials scientists because of their versatile applications. Various strategies have been developed to generate smart coatings in the past 2 decades. The layer-by-layer (LbL) technique is the most commonly employed strategy to produce a smart coating for suitable applications. Here, we present a smart coating with healing, antifogging, and fluorescence properties fabricated by the LbL assembly of an anionic amphiphilic block copolymer latex and cationic inorganic POSS (polyhedral-oligomeric-silsesquioxane) nanoparticles. In this case, a new anionic block copolymer (BCP), {poly(sodium styrene sulfonate)-block-poly[2-(acetoacetoxy)ethyl methacrylate]}, (PSS-b-PAAEMA) was synthesized via surfactant-free RAFT-mediated emulsion polymerization using the PISA technique. The PSS-b-PAAEMA was characterized by 1H NMR, dynamic light scattering, scanning electron microscopy, and transmission electron microscopy analyses as well as by UV-vis and photoluminescence spectroscopy. For LbL coating fabrication, an amine-modified glass was successively dipped in the anionic latex and cationic POSS solution. The transparent coating exhibited good fluorescence properties under UV light (blue color). The antifogging performance of the coating was also investigated using both cold-warm and hot-vapor techniques. Additionally, the coating surface showed a significant healing activity with a healing efficiency of >75% through ionic interaction. Thus, this finding provides a simple low volatile organic compound (VOC) water-based LbL coating with multifunctional properties that can be a potential material for versatile applications.

Graphene Quantum Dots-Ornamented Waterborne Epoxy-Based Fluorescent Adhesive via Reversible Addition-Fragmentation Chain Transfer-Mediated Miniemulsion Polymerization: A Potential Material for Art Conservation.

Epoxy-based adhesives have gotten significant attention in the conservation of antiquities and repair or reconstruction of artifacts due to their excellent adhesion strength. However, it has become hard to detect repaired work in artifacts due to the transparent nature of epoxy-based adhesives. Hence, the making of fluorescent adhesives has become an exciting topic for art conservators. Here, we have synthesized a new kind of waterborne epoxy-based fluorescent adhesive decorated with graphene quantum dots (GQDs) via reversible addition-fragmentation chain transfer (RAFT)-mediated surfactant-free miniemulsion polymerization. In this case, a new block copolymer (BCP), poly(1-vinyl-2-pyrrolidone)-block-poly(glycidyl methacrylate), has been synthesized via surfactant-free RAFT-mediated miniemulsion polymerization using a polymerization-induced self-assembly technique. The GQDs were prepared from citric acid by a hydrothermal process, and this was used for making a fluorescence-active BCP/GQD nanocomposite emulsion. The obtained BCP/GQD nanocomposite adhesive was transparent and showed blue fluorescence under ultraviolet-visible light, indicating the easy detection of its mark on the artifacts. The BCP and BCP/GQD emulsions were applied to adhere ceramic and glass substrates, and their adhesion strength was evaluated by lap shear tests. The BCP/GQDs showed better adhesion strength than the BCP only, indicating better adhesive performance. Additionally, the synthesis process was carried out in aqueous media, indicating the sustainability and environment-friendliness of the process. We believe that this kind of new waterborne epoxy-based fluorescent adhesive will provide a new contrivance among art conservators to repair or reconstruct artifacts.

A self-healable and antifouling hydrogel based on PDMS centered ABA tri-block copolymer polymersomes: a potential material for therapeutic contact lenses.

Herein we have prepared an antifouling and self-healable poly(dimethyl siloxane) (PDMS) based hydrogel which consists of a mixture of curcumin loaded zwitterionic PDMS polymersomes and amine functionalized PDMS polymersomes prepared via Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization and a Schiff-base reaction. The curcumin loaded polymersome consists of a PDMS and poly([dimethyl-[3-(2-methyl-acryloylamino)-propyl]-(3-sulfopropyl)ammonium)] (poly(sulfobetaine)) based tri-block copolymer (BCP) and it was characterized by dynamic light scattering (DLS), high resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) analyses. To prepare the hydrogel, amine functionalized PDMS polymersomes were crosslinked with polyethylene glycol dialdehyde (PEG-DA) in pH 7.4 buffer solution via a Schiff-base reaction. This hydrogel was able to show sustained delivery of the entrapped curcumin drug for more than 72 h. The self-healing characteristic of the prepared hydrogel in the presence of saline water was elucidated by the "scratch and heal" method and subsequently analyzed through tensile study. Due to the presence of the poly(zwitterionic) moiety in the hydrogel system, it was observed that the hydrogel can efficiently reduce protein deposition, where Bovine Serum Albumin (BSA) was taken as a model protein. It was observed that the curcumin loaded hydrogel was detrimental towards both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. This type of smart soft hydrogel system can be a potential material for therapeutic applications for several eye diseases.

Hydrothermal synthesis of gelatin quantum dots for high-performance biological imaging applications.

In the present study, we are reporting a one-pot synthesis of gelatin quantum dots (GeQDs) by the hydrothermal process. The synthesized GeQDs were characterized by fourier transform infrared spectroscopy, nuclear magnetic resonance, ultraviolet-visible and photoluminescence spectroscopic techniques, and also by using high-resolution transmission electron microscopy. The GeQDs showed a high level of photoluminescence quantum yield (PLQY) with significantly higher stability for up to 6 months and presented similar fluorescent intensity as the initial PLQY without any precipitation and aggregation at ambient condition. The cell imaging ability of synthesized GeQDs was examined using cells belonging to diverse clinical backgrounds like bacterial cells including Escherichia coli and Staphylococcus aureus, yeast cells including Candida albicans, C. krusei, C. parapsilosis, and C. tropicalis, mycelial fungi including Aspergillus flavus and A. fumigatus cells, cancer cell lines A549, HEK293 and L929. The results demonstrated that the GeQDs illuminates the cells and can be utilized as potential cell labeling non-toxic biomarkers. In conclusion, it can be said that the gelatin stabilized QDs are a promising candidate for stable and long-term fluorescent imaging of different types of cells.

Smart Polyacrylate Emulsion Based on a New ABC-Type Triblock Copolymer via RAFT-Mediated Surfactant-Free Miniemulsion Polymerization: Its Multifunctional Properties.

The present investigation deals with the development of an acrylic-based polymeric emulsion that offers multifunctional properties such as superhydrophobic, antimicrobial, anti-icing, and self-cleaning. The said multifunctional waterborne emulsion was prepared via a surfactant-free reversible addition-fragmentation chain transfer (RAFT) polymerization technique. To accomplish this, a new class of ABC-type triblock copolymer (PMTAC-b-PBA-b-PIBA) based on 2-(methacryloyloxy) ethyl ammonium chloride (MTAC), n-butyl acrylate, and isobornyl acrylate (IBA) was synthesized via a polymerization-induced self-assembly technique in a surfactant-free miniemulsion process. The cationic polymer PMTAC was used as a macro-RAFT agent to prepare the rest of the blocks in the presence of nanosize monodisperse colloidal silica particles, leading to a raspberry-like morphology via ionic interaction between anionic silica particles and the cationic block copolymer (BCP). A water contact angle of more than 150° was achieved for the emulsion coating after the fluorosilane treatment which delineates its superhydrophobic nature. The prepared emulsion showed antimicrobial property both in Gram-positive  (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The resultant BCP emulsion was coated over different substrates like glass, paper, and cotton, and the coating material showed anti-icing and self-cleaning properties.

REDOX Responsive Fluorescence Active Glycopolymer Based Nanogel: A Potential Material for Targeted Anticancer Drug Delivery.

A well-defined glycopolymer based fluorescence active nanogel has been prepared via the combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and Diels-Alder (DA) "click" chemistry. To prepare the nanogel, initially, a functional AB block copolymer (BCP) poly(pentafluorophenyl acrylate)-b-poly(furfuryl methacrylate) (PPFPA-b-PFMA), having activated pentafluorophenyl ester group, was synthesized via RAFT polymerization. The activated pentafluorophenyl functionality was replaced by the amine functionality of glucosamine to introduce the amphiphilic BCP poly[2-(acrylamido) glucopyranose]-b-poly(furfuryl methacrylate) (PAG-b-PFMA). Furthermore, the terminal acid (-COOH) functionality of the RAFT agent was modified by gelatin QDs (GQDs) to generate fluorescence active glycopolymer. An anticancer drug, Doxorubicin, was loaded in the micelle via the successive addition of the drug molecule and cross-linking using dithio-bismaleimidoethane (DTME), a REDOX responsive cross-linker. The anticancer activity of the drug loaded nanogel was observed over MBA-MD-231, human breast cancer cell line, and monitored via fluorescence spectroscopy and flow cytometric analyses (FACS). The cytotoxicity of the prepared glycopolymer based nanogel over the MBA-MD-231 cell line was assessed via MTT assay test, and it was observed that the synthesized nanogel was noncytotoxic in nature.

Curcumin entrapped gelatin/ionically modified bacterial cellulose based self-healable hydrogel film: An eco-friendly sustainable synthesis method of wound healing patch.

In this context, we have prepared a biocompatible gelatin based polyelectrolyte hydrogel patch that has an inherent ability to self-heal in the presence of physiological pH (pH = 7.4). The gelatin-based hydrogel patch consists of the ionically modified self-assembled bacterial cellulose (iBC), extracted from Glucanoacetobacter xylinus (MTCC7795) bacterial strain. Presence of the iBC provides a sturdy cage to the gelatin matrix and also participates into the self-healing activity via formation of the ionic interlocking system in the presence of buffer solution having a pH of 7.4 after being damaged. The self-healing activity of the patch has been monitored through tensile strength measurement and AFM depth profilometry analyses. Loading of the curcumin in the hydrogel patch system incorporates the wound healing activity, examined over the NIH 3 T3 fibroblast cell line. The patch is also able to show antimicrobial activity which has been assessed via FESEM analysis and live-dead assay using propidium iodide (PI) and 4',6-diamidino-2-phenylindole (DAPI) as a fluorescent indicator. This self-healable, ionically interlocked, mechanically robust, bio-derived smart hydrogel patch system can pave a new direction in the transdermal drug delivery system.

Self-Healable Antifouling Zwitterionic Hydrogel Based on Synergistic Phototriggered Dynamic Disulfide Metathesis Reaction and Ionic Interaction.

A self-healable antifouling hydrogel based on zwitterionic block copolymer was prepared via reversible addition-fragmentation chain transfer polymerization and Diels-Alder "click" chemistry. The hydrogel consists of a core-cross-linked zwitterionic block copolymer having poly(furfuryl methacrylate) as core and poly(dimethyl-[3-(2-methyl-acryloylamino)-propyl]-(3-sulfopropyl)ammonium) (poly(sulfobetaine)) as shell. The core was cross-linked with dithiobismaleimidoethane. The block copolymers were characterized by dynamic light scattering, field emission scanning electron microscopy, high-resolution transmission electron microscopy, atomic force microscopy (AFM), differential scanning calorimetry, water contact angle, and small-angle X-ray scattering analyses. This zwitterionic hydrogel showed self-healing activity via combined effect of phototriggered dynamic disulfide metathesis reaction and zwitterionic interaction, which was monitored by optical microscopy and AFM depth profilometry. The mechanical properties of the hydrogel before and after self-healing were studied using depth-sensing nanoindentation method. It was observed that the prepared zwitterionic hydrogel could reduce the formation of biofilm, which was established by studying the bovine serum albumin (model protein) adsorption over the coating. This multifunctional hydrogel can pave a new direction in antifouling self-healable gel coating applications.