Chemically manipulating bacterial surface structures, a cutting-edge research direction in the biomedical field, predominantly relies on metabolic labeling by now. However, this method may involve daunting precursor synthesis and only labels nascent surface structures. Here, we report a facile and rapid modification strategy based on a tyrosinase-catalyzed oxidative coupling reaction (TyOCR) for bacterial surface engineering. This strategy employs phenol-tagged small molecules and tyrosinase to initiate direct chemical modification of Gram-positive bacterial cell walls with high labeling efficiency, while Gram-negative bacteria are inert to this modification due to the hindrance of an outer membrane. By using the biotin‒avidin system, we further present the selective deposition of various materials, including photosensitizer, magnetic nanoparticle, and horseradish peroxidase, on Gram-positive bacterial surfaces, and realize the purification/isolation/enrichment and naked-eye detection of bacterial strains. This work demonstrates that TyOCR is a promising strategy for engineering live bacterial cells.

Sayed Mir Sayed1,2* and Imtiaz Hussain3 Author Affiliations 1Department of Chemistry, University of Sialkot, Sialkot, Pakistan 2State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, 2 Sipailou Road, Nanjing 210096, P. R. China 3College of Science, Nanjing Forestry University, Nanjing P. R. China Received: March 22, 2022 | Published: March 30, 2022 Corresponding author: Sayed Mir Sayed, Department of Chemistry, University of Sialkot, Sialkot, Pakistan State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, 2 Sipailou Road, Nanjing 210096, P. R. China DOI: 10.26717/BJSTR.2022.43.006837

In this research, the authors demonstrate for the first time that a tyrosinase-mediated oxidative coupling reaction can serve as a general platform that enables rapid (within 10 min), facile (all reagents involved are commercially available), and controllable chemical labeling of bacterial cell surfaces.

This study aimed to add two functional components—antibacterial 45S5BGs particles and AIE nanoparticles (TPE-NIM+) with bioprobe characteristics—to the guided tissue regeneration (GTR) membrane, to optimize the performance. The PLGA/BG/TPE-NIM+ membrane was synthesized. The static water contact angle, morphologies, and surface element analysis of the membrane were then characterized. In vitro biocompatibility was tested with MC3T3-E1 cells using CCK-8 assay, and antibacterial property was evaluated with Streptococcus mutans and Porphyromonas gingivalis by the LIVE/DEAD bacterial staining and dilution plating procedure. The fluorescence staining of bacteria was observed by Laser Scanning Confocal Microscope. The results showed that the average water contact angle was 46°. In the cytotoxicity test, except for the positive control group, there was no significant difference among the groups (p > 0.05). The antibacterial effect in the PLGA/BG/TPE-NIM+ group was significantly (p < 0.01), while the sterilization rate was 99.99%, better than that in the PLGA/BG group (98.62%) (p < 0.01). Confocal images showed that the membrane efficiently distinguished G+ bacteria from G− bacteria. This study demonstrated that the PLGA/BG/TPE-NIM+ membrane showed good biocompatibility, efficient sterilization performance, and surface mineralization ability and could be used to detect pathogens in a simple, fast, and wash-free protocol.

Congo red (CR) is a hazardous pigment, posing increasing dangerous to the environment and human health. However, the in-situ detection of CR in living cells has not been reported, as far as we know. Here, negatively-charged green-emitting Ca, N, S-doped carbon dots (Mis-mPD-CDs) were fabricated from plant and m-phenylenediamine (mPD) by facile one-step hydrothermal carbonization. Mis-mPD-CDs were capable of rapidly detecting CR on the basis of their fluorescence quenching by CR due to the in-ner filter effect. This CR detection based on Mis-mPD-CDs displayed a linear range of 0.2-1.2 mu M and a low limit of detection (58 nM), and was not interfered by metal ions, important biological molecules, and other dyes, showing high sensitivity and selectivity. More interestingly, Mis-mPD-CDs can rapidly enter and label animal cells (A549, 4T1, and HUVEC), fungi (S. cerevisiae, C. albicans, and T. reesei), and bacteria (E. coli and S. aureus) for long term with high stability and appealing biocompatibility. Based on these compelling characteristics, we applied Mis-mPD-CDs for sensing and imaging CR in living cells (A549, C. albicans, E. coli, and S. aureus) and zebra fish. On the other hand, the quantitative detection of CR by Mis-mPD-CDs was realized in real samples like fish tissues and industrial wastewater. This is the first report on applying CDs for rapid CR detection in living cells and in vivo. Mis-mPD-CDs provides a novel efficient platform for probing intracellular CR, expanding the applications of CDs as biosensors for toxic dyes. (c) 2022 Elsevier B.V. All rights reserved.

Pathogenic infections, particularly caused by Gram-positive bacteria (G+), pose a serious threat to human health, and therefore the fast and accurate discrimination of G+ bacteria from Gram-negative bacteria (G–) and fungi is highly desirable. Organic molecules with facile synthesis, robust photostability, good biocompatibility, and high selectivity toward pathogens are urgently needed in the clinical diagnosis and therapy. To this end, herein we report the synthesis of two naphthalimide-based bioprobes named tetraphenylethylene-naphthalimide (TPE-NIM) and triphenylamine-naphthalimide (TPA-NIM) with aggregation-induced emission (AIE) characteristic. First, the staining capacity of the designed AIEgens toward six kinds of bacteria and two kinds of fungi was evaluated. Both TPE-NIM and TPA-NIM showed a high degree of binding/imaging selectivity for G+ bacteria over G− bacteria and fungi via a wash-free protocol. Second, the two AIEgens had the ability to visualize the biofilms formed by G+ bacteria (Staphylococcus aureus) and can quickly track the G+ bacteria (Staphylococcus aureus) in red blood cell suspensions. Third, we have revealed that electrostatic attraction and hydrophobic interaction both contribute to the selective binding of the AIEgens toward G+ bacteria. In view of the high binding/imaging specificity toward G+ bacteria, low hemolysis rates, and low toxicity toward the bacterial cells, these AIEgens can be applied for the clinical detection of pathogenic infections caused by G+ bacteria and broaden the theranostic applications of AIE materials.

Lipid droplets (LDs) are spherical dynamic subcellular organelles, and play crucial roles in a number of cellular functions, such as lipid metabolism, protein degradation, membrane formation, energy storage, and signal transduction. It is widely recognized that the dysfunction of LDs can lead to many diseases, and hence it is important to monitor the size, distribution, and movement of LDs in living cells. Herein, we report a dibenzothiopene core-based fluorescent probe named triphenylamine dibenzothiophene-S,S-dioxide (TPA-DBTD), which can exhibit aggregation-induced emission (AIE) characteristic and realize selective and wash-free imaging of LDs in live cells. Most importantly, this probe can efficaciously track the dynamic changes of LDs including lipophagy (an autophagic process that is responsible for the degradation of lipids) in live mammalian cells and stain LDs in fungi. Hence, we believe that TPA-DBTD with high photostability, good biocompatibility, AIE characteristic, and LD staining ability in diverse biological systems (mammalian cells and microorganisms) can find practical applications in the fields of biomedical science, cell biology, and diagnosis of LDs-associated diseases.

Plasma membrane (PM), a fundamental building component of a cell, is responsible for a variety of cell functions and biological processes. However, it is still challenging to acquire its morphology and morphological variation information via an effective approach. Herein, we report a PM imaging study regarding an aggregation-induced emission luminogen (AIEgen) called tetraphenylethylene-naphthalimide(+) (TPE-NIM+), which is derived from our previously reported tetraphenylethylene-naphthalimide (TPE-NIM). The designed AIEgen (TPE-NIM+) shows significant characteristics of ultrafast staining, high photostability, wash-free property, and long retention time at the PM, which can structurally be correlated with its positively charged quaternary amine and hydrophobic moiety. TPE-NIM+ is further applied for staining of different cell lines, proving its universal PM imaging capability. Most importantly, we demonstrate that TPE-NIM+ can clearly delineate the contours of densely packed living cells with high cytocompatibility. Therefore, TPE-NIM+ as a PM imaging reagent superior to currently available commercial PM dyes shall find a number of applications in the biological/biomedical fields and even beyond.

Water pollution created by heavy metal ions becomes worldwide concern because of indiscriminate disposal of industrial wastewater in pure water system. In this work, we report a natural and highly efficient sodium alginate (ALG)/polyethyleneimine (PEI) composite hydrogel fabricated by a chemical crosslinking method for the removal of heavy metal ions from wastewater. The adsorption of heavy metal ions was thoroughly investigated in single ion adsorption and multi ions adsorption systems. In addition, after the adsorption we in situ reduced the Cu+2 ions forming a Cu NPs-loaded hydrogel, which proved an excellent catalyst as evidenced by the reduction reaction of 4- nitrophenol. We believe that the as-prepared ALG/PEI hydrogel will present an effective and practical paradigm for the cascaded treatment and recycling of heavy metal ions in wastewater.

The water pollution caused by the heavy metal ions have raised potent damages to the water ecosystem and human health. It is thus important to develop materials that can capture the heavy metal ions effectively and efficiently in the wastewater to resolve this issue. Herein, a highly porous functional hydrogel from the egg white (EW) integrated with polyethyleneimine (PEI) was prepared and examined for the adsorptive removal of the Cu2+, Pb2+ and Cd2+ ions in aqueous solutions. A systematic study was performed to illustrate the EW/PEI hydrogel's excellent affinity to the metallic ions in both the mono- and competitive adsorption systems. The maximum adsorption capacities for the Cu2+, Pb2+ and Cd2+ ions in the mono-adsorption system were determined to be 7.494, 2.194 and 3.705 mmol g(-1), respectively with the adsorption rates and isotherms complying with the pseudo-second order kinetics and Langmuir isotherm model, respectively. Furthermore, in situ reduction turned the adsorbed Cu2+ ions into uniformly distributed Cu nanoparticles (NPs) in the EW/PEI hydrogel. This material can serve as an excellent catalyst as confirmed by a similar to 98% conversion of 4-nitrophenol (20 mmol) to 4-aminophenol in 10 min at the ambient temperature. The EW/PEI hydrogel and the Cu NPs-decorated EW/PEI hydrogel catalyst can be regenerated easily as proved by the consecutive adsorption/desorption and catalysis experiments for several repetitions, respectively. Therefore, the current study highlights the application of the EW/PEI hydrogel as an effective and practical approach for capturing and recycling/utilizing the toxic metal ions in the wastewater.

Two luminescent Charge Transfer (CT) cocrystals involving planar phenanthrene derivatives namely, formyl phenanthrene (FP) and acetyl phenanthrene (AP) as donors (D) and 1,2,4,5-tetracyanobenzene (TCNB) as an acceptor (A) building block, are formed by molecular self-assembly. Detailed structural and spectroscopic measurements elucidated the mixed stack sequence DADAD in the CT cocrystals. The solid supramolecular architecture for both the cocrystals forms 2D sheet, supported by the extended network of C-H···O, and C-H···N hydrogen bonds as evidenced by the crystallographic observation. Interestingly, the two cocrystals display tunable emissions compared to the blue emissions of donor compounds, which correlate with the formation of excited CT state between the donor and acceptor motifs as a result of mixed stack orientation. The nature of the CT interactions in the two cocrystals was further explored by applying density functional theoretical (DFT) studies. Such a supramolecular cocrystal approach provides a facile platform towards the design of new luminescent two component CT complexes with desired functionalities.

Rapid and quantitative discrimination between live and dead cells is highly desirable yet remains a challenging task. Here, we report the use of the ultrabright green-emitting organosilica nanodots (OSiNDs, photo-luminescence quantum yield: (similar to)100%) for fast (1 min in vitro and 5 min in vivo), wash-free, and universal labeling of the dead bacterial, fungal, and mammalian cells, which meets the demand of the green fluorescent probes that can specifically image the dead cells. The photostability of OSiNDs surpasses that of the commercial dyes, such as propidium iodide (PI) and SYTOX Green nucleic acid stain (SYTOX), making OSiNDs more suitable for long-term and stable monitoring of the cell viability. With the assistance of a commercial red fluorescent dye SYTO 60, we develop an in situ method for rapid and accurate quantification of live/dead cells. Motivated by the unique optical advantages and high sensitivity of OSiNDs to the cell viability, the OSiNDs are employed to observe the in vivo cellular changes induced by doxorubicin using zebrafish as a model, demonstrating their great potential for evaluating the toxicity/efficacy of the therapeutic agents in real time. Owing to the excellent biocompatibility and low cost, the OSiNDs can be a universal probe for efficient and accurate differentiation and quantification of the live and dead cells, which may find wide applications in the biomedical field.

Exploiting molecular systems to attain tunable emission characteristics out of the organic fluorophore is of great pertinence for the construction of solid-state luminescent materials owing to their fascinating applications in optoelectronics. Herein, we have designed three charge transfer (CT) molecular assemblies utilizing carbazole luminophores (9-benzoyl carbazole (BC), 9-(para-tolyl carbazole (TC), and N-(4-formylphenyl)carbazole (FC)) as donor compounds and 1,2,4,5-tetracyanobenzene (TCNB) as an acceptor building block to tailor the structure and emission properties. Unlike TC and FC, BC has a carbonyl spacer between carbazole and phenyl group, which allow more short contacts and, therefore, effect the binary crystalline self-assembly. Detail structural and spectroscopic studies revealed the formation of alternate sandwich motifs between the donors and acceptor in a cofacial fashion, which resulted in tunable molecular structure and photophysical properties. Cocrystals XII and XIII present identical emissions due to the similar molecular packing modes (DAD center dot center dot center dot DAD) and stoichiometric ratio (2:1), whereas cocrystal XI exhibits varied molecular packing features (DADA) and molar ratio (3:2) with yellow-green fluorescence. The present study demonstrates the significance of molecular design as an effective route that could fine-tune the molecular packing, stoichiometry, and luminescence characteristics, thereby bringing out efficient optical properties out of the single component via cocrystal strategy for construction of novel solid state luminescent materials.

Natural polymer based self-healing hydrogels have attracted intense consideration due to their attributable and a wide range of applications. However, to design hydrogels having excellent self-healing efficiency and super mechanical strength is still a big challenge. Herein, we report hydroxyethyl cellulose based self-healing conducting hydrogels with enhanced mechanical properties by the molecular engineering of Fe3+ ions among the functional groups of polyacrylic acid-co-polyacrylamide and hydroxyethyl cellulose chain through supramolecular interactions. The engineered hydrogels exhibit a high mechanical strength with a tensile stress of 3.50 MPa and tensile strain of 1245%, along with compression stress of 32 MPa. These hydrogels also show about 98% self healing efficiency as well as exhibit 2.4 x 10(-3)S/cm electrical conductive. Moreover, manipulating the various parameters, the mechanical and self-healing efficiency of the prepared hydrogel can be adjusted. This work will encourage researchers to focus on this facile technique for the synthesis of self-healing hydrogel materials with enhanced mechanical properties.

Heavy metal ion pollution leads to severe health risk to human beings. Herein, a natural and highly efficient sodium alginate (ALG)/polyethyleneimine (PEI) composite hydrogel was designed and fabricated for the removal of heavy metal ions from wastewater. The adsorption of heavy metal ions on the ALG based, 3D composite hydrogel were thoroughly investigated in this study. Furthermore, the in situ reduced metal nanoparticle-loaded ALG/PEI composite hydrogel provided us a sustainable utilization route of the heavy metal ion with a promising adsorption-catalysis ability. In general, this research will present an effective and practical paradigm for the cascaded treatment and recycling of heavy metal ions in wastewater.

In materials science and engineering, the designing of hydrogels with excellent self-healing and tunable mechanical properties is an inviting issue. In this study, we introduce the sacrificial bonds interactions in a hybrid hydrogel of natural and synthetic polymers, to give a hydrogel with autonomous self-healing ability and tunable mechanical properties. Glycogen, a natural polymer tends to strengthen the hydrogel while PVA, a synthetic polymer plays a critical role in the flexibility and stretchability of the hydrogel. Hydrogels were designed by the sacrificial non-covalent interactions with physical cross-linking of the polymer chains to the trivalent metal ions. Functional groups of the polymers interact with sacrificial hydrogen bonds with and with the metal ions, they interact through sacrificial coordination interactions with different strength, results tunable sacrificial bonds. Weaker sacrificial bonds rupture prior to the strong sacrificial bonds upon external loading, which dissipate the energy and endow the hydrogel with adjustable mechanical and self-healing properties. The tunable mechanical properties and excellent self-healing efficiency enlarge the application areas of the developed hydrogel in various fields.

The development of hydrogel materials with enhanced mechanical properties is the primary focus in designing autonomous self-healable hydrogel materials. Here, we present a facile and cost-effective method for the autonomous self-healing hydrogel based on Glycogen (Gly/PAA-Fe3+) with enhanced mechanical properties by simple insertion of ferric ions in the physically cross-linked network via metal-ligand interactions. This dual physically cross-linked hydrogel has an excellent elongation at break and self-healing properties due to the dynamic ionic cross-linking point. This work will encourage researchers to focus on this facile technique for the synthesis of self-healing hydrogel materials with enhanced mechanical properties.

Self-healing hydrogels with robust mechanical properties is the primary objective of hydrogel materials. In this work, we report the synthesis of iron (III) containing hydroxyethyl cellulose based hydrogel (HEC/PAA-Fe3+) through dynamic metal-ligand (M-L) interactions with enhanced self-healing and mechanical properties. The decoration of ferric ions (Fe3+) in a physically cross-linked polymer network (HEC/PAA) introduces dynamic energy dissipative coordination bonds, which dramatically enhance the overall mechanical properties and self healing efficiency. The mechanical properties and self-healing ability can be optimized by a variety of parameters such as HEC, Fe3+ ions, and AA monomer concentration. The HEC/PAA-Fe3+ hydrogel exhibits high tensile strength (1.35 MPa), extensive fracture strain (1660%), high toughness (8.8 MJ m(-3)) and outstanding self-healing efficiency (87%) without any external intervention. We predict that this forthright dynamic bond archetype fabrication can improve the self-healing efficiency of hydrogels with enhanced mechanical properties.

Heptazine is the fundamental structural and functional unit of graphitic carbon nitrides and has a pi-conjugated planar symmetry with semiconducting properties. Molecular self-assembly is one of the key factors to drive the electronic behaviour of pi-conjugated organic molecules. To enhance the semiconductivity, heptazine is decorated at its active sites with 2,3,5-tris(dodecyloxy)aniline to get well-organised columnar packing. A novel heptazine-core room-temperature discotic liquid crystal (HDLC) with hexagonal columnar geometry is discovered. The molecular structure and mesomorphic properties of HDLC are investigated by H-1-NMR, C-13-NMR, IR, polarised optical microscopy, differential scanning calorimetry and X-ray diffraction. Photophysical and electrochemical properties of HDLC are studied by UV-vis/fluorescence spectroscopy and cyclic voltammetry (CV), respectively. The energy band gap of HDLC estimated from CV at room temperature is 1.63 eV, which is much narrower than the previously reported band gap for heptazine derivatives. This decrease in the energy band can be attributed to the particular designing of HDLC for columnar packing. As a columnar liquid crystal providing a smooth path to the charge transport, HDLC with such a narrow energy band gap may find applications in organic electronics. [GRAPHICS] .

In this communication, we describe a two-stage temperature-varied photopatterning protocol to synthesize a series of single-layer dual-phase liquid crystalline elastomer films, which have the capabilities to perform versatile three-dimensional motions, such as bending, accordion-folding, wrinkling, curling, and buckling, under thermal stimulus.