Tyrosine-Templated Dual-Component Silver Nanomaterials Exhibit Photoluminescence and Versatile Antimicrobial Properties through ROS Generation

Ultrathin, Stimuli-Responsive, Antimicrobial, Self-Cleaning, Reusable, and Biodegradable, Micro/Nanofibrous Electrospun Mat as an Efficient Face Mask Filter for Airborne Disease Prevention

A multifunctional, electrospun, ultrathin face mask is desirable for preventing disease spread while ensuring breathability. However, balancing ultrathin construction with antimicrobial efficacy is challenging. Here, we fabricated an ultrathin micro/nanofibrous electrospun matrix, consisting of three biodegradable polymer layers, for high antibacterial efficiency, breathability, and biodegradability. The outer layer, with an average thickness of 9.01 ± 3.1 μm, is composed of polycaprolactone (PCL), silver nitrate (AgNO3), and β-cyclodextrin (β-CD). The middle layer, with a thickness of 4.61 ± 1.4 μm, comprises poly(vinyl alcohol) (PVA) and multiwalled carbon nanotubes (MWCNT) as a conductive layer. The inner layer, with a thickness of 5.12 ± 1.4 μm, contains PVA, carboxymethyl chitosan (CMC), and cellulose nanofibrils (CNFs) as a superabsorbent layer, supported by medical gauze. With a total thickness of ∼300 μm, the mask provides antibacterial efficacy, self-cleaning, reusability, mechanical stability, and biodegradability. This design advances filtering face masks, offering a solution to combat contagious diseases while minimizing environmental impact.

PyDNA-templated AgNPs coupled with poly (β‑cyclodextrin) enhanced fluorescence: A facile platform for signal amplification detection of biothiols in living cells and zebrafish

Accurate and sensitive fluorescence imaging of biothiols is essential for understanding the mechanism underlying some physiological and pathological events, as well as the prevention and diagnosis of diseases. However, low signal transduction efficiency and poor biocompatibility of fluorescence tags associated with current sensors hinder their potential utilizations. Herein, a smart biothiols sensitive vivo imaging platform on the basis of amplifying nanoprobe has been designed. The as-prepared nanoprobe are composed of 5'-pyrene-labeled single-stranded DNA with C-rich (PyDNA), DNA-templated silver nanoparticles (AgNPs) and amplification carrier β-cyclodextrin-based polymer (βCDP). PyDNA was not only used as a signal tag, but also as a templated DNA for in situ growth of silver nanoparticles (PyDNA-AgNPs), resulting in fluorescence quenching of PyDNA through FRET. In the presence of GSH as a model biothiol, replace PyDNA off from the surface of AgNPs owing to the interact intensely between biothiol and AgNPs by forming S-Ag bonds, resulting in a fluorescence enhancement. Simultaneously, the released PyDNA was able to form a host-guest inclusion complex with βCDP to achieve signal amplification (10.1-fold enhancement). The obtained nanoprobe exhibits high sensitivity and selectivity to glutathione (GSH) with a detection limit as low as 71 nM. Using HeLa cells as a model, this nanoprobe not only realizes the highly sensitive amplifying detection and imaging of GSH in living cells, but also applies in vivo monitoring of exogenous GSH level in zebrafish. Further use of probes to reveal the overexpression of GSH with the high-contrast imaging in the tumor tissues from the lung disease model mice and clinical lung cancer patients was successfully demonstrated. It provides a facile tool for highly sensitive biothiols imaging and may pave a new avenue for the early and accurate diagnosis of tumors.

Construction of a one-stop N-doped negatively charged carbon dot nanoplatform with antibacterial and anti-inflammatory dual activities for wound infection based on biocompatibility

The development of bacterial resistance significantly contributes to the persistence of infections. Although previous studies have highlighted the benefits of metal-doped positive carbon nanodots in managing bacterial wound infections, their mechanism of action is relatively simple and they may pose potential hazards to human cells. Therefore, it is essential to develop a one-stop carbon dot nanoplatform that offers high biocompatibility, antibacterial properties, and anti-inflammatory activities for wound infection management. This study explores the antibacterial efficacy, without detectable resistance, and wound-healing potential of nitrogen-doped (N-doped) negatively charged carbon dots (TPP-CDs). These carbon dots are synthesized using tannic acid (TA), polyethylene polyamine, and polyethylene glycol (PEG) as precursors, with a focus on their biocompatibility. Numerous systematic studies have shown that TPP-CDs can effectively destroy bacterial biofilms and deoxyribonucleic acid (DNA), while also inducing oxidative stress, leading to a potent antimicrobial effect. TPP-CDs also demonstrate the ability to scavenge excess free radicals, promote cellular proliferation, and inhibit inflammatory factors, all of which contribute to improved wound healing. TPP-CDs also demonstrate favorable cell imaging capabilities. These findings suggest that N-doped negatively charged TPP-CDs hold significant potential for treating bacterial infections and offer practical insights for their application in the medical field.

Rosemary-Mediated Green Synthesis of ZnO Nanoparticles and their Integration into Hydrogel Matrices: Evaluating Effects on Wheat Growth and Antibacterial Properties

In this study, the impact of zinc oxide nanoparticles (ZnO-NPs) generated using rosemary extract, synthesized using environmentally friendly processes and integrated into a cross-linked polymer matrix, on growth performance of wheat is evaluated. Rosemary extract used as coating, stabilizing, and reducing agents in this green synthesis method. Fourier transform infrared spectroscopy analyses demonstrated the presence of phytochemical constituents of the plant extract that served as capping agents during the synthesis process. The nanoparticles are sprayed to the plant leaves. The effects of nanoparticles within the hydrogel on plant development are compared with the effects of nanoparticles in suspension. The percentage of seed germination is unaffected by either rosemary- or raw-ZnO-NPs; however, the root and shoot elongation are considerably impacted by the nanoparticle treatments. The threshold concentrations are determined as 3000 mg L-1 for rosemary-ZnO-NPs and 2000 mg L-1 for raw-ZnO-NPs. Additionally, antibacterial test results showed that the activity level on Escherichia coli is higher for rosemary-ZnO-NPs compared to raw-ZnO-NPs. The results of this research may provide guidance on how green synthesis methods and the use of nanoparticle-hydrogel composites in plant breeding can be used in future agricultural applications. This can be considered an important step in terms of agricultural innovations and sustainability.

One- and two-photon brightness of proteins interacting with gold. A closer look at gold-insulin conjugates

Red luminophores displaying large Stokes shift and high-quantum yields are obtained when gold salts are reacted with proteins under strongly alkaline conditions. Although bovine serum albumin (BSA) has mainly been used as a protein template, other attempts to prepare red luminophores have been proposed using other proteins. Here, we report on the structural characterization and nonlinear optical properties of insulin-gold conjugates. Such conjugates display strong luminescence at ∼670 nm with quantum yields that reach 5.4%. They also display long luminescence lifetimes allowing efficient reactive oxygen species generation, with a quantum yield of 1O2 generation reaching 13%. In addition, they exhibit remarkable nonlinear optical properties and in particular a strong two-photon excited fluorescence (TPEF) cross section in the range of 800-1100 nm. By combining experimental studies and time-dependent density functional theory simulations (TD-DFT), we show the formation of insulin-Au(III) conjugates. The interaction of Au(III) ions with the aromatic rings of tyrosine induces charge transfer-like excitation in the visible range. Experimental investigations, together with molecular dynamics simulations of insulin and calculations of electronic properties in a model system, are performed to explore the origin of optical features and the structure-optical property relationship, leading the way to new concepts for nonlinear optics using protein-Au(III) conjugates.

Assemble-Disassemble-Reassemble Dynamics in Copper Nanocluster-Based Superstructures

Assembling metal nanoclusters (MNCs) to form superstructures generates exciting photophysical properties distinct from those of their discrete precursors. Controlling the assembly process of MNCs and understanding the assembly-disassembly dynamics can have implications in achieving the reversible self-assembly of MNCs. The formation of self-assembled copper nanoclusters (CuNCs) as homogeneous superstructures and the underlying mechanisms governing such a process remain unexplored. Smart molecular imprinting of surface ligands can establish the forces necessary for the formation of such superstructures. Herein, we report highly luminescent, ordered superstructures of 4-phenylimidazole-2-thiol (4-PIT)-protected CuNCs with the help of l-ascorbic acid as a secondary ligand. Through a comprehensive spectroscopic analysis, we deciphered the mechanism of the self-assembly process, where the role of interligand H-bonding and C-H-π interactions was established. Notably, efficient reversibility of assembly-disassembly was demonstrated by re-establishing the interligand interactions and regenerating their photophysical and morphological signatures.

Plasmon-emitter coupling in cytosine-rich hairpin DNA-templated silver nanoclusters: Thermal reversibility, white light emission, and dynamics inside live cells

Bio-templated luminescent noble metal nanoclusters (NCs) have attracted great attention for their intriguing physicochemical properties. Continuous efforts are being made to prepare NCs with high fluorescence quantum yield (QY), good biocompatibility, and tunable emission properties for their widespread practical applications as new-generation environment-friendly photoluminescent materials in materials chemistry and biological systems. Herein, we explored the unique photophysical properties of silver nanoclusters (AgNCs) templated by cytosine-rich customized hairpin DNA. Our results indicate that a 36-nucleotide containing hairpin DNA with 20 cytosine (C20) in the loop can encapsulate photostable red-emitting AgNCs with an absolute QY of ∼24%. The luminescent properties in these DNA-templated AgNCs were found to be linked to the coupling between the surface plasmon and the emitter. These AgNCs exhibited excellent thermal sensitivity and were employed to produce high-quality white light emission with an impressive color rendering index of 90 in the presence of dansyl chloride. In addition, the as-prepared luminescent AgNCs possessing excellent biocompatibility can effectively mark the nuclear region of HeLa cells and can be employed as a luminescent probe to monitor the cellular dynamics at a single molecular resolution.

Fluorescent metal nanoclusters: prospects for photoinduced electron transfer and energy harvesting

Research on noble metal nanoclusters (MNCs) (elements with filled electron d-bands) is progressing forward because of the extensive and extraordinary chemical, optical, and physical properties of these materials. Because of the ultrasmall size of the MNCs (typically within 1-3 nm), they can be applied in areas of nearly all possible scientific domains. The greatest advantage of MNCs is the tunability that can be imposed, not only on their structures, but also on their chemical, physical, and biological properties. Nowadays, MNCs are very effectively used as energy donors and acceptors under suitable conditions and hence act as energy harvesters in solar cells, semiconductors, and biomarkers. In addition, ultrafast photoinduced electron transfer (PET) can be practised using MNCs under various circumstances. Herein, we have focused on the energy harvesting phenomena of Au-, Ag-, and Cu-based MNCs and elaborated on different ways to apply them.

Flexible Heater Fabrication Using Amino Acid-Based Ink and Laser-Direct Writing

Nature's systems have evolved over a long period to operate efficiently, and this provides hints for metal nanoparticle synthesis, including the enhancement, efficient generation, and transport of electrons toward metal ions for nanoparticle synthesis. The organic material-based ink composed of the natural materials used in this study requires low laser power for sintering compared to conventional nanoparticle ink sintering. This suggests applicability in various and sophisticated pattern fabrication applications without incurring substrate damage. An efficient electron transfer mechanism between amino acids (e.g., tryptophan) enables silver patterning on flexible polymer substrates (e.g., PET) by laser-direct writing. The reduction of silver ions to nanoparticles was induced and sintered by simultaneous photo/thermalchemical reactions on substrates. Furthermore, it was possible to fabricate a stable, transparent, and flexible heater that operates under mechanical deformation.

Effects of protecting groups on luminescent metal nanoclusters: spectroscopic signatures and applications

Luminescent metal nanoclusters (NCs) have been established as next-generation fluorophores. Their biocompatible and non-toxic nature, along with excellent chemical- and photo-stability, enables them to find applications in multi-disciplinary areas. However, preparing NCs which are stable is always challenging, primarily owing to their small size and propensity to self-aggregate. In this review, we highlight a holistic approach as to how ligands and templates can monitor the stability of NCs, tune their spectroscopic signatures, and alter their applications. The role of small molecules of a large ligand in the preparation of NCs and their associated limitations are also discussed. We have summarized how these NCs can be utilized in sensing several metal ions, pH, viscosity and temperature of many systems which have biological relevance. Additionally, these luminescent metal NCs find usage in cell-imaging, discriminating between cancerous and non-cancerous cell lines and also targeting specific organelles within the cellular environment.