Smart photochromic and fluorescent products can respond to an external stimulus by changing their colour and emission spectra with light. Here, we developed a simple formulation of an organic–inorganic nanocomposite photoluminescent cellulose acetate (CA) film based on immobilization of a lanthanide‐doped pigment. Strontium aluminium oxide pigment doped with Eu2+ and Dy3+ (SAOED) exhibits an optimal excitation wavelength at 365 nm. For better fabrication of the multifunctional colourless pigment–cellulose acetate composites (CA–SAOED), the lanthanide‐doped colourant must be well‐dispersed physically without agglomeration. The fabricated photoluminescence cellulose film exhibited an excitation peak at 436 nm and two fluorescence peaks at 494 and 524 nm. The findings revealed that the originated nanocomposite films demonstrated improved superhydrophobic activity, high ultraviolet light protection and enhanced antibacterial activity without adversely influencing its native physico‐mechanical characteristics. The films demonstrated fast and reversible photochromic responsiveness without fatigue during ultraviolet light irradiation.

Here we report the synthesis and size-dependent optical study of a series of bulky t-butyl thiolated monodisperse nanomolecules (NMs): Au23(S-tBu)16, Au30(S-tBu)18, Au46(S-tBu)24, and Au65(S-tBu)29. We further employ this series of NMs to address how the NM core size affects electrocatalytic oxygen reduction reactivity of these NMs in alkaline media. Though Au23(S-tBu)16 and Au30(S-tBu)18 have been reported before, the expansion of this series is brought about by the discovery, through the synthesis and characterization, of two new and larger species, in the bulky t-butyl thiolated NM series: namely Au46(S-tBu)24 and Au65(S-tBu)29. Furthermore, we take an in-depth look at the ligand effects in the bulky thiolated NM series and ligand dictation over the gold atoms to surface ligands. Assignments of molecular formulae are based on results obtained in high-resolution nanoelectrospray ionization mass spectrometry (nESI-MS). Purity was confirmed with matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Further analysis of the new bulky thiolated NMs, Au46(S-tBu)24 and Au65(S-tBu)29, was conducted using UV–vis-NIR spectroscopy to observe their unique optical properties. With the expansion of this series, we conclude that the bulky t-butyl thiolated series is unique from those observed with aliphatic and aromatic ligands; that is, how the bulky ligands dictate the size, composition, and structure of the NM is distinct from those of aliphatic and aromatic ligands. This provides insight into the tunability and core size manipulation of gold thiolate NM (i.e., we can make different sizes of NMs using specific types of ligands by varying the gold to thiol ratio). The largest NM Au65(S-tBu)29 was found to facilitate 80% OH– production, while the smallest size NM Au23(S-tBu)16 produced 53% OH–. From the optical measurements we determined that the excited state lifetimes of this series of t-butyl thiolate protected gold NMs follow the energy gap law except for Au30(S-tBu)18 which can be ascribed to its symmetry.

Textile manufacturing has been one of the highest polluting industrial sectors. It represents about one-fifth of worldwide industrial water pollution. It uses a huge number of chemicals, numerous of which are carcinogenic. The textile industry releases many harmful chemicals, such as heavy metals and formaldehyde, into water streams and soil, as well as toxic gases such as suspended particulate matter and sulphur dioxide to air. These hazardous wastes, may cause diseases and severe problems to human health such as respiratory and heart diseases. Pollution caused by the worldwide textile manufacturing units results in unimaginable harm, such as textile polymers, auxiliaries and dyes, to the environment. This review presents a systematic and comprehensive survey of all recently produced high-performance textiles; and will therefore assist a deeper understanding of technical textiles providing a bridge between manufacturer and end-user. Moreover, the achievements in advanced applications of textile material will be extensively studied. Many classes of technical textiles were proved in a variety of applications of different fields. The introductory material- and process-correlated identifications regarding raw materials and their transformation into yarns, fibers and fabrics followed by dyeing, printing, finishing of technical textiles and their further processing will be explored. Thus, the environmental impacts of technical textiles on soil, air and water are discussed.

Zinc oxide nanoparticles have become one of the most popular metal oxide nanoparticles and recently emerged as a promising potential candidate in the fields of optical, electrical, food packaging, and biomedical applications due to their biocompatibility, low toxicity, and low cost. They have a role in cell apoptosis, as they trigger excessive reactive oxygen species (ROS) formation and release zinc ions (Zn2+) that induce cell death. The zinc oxide nanoparticles synthesized using the plant extracts appear to be simple, safer, sustainable, and more environmentally friendly compared to the physical and chemical routes. These biosynthesized nanoparticles possess strong biological activities and are in use for various biological applications in several industries. Initially, the present review discusses the synthesis and recent advances of zinc oxide nanoparticles from plant sources (such as leaves, stems, bark, roots, rhizomes, fruits, flowers, and seeds) and their biomedical applications (such as antimicrobial, antioxidant, antidiabetic, anticancer, anti-inflammatory, photocatalytic, wound healing, and drug delivery), followed by their mechanisms of action involved in detail. This review also covers the drug delivery application of plant-mediated zinc oxide nanoparticles, focusing on the drug-loading mechanism, stimuli-responsive controlled release, and therapeutic effect. Finally, the future direction of these synthesized zinc oxide nanoparticles’ research and applications are discussed.

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Accurate measurements of intracellular pH are of crucial importance in understanding the cellular activities and in the development of intracellular drug delivery systems. Here we report a highly sensitive pH probe based on a fluorescein-conjugated Au nanocluster. Steady-state photoluminescence (PL) measurements have shown that, when conjugated to Au, fluorescein exhibits more than 160-fold pH-contrasting PL in the pH range of 4.3-7.8. Transient absorption measurements show that there are two competing ultrafast processes in the fluorescein-conjugated Au nanocluster: the intracore-state relaxation and the energy transfer from the nonthermalized states of Au to fluorescein. The latter becomes predominant at a higher pH, leading to dramatic PL enhancement of fluorescein. In addition to the intrinsically low toxicity, fluorescein-conjugated Au nanoclusters exhibit high pH sensitivity, wide dynamic range, and excellent photostability, providing a powerful tool for the study of intracellular processes.

Biofilms not only protect bacteria and Candida species from antibiotics, but they also promote the emergence of drug-resistant strains, making eradication more challenging. As a result, novel antimicrobial agents to counteract biofilm formation are desperately needed. In this study, Terminalia catappa leaf extract (TCE) was used to optimize the TCE-capped silver nanoparticles (TCE-AgNPs) via a one-pot single-step method. Varied concentrations of TCE have yielded different sized AgNPs. The physico-chemical characterization of TCE-AgNPs using UV-Vis, SEM, TEM, FTIR, and Raman spectroscopy have confirmed the formation of nanostructures, their shape and size and plausible role of TCE bio-active compounds, most likely involved in the synthesis as well as stabilization of NPs, respectively. TCE-AgNPs have been tested for antibiofilm and antimicrobial activity against multidrug-resistant Pseudomonas aeruginosa (MDR-PA), methicillin-resistant Staphylococcus aureus (MRSA), and Candida albicans using various microbiological protocols. TCE-Ag-NPs−3 significantly inhibits biofilm formation of MDR-PA, MRSA, and C. albicans by 73.7, 69.56, and 63.63%, respectively, at a concentration of 7.8 µg/mL, as determined by crystal violet microtiter assay. Furthermore, SEM micrograph shows that TCE-AgNPs significantly inhibit the colonization and adherence of biofilm forming cells; individual cells with loss of cell wall and membrane integrity were also observed, suggesting that the biofilm architecture and EPS matrix were severely damaged. Moreover, TEM and SEM images showed that TCE-AgNPs brutally damaged the cell wall and membranes of MDR-PA, MRSA, and C. albicans. Additionally, extreme ultrastructural changes such as deformation, disintegration, and separation of cell wall and membrane from the cells, have also been observed, indicating significant loss of membrane and cell wall integrity, which eventually led to cell death. Overall, the research revealed a simple, environmentally friendly, and low-cost method for producing colloidal TCE-AgNPs with promising applications in advanced clinical settings against broad-spectrum biofilm-forming antibiotic-resistant bacteria and candida strains.

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