Direct Comparative Studies Revealing the Contribution of TADF Activity of Organic Emitters Towards Efficient Electrochemiluminescence.

Electrochemiluminescence (ECL) featuring thermally activated delayed fluorescence (TADF) properties has attracted considerable interest, showcasing their potential for 100 % exciton harvesting, which marks a significant advancement in the realm of organic ECL. However, the challenge of elucidating the precise contribution of TADF to the enhanced ECL efficiency arises due to the lack of comparative studies of organic compounds with or without efficient TADF properties. In this study, we present four carbazole-benzonitrile molecules possessing similar chemical structures and comparable exchange energy (ΔEST). Despite their comparable properties, these compounds exhibited varying TADF efficiencies, warranting a closer examination of their underlying structural and electronic characteristics governing the optical properties. Consequently, intense ECL emission was only observed from 4CzBN with a remarkable TADF efficiency, underscoring the substantial difference in the ECL signal among molecules with comparable ΔEST and similar spectral properties but varying TADF activity.

Visible-UVC upconversion polymer films for prevention of microbial infection.

Bacterial infections caused by the growth and reproduction of pathogenic bacteria on wounds are one of the main reasons that hinder wound healing. Antibacterial wound dressings protect wounds from bacterial infections. Herein, we developed a polymeric antibacterial composite film using polyvinyl alcohol (PVA) and sodium alginate (SA) as the substrate. The film used praseodymium-doped yttrium orthosilicate (Y2SiO5: Pr3+, YSO-Pr) to convert visible light into short-wavelength ultraviolet light (UVC) to kill bacteria. The YSO-Pr/PVA/SA showed upconversion luminescence in photoluminescence spectrometry tests, and the emitted UVC inhibited Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria in antibacterial tests. In vivo animal tests showed that YSO-Pr/PVA/SA is effective and safe for inhibiting bacteria in real wounds. The in vitro cytotoxicity test further confirmed the good biocompatibility of the antibacterial film. In addition, YSO-Pr/PVA/SA exhibited sufficient tensile strength. Overall, this study demonstrates the potential of upconversion materials for use in medical dressings.

Vis-UV Upconverting bacteriostatic hydrophobic bacterial cellulose film for personal protective masks.

Masks are key to personal protection and their bacteriostatic properties, which are generally overlooked, should be maximized. Towards this goal, a YPS-Pr-Li/BC upconversion antibacterial composite film was prepared by mixing upconversion powder with bacterial cellulose (BC) using a vacuum assisted method. When combined with the low surface energy of stearic acid (STA), the resulting YPS-Pr-Li/BC/STA film had an improved hydrophobic surface. The developed film was characterized by FT-IR, SEM, XRD, and fluorescence spectrophotometry. The results showed that the composite film was successfully prepared and had ultraviolet, visible upconversion luminescence. The bacteriostatic experiments showed that the material had excellent bacteriostatic performance against E. coli and S. aureus under visible light, with a bacteriostatic rate reaching 99 %. The in-vitro cytotoxicity tests showed that YPS-Pr-Li/BC/STA had excellent biocompatibility and could be used in personal protective clothing with close contact with human skin.

2D mesoporous silica-confined CsPbBr3 nanocrystals and N-doped graphene quantum dot: A self-enhanced quaternary composite structures for electrochemiluminescence analysis.

Lead halide perovskites have become a potential candidate as electrochemiluminescence (ECL) emitters owing to their appealing electronic-to-optical merits. It remains extremely challenging, however, to improve stability and enhance charge transfer. Herein, a self-enhanced superstructures was constructed by successively loading N-doped graphene quantum dot (NGQDs) and CsPbBr3 perovskite nanocrystals (PNCs) onto graphene supported two-dimensional mesoporous SiO2 nanosheets (2D mSiO2-G). This special architecture ensures improved stability and accelerated charge transport, leading to efficient self-enhanced ECL between NGQDs and PNCs in a confined mesoporous structure. Additionally, using molecular imprinting (MIP) as a protective barrier, an ECL sensor with high affinity for Ochratoxin A (OTA) detection was developed, which expressed the widest linear range of 10-5 ng/mL to 1.0 ng/mL and the lowest detection limit of 0.2 pg/mL. This work catches a glimpse of a new generation of desirable perovskite-based ECL emitters, which would be beneficial for its further application.

Bacteriostatic activity and cytotoxicity of bacterial cellulose-chitosan film loaded with in-situ synthesized silver nanoparticles.

Bacterial infections on open wounds have always been a threat to human health. Herein, we prepared a silver (Ag)-polydopamine (PDA)/bacterial cellulose (BC)-chitosan (CTS) film using biological self-generation and in situ reduction. CTS was added to culture medium to allow BC to intertwine with CTS during film formation. Silver nitrate was reduced in situ to Ag nanoparticles under ultraviolet irradiation, and the nanoparticles were well dispersed in the BC-CTS film with the help of PDA, which worked synergistically with the CTS. The Ag-PDA/BC-CTS film was enriched in functional groups, and it had good tensile and swelling properties. The inhibition film demonstrated broad-spectrum inhibition of Gram-positive and Gram-negative bacteria, and this inhibition was maintained at more than 80% after 48 h of continuous use. The good biocompatibility of the film was verified using NIH3T3 fibroblasts. The results suggested that the Ag-PDA/BC-CTS film inhibited the growth of harmful bacteria while having little effect on healthy cells.