Poly(lactic acid)/artificially cultured diatom frustules nanofibrous membranes with fast and controllable degradation rates for air filtration

Nanopatterning of beaded poly(lactic acid) nanofibers for highly electroactive, breathable, UV-shielding and antibacterial protective membranes

Despite great potential in fabrication of biodegradable protective membranes by electrospinning of poly(lactic acid) (PLA) nanofibers, it is still thwarted by smooth surfaces and poor electroactivity that challenge the promotion of electret properties and long-term air filtration performance. Here, a microwave-assisted synthetic method was used to customize dielectric TiO2 nanocrystals of ultrasmall and uniform dimensions (∼30 nm), which were homogeneously embedded at beaded PLA nanofibers (PLA@TiO2, diameter of around 280 nm) by the combined "electrospinning-electrospray" approach. With small amounts of TiO2 (2, 4 and 6 wt%), the nanopatterned PLA@TiO2 nanofibrous membranes (NFMs) were characterized by largely increased dielectric constants (nearly 1.9), surface potential (up to 1.63 kV) and triboelectric properties (output voltage of 12.2 V). Arising from the improved electroactivity and self-charging mechanisms, the nanopatterned PLA@TiO2 NFMs exhibited remarkable PM0.3 filtration properties (97.9 %, 254.6 Pa) even at the highest airflow rate of 85 L/min, surpassing those of pure PLA membranes (86.2 %, 483.7 Pa). This was moreover accompanied by inhibition rates of 100 % against both E. coli and S. aureus, as well as excellent UV-blocking properties (UPF as high as 3.8, TUVA of 50.9 % and TUVB of 20.1 %). The breathable and electroactive nanopatterned PLA NFMs permit promising applications in multifunctional protective membranes toward excellent UV shielding and high-efficiency removal of both PMs and pathogens.

An overview of green synthesized silver nanoparticles towards bioactive antibacterial, antimicrobial and antifungal applications

Present review emphatically introduces the synthesis, biocompatibility, and applications of silver nanoparticles (AgNPs), including their antibacterial, antimicrobial, and antifungal properties. A comprehensive discussion of various synthesis methods for AgNPs, with a particular focus on green chemistry mediated by plant extracts has been made. Recent research has revealed that the optical properties of AgNPs, including surface plasmon resonance (SPR), depend on the particle size, as well as the synthesis methods, preparation synthesis parameters, and used reducing agents. The significant emphasis on the use of synthesized AgNPs as antibacterial, antimicrobial, and antifungal agents in various applications has been reviewed. Furthermore, the application areas have been thoroughly examined, providing a detailed discussion of the underlying mechanisms, which aids in determining the optimal control parameters during the synthesis process of AgNPs. Furthermore, the challenges encountered while utilizing AgNPs and the corresponding advancements to overcome them have also been addressed. This review not only summarizes the achievements and current status of plant-mediated green synthesis of AgNPs but also explores the future prospects of these materials and technology in diverse areas, including bioactive applications.

Ultrasensitive electrochemical biosensors based on zinc sulfide/graphene hybrid for rapid detection of SARS-CoV-2

The coronavirus disease 2019 (COVID-19) is a highly contagious and fatal disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In general, the diagnostic tests for COVID-19 are based on the detection of nucleic acid, antibodies, and protein. Among different analytes, the gold standard of the COVID-19 test is the viral nucleic acid detection performed by the quantitative reverse transcription polymerase chain reaction (qRT-PCR) method. However, the gold standard test is time-consuming and requires expensive instrumentation, as well as trained personnel. Herein, we report an ultrasensitive electrochemical biosensor based on zinc sulfide/graphene (ZnS/graphene) nanocomposite for rapid and direct nucleic acid detection of SARS-CoV-2. We demonstrated a simple one-step route for manufacturing ZnS/graphene by employing an ultrafast (90 s) microwave-based non-equilibrium heating approach. The biosensor assay involves the hybridization of target DNA or RNA samples with probes that are immersed into a redox active electrolyte, which are detectable by electrochemical measurements. In this study, we have performed the tests for synthetic DNA samples and, SARS-CoV-2 standard samples. Experimental results revealed that the proposed biosensor could detect low concentrations of all different SARS-CoV-2 samples, using such as S, ORF 1a, and ORF 1b gene sequences as targets. This microwave-synthesized ZnS/graphene-based biosensor could be reliably used as an on-site, real-time, and rapid diagnostic test for COVID-19.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s42114-023-00630-7.

Advances in the Application of Electrospun Drug-Loaded Nanofibers in the Treatment of Oral Ulcers

Oral ulcers affect oral and systemic health and have high prevalence in the population. There are significant individual differences in the etiology and extent of the disease among patients. In the treatment of oral ulcers, nanofiber films can control the drug-release rate and enable long-term local administration. Compared to other drug-delivery methods, nanofiber films avoid the disadvantages of frequent administration and certain side effects. Electrospinning is a simple and effective method for preparing nanofiber films. Currently, electrospinning technology has made significant breakthroughs in energy-saving and large-scale production. This paper summarizes the polymers that enable oral mucosal adhesion and the active pharmaceutical ingredients used for oral ulcers. Moreover, the therapeutic effects of currently available electrospun nanofiber films on oral ulcers in animal experiments and clinical trials are investigated. In addition, solvent casting and cross-linking methods can be used in conjunction with electrospinning techniques. Based on the literature, more administration systems with different polymers and loading components can be inspired. These administration systems are expected to have synergistic effects and achieve better therapeutic effects. This not only provides new possibilities for drug-loaded nanofibers but also brings new hope for the treatment of oral ulcers.

Electrospun Core (HPMC-Acetaminophen)-Shell (PVP-Sucralose) Nanohybrids for Rapid Drug Delivery

The gels of cellulose and its derivatives have a broad and deep application in pharmaceutics; however, limited attention has been paid to the influences of other additives on the gelation processes and their functional performances. In this study, a new type of electrospun core-shell nanohybrid was fabricated using modified, coaxial electrospinning which contained composites of hydroxypropyl methyl cellulose (HPMC) and acetaminophen (AAP) in the core sections and composites of PVP and sucralose in the shell sections. A series of characterizations demonstrated that the core-shell hybrids had linear morphology with clear core-shell nanostructures, and AAP and sucralose distributed in the core and shell section in an amorphous state separately due to favorable secondary interactions such as hydrogen bonding. Compared with the electrospun HPMC-AAP nanocomposites from single-fluid electrospinning of the core fluid, the core-shell nanohybrids were able to promote the water absorbance and HMPC gelation formation processes, which, in turn, ensured a faster release of AAP for potential orodispersible drug delivery applications. The mechanisms of the drug released from these nanofibers were demonstrated to be a combination of erosion and diffusion mechanisms. The presented protocols pave a way to adjust the properties of electrospun, cellulose-based, fibrous gels for better functional applications.