Amoxicillin loaded bentonite, advanced low-cost antibacterial and environmentally friendly materials

Natural Nano-Minerals (NNMs): Conception, Classification and Their Biomedical Composites

Natural nano-minerals (NNMs) are minerals that are derived from nature with a size of less than 100 nm in at least one dimension in size. NNMs have a number of excellent properties due to their unique nanostructure and have been applied in various fields in recent years. They are rising stars in various disciplines, such as materials, biomedicine, and chemistry, taking advantage of their huge surface area, multiple active sites, excellent adsorption capacity, large quantity, low cost, and nontoxicity, etc. To provide a more comprehensive overview of NNMs and the biomedical applications of NNMs-based nanocomposites, this review classifies NNMs into three types by dimension, lists the structure and properties of typical NNMs, and illustrates their biomedical applications. Furthermore, a novel concept of natural nanomineral medical materials (NNMMs) is proposed, focusing on the medical value of NNMs. In addition, this review attempts to address the current challenges and delineate future directions for the advancement of NNMs. With the deepening of biomedical applications, it is believed that NNMMMs will inevitably play an important role in the field of human health and contribute to its promotion.

DP1, a multifaceted synthetic peptide: Mechanism of action, activity and clinical potential

AIMS

Microbial infections remain a leading cause of mortality worldwide, with Staphylococcus aureus (S. aureus) being a prominent etiological agent, responsible for causing persistent bacterial infections in humans. It is a nosocomial, opportunistic pathogen, capable to propagate within the bloodstream and withstand therapeutic interventions. In the current study, a novel, indigenously designed synthetic antimicrobial peptide (sAMP) has been evaluated for its antimicrobial potential to inhibit the growth and proliferation of S. aureus.

MAIN METHODS

The sAMP, designed peptide (DP1) was evaluated for its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against a panel of pathogenic bacterial strains. Membrane mechanistic studies were performed by measuring membrane conductivity via dielectric spectroscopy and visualizing changes in bacterial membrane structure through field emission scanning electron microscopy (FE-SEM). Further, DP1 was tested for its in vivo antimicrobial potential in an S. aureus-induced systemic infection model.

KEY FINDINGS

The results indicated that DP1 has the potential to inhibit the growth and proliferation of a broad spectrum of Gram-positive, Gram-negative and multidrug-resistant (MDR) bacterial strains. Strong bactericidal effect attributed to change in electrical conductivity of the bacterial cells leading to membrane disruption was observed through dielectric spectroscopy and FE-SEM micrographs. Further, in the in vivo murine systemic infection study, 50 % reduction in S. aureus bioburden was observed within 1 day of the administration of DP1.

SIGNIFICANCE

The results indicate that DP1 is a multifaceted peptide with potent bactericidal, antioxidant and therapeutic properties. It holds significance as a novel drug candidate to effectively combat S. aureus-mediated systemic infections.

Insights on the Synthesis of Al-MCM-41 with Optimized Si/Al Ratio for High-Performance Antibiotic Adsorption

Studies indicate that approximately two-thirds of the rivers of the world are contaminated by pharmaceutical compounds, especially antibiotics and hormones. Data reported by the World Health Organization (WHO, 2015) revealed an increase of 65% in antibiotic consumption between 2000 and 2015, with a worldwide increase of 200% expected up to 2030. Environmental contamination by antibiotics and their metabolites can cause the alteration of bacterial genes, leading to the generation of superbacteria. In this work, adsorption was explored as a strategy to mitigate antibiotic contamination, proposing the use of the Al-MCM-41 mesoporous material as an efficient and high-capacity adsorbent. Evaluation of the influence of the synthesis parameters enabled understanding of the main variables affecting the adsorption capacity of Al-MCM-41 for the removal of a typical antibiotic, amoxicillin (AMX). It was found that the adsorbent composition and specific surface area were the main factors that should be optimized in order to obtain the highest AMX removal capacity. Using statistical tools, the best Si/Al ratio in Al-MCM-41 was found to be 10.5, providing an excellent AMX uptake of 132.2 mg per gram of adsorbent. The Si/Al ratio was the most significant factor affecting the adsorption. The cation-π interactions increased with an increase of the Al content, while the interactions involving silanols (Yoshida H-bonding and dipole-dipole hydrogen bridges) decreased.

Ag Nanoparticles Decorated CuO@RF Core-Shell Nanowires for High-Performance Surface-Enhanced Raman Spectroscopy Application

Vertical-aligned CuO nanowires have been directly fabricated on Cu foil through a facile thermal oxidation process by a hotplate at 550 °C for 6 h under ambient conditions. The intermediate layer of resorcinol-formaldehyde (RF) and silver (Ag) nanoparticles can be sequentially deposited on Cu nanowires to form CuO@RF@Ag core-shell nanowires by a two-step wet chemical approach. The appropriate resorcinol weight and silver nitrate concentration can be favorable to grow the CuO@RF@Ag nanowires with higher surface-enhanced Raman scattering (SERS) enhancement for detecting rhodamine 6G (R6G) molecules. Compared with CuO@Ag nanowires grown by ion sputtering, CuO@RF@Ag nanowires exhibited a higher SERS enhancement factor of 5.33 × 10⁸ and a lower detection limit (10^-12 M) for detecting R6G molecules. This result is ascribed to the CuO@RF@Ag nanowires with higher-density hot spots and surface-active sites for enhanced high SERS enhancement, good reproducibility, and uniformity. Furthermore, the CuO@RF@Ag nanowires can also reveal a high-sensitivity SERS-active substrate for detecting amoxicillin (10^-10 M) and 5-fluorouracil (10^-7 M). CuO@RF@Ag nanowires exhibit a simple fabrication process, high SERS sensitivity, high reproducibility, high uniformity, and low detection limit, which are helpful for the practical application of SERS in different fields.

Optimization Temperature Programming of Microwave-Assisted Synthesis ZnO Nanoneedle Arrays for Optical and Surface-Enhanced Raman Scattering Applications

This study used a rapid and simple microwave-assisted synthesis method to grow ZnO nanoneedle arrays on the silicon substrate with the ZnO seed layer. The effects of reaction temperature and time on the lengths of ZnO nanoneedle arrays were investigated. The appropriate temperature programming step can grow the longer ZnO nanoneedle arrays at the same reaction time (25 min), which is 2.08 times higher than without the temperature programming step. The geometry of the ZnO nanoneedle arrays features a gradual decrease from the Si substrate to the surface, which provides an excellent progressive refractive index between Si and air, resulting in excellent antireflection properties over an extensive wavelength range. In addition, the ZnO nanoneedle arrays exhibit a suitable structure for uniform deposition of Ag nanoparticles, which can provide three-dimensional hot spots and surface active sites, resulting in higher surface-enhanced Raman scattering (SERS) enhancement, high uniformity, high reusability, and low detection limit for R6G molecule. The ZnO/Ag nanoneedle arrays can also reveal a superior SERS-active substrate detecting amoxicillin (10^-8 M). These results are promising for applying the SERS technique for rapid low-concentration determination in different fields.