Metal doped silica nanohybrids with extensive bacterial coverage for antibacterial applications exhibit synergistic activity

Nanotechnology has triumphantly overcome several barriers that have formed in modern life. Bacterial infections are a critical public health issue. They emphasized the failure of conventional treatments, high mortality and morbidity rates, antibiotic resistance, and other factors leading to the development of novel and affordable antibacterial medications. In this study, three types of metals (Ag, Cu, and Co) were doped separately into a silanol network in silica nanoparticles. The synthesized monometallic nanohybrids were combined in equal proportions to formulate bi and trimetallic nanohybrids. They were characterized structurally and morphologically. Fourier transform infrared (FTIR) and Raman spectroscopy studies were used to investigate the formation of the bonds and the pertinent peak positions. X-ray diffractograms (XRD) validated the crystalline structures of the metal nanohybrids. X-ray photoelectron spectroscopic study (XPS) confirmed the successful addition of metals to the silanol network. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images were used to characterize the morphology of nanohybrids and demonstrate their dimensions are on the nanoscale. The fraction of each metal doped in the silanol network was determined using energy dispersive spectroscopy (EDS) and atomic absorption spectrometry (AAS). To assess activity and confirm antibacterial synergy, the antibacterial activity of all synthesized nanohybrids was examined. The minimum inhibitory concentration-MIC (Ranged from 12.25 to 1560.00 μg/mL), minimum bactericidal concentration-MBC (Ranged from 197.00 to 3125.00 μg/mL), IC50 values (Ranged from 30.56 to 1683.00 μg/mL-) and fractional inhibitory concentration index (FICI) were determined and compared. Well diffusion assay was conducted against both ATCC cultures and clinical samples of gram-positive bacteria; Staphylococcus aureus (ATCC 25923), Streptococcus pneumoniae (ATCC 49619), MRSA (ATCC 33591) and gram-negative bacteria; Escherichia coli (ATCC 25922), Klebsiella pneumoniae (ATCC BAA 1706) and Pseudomonas aeruginosa (ATCC 27853). The highest synergistic radical scavenging performance of trimetallic nanohybrid (90.67 ± 0.095 %) was established by the DPPH (2,2 diphenyl-1-picrylhydrazil) experiment. Finally, when compared to monometallic nanohybrids, it was demonstrated that the synthesized multimetallic nanohybrids have a substantial potential as an emerging and cost-effective antibacterial agent.

The "Maskne" microbiome - pathophysiology and therapeutics

"Maskne" is a new term coined during the 2020 COVID-19 pandemic. It refers to a subset of acne mechanica, deserving consideration in view of widespread reusable fabric mask-wearing to control the pandemic worldwide. Understanding of underlying pathophysiology directly relates to the novel skin microenvironment and textile-skin friction created by mask-wearing, distinct from nontextile-related acne mechanica previously linked to wearing of headgear. Specifically, the occlusive microenvironment leads to microbiome dysbiosis, which is linked to various dermatological conditions. Additional textile-skin interactions include factors such as breathability, stickiness sensations, moisture saturation, and hygiene maintenance. Increased skin temperatures can trigger sweat/heat-related dermatoses, and ear loops potentially trigger pressure-induced dermatoses. Important therapeutic considerations include increased skin irritation potential of conventional acne treatments under occlusion, exacerbation of chronic dermatoses, that is, perioral dermatitis, rosacea, and eczema, and susceptibility of these same patient groups to heightened discomfort with mask-wearing. Cotton, as the traditional fabric of choice for dermatology patients, has limited benefits in the context of face masks - increased subjective discomfort relates to increased moisture saturation and stickiness, inevitable because of high biofluid load of the nasal and oral orifices. Prolonged textile-skin contact time, directly proportional to the risk of maskne, can be an opportunity for the application of biofunctional textiles.

Silver nanoparticles deposited on calcium hydrogenphosphate – silver phosphate matrix; biological activity of the composite

The composite containing nanosilver uniformly deposited on matrix composed of CaHPO4 x 2H2O (brushite, ca 89 mass %), CaHPO4 (monteonite, ca 9.5 mass%), and Ag3PO4 (0.5 mas%) was obtained by addition of calcium nitrate and silver nitrate aqueous solution at 30:1 Ca:Ag molar ratio into excess of (NH4)2PO4 solution at pH 5.0 – 5.5. The isolated solid was characterized by STEM, XRD, and LDI mass spectrometry. It has been found that nanosilver was uniformly distributed within composite as <10 nm diameter sized nanoparticles. Determination of silver by AAS showed that 60% of silver is present as Ag(0) nanoparticles, the present as matrix Ag3PO4 as identified by XRD method. The composite showed strong growth inhibition in E. coli and P. aeruginosa strains, and moderate towards S. aureus. The C. albicans cells were the most resistant to the tested material, although still composite was moderately cytostatic for the yeast.

Nanomaterials for Functional Textiles and Fibers

Nanoparticles are very interesting because of their surface properties, different from bulk materials. Such properties make possible to endow ordinary products with new functionalities. Their relatively low cost with respect to other nano-additives make them a promising choice for industrial mass-production systems. Nanoparticles of different kind of materials such as silver, titania, and zinc oxide have been used in the functionalization of fibers and fabrics achieving significantly improved products with new macroscopic properties. This article reviews the most relevant approaches for incorporating such nanoparticles into synthetic fibers used traditionally in the textile industry allowing to give a solution to traditional problems for textiles such as the microorganism growth onto fibers, flammability, robustness against ultraviolet radiation, and many others. In addition, the incorporation of such nanoparticles into special ultrathin fibers is also analyzed. In this field, electrospinning is a very promising technique that allows the fabrication of ultrathin fiber mats with an extraordinary control of their structure and properties, being an ideal alternative for applications such as wound healing or even functional membranes.