Skin, an exterior interface of the human body is home to commensal microbiota and also acts a physical barrier that protects from invasion of foreign pathogenic microorganisms. In recent years, interest has significantly expanded beyond the gut microbiome to include the skin microbiome and its influence in managing several skin disorders. Probiotics play a major role in maintaining human health and disease prevention. Topical probiotics have demonstrated beneficial effects for the treatment of certain inflammatory skin diseases such as acne, rosacea, psoriasis etc., and also found to have a promising role in wound healing. In this review, we discuss recent insights into applications of topical probiotics and their influence on health and diseases of the skin. Patents, commercially available topical probiotics, and novel probiotic impregnated fabrics have been emphasized. A thorough understanding of the relationship between probiotics and the skin microbiome is important for designing novel therapeutic approaches in using topical probiotics.

Background: Intranasal route offers a direct nose-to-brain delivery via olfactory and trigeminal nerves and minimizes the systemic exposure of the drug. Although reliable and non-invasive, intranasal administration of lipophilic neuroprotective agents for brain targeting is still challenging. Literature focuses on naturally-derived compounds as a promising therapeutics for chronic brain diseases. Naringin, a natural flavonoid obtained from citrus fruits possesses neuroprotective effects. By regulating multiple crucial cellular signaling pathways, naringin acts on several therapeutic targets that make it suitable for the treatment of neurodegenerative diseases like Alzheimer’s disease and making it a suitable candidate for nasal administration. However, the hydrophobicity of naringin is the primary challenge to formulate it in an aqueous system for nasal administration. Method: We designed a lipid-based nanoemulsifying drug delivery system of naringin using Acrysol K140 as an oil, Tween 80 as a surfactant and Transcutol HP as a cosolvent, to improve solubility and harness the benefits of nanosizing like improved cellular penetration. Intranasal instillations of therapeutic agents have limited efficacy due to drug washout and inadequate adherence to the nasal mucosa. Therefore, we reconstituted the naringin self-emulsifying system in a smart, biodegradable, ion-triggered in situ gelling hydrogel and optimized for desirable gel characteristics. The naringin-loaded composition was optimized and characterized for various physicochemical and rheological properties. Results: The formulation showed a mean droplet size 152.03 ± 4.6 nm with a polydispersity index <0.23. Ex vivo transmucosal permeation kinetics of the developed formulation through sheep nasal mucosa showed sustained diffusion and enhanced steady-state flux and permeability coefficient. Scanning and transmission electron microscopy revealed the spherical shape of emulsion droplets and entrapment of droplets in a gel structure. The formulation showed excellent biocompatibility as analyzed from the viability of L929 fibroblast cells and nasal mucosa histopathology after treatment. In vivo biodistribution studies revealed significantly higher drug transport and brain targeting efficiency. Conclusion: In situ gelling system with nanoemulsified naringin demonstrated a safe nasal delivery providing a new dimension to the treatment of chronic neurodegenerative diseases using small hydrophobic phytoconstituents with minimization of dose and related systemic adverse effects.

Recently, carbon nanostructures have attracted interest because of their unique properties and interesting applications. Here, CoC@SiO₂-850 (3) and CoC@SiO₂-600 (4) cobalt–carbon/silica nanocomposites were prepared by solid-state pyrolysis of anthracene with Co(tph)(2,2′-bipy)·4H₂O (1) complex in the presence of silica at 850 and 600 °C, respectively, where 2,2′-bipy is 2,2′-bipyridine and tph is the terephthalate dianion. Moreover, Co(μ-tph)(2,2′-bipy) (2) was isolated and its X-ray structure indicated that cobalt(II) has a distorted trigonal prismatic coordination geometry. 2 is a metal–organic framework consisting of one-dimensional zigzag chains within a porous grid network. 3 and 4 consist of cobalt(0)/cobalt oxide nanoparticles with a graphitic shell and carbon nanotubes embedded in the silica matrix. They were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). XPS revealed that the nanocomposites are functionalized with oxygen-containing groups, such as carboxylic acid groups. In addition, the presence of metallic cobalt nanoparticles embedded in graphitized carbon was verified by XRD and TEM. The efficiency of 3 for adsorption of crystal violet (CV) dye was investigated by batch and column experiments. At 25 °C, the Langmuir adsorption capacity of 3 for CV was 214.2 mg g⁻¹ and the fixed-bed column capacity was 36.3 mg g⁻¹. The adsorption data were well fitted by the Freundlich isotherm and pseudo-second-order kinetic model. The adsorption process was spontaneous and endothermic.

Congo red is a hazardous material in the environment. The present work describes the synthesis of TiO₂/CoC@SiO₂-bipy (1) and TiO₂/CoC@SiO₂-phen (2) nanocomposites for the photodegradation of azo-dye Congo red (CR) dye in aqueous solution, by combining pure TiO₂ with CoC@SiO₂-bipy (s1) and CoC@SiO₂-phen (s2) nanoparticles. The prepared nanocomposites were evaluated in term of photocatalytic activity rates in aqueous solution using CR. The nanocomposites TiO₂/CoC@SiO₂-bipy (1) and TiO₂/CoC@SiO₂-phen (2) were prepared from TiO₂ (75%) and CoC@SiO₂-bipy (s1) or CoC@SiO₂-phen (s2) (25%) (weight ratio). Ultra-sonication and milling were used to prepare the heterogeneous nano catalysts. The pH, initial dye concentration, and catalyst dosage appeared to have a significant impact on the photocatalytic degradation performance. Molecular oxygen and other active species played a significant role in the photocatalyst degradation of CR with sunlight energy (UV-index 5.0). The chemical reactions were accelerated depending upon electrophilicity (ω) and energy gap (E_g) of azo dye species CR-N=N, CR-N=NH and CR=N-NH species which were calculated by density function theory (DFT). It can be concluded that the rate of electron–hole recombination of the TiO₂ catalyst, when adding CoC@SiO₂-bipy (s1) or CoC@SiO₂-phen (s2), not only enhances the degradation but also effectively removes toxic dye molecules and their by-products. The newly prepared TiO₂/CoC@SiO₂-bipy (1) nanocomposites showed increased photocatalytic efficiency at low catalyst dose and faster rate of degradation of Congo red compared to TiO₂/CoC@SiO₂-phen (2) and TiO₂ catalysts. The novel catalysts (1) and (2) can be easily separated by centrifugation and filtration, from the reaction mixture compared to TiO₂.

Cobalt hierarchical graphitic carbon nanoparticles (Co@HGC) (1), (2), and (3) were prepared by simple pyrolysis of a cobalt phenanthroline complex in the presence of anthracene at different temperatures and heating times, under a nitrogen atmosphere. The samples were used for the catalytic hydrogenation of 2,4-dinitrophenol. Samples (1) and (3) were prepared by heating at 600 °C and 800 °C respectively, while (2) was prepared by heating at 600 °C with an additional intermediate stage at 300 °C. This work revealed that graphitization was catalyzed by cobalt nanoparticles and occurred readily at temperatures of 600 °C and above. The nanocatalysts were characterized by Scanning Electron Microscopy SEM, energy dispersive X-ray analysis EDX, Raman, Xrd, and XPS. The analysis revealed the presence of cobalt and cobalt oxide species as well as graphitized carbon, while TEM analysis indicated that the nanocatalyst contains mainly cobalt nanoparticles of 3–20 nm in size embedded in a lighter graphitic web. Some bamboo-like multiwall carbon nanotubes and graphitic onion-like nanostructures were observed in (3). The structures and chemical properties of the three catalysts were correlated with their catalytic activities. The apparent rate constants k_app (min⁻¹) of the 2,4-dinitrophenol reductions were 0.34 for (2), 0.17 for (3), 0.04 for (1), 0.005 (no catalyst). Among the three studied catalysts, the highest rate constant was obtained for (2), while the highest conversion yield was achieved by (3). Our data show that an increase in agglomeration of the cobalt species reduces the catalytic activity, while an increase in pyrolysis temperature improves the conversion yield. The nanocatalyst enhances hydrogen generation in the presence of sodium borohydride and reduces 2,4-dinitrophenol to p-diamino phenol. The best nanocatalyst (3) was prepared at 800 °C. It consisted of uniformly distributed cobalt nanoparticles sheltered by hierarchical graphitic carbon. The nanocatalyst is easily separated and recycled from the reaction system and proved to be degradation resistant, to have robust stability, and high activity towards the reduction reaction of nitrophenols.