Photocatalysis of nanocomposite titania–natural silica as antibacterial against Staphylococcus aureus and Pseudomonas aeruginosa

The entries of pathogenic bacteria into the human body remain a severe problem to health that can be prevented using antibacterial agents. Meanwhile, the photocatalytic technique using semiconductor nanocomposite TiO₂–SiO₂ has great potential as an antibacterial method. In order to utilize natural resources, SiO₂ supporting materials are obtained from the extraction of beach sand due to the high silica content. Therefore, this study aims to synthesize a nanocomposite of TiO₂ with SiO₂ extracted from beach sand as an antibacterial agent against Staphylococcus aureus and Pseudomonas aeruginosa. The antibacterial activity test used the dilution and optical density method. Based on XRD analysis, the crystals of TiO₂ in the synthesized composites showed a more dominant anatase structure. Furthermore, Ti–O–Si bonds were identified from the IR spectrum, which showed the interaction between TiO₂ and SiO₂. In addition, SEM-EDX results showed agglomerated spherical particles with a TiO₂–SiO₂ nanocomposite particle size of 40–107 nm. The best antibacterial activity was demonstrated by the 1 : 0.5 TiO₂–SiO₂ nanocomposite, with inactivation percentages of S. aureus and P. aeruginosa of 98.69% and 97.44%, respectively.

TiO₂ material is composited with silica obtained from natural sand with indirect sonochemistry method. The addition of SiO₂ increase the photocatalyst activity of TiO₂ as an antibacterial against S. aureus and P. aeruginosa.     

Efficacy of late concurrent hypofractionated radiotherapy in advanced melanoma patients failing anti-PD-1 monotherapy

Advanced melanoma patients who failed anti-PD-1 therapy have limited options. We analyzed a cohort of 133 advanced melanoma patients receiving anti-PD-1 monotherapy in a referral center between April 2015 and December 2017, and included the 26 patients with confirmed progressive (PD) or stable disease who received additional radiotherapy with an unmodified anti-PD-1 mAb regimen. Tumor evaluations were done on radiated and nonradiated (RECIST 1.1) lesions, with abscopal effect defined as a partial (PR) or complete response (CR) outside radiated fields. Primary endpoint was the CR + PR rate in radiated + nonradiated lesions. Secondary endpoints were progression-free survival (PFS), melanoma-specific survival (MSS) and safety. First late radiotherapy, consisting of hypofractionated radiotherapy (3–5 sessions, 20–26 Gy), standard palliative radiotherapy or brain radiosurgery was begun after a median of 6.3 months of anti-PD-1 in 23, 2 and 1 patient(s), respectively. Best response was 8 (31%) CR, 2 (8%) profound PR allowing surgical resection of remaining metastases and 16 (62%) PD. Abscopal effect was seen in 35% of patients. Median PFS and MSS since anti-PD-1 initiation was 15.2 [95% CI: 8.0 not achieved (na)] and 35.3 [95% CI: 18.5 na] months, respectively. PFS curves seemed to achieve a plateau. We discontinued anti-PD-1 therapy in 9/10 of patients with no residual evaluable disease and observed one relapse after a median of 10 months off anti-PD1-therapy. No unusual adverse event was recorded. Limitations of the study include its retrospective nature and limited size. Hypofractionated radiotherapy may enhance anti-PD1 monotherapy efficacy in patients who previously failed anti-PD-1 therapy. Controlled studies are needed.     

Corrosion and Microstructural Investigation on Additively Manufactured 316L Stainless Steel: Experimental and Statistical Approach

The use of metal additive manufacturing (AM) has strongly increased in the industry during the last years. More specifically, selective laser melting (SLM) is one of the most used techniques due to its numerous advantages compared to conventional processing methods. The purpose of this study is to investigate the effects of process parameters on the microstructural and corrosion properties of the additively manufactured AISI 316L stainless steel. Porosity, surface roughness, hardness, and grain size were studied for specimens produced with energy densities ranging from 51.17 to 173.91 J/mm³ that resulted from different combinations of processing parameters. Using experimental results and applying the Taguchi model, 99.38 J/mm³ was determined as the optimal energy density needed to produce samples with almost no porosity. The following analysis of variance ANOVA confirmed the scanning speed as the most influential factor in reducing the porosity percentage, which had a 74.9% contribution, followed by the position along the building direction with 22.8%, and finally, the laser energy with 2.3%. The influence on corrosion resistance was obtained by performing cyclic potentiodynamic polarization tests (CPP) in a 3.5 wt % NaCl solution at room temperature for different energy densities and positions (Z axis). The corrosion properties of the AM samples were studied and compared to those obtained from the traditionally manufactured samples. The corrosion resistance of the samples worsened with the increase in the percentage of porosity. The process parameters have consequently been optimized and the database has been extended to improve the quality of the AM-produced parts in which microstructural heterogeneities were observed along the building direction.     

Magnesium ascorbyl phosphate vesicular carriers for topical delivery; preparation,in-vitro and ex-vivo evaluation,factorial optimization and clinical assessment in melasma patients

Ascorbic acid (vitamin C) is an antioxidant that is widely used in cosmetics in skincare products. Due to the excessive low stability of ascorbic acid in cosmetic formulations, the stabilized ascorbic acid derivative, magnesium ascorbyl phosphate (MAP) was formulated as vesicular carriers; ethosomes and niosomes. The aim was to deliver MAP at the intended site of action, the skin, for sufficient time with enhanced permeation to get an effective response. Ethosomes were formulated using a full 3² factorial design to study ethanol and phospholipid concentration effect on ethosomes properties. Niosomes were formulated using 2³ factorial designs to study the effect of surfactant type, surfactant concentration and cholesterol concentration on niosomes properties. The prepared formulations were evaluated for their Entrapment efficiency, particle size, polydispersity index, zeta potential and % drug permeated. The optimized ethosomal and niosomal formulations were incorporated into carbopol gel and evaluated for their permeation, skin retention and stability. A comparative split-face clinical study was done between the ethosomal and niosomal formulations for melasma treatment using Antera 3 D^® camera. The optimized ethosomal and niosomal gels showed comparable controlled permeation and higher skin retention over their ethosomes and niosomes formulations respectively. Magnesium ascorbyl phosphate ethosomal gel showed clinically and statistically significant melanin level decrease after one month while MAP niosomal gel showed clinically and statistically significant melanin level decrease after six months. A combination of MAP ethosomes and niosomes could be promising skincare formulations for melasma and hyperpigmentation short and long-term treatment.     

Pharmacovigilance in developing countries (part I): importance and challenges

The thalidomide disaster was the significant historical event that acted as a catalyst for pharmacovigilance activity. Following this event developed countries initiated drug monitoring systems that evolved and now extend their scope to broader drug-related safety issues; however, this was not the case in developing countries. Pharmacovigilance is still a relatively new concept with low priority in developing countries although various issues are raising concerns that magnify the need for systems to monitor post marketing drug safety in these countries. This article analyzes the barriers to introducing robust pharmacovigilance systems in developing countries.