Sterilization effects of UV laser irradiation on Bacillus atrophaeus spore viability, structure, and proteins

Nano TiO2 photocatalytic combined with optimized operating room care in postoperative infection after gynecological open abdominal surgery

BACKGROUND

Disinfection of the operating room environment is essential to reduce the incidence of infection after laparotomy in obstetrics and gynecology. With the development of science and technology, nano-titanium dioxide (TiO2) photocatalytic technology has attracted much attention due to its high efficiency and low cost. To explore the effect of TiO2 photocatalytic technology and optimized operating room care in the prevention of postoperative infection in obstetrics and gynecology department.

METHODS

Nano-TiO2 photocatalysts were prepared and characterized, and their bactericidal effect was analyzed. A total of 96 patients with gynecological open abdominal surgery were randomly divided into control group (CG) and observation group (BG), 48 cases in each group. The CG received routine care and the BG received optimized care. The wound healing rate, infection rate, serum immunoglobulin, and inflammatory factor levels were compared.

RESULTS

The specific surface area of the nano-TiO2 photocatalyst was 75.1 m2/g, and the particle size was 16.6 nm, with rutile crystal structure. Compared with ultraviolet light, nano-TiO2 photocatalyst had better disinfection effect. Compared with the CG, the wound healing rate and IgG level were higher, and the infection rate, C-reactive protein, interleukin-6, and tumor necrosis factor-α were lower in the BG (P < 0.05).

CONCLUSION

The combination of nano-TiO2 photocatalytic disinfection and optimized nursing care resulted in a 16.66 % reduction in postoperative infections and a 14.58 % improvement in wound healing. This is associated with lower airborne pathogens (66.6 CFU/m3) and improved immune-inflammatory markers (↑IgG, ↓CRP/IL-6/TNF-α).

Sterilization efficacy of a homemade UV lamp system on ceramic and porcelain tiles

Ultraviolet (UV) sterilization of Bacillus atrophaeus spores attached to eight types of tiles, consisting of combinations of ceramic and porcelain, white and black, and matte and glossy surfaces, was investigated using a homemade UV lamp system with different irradiation times (10 s, 30 s, and 60 s) and UV lamp-to-tile distances (32 mm, 76 mm, and 120 mm). The results demonstrated a reduction in colony numbers with increasing irradiation time and decreasing lamp-to-tile distance, with nearly complete sterilization observed for a 120 mm lamp-to-tile distance with 60 s UV irradiation and for a 32 mm lamp-to-tile distance with 10 s UV irradiation. Specifically, superior UV sterilization efficacy was observed on porcelain compared to ceramic tiles, on white compared to black tiles, and on matte compared to glossy tiles, consistent with the reflectance trend. In conclusion, among the tested tile surfaces, the white matte porcelain tile exhibited the most efficient UV sterilization, attributed to its highest UV reflectance.

Single-cell analysis reveals microbial spore responses to sodium hypochlorite

Pollution from toxic spores has caused us a lot of problems because spores are extremely resistant and can survive most disinfectants. Therefore, the detection of spore response to disinfectant is of great significance for the development of effective decontamination strategies. In this work, we investigated the effect of 0.5% sodium hypochlorite on the molecular and morphological properties of single spores of Bacillus subtilis using single-cell techniques. Laser tweezers Raman spectroscopy showed that sodium hypochlorite resulted in Ca2+-dipicolinic acid release and nucleic acid denaturation. Atomic force microscopy showed that the surface of treated spores changed from rough to smooth, protein shells were degraded at 10 min, and the permeability barrier was destroyed at 15 min. The spore volume decreased gradually over time. Live-cell imaging showed that the germination and growth rates decreased with increasing treatment time. These results provide new insight into the response of spores to sodium hypochlorite.

Synergistic inhibition effect of ultraviolet irradiation and benzalkonium chloride on the corrosion of 316L stainless steel caused by Aspergillus terreus

Microbiologically influenced corrosion (MIC) is a key factor that damages engineering materials in marine environments. One of the major concerns in this regard is the corrosion protection of stainless steel (SS) caused against fungal attacks. This study investigated the effect of ultraviolet (UV) irradiation and benzalkonium chloride (BKC) on the corrosion of 316L stainless steel (316L SS) induced by marine Aspergillus terreus in 3.5 wt% NaCl solution. This was accomplished by employing microstructural characterisations and electrochemical analysis to analyse the synergistic inhibition behaviour of the two methods. The results indicated that while UV and BKC demonstrated individual abilities to suppress the biological activity of A. terreus, their inhibitory effects were not significant. The combination of UV light and BKC was found to cause a further decline in the biological activity of A. terreus. The analysis revealed that the combination of BKC and UV significantly decreased the sessile cell counts of A. terreus by more than three orders of magnitude. The fungal corrosion inhibition effect of individual application of UV light or BKC did not yield satisfactory results owing to the low intensity of UV and low concentration of BKC. Furthermore, the corrosion inhibition of UV and BKC occurred mainly during the early stages. The corrosion rate of the 316L SS declined rapidly when the combination of UV light and BKC were used, indicating that UV light and BKC exert a good synergistic inhibitory effect on the corrosion of the 316L SS caused by A. terreus. Therefore, the results suggest that the combination of UV light and BKC can be an effective approach to control the MIC of 316L SS in marine environments.

Effective inactivation of Bacillus atrophaeus spores and Escherichia coli on disposable face masks using ultraviolet laser irradiation

Due to the widespread emergence of COVID-19, face masks have become a common tool for reducing transmission risk between people, increasing the need for sterilization methods against mask-contaminated microorganisms. In this study, we measured the efficacy of ultraviolet (UV) laser irradiation (266 nm) as a sterilization technique against Bacillus atrophaeus spores and Escherichia coli on three different types of face mask. The UV laser source demonstrated high penetration of inner mask layers, inactivating microorganisms in a short time while maintaining the particle filtration efficiency of the masks. This study demonstrates that UV laser irradiation is an efficient sterilization method for removing pathogens from face masks.