Antibacterial Properties of Visible-Light-Responsive Carbon-Containing Titanium Dioxide Photocatalytic Nanoparticles against Anthrax.

The bactericidal activity of conventional titanium dioxide (TiO2) photocatalyst is effective only on irradiation by ultraviolet light, which restricts the applications of TiO2 for use in living environments. Recently, carbon-containing TiO2 nanoparticles [TiO2(C) NP] were found to be a visible-light-responsive photocatalyst (VLRP), which displayed significantly enhanced antibacterial properties under visible light illumination. However, whether TiO2(C) NPs exert antibacterial properties against Bacillus anthracis remains elusive. Here, we evaluated these VLRP NPs in the reduction of anthrax-induced pathogenesis. Bacteria-killing experiments indicated that a significantly higher proportion (40%-60%) of all tested Bacillus species, including B. subtilis, B. cereus, B. thuringiensis, and B. anthracis, were considerably eliminated by TiO2(C) NPs. Toxin inactivation analysis further suggested that the TiO2(C) NPs efficiently detoxify approximately 90% of tested anthrax lethal toxin, a major virulence factor of anthrax. Notably, macrophage clearance experiments further suggested that, even under suboptimal conditions without considerable bacterial killing, the TiO2(C) NP-mediated photocatalysis still exhibited antibacterial properties through the reduction of bacterial resistance against macrophage killing. Our results collectively suggested that TiO2(C) NP is a conceptually feasible anti-anthrax material, and the relevant technologies described herein may be useful in the development of new strategies against anthrax.

Visible Light-Responsive Platinum-Containing Titania Nanoparticle-Mediated Photocatalysis Induces Nucleotide Insertion, Deletion and Substitution Mutations.

Conventional photocatalysts are primarily stimulated using ultraviolet (UV) light to elicit reactive oxygen species and have wide applications in environmental and energy fields, including self-cleaning surfaces and sterilization. Because UV illumination is hazardous to humans, visible light-responsive photocatalysts (VLRPs) were discovered and are now applied to increase photocatalysis. However, fundamental questions regarding the ability of VLRPs to trigger DNA mutations and the mutation types it elicits remain elusive. Here, through plasmid transformation and ß-galactosidase α-complementation analyses, we observed that visible light-responsive platinum-containing titania (TiO2) nanoparticle (NP)-mediated photocatalysis considerably reduces the number of Escherichia coli transformants. This suggests that such photocatalytic reactions cause DNA damage. DNA sequencing results demonstrated that the DNA damage comprises three mutation types, namely nucleotide insertion, deletion and substitution; this is the first study to report the types of mutations occurring after photocatalysis by TiO2-VLRPs. Our results may facilitate the development and appropriate use of new-generation TiO2 NPs for biomedical applications.

Antibacterial performance of nanoscaled visible-light responsive platinum-containing titania photocatalyst in vitro and in vivo.

BACKGROUND: Traditional antibacterial photocatalysts are primarily induced by ultraviolet light to elicit antibacterial reactive oxygen species. New generation visible-light responsive photocatalysts were discovered, offering greater opportunity to use photocatalysts as disinfectants in our living environment. Recently, we found that visible-light responsive platinum-containing titania (TiO2-Pt) exerted high performance antibacterial property against soil-borne pathogens even in soil highly contaminated water. However, its physical and photocatalytic properties, and the application in vivo have not been well-characterized. METHODS: Transmission electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, ultraviolet-visible absorption spectrum and the removal rate of nitrogen oxides were therefore analyzed. The antibacterial performance under in vitro and in vivo conditions was evaluated. RESULTS: The apparent quantum efficiency for visible light illuminated TiO2-Pt is relatively higher than several other titania photocatalysts. The killing effect achieved approximately 2 log reductions of pathogenic bacteria in vitro. Illumination of injected TiO2-Pt successfully ameliorated the subcutaneous infection in mice. CONCLUSIONS: This is the first demonstration of in vivo antibacterial use of TiO2-Pt nanoparticles. When compared to nanoparticles of some other visible-light responsive photocatalysts, TiO2-Pt nanoparticles induced less adverse effects such as exacerbated platelet clearance and hepatic cytotoxicity in vivo. GENERAL SIGNIFICANCE: These findings suggest that the TiO2-Pt may have potential application on the development of an antibacterial material in both in vitro and in vivo settings.

Visible light-responsive core-shell structured In2O3@CaIn2O4 photocatalyst with superior bactericidal properties and biocompatibility.

Antibacterial activity of photocatalytic substrates is primarily induced by ultraviolet light irradiation. Visible light-responsive photocatalysts were recently discovered, offering greater opportunity to use photocatalysts as disinfectants in our living environment. The development of antibacterial photocatalysts, however, has mainly focused on titanium oxide (TiO(2))-related materials with antibacterial properties not comparable with conventional chemical disinfectants. This study demonstrated that a core-shell structured In(2)O(3)@CaIn(2)O(4) substrate has superior visible light-induced bactericidal properties, as compared with several commercially available and laboratory-prepared visible light-responsive photocatalysts. The high performance is enhanced by more easily photoexcited electron transfer between the interfaces of In(2)O(3) and CaIn(2)O(4) to minimize the electron-hole recombination during photocatalysis. Additionally, when compared with TiO(2)-based photocatalysts, In(2)O(3)@CaIn(2)O(4) treatments did not induce significant cell death and tissue damage, implying a superior biocompatibility. These findings suggest that In(2)O(3)@CaIn(2)O(4) may have potential application in the development of a safer and highly bactericidal photocatalyst. FROM THE CLINICAL EDITOR: A photocatalytic susbstrate is described that functions in visible light, possesses bactericidal properties and better biocompatibility than the standard TiO(2) based methods.

PINK1 mutation in Taiwanese early-onset parkinsonism : clinical, genetic, and dopamine transporter studies.

The PINK1 gene mutation is probably the second most common genetic cause of early-onset Parkinson's disease (EOPD). The frequency and the characteristics of the PINK1 mutation in the Taiwanese population are unknown. This study was designed to investigate the genotype, phenotype and dopaminergic function of PINK1 in a cohort of EOPD patients. The genetic settings were to detect the PINK1 gene mutations in 138 EOPD patients and in 191 controls. Using the (99m)Tc-TRODAT-1 (TRODAT) scan, we investigated the differences in the dopamine transporter (DAT) activities between the PINK1 patients, late-onset Parkinson's disease (LOPD) patients and healthy controls. Four EOPD patients with 3 genotypic mutations in the PINK1 gene were found: a compound heterozygous mutation (Q239X/R492X) in 2 sisters, a novel homozygous mutation (R492X) in a woman, and a novel heterozygous mutation (G193R) in a man. The three PINK1 patients had typical phenotype with juvenile onset, benign course, and frequently with dyskinesias. The TRODAT scan showed a rather even and symmetrical reduction of uptake in PINK1 patients, unlike the dominant decline in the putamen in the LOPD patients. The annual reduction rate of uptake in the striatum was much slower in PINK1 patients than that in the LOPD patients (1.7 % vs. 4.1%; p<0.005). In the patient with a heterozygous mutation in the PINK1 gene, the reduction ratio in the striatum, as well as the annual reduction rate, were closer to those in the LOPD group. We conclude that the incidence of carrying PINK1 mutations in the present cohort of Taiwanese EOPD patients was low, accounting for 2/39 (5.1 %) in familial cases, and 2/99 (2 %) in sporadic cases. The slower annual reduction of DAT activity might indicate the insidious degeneration of dopamine neurons and a benign prognosis.

DYT1 mutation in a cohort of Taiwanese primary dystonias.

To investigate the DYT1 gene mutation in Chinese ethnic, we examined a series of 200 patients with primary dystonias (11 familial and 189 sporadic), 53 of their asymptomatic relatives, 97 patients with familial or early-onset parkinsonism, and 200 healthy subjects. The GAG deletion at codon 946 was only found in three sporadic dystonia patients and seven of their asymptomatic familial members. The frequency of GAG deletion was 1.5% in dystonia patients, and was 6.7% in early-onset dystonias (< or = 26 years). We conclude that DYT1 mutation is a minor cause of primary dystonias in a cohort of Taiwanese population.

The parkinsonian phenotype of spinocerebellar ataxia type 3 in a Taiwanese family.

We report a parkinsonian phenotype of spinocerebellar ataxia type 3 (SCA3) in three female sibs from one Taiwanese family, found in a genetic analysis of 60 patients from 49 families with familial parkinsonism. Initially, all three patients presented with early onset resting tremor, rigidity, bradykinesia, and good response to levodopa. In the later stages, peripheral neuropathy developed in one sib and mild ataxia in another one. Decreased concentration of dopamine transporter in the striatum was demonstrated by (99m)Tc-TRODAT-1 SPECT imaging in the two sibs studied. Therefore, SCA3 should be considered as an important etiology of familial parkinsonism.