Using visible light to activate antiviral and antimicrobial properties of TiO2 nanoparticles in paints and coatings: focus on new developments for frequent-touch surfaces in hospitals

The COVID-19 pandemic refocused scientists the world over to produce technologies that will be able to prevent the spread of such diseases in the future. One area that deservedly receives much attention is the disinfection of health facilities like hospitals, public areas like bathrooms and train stations, and cleaning areas in the food industry. Microorganisms and viruses can attach to and survive on surfaces for a long time in most cases, increasing the risk for infection. One of the most attractive disinfection methods is paints and coatings containing nanoparticles that act as photocatalysts. Of these, titanium dioxide is appealing due to its low cost and photoreactivity. However, on its own, it can only be activated under high-energy UV light due to the high band gap and fast recombination of photogenerated species. The ideal material or coating should be activated under artificial light conditions to impact indoor areas, especially considering wall paints or frequent-touch areas like door handles and elevator buttons. By introducing dopants to TiO₂ NPs, the bandgap can be lowered to a state of visible-light photocatalysis occurring. Naturally, many researchers are exploring this property now. This review article highlights the most recent advancements and research on visible-light activation of TiO₂-doped NPs in coatings and paints. The progress in fighting air pollution and personal protective equipment is also briefly discussed.

Graphical Abstract

Indoor visible-light photocatalytic activation of reactive oxygen species (ROS) over TiO₂ nanoparticles in paint to kill bacteria and coat frequently touched surfaces in the medical and food industries.

NMR data of a Grubbs 2nd generation catalyst p-cresolate derivative

The data presented in this article is related to the research article entitled “Spectroscopic characterisation of Grubbs 2^nd generation catalyst and its p-cresol derivatives” (Swart et al. 2021). The 1D and 2D NMR characterisation data of the p-cresol derivative of the Grubbs 2^nd generation catalyst, where one of the chloride ligands is replaced by the p-cresolate to form a Ru-O coordination compound (3) is reported. The characterization data include information obtained from ¹H, ¹³C, Heteronuclear Single Quantum Coherence (HSQC), Heteronuclear Multiple Bond Correlation (HMBC), Homonuclear Correlation Spectroscopy (COSY), Nuclear Overhauser Effect (NOE) and Distortionless Enhancement by Polarization Transfer (DEPT) NMR spectroscopy.

Palladium/graphene oxide nanocomposites with carbon nanotubes and/or magnetite for the reduction of nitrophenolic compounds

Graphene oxide (GO) was synthesised via the oxidation of graphite and was characterised using ATR FTIR, PXRD, SEM, TEM and TGA. These techniques confirmed the presence of characteristic oxygen-containing functional groups and the resulting increase in interlayer spacing in the nanostructure. GO is used as the support to form nanocomposites composed of combinations of the following: iron oxide nanoparticles (Fe₃O₄), carbon nanotubes (CNT) and palladium nanoparticles (Pd). The four final nanocomposites formed are: Pd/GO, Pd/Fe₃O₄/GO, Pd/CNT/GO, and Pd/CNT/Fe₃O₄/GO. Key intermediates were analysed using ATR FTIR for the confirmation of the modification. Additionally, all composites and their precursors underwent electron microscopic analysis to visually assess composite morphologies and the size distribution of deposited nanoparticles. The Fe₃O₄ and Pd nanoparticles were indistinguishable from each other in their spherical shape and particle diameters, which were no bigger than 32 nm. From the TGA, incorporation of Fe₃O₄, CNT and finally Pd into the nanocomposites increased total thermal stability in terms of mass percentage lost over the temperature programme. GO showed significant decomposition, with all nanocomposites remaining relatively stable up to 120 °C. ICP OES results showed total Pd content by mass percentage for each final composite, varied from 7.9% to 9.1% mass Pd/collective mass. XPS confirmed the expected elemental compositions of composites according to their structures and the Pd⁰ : Pd^II ratios are obtained. The nanocomposites were tested for the catalytic reduction of nitrophenols. Pd/CNT/Fe₃O₄/GO gave the highest TOF′ for the reduction of 4-NP and 2-NP. For the reduction of 3-NP, Pd/GO showed the highest TOF′. Nitrophenol's pK_a and catalyst TOF′ correlated in a direct proportional relationship for Pd/GO and Pd/Fe₃O₄/GO. It was found that Pd⁰ surpassed Pd^II in catalytic activity. Reduction of Pd^II to Pd⁰ took place during the first catalytic cycle.

Comparison of the catalytic activity for the reduction of nitrophenol over palladium-supported graphene oxide nanocomposites modified with iron oxide nanoparticles and/or carbon nanotubes.

Crystallization and sintering of borosilicate bioactive glasses for application in tissue engineering

Typical silicate bioactive glasses are known to crystallize readily during the processing of porous scaffolds. New borosilicate bioactive glass can be sintered without significant sign of crystallization.

Mapping the existing body of health policy implementation research in lower income settings: what is covered and what are the gaps?

This article uses 85 peer-reviewed articles published between 1994 and 2009 to characterize and synthesize aspects of the health policy analysis literature focusing on policy implementation in low- and middle-income countries (LMICs). It seeks to contribute, first, to strengthening the field of LMIC health policy analysis by highlighting gaps in the literature and generating ideas for a future research agenda and, second, to thinking about the value and applicability of qualitative synthesis approaches to the health policy analysis field. Overall, the article considers the disciplinary perspectives from which LMIC health policy implementation is studied and the extent to which the focus is on systems or programme issues. It then works with the more specific themes of the key thrusts of the reviewed articles, the implementation outcomes studied, implementation improvement recommendations made and the theories used in the reviewed articles. With respect to these more specific themes, the article includes explorations of patterns within the themes themselves, the contributions of specific disciplinary perspectives and differences between systems and programme articles. It concludes, among other things, that the literature remains small, fragmented, of limited depth and quite diverse, reflecting a wide spectrum of health system dimensions studied and many different suggestions for improving policy implementation. However, a range of issues beyond traditional 'hardware' health system concerns, such as funding and organizational structure, are understood to influence policy implementation, including many 'software' issues such as the understandings of policy actors and the need for better communication and actor relationships. Looking to the future, there is a need, given the fragmentation in the literature, to consolidate the existing body of work where possible and, given the often broad nature of the work and its limited depth, to draw more explicitly on theoretical frames and concepts to deepen work by sharpening and focusing concerns and questions.

Policy interventions that attract nurses to rural areas: a multicountry discrete choice experiment

OBJECTIVE

To evaluate the relative effectiveness of different policies in attracting nurses to rural areas in Kenya, South Africa and Thailand using data from a discrete choice experiment (DCE).

METHODS

A labelled DCE was designed to model the relative effectiveness of both financial and non-financial strategies designed to attract nurses to rural areas. Data were collected from over 300 graduating nursing students in each country. Mixed logit models were used for analysis and to predict the uptake of rural posts under different incentive combinations.

FINDINGS

Nurses' preferences for different human resource policy interventions varied significantly between the three countries. In Kenya and South Africa, better educational opportunities or rural allowances would be most effective in increasing the uptake of rural posts, while in Thailand better health insurance coverage would have the greatest impact.

CONCLUSION

DCEs can be designed to help policy-makers choose more effective interventions to address staff shortages in rural areas. Intervention packages tailored to local conditions are more likely to be effective than standardized global approaches.

Amino-acid depletion induced by abnormal amino-acid conjugation and protein restriction in isovaleric acidemia

BACKGROUND

Previously, we detected 19 'new' amino-acid conjugates in the urine of patients with isovaleric acidemia. There is currently a poor understanding of the relationship between the clinical symptoms and the excreted metabolites occurring in these patients, owing to insufficient metabolite characterization and quantification. Consequently, controversial treatment protocols exist, particularly pertaining to dietary protein restriction.

OBJECTIVE

To determine the effect of the previously identified amino-acid conjugates and conventional dietary protein restriction therapy, on the free amino-acid concentrations in isovaleric acidemia patients, to better explain the clinical symptoms and develop more effective therapy.

DESIGN

Free amino-acid quantification via liquid chromatography mass spectrometry (LC-MS-MS) was performed on pre- and post-treatment urine or serum samples collected from six isovaleric acidemia patients, previously investigated for the presence of new induced N-isovaleryl and N-acetyl-amino-acid conjugates.

RESULTS

Depleted amino-acid concentrations were detected in varying degrees in all six patients and did not recover after conventional treatment.

CONCLUSIONS

The 19 potentially toxic metabolites previously identified and the consequent amino-acid depletions detected in this study, may explain many of the clinical symptoms associated with isovaleric acidemia. Furthermore, the occurrence of amino-acid depletions in these patients, steers away from the controversial dietary protein restriction treatment protocols, and towards dietary leucine restriction alone with essential amino-acid supplementation, in combination with glycine and L-carnitine supplementation.

Chemical analyses of Ukrain, a semi-synthetic Chelidonium majus alkaloid derivative, fail to confirm its trimeric structure

Ukrain has been described as a semi-synthetic Chelidonium majus alkaloid derivative, consisting of three chelidonine alkaloids combined to triaziridide. We found the actions of Ukrain to be similar to the Chelidonium alkaloids it is prepared from, and therefore became concerned about its chemical integrity. Chemical analyses of Ukrain by thin layer chromatography, high-performance liquid chromatography and liquid chromatography-mass spectrometry was inconsistent with the proposed trimeric structure and demonstrated that at least some commercial preparations of Ukrain consist of a mixture of C. majus alkaloids (including chelidonine).

The utilization of alanine, glutamic acid, and serine as amino acid substrates for glycine N-acyltransferase

The conjugation of benzoyl-CoA with the aliphatic and acidic amino acids by glycine N-acyltransferase, as well as the amides of the latter group, was investigated. Bovine and human liver benzoyl-amino acid conjugation were investigated using electrospray ionization tandem mass spectrometry (ESI-MS-MS). Bovine glycine N-acyltransferase catalyzed conjugation of benzoyl-CoA with Gly (Km(Gly) = 6.2 mM), Asn (Km(Asn) = 129 mM), Gln (Km(Gln) = 353 mM), Ala (Km(Ala) = 1573 mM), Glu (Km(Glu) = 1148 mM) as well as Ser in a sequential mechanism. In the case of the human form, conjugation with Gly (Km(Gly) = 6.4 mM), Ala (Km(Ala) = 997 mM), and Glu was detected. The presence of these alternative conjugates did not inhibit bovine glycine N-acyltransferase activity significantly. Considering the relatively low levels at which these conjugates are formed, it is unlikely that they will have a significant contribution to acyl-amino acid conjugation under normal conditions in vivo. However, their cumulative contribution to acyl-amino acid conjugation under metabolic disease states may prove to have a useful contribution to detoxification of elevated acyl-CoAs.

Nutritional status of HIV-1 seropositive patients in the Free State Province of South Africa: anthropometric and dietary profile

OBJECTIVE

To evaluate the nutritional intake and status of HIV-1 seropositive patients, as well as the relationship between malnutrition and disease stage.

DESIGN

A cross-sectional study.

SETTINGS

The Immunology Clinic at the Pelonomi Hospital in Bloemfontein, South Africa.

SUBJECTS

Eighty-one HIV/AIDS patients in different stages of disease were recruited consecutively from January to May 1995. Eleven of these patients were followed in 1997.

MAIN OUTCOME MEASURES

Anthropometric data including current weight, height, triceps skinfold thickness, mid-upper-arm circumference, body mass index and bone-free arm muscle area were collected. Nutrient intake was estimated using a diet history in combination with a standardised food frequency questionnaire. The patients were divided into 3 groups according to their CD4+ T cell counts.

RESULTS

The men were leaner (BMI = 18.9) than the women (BMI = 22.7) and patients with a CD4+ T cell count < 200 (stage III) tended to have the lowest median values for all anthropometric measurements. More than half the patients had a low intake (< 67% of the recommended dietary allowances) of vitamin C, vitamin B6, vitamin D, vitamin A, calcium, iron and zinc.

CONCLUSIONS

The results confirms that HIV/AIDS patients from this population are malnourished. There was, however, no association between disease stage and nutritional status. Nutritional supplementation of HIV/AIDS patients should be considered, as this might lead to improved immune function in these patients.

Carnitine palmitoyltransferase I activity monitoring in fibroblasts and leukocytes using electrospray ionization mass spectrometry

Carnitine palmitoyltransferase I (CPT I) is one of the enzymes associated with normal mitochondrial membrane transport of certain metabolites. The importance of the enzyme in normal energy production is well illustrated during fasting conditions when a large flux of long-chain fatty acids must be transported over the mitochondrial membrane to undergo beta-oxidation. Up to now CPT I activity has been assayed in various tissues, including liver, leukocytes, platelets, and fibroblasts by the use of an isotope exchange forward assay which measures the rate of palmitoyl-l-[methyl-3H]carnitine formation from palmitoyl-CoA and l-[methyl-3H]carnitine. We have developed an electrospray ionization mass spectrometric method for detecting palmitoylcarnitine formation from palmitoyl-CoA and carnitine, thus avoiding the use of radiolabeled isotopes. In this assay, time-dependent conversion of free carnitine by CPT I to palmitoylcarnitine is measured quantitatively, relative to isotopically labelled palmitoylcarnitine, by parent ion monitoring of fragment ion m/z 85. The specific activity of CPT I in fibroblasts and leukocytes compared well with the activity determined with the isotope exchange method, however, the combination of high sensitivity and selectivity of tandem mass spectrometry along with the environment-friendly nature of the electrospray method makes it an ideal technique to measure CPT I activity.

Effect of sperm preincubation time on GIFT pregnancy outcome

This investigation was conducted to evaluate the effect of human sperm preincubation time on the pregnancy outcome in gamete intrafallopian tube transfers. This was determined in a retrospective study on gamete intrafallopian transfer patients (ideopathic infertility) using logistic regression with the covariates, preincubation time (< or = 60 and > 60 min) and age (< or = 35 and > 35 years). The study included 485 consecutive gamete intrafallopian transfer cycles in which 3 metaphase II oocytes were transferred. Pregnancy outcome was evaluated by beta hCG levels on days 12 and 16 and was confirmed by the presence of a fetal heart 8 weeks after the procedure by means of sonography. The wife's age and sperm preincubation time were significant covariates in the prediction of ongoing pregnancy. The odds ratio for age (< or = 35 years) was 2.2 in the prediction of ongoing pregnancy, while the age-adjusted odds ratios for preincubation time (< or = 60 min) was 1.9. There was a critical relationship between sperm preincubation time and GIFT success, which confirms the effect of the wife's age on pregnancy. Close coordination is of importance between the clinical scientist and the physician to restrict the preincubation time to 1 h. The sperm preincubation time is a significant factor that has to be considered in the prediction of ongoing pregnancy in GIFT patients.

Urinary excretion of homocitric acid and methylhomocitric acid in propionic acidaemia: minor metabolic products of the citrate synthase aldol condensation reaction

The identity of two formerly novel citric acid analogues, homocitric acid and methylhomocitric acid, in urine samples from patients with propionic acidaemia was confirmed by gas chromatography and mass spectrometry. Authentic reference substances were synthesized using a Reformatskii reaction. Homocitric acid and methylhomocitric acid were detected as minor metabolites in the urine samples from propionyl coenzyme A carboxylase deficient individuals. It was shown that these substances can be formed by the citrate synthase condensation reaction of alpha-ketoglutarate with acetyl coenzyme A and propionyl coenzyme A, respectively.

The detection of 3-methylglutarylcarnitine and a new dicarboxylic conjugate, 3-methylglutaconylcarnitine, in 3-methylglutaconic aciduria

Two patients, diagnosed with 3-methylglutaconic aciduria, who presented with diverse clinical and metabolic manifestations, were studied. Glycine conjugation as a possible detoxification mechanism in these two patients yielded negative results. Carnitine conjugates were however detected. 3-Methylglutarylcarnitine was observed in the urine of both patients, while one of the patients excreted detectable quantities of 3-methylglutaconylcarnitine, a previously unknown metabolite. The presence of this metabolite in urine samples from one patient and the apparent correlation between administered carnitine and the conjugate excretion profile seems to indicate that carnitine may play an important role in future therapeutic programmes.

Identification of the stereoisomeric configurations of methylcitric acid produced by si-citrate synthase and methylcitrate synthase using capillary gas chromatography-mass spectrometry

The absolute separation of the four stereoisomeric configurations of methylcitric acid can be achieved on a nonchiral stationary phase SE30 capillary column using the corresponding O-acetylated (tri-(-)-2-butyl ester derivatives. Identification of the separated isomers was done using methylcitric acid produced by si-citrate synthase and methylcitrate synthase of Candida lipolitica. si-Citrate synthase produces the (2S,3S)-, (2S,3R)- and a small amount of the (2R,3S)-isomers. Methylcitrate synthase produces the (2R,3S)-isomer, indicating that this enzyme is more stereospecific than the animal citrate synthase enzyme. The (2R,3R)-isomer may act as an inhibitor of aconitase.

Prenatal analysis in two suspected cases of glutathione synthetase deficiency

Prenatal diagnosis was performed in a family affected by generalized glutathione synthetase deficiency. The disorder is transmitted by autosomal recessive inheritance. The first child born in this family died of the disorder at 6 weeks of age. Prenatal diagnosis was performed in two subsequent pregnancies. Amniotic fluid samples were collected by amniocentesis in the 16th and 17th weeks of pregnancy, respectively. In the case of the second pregnancy the concentration of 5-oxoproline in the amniotic fluid was measured by stable isotope dilution, while both stable isotope dilution and glutathione synthetase activity measurements were employed in the prenatal analysis of the third pregnancy. The 5-oxoproline concentration in the second pregnancy was even lower than that of the controls and in the case of the third pregnancy the results fell within the control range. The second pregnancy resulted in the birth of a clinically healthy girl, and the outcome of 5-oxoproline concentration in a urine sample taken just after birth confirmed the unaffected state. The third pregnancy resulted in the birth of a healthy boy at term, and the 5-oxoproline concentration in his urine and the glutathione synthetase activity in haemolysates were determined. The results confirmed that this infant was also unaffected and he apparently had two normal alleles for the enzyme.

Antibody response in cattle to oil emulsion rabies and ephemeral fever vaccines

A stable oil emulsion rabies vaccine with a low viscosity was composed by a formula previously employed for Newcastle disease vaccine. Cattle developed high and sustained antibody levels, and guinea pigs were found to be solidly immune after a single injection of this vaccine. Antibody responses in cattle to 2 oil emulsion ephemeral fever vaccines were not satisfactory after a single injection, and severe local reactions were encountered when booster injections were applied.

Postnatal and antenatal laboratory diagnosis of glutaric aciduria II in a South African family

Glutaric aciduria type II (GA II) was proved in a neonate who presented shortly after birth with respiratory distress, metabolic acidosis, non-ketotic hypoglycaemia and a sweaty-feet-like odour. The diagnosis was based on elevated levels of glutaric and other acids in the urine and on studies on cultured skin fibroblasts where defective metabolism of fatty acids of varying chain length was demonstrated. Antenatal diagnosis was performed on a subsequent pregnancy in this family where an abnormal amniotic fluid organic acid profile together with defective fatty acid oxidation in cultured amnion cells was indicative of GA II in the fetus. This is the first report of this genetic disorder in a South African family and it should be considered in suspected organic acidaemia in the neonatal period.