Photodynamic inactivation assisted by localized surface plasmon resonance of silver nanoparticles: In vitro evaluation on Escherichia coli and Streptococcus mutans.

Localized surface plasmon resonance (LSPR) of gold nanoparticles has been reported to increase the antimicrobial effect of the photodynamic therapy. Although silver nanoparticles (AgNPs) are an efficient growth inhibitor of microorganisms, no studies exploring LSPR of AgNPs to enhance the photodynamic inactivation (PDI) have been related. In this work, we described the LSPR phenomenon of AgNP sand investigated its interaction with riboflavin, a natural photosensitizer. We evaluated the use of AgNPs coated with pectin (p-AgNP) in riboflavin (Rb)-mediated PDI of Escherichia coli (Gram- bacteria) and Streptococcus mutans (Gram + bacteria) using a blue light-emitting diode (λ = 455 ±â€¯20 nm) of optical power 200 mW. Irradiance was 90 mW/cm2 and radiant exposure varied according to the time exposure. Uptake of Rb and p-AgNP by the cells was evaluated by measuring the supernatant absorption spectra of the samples. We observed that LSPR of p-AgNPs was able to enhance the riboflavin photodynamic action on S. mutans but not on E. coli, probably due to the lower uptake of Rb by E. coli. Taken together, our results provide insights to explore the use of the LPRS promoted by silver nanostructures to optimize antimicrobial PDI protocols.

Comparison between boiling and vacuum cooking (sous-vide) in the bioaccessibility of minerals in bovine liver samples.

Only some of ingested nutrients are available for absorption by the organism. The foods generally are submitted to some heat processing that may interfere in the bioaccessibility of nutrients. There are no studies of the influence of cooking under vacuum (sous vide) on the bioaccessibility of minerals. This study evaluated the in vitro bioaccessibility of Ca, Cu, Fe, K, Mg and Zn in bovine liver samples after traditional cooking in water and using the sous vide procedure. All heat treatments of bovine liver promoted the increase of the bioaccessibility of Ca, Cu, Fe, K and Mg, except for Zn when the effect was the opposite. The sous vide method provided higher bioaccessibility of these minerals than cooking in boiling water, except for K when both methods presented equivalent values. Samples of raw liver and liver cooked using sous vide method presented the following percentage of bioaccessible fraction, respectively: 39.7% and 95.8% (Ca), 8.78% and 26.9% (Cu), 8.80% and 39.5% (Fe), 30.2% and 42.6% (K), 26.4% and 43.9% (Mg), 24.8% and 36.3% (Zn). Thus, under the aspect of improvement availability of studied minerals by organism, the sous-vide technique was the most suitable to cook bovine liver.

Development of a wet digestion method for paints for the determination of metals and metalloids using inductively coupled plasma optical emission spectrometry.

Paints, a complex matrix, have a variable composition that is dependent on the application. In this work, a new wet digestion procedure for the determination of Al, As, Ba, Cd, Cr, Cu, Mn, Ni, Pb, Sn, Sr, Ti and Zn in paint samples using inductively coupled plasma optical emission spectrometry (ICP OES) has been developed. An experimental design approach was employed to determine the optimal conditions for achieving complete solubilization and/or decomposition in the sample preparation method. An efficient sample preparation was developed that consisted of a pre-digestion step at 40°C for 20 min using 1 mL of HNO3 to eliminate organic solvents followed by digestion at 120°C for 3h using 5 mL of HCl and 1 mL of HF in a block digestion. The proposed procedure promotes the complete solubilization of different bases of paints at low temperature and atmospheric pressure. The accuracy was determined by addition/recovery tests and comparing the results with those obtained using the ASTM D335-85a standard sample preparation method. The limits of quantification were 1.78, 0.11, 0.006, 0.006, 0.01, 0.04, 0.006, 0.006, 0.02, 0.07, 0.30, 1.30 and 0.30 mg kg(-1) for Al, As, Ba, Cd, Cr, Cu,Mn, Ni, Pb, Sn, Sr, Ti and Zn, respectively. The proposed method was applied for the analysis of inorganics via the ICP OES of paints with different colors and bases used to cover wall surfaces.

Singlet oxygen generation enhanced by silver-pectin nanoparticles.

We demonstrate the potential application of silver-pectin nanoparticles on photodynamic therapy, on a solution-base platform. Photodynamic therapy is a medical technique which uses a combination of photosensitizing drugs and light to induce selective damage on the target tissue, by electronically excited and highly reactive singlet state of oxygen. Metal enhanced singlet oxygen generation in riboflavin water solution with silver-pectin nanoparticles was observed and quantified. Here 13 nm silver nanospheres enclosed by a pectin layer were synthesized and it interaction with riboflavin molecule was analyzed. Pectin, a complex carbohydrate found in plants primary cell walls, was used to increase the biocompatibility of the silver nanoparticles and to improve metal enhanced singlet oxygen generation (28.5 %) and metal-enhanced fluorescence (30.7 %) processes at room temperature. The singlet oxygen sensor fluorescent green reagent was used to quantify the enhancement of the riboflavin singlet oxygen production induced by the silver colloid. We report a 1.7-fold increase of riboflavin emission and a 1.8-fold enhancement of singlet oxygen production.

Tratamento da leishmaniose cutânea difusa (LCD) com a associaçäo antimoniato-N-metilglucamina (Glucantime) e sulfato de paramomicina (Gabbrox) / Treatment of diffuse cutaneous leishmaniasis (DCL) with meglumine anthimoniate (glucantime) associated with paramomicine sulphate (Gabbrox)

A leishmaniose cutânea difusa (LCD) é considerada forma rara da leishmaniose tegumentar (LT), estimando-se que existam aproximadamente 350 casos descritos na literatura mundial. Até o momento, no Brasil, foram descritos 31 casos, correspondendo a 8,9 porcento da casuística mundial, tendo o estado do Maranhäo contribuído com dez (32,3 porcento) descriçöes nacionais. Recentemente houve oportunidade de acompanhar dois casos novos de LCD, ambos do interior do estado, elevando a casuística para 12 casos. O parasita responsável pela doença foi a Leishmania L. amazonensis, reiterando os dados disponíveis de que essa é a única espécie a produzir essa forma da doença nesse Estado. Como tratamento foi utilizada a associaçäo de antimoniato-N-metilglucamina (Glucantime, via sistêmica), com sulfato de paramomicina (Gabbrox, por via oral), durante 90 dias, que mostrou boa tolerância, com resposta terapêutica favorável, constituindo mais uma opçäo terapêutica para a forma LCD, que, até o presente momento, se demonstrava num desafio para a ciência