Quantification of neomycin in rubella vaccine by off/on metal ion mediated photoluminescence from functionalized graphene quantum dots.

The determination of neomycin sulfate was made using photoluminescent amino-functionalized graphene quantum dots (obtained from hydro-exfoliation of a mixture of citric acid and glutathione). From the several ions tested, Fe3+ was the best mediator to enable an off/on photoluminescence effect used for quantification. The mediation of Fe3+ was found to be crucial as it is responsible for the photoluminescence quenching effect, due to the interaction with quantum dots surface, also having large affinity towards neomycin that removes Fe3+ from the surface of GQDs, consequently, promoting restoration of the original nanomaterial photoluminescence. Such signal restoration was proportional to the neomycin sulfate concentration added. The linearized analytical response covered three orders of magnitude (10-7 to 10-5 mol L-1). The proposed method is an alternative to those requiring labor-intensive procedures for chemical the derivatization of neomycin (due to the lack of chromophore groups in aminoglycosides). The method was successfully tested in the analysis of rubella vaccine containing trace residues of neomycin and in pharmaceutical compositions containing neomycin sulfate after solid phase extraction using an aminoglycoside imprinted polymer to improve selectivity in determinations.

Gold nanoparticles coupled with graphene quantum dots in organized medium to quantify aminoglycoside anti-biotics in yellow fever vaccine after solid phase extraction using a selective imprinted polymer.

The determination of kanamycin sulfate was made indirectly by measuring its effect on photoluminescent amino functionalized graphene quantum dots (GQDs-amino) associated with gold nanoparticles (AuNPs) that were produced by the reduction of AuCl4 with NaBH4 in an aqueous dispersion of GQDs-amino (obtained by the pyrolysis of citric acid and glutathione) also containing the cationic surfactant CTAB. The AuNPs-GQDs-amino-CTAB system presents a suppressed photoluminescence that is amplified in the presence of kanamycin. Under optimized experimental conditions, the photoluminescence amplification of the nanomaterial system showed a linear response as a function of kanamycin concentration, covering three orders of magnitude (10-7 to 10-5 mol L-1). The use of solid phase extraction with a cartridge packed with aminoglycoside selective molecularly imprinted polymer ensured selectivity in determinations made on yellow-fever vaccine and veterinary pharmaceutical formulations. The analytical results were statistically similar to those obtained with an HPLC-based fluorescence method (after chemical derivatization). The proposed method is a simple, sensitive and selective approach that does not involve the use of toxic reagents employed for chemical derivatization of aminoglycoside antibiotics.

Kanamycin detection at graphene quantum dot-decorated gold nanoparticles in organized medium after solid-phase extraction using an aminoglycoside imprinted polymer.

This is a description of the indirect determination of kanamycin sulfate though the photoluminescence enhancement of an aqueous dispersion of amino-functionalized graphene quantum dots (amino-GQDs) coupled with gold nanoparticles (AuNPs) in a cationic surfactant-rich medium. Specifically, cetyltrimethylammonium bromide (CTAB) was used as the cationic surfactant in our work. Previously, solid phase extraction with a cartridge packed with aminoglycoside-selective imprinted polymer ensured selectivity in kanamycin determination in yellow-fever vaccine and veterinary pharmaceutical samples. The proposed method has trace analysis capability and it is simple to perform as it does not involve the use of toxic reagents employed for chemical derivatization of aminoglycoside antibiotics.

Spherical gold nanoparticles and gold nanorods for the determination of gentamicin.

Gentamicin is an antibiotic indicated to treat mastitis in dairy cattle and for the treatment of bacterial resistance in the context of hospital infections. The effect caused by gentamicin on the optical properties of gold nanoparticles aqueous dispersions were used to develop quantitative methods to determine this antibiotic. Two different aqueous dispersions, one containing spherical Au nanoparticles (AuNPs) and the other containing Au nanorods (AuNRs), had their conditions adjusted to enable a stable and sensitive response towards gentamicin. The use of AuNPs, with measurement at 681nm of the rising coupling plasmon band, enabled a limit of detection (LOD) of 0.4ngmL-1 (0.02ng absolute LOD), ten times lower than the one achieved by measuring the decreasing of the longitudinal surface plasmon resonance band (at 662nm). The linear analytical response of AuNPs measured at 681nm did not require rationing of signal values to correct for linearity. Stability of the analytical response resulted in intermediary precision below 2%. No significant interference was imposed by excipients traditionally present in injectable solutions for veterinary use. Percent recoveries obtained in such formulations were between 94.5 and 98.2% regardless the existence of any difference in the proportion of the compounds known as gentamicin (C1, C1a and C2) in standard and in the samples. The method requires no derivatization with toxic reagents as usually is required in other spectroscopic approaches.

Study of the interaction of flavonoids with 3-mercaptopropionic acid modified CdTe quantum dots mediated by cetyltrimethyl ammonium bromide in aqueous medium.

Flavonoids are polyphenols that help the maintenance of health, aiding the prevention of diseases. In this work, CdTe QDs coated with 3-mercaptopropionic acid (3MPA), with an average size of 2.7nm, were used as photoluminescence probe for flavonoids in different conditions. The interaction between 14 flavonoids and QDs was evaluated in aqueous dispersions in the absence and in the presence of cetyltrimethylammonium bromide (CTAB). To establish a relationship between photoluminescence quenching and the concentration of flavonoids, the Stern-Volmer model was used. In the absence of CTAB, the linear ranges for quercetin, morin and rutin were from 5.0×10-6molL-1 to 6.0×10-5molL-1 and from 1.0×10-5molL-1 to 6.0×10-4molL-1 for kaempferol. The sensibility of the Stern-Volmer curves (Ks) indicated that quercetin interacts more strongly with the probe: Ks quercetin>Ks kaempferol>Ks rutin>Ks morin. The conjugation extension in the 3 rings, and the acidic hydroxyl groups (positions 3'and 4') in the B-ring enhanced the interaction with 3MPA-CdTe QDs. The other flavonoids do not interact with the probe at 10-5molL-1 level. In CTAB organized dispersions, Ks 3-hydroxyflavone>Ks 7-hydroxyflavone>Ks flavona>Ks rutin in the range from 1.0×10-6molL-1 to 1.2×10-5molL-1 for flavones and of 1.0×10-6molL-1 to 1.0×10-5molL-1 for rutin. Dynamic light scattering, conductometric measurements and microenvironment polarity studies were employed to elucidate the QDs-flavonoids interaction in systems containing CTAB. The quenching can be attributed to the preferential solubility of hydrophobic flavonoid in the palisade layer of the CTAB aggregates adsorbed on the surface of the 3MPA CdTe QDs.

Determination of enrofloxacin by room-temperature phosphorimetry after solid phase extraction on an acrylic polymer sorbent.

A phosphorimetric method was developed to enable the determination of enrofloxacin using photochemical derivatization which was used to both improve detection limits and to minimize the uncertainty of measurements. Phosphorescence was induced on cellulose containing TlNO(3). Absolute limit of detection at the ng range and linear analytical response over three orders of magnitude were achieved. A metrological study was made to obtain the combined uncertainty value and to identify that the precision was mainly affected by the changing of substrates when measuring the signal from each replicate. Pharmaceutical formulations containing enrofloxacin were successfully analyzed by the method and the results were similar to the ones achieved using a HPLC method. A solid phase extraction on an acrylic polymer was optimized to separate enrofloxacin from interferents such as diclofenac and other components from biological matrices, which allowed the successful use of the method in urine analysis.

Determination of lapachol in the presence of other naphthoquinones using 3MPA-CdTe quantum dots fluorescent probe.

3MPA-CdTe QDs in aqueous dispersion was used as a fluorescent probe for the determination of lapachol, a natural naphthoquinone found in plants of the Bignoniaceae family genus Tabebuia. Working QDs dispersions (4.5×10(-8) mol L(-1) of QDs) was prepared in aqueous media containing Tris-HCl buffer pH 7.4 and methanol (10% in volume). The excitation was made at 380 nm with signal measurement at 540 nm. To establish a relationship between fluorescence (corrected to inner filter effect) and concentration of lapachol, a Stern-Volmer model was used. The linear range obtained was from 1.0×10(-5) to 1.0×10(-4) mol L(-1). The limit of detection (x(b)-3s(b)) was 8.0×10(-6) mol L(-1). The 3MPA-CdTe QDs probe was tested in the determination of lapachol in urine, previously cleansed in an acrylic polymer. The average recovery was satisfactory.

Crystal structure and hydrogen bonding study of (10E)-2,2-dimethyl-3,4-dihydro-2H-benzo[g]chromene-5,10-dione 10-oxime derived from α-lapachone.

The compound (10E)-2,2-dimethyl-3,4-dihydro-2H-benzo[g]chromene-5,10-dione-10-oxime (1) was synthesized from a-lapachone and hydroxylamine chloride in alkaline medium. Single-crystals suitable for X-ray diffraction measurements were grown from an ethanol solution, and the crystal structure of the title molecule is reported for the first time. The title molecule was also characterized by ¹H- and ¹³C-NMR in CDCl3 solution, FTIR and MS. The crystal structure of 1 shows an E stereochemistry and dimers formed through classical hydrogen bonds.

Blitz do preservativo masculino e feminino: porte, acondicionamento r uso / Blitz of the masculine and feminine preservative: carry, keepes and use

Efetua a blitz do preservativo masculino e feminino: porte, acondicionamento e uso, em condutores e passageiros de automóveis e motos de passeio, circulando em vias públicas de Rio Branco - Acre. Estudo exploratório-descritivo desenvolvido junto a 1.011 sujeitos através de um formulário com questoes prioritariamente fechadas, com apresentaçäo de frequencia e percentual