Magnetic Mesoporous Silica for Targeted Drug Delivery of Chloroquine: Synthesis, Characterization, and In Vitro Evaluation.

Malaria is a dangerous tropical disease, with high morbidity in developing countries. The responsible parasite has developed resistance to the existing drugs; therefore, new drug delivery systems are being studied to increase efficacy by targeting hemozoin, a parasite paramagnetic metabolite. Herein, magnetic mesoporous silica (magMCM) was synthesized using iron oxide particles dispersed in the silica structure for magnetically driven behavior. The X-ray diffractogram (XRD) and Mössbauer spectra show patterns corresponding to magnetite and maghemite. Furthermore, Mössbauer spectroscopy revealed superparamagnetic behavior, attributed to single magnetic domains in particles smaller than 10 nm. Even in the presence of iron oxide particles, the hexagonal structure of MCM is clearly identified in XRD (low-angle region) and the channels are visible in TEM images. The drug chloroquine (CQ) was encapsulated by incipient wetness impregnation (magMCM-CQ). The N2 adsorption-desorption isotherms show that CQ molecules were encapsulated in the pores, without completely filling the mesopores. BET surface area values were 630 m2 g-1 (magMCM) and 467 m2 g-1 (magMCM-CQ). Encapsulated CQ exhibited rapid delivery (99% in 3 h) in buffer medium and improved solubility compared to the non-encapsulated drug, attributed to CQ encapsulation in amorphous form. The biocompatibility assessment of magMCM, magMCM-CQ, and CQ against MRC5 non-tumoral lung fibroblasts using the MTT assay after 24 h revealed no toxicity associated with magMCM. On the other hand, the non-encapsulated CQ and magMCM-CQ exhibited comparable dose-response activity, indicating a similar cytotoxic effect.

The effect of argon and nitrogen ion implantation on nickel-titanium rotary instruments.

INTRODUCTION: This qualitative study investigated the effect of N(2)(+) and Ar(+) ion implantation on morphologic alterations and fatigue resistance in Pro Taper S1 NiTi (Dentsply-Maillefer, Ballaigues, Switzerland) rotary instruments. METHODS: Instruments were divided into three groups: N(2)(+) implanted, Ar(+) implanted, and unmodified control group. All instruments were used to prepare five curved canals in epoxy resin blocks with brushing motion. The instruments were examined in a scanning electron microscope (SEM) before use, after first use, and after the fifth use. A more demanding cyclic fatigue test was undertaken, submitting the instruments to 15-second periods of continuous rotation inside the curved canals without a brushing motion. Crack formation was analyzed with the SEM, and the number of 15-second periods required to fracture each instrument was recorded. RESULTS: No significant morphologic alterations were observed in the instruments after the preparation of five canals. Crack density was similar in all groups. In the subsequent cyclic fatigue test, instruments implanted with nitrogen performed worse than those implanted with argon and the control group. Fracture faces show differences in the fracture modes. CONCLUSIONS: Ar(+) implantation improved the performance of S1 files moderately, whereas nitrogen ion-implanted files performed worse in the fatigue test. A reduction in file performance seems to be caused by nitrogen diffusion in the grain boundaries, instead of the desired improvement caused by titanium nitride formation.

Electron probe microanalysis of in situ root caries / Microanálise por sonda eletrônica de cárie radicular in situ

Lesões de cárie radicular in situ foram investigadas por meio de microanálise por sonda eletrônica (MASE), utilizando-se imagens de elétrons retroespalhados (ERE) para identificar regiões alteradas, e espectrometria por dispersão de comprimento de onda (EDC) para avaliar quantitativamente Ca e P. Cinco indivíduos, habitantes de área abastecida com água fluoretada, receberam duas amostras de superfície radicular em suas bocas. Os segmentos foram fixados em próteses parciais por 3 meses, ficando sujeitos a livre acumulação de placa. Três amostras de raiz foram usadas como controle. Todos os corpos-de-prova (n = 9) desenvolveram lesões de cárie radicular, com grande variação entre indivíduos quanto à profundidade das lesões (100-700 µm). Verificou-se que a razão Ca:P foi constante tanto para amostras sãs (2,02 ± 0,1) quanto para as cariadas (2,06 ± 0,05). Os perfis de Ca e P e as imagens por ERE das lesões cariosas sugerem desmineralização subsuperficial (n = 7), bem como desmineralização superficial (n = 2). O conteúdo de Ca, em massa, variou de 29 a 21 por cento na camada superficial e de 21 a 15 por cento no corpo da lesão; o conteúdo de P variou de 14 a 11 por cento e de 10 a 6 por cento respectivamente. As características histopatológicas de lesões cariosas radiculares podem ser descritas por meio de MASE, resultando em informações qualitativas e quantitativas