Design and characterization of nanocarriers loaded with Levofloxacin for enhanced antimicrobial activity; physicochemical properties, in vitro release and oral acute toxicity

Inorganic and carbon based nanomaterials are widely used against several diseases, such as cancer, autoimmune diseases as well as fungi and bacteria colonization. In this work, Santa Barbara Amorphous mesoporous silica (SBA), Halloysite Nanotubes (HNTs) and Multiwalled Carbon Nanotubes (CNTs) were loaded with fluoroquinolone Levofloxacin (LVF) to be applied as antimicrobial agents. The prepared via adsorption nanocarriers were characterized by Fourier-Transformed Spectroscopy, Scanning Electron Microscopy as well as High Pressure liquid Chromatography. In vitro release studies were carried out using Simulated Body Fluid at 37oC and data analyzed by various kinetic models showing slow dissolution over 12-24 hours. Antimicrobial studies showed improved antibacterial activity against Escherichia coli, Enterococcus faecalis, Listeria monocytogenes, Staphylococcus aureus, and Staphylococcus epidermidis compared to neat nanomaterials. CNTs were found to be the most promising candidates for LVF delivery and they were chosen to be further studied for their acute oral toxicity and histopathological examination using C57/Black mice. Histological examination depicted that drug loading did not affect mice organs morphology as well as hepatocyte degeneration, central vein degeneration and parenchymal necrosis scores. To conclude, the prepared nanomaterials present significant characteristics and can act as antimicrobial drug carriers; CNTs found to be safe candidates when orally fed to mice.

Controlled Preparation and Characterization of Aspirin Surface Molecularly Imprinted Separating Medium Based on Halloysite Nanotubes / 分析化学

The molecularly imprinted separating medium with halloysite nanotubes as carrier, which were environmentally friendly natural silica substrate nano-materials, aspirin as template molecule and acrylamide as functional monomer was synthesized using reversible addition fragmentation chain transfer polymerization. The template molecule and monomer were bound to stable composite at 1: 2 using the method of ultraviolet spectroscopy combined with Lamber-Beer theory at molecular level. The morphology and adsorption capacity of imprinted material was studied with Fourier transform infrared spectrometer ( FT-IR ) , transmission electron microscope ( TEM) , static adsorption and selective adsorption. The experimental results showed that a good uniformity of imprinted layer with the thickness of 38 nm was coated steadily on the halloysite nanotubes surface. Compared with the conventional surface imprinted material and the material with silica gel as carrier, our molecularly imprinted material had the characteristics of high adsorption capacity and favorable imprinted effect. Its imprinted factor achieved to 3. 5. The molecularly imprinted material was applied for mimetic intestinal juice diffusion experiment. The experimental results indicated that the imprinted material release the aspirin for 12 h, which was 2 times for non imprinted material for only 6 h, demonstrating excellent drug release result, which provided basic data for potential applications of drug carrier.

Coexistence of halloysite and kaolinite: a study on the genesis of kaolin clays of Campo Alegre Basin, Santa Catarina State, Brazil

Kaolin at Campo Alegre Basin, Santa Catarina State, Brazil was formed from alteration of volcanic acid rocks. Halloysite clays dominate the clay fraction of the matrix of the kaolin body, whereas a poorly crystalline kaolinite is abundant in veins. Some primary blocky structures have high amounts of illite, in one mine, but in general, only low contents of illite-smectite, illite, chlorite-vermiculite, vermiculite and quartz were identified in the clay fraction of the samples. Toward the top of the mines, hematite and lepidocrocite appear in horizontal red and ochre colored levels and the amount of kaolinite increases compared to halloysite. The vertical zoning of alteration levels, the changes in mineralogy, the positive correlation between depth and Cation Exchange Capacity of the clays, the preservation of different types of rock textures in the kaolin bodies, the dominant tube morphology of the halloysite clays indicate a supergene genesis for the deposits. Criteria to distinguish between supergene and hypogene kaolin are discussed. Transmission Electron Microscopy of the cross sections of halloysite tubes showed polygonal forms that are ascribed to be transitional between kaolinite and halloysite. It is proposed that some of the kaolinite of these deposits be inherited from the dehydration of halloysite tubes.

O caolim da Bacia de Campo Alegre, Estado de Santa Catarina, Brasil, formou-se da alteração de rochas vulcânicas ácidas. A haloisita predomina na fração argila da matriz do corpo de caolim, enquanto a caolinita, de baixa cristalinidade, é abundante nos veios. Algumas estruturas em blocos, primários, têm altos teores de ilita em uma mina, mas no geral, somente foram identificadas, na fração argila das amostras, baixas quantidades de ilita-esmectita, ilita, clorita-vermiculita, vermiculita e quartzo. Em direção ao topo das minas aparecem hematita e lepidocrocita em níveis vermelhos e ocres e as quantidades de caolinita aumentam, se comparadas às de haloisita. O zoneamento vertical dos níveis de alteração, as mudanças mineralógicas, a correlação positiva entre profundidade e Capacidade de Troca de Cátions das argilas, a preservação de diferentes tipos de textura de rochas nos corpos de caolim e o predomínio da morfologia tubular da haloisita indicam uma origem supergênica para os depósitos. São discutidos critérios para distinguir entre caolins supergênicos e hipogênicos. A Microscopia Eletrônica de Transmissão das secções transversais dos tubos de haloisita mostrou formas poligonais que são atribuídas a transições entre caolinita e haloisita. Propõe-se que algumas das caolinitas destes depósitos sejam herdadas da desidratação de tubos de haloisita.