Chitosan, which is derived from a deacetylation reaction of chitin, has attractive antimicrobial activity. However, chitosan applications as a biocide are only effective in acidic medium due to its low solubility in neutral and basic conditions. Also, the positive charges carried by the protonated amine groups of chitosan (in acidic conditions) that are the driving force for its solubilization are also associated with its antimicrobial activity. Therefore, chemical modifications of chitosan are required to enhance its solubility and broaden the spectrum of its applications, including as biocide. Quaternization on the nitrogen atom of chitosan is the most used route to render water-soluble chitosan-derivatives, especially at physiological pH conditions. Recent reports in the literature demonstrate that such chitosan-derivatives present excellent antimicrobial activity due to permanent positive charge on nitrogen atoms side-bonded to the polymer backbone. This review presents some relevant work regarding the use of quaternized chitosan-derivatives obtained by different synthetic paths in applications as antimicrobial agents.

N-Trimethyl chitosan (TMC), an antibacterial agent, and heparin (HP), an antiadhesive biopolymer, were alternately deposited on modified polystyrene films, as substrates, to built antiadhesive and antibacterial multilayer films. The properties of the multilayer films were investigated by Fourier transform infrared spectroscopy, atomic force microscopy, scanning electron microscopy, and Kelvin force microscopy. In vitro studies of controlled release of HP were evaluated in simulated intestinal fluid and simulated gastric fluid. The initial adhesion test of E. coli on multilayer films surface showed effective antiadhesive properties. The in vitro antibacterial test indicated that the multilayer films of TMC/HP based on TMC80 can kill the E. coli bacteria. Therefore, antiadhesive and antibacterial multilayer films may have good potential for coatings and surface modification of biomedical applications.

High-risk human papillomavirus (HPV) infection, mainly with HPV16 type, has been increasingly considered as an important etiologic factor in head and neck cancers. Detection of HPV16 is therefore crucial for these types of cancer, but clinical tests are not performed routinely in public health systems owing to the high cost and limitations of the existing tests. In this article, we report on a potentially low-cost genosensor capable of detecting low concentrations of HPV16 in buffer samples and distinguishing, with high accuracy, head and neck cancer cell lines according to their HPV16 status. The genosensor consisted of a microfluidic device that had an active layer of a HPV16 capture DNA probe (cpHPV16) deposited onto a layer-by-layer film of chitosan and chondroitin sulfate. Impedance spectroscopy was the principle of detection utilized, leading to a limit of detection of 10.5 pM for complementary ssDNA HPV16 oligos (ssHPV16). The genosensor was also able to distinguish among HPV16 + and HPV16 − cell lines, using the multidimensional projection technique interactive document mapping. Hybridization between the ssHPV16 oligos and cpHPV16 probe was confirmed with polarization-modulated infrared reflection-absorption spectroscopy, where PO 2 and amide I and amide II bands from adenine and thymine were monitored. The electrical response could be modeled as resulting from an adsorption process represented in a Freundlich model. Because the fabrication procedures of the microfluidic devices and genosensors and the data collection and analysis can be implemented at low cost, the results presented here amount to a demonstration of possible routine screening for HPV infections.

No abstract

No abstract