Strategy of red blood cells immobilisation onto a gold electrode: Characterization by electrochemical impedance spectroscopy and quartz crystal microbalance

Bifunctionalized Redox-Responsive Layers Prepared from a Thiolactone Copolymer

The development of multifunctional surfaces is of general interest for the fabrication of biomedical, catalytic, microfluidic or biosensing devices. Herein, we report on the preparation of copolymer layers immobilized on gold surface and showing both free thiol and amino groups. These layers are produced by aminolysis of a thiolactone-based copolymer in the presence of a diamine, according to a one-step procedure. The free thiol and amino groups present in the modified copolymer layers can be successfully functionalized with respectively thiolated and carboxylic derivatives, in order to produce bifunctionalized surfaces. In addition, we show that the grafted thiolated derivative can be released by cleavage of the disulfide bond under mild reducing conditions. On the other hand, a side cross-linking reaction occurring during the grafting process and resulting in the formation of copolymer aggregates on the metal surface is evidenced. The methodology developed for the preparation of these bifunctionalized redox-responsive layers should be advantageously used to produce bioactive surfaces with drug loading/release properties.

Protein retention on plasma-treated hierarchical nanoscale gold-silver platform

Dense arrays of gold-supported silver nanowires of about 100 nm in diameter grown directly in the channels of nanoporous aluminium oxide membrane were fabricated and tested as a novel platform for the immobilization and retention of BSA proteins in the microbial-protective environments. Additional treatment of the silver nanowires using low-temperature plasmas in the inductively-coupled plasma reactor and an atmospheric-pressure plasma jet have demonstrated that the morphology of the nanowire array can be controlled and the amount of the retained protein may be increased due to the plasma effect. A combination of the neutral gold sublayer with the antimicrobial properties of silver nanowires could significantly enhance the efficiency of the platforms used in various biotechnological processes.

Plasma treatment for next-generation nanobiointerfaces

Energy deficiency, global poverty, chronic hunger, chronic diseases, and environment conservation are among the major problems threatening the whole mankind. Nanostructure-based technologies could be a possible solution. Such techniques are now used for the production of many vitally important products including cultured and fermented food, antibiotics, various medicines, and biofuels. On the other hand, the nanostructure-based technologies still demonstrate low efficiency and controllability, and thus still are not capable to decisively address the global problems. Furthermore, future technologies should ensure lowest possible environmental impact by implementing green production principles. One of the most promising approaches to address these challenges are the sophisticatedly engineered biointerfaces. Here, the authors briefly evaluate the potential of the plasma-based techniques for the fabrication of complex biointerfaces. The authors consider mainly the atmospheric and inductively coupled plasma environments and show several examples of the artificial plasma-created biointerfaces, which can be used for the biotechnological and medical processes, as well as for the drug delivery devices, fluidised bed bioreactors, catalytic reactors, and others. A special attention is paid to the plasma-based treatment and processing of the biointerfaces formed by arrays of carbon nanotubes and graphene flakes.

Polythiolactone-based redox-responsive layers for the reversible release of functional molecules

The development of thin macromolecular layers with incorporated disulfide bonds that can be disrupted and formed again under redox stimulation is of general interest for drug release applications, because such layers can provide rapid and reversible responses to specific biological systems and signals. However, the preparation of such layers from polythiols remains difficult, because of the fast oxidation of thiol groups in ambient conditions. Here we propose water-soluble thiolactone-containing copolymers as stable precursors containing protected thiol groups, allowing us to produce on demand polythiol layers on gold substrates in the presence of amine derivatives. Electrochemical, water contact angle, X-ray photoelectron spectroscopy, and X-ray reflectometry measurements evidence the formation of uniform copolymer layers containing both anchored and free thiol groups. The number of free thiols increases with the content of thiolactone units in the copolymers. In a second step, a thiolated dye, used as a model drug, was successfully grafted on the free thiol groups through disulfide bonds using mild oxidizing conditions, as proved by fluorescence and quartz crystal microbalance measurements. Finally, the reversible release/regrafting of the dye under redox stimulation is demonstrated.