A Stimuli-Responsive Biosensor of Glucose on Layer-by-Layer Films Assembled through Specific Lectin-Glycoenzyme Recognition

The research on intelligent bioelectrocatalysis based on stimuli-responsive materials or interfaces is of great significance for biosensors and other bioelectronic devices. In the present work, lectin protein concanavalin A (Con A) and glycoenzyme glucose oxidase (GOD) were assembled into {Con A/GOD}n layer-by-layer (LbL) films by taking advantage of the biospecific lectin-glycoenzyme affinity between them. These film electrodes possess stimuli-responsive properties toward electroactive probes such as ferrocenedicarboxylic acid (Fc(COOH)2) by modulating the surrounding pH. The CV peak currents of Fc(COOH)2 were quite large at pH 4.0 but significantly suppressed at pH 8.0, demonstrating reversible stimuli-responsive on-off behavior. The mechanism of stimuli-responsive property of the films was explored by comparative experiments and attributed to the different electrostatic interaction between the films and the probes at different pH. This stimuli-responsive films could be used to realize active/inactive electrocatalytic oxidation of glucose by GOD in the films and mediated by Fc(COOH)2 in solution, which may establish a foundation for fabricating novel stimuli-responsive electrochemical biosensors based on bioelectrocatalysis with immobilized enzymes

A Stimuli-Responsive Biosensor of Glucose on Layer-by-Layer Films Assembled through Specific Lectin-Glycoenzyme Recognition

The research on intelligent bioelectrocatalysis based on stimuli-responsive materials or interfaces is of great significance for biosensors and other bioelectronic devices. In the present work, lectin protein concanavalin A (Con A) and glycoenzyme glucose oxidase (GOD) were assembled into {Con A/GOD}n layer-by-layer (LbL) films by taking advantage of the biospecific lectin-glycoenzyme affinity between them. These film electrodes possess stimuli-responsive properties toward electroactive probes such as ferrocenedicarboxylic acid (Fc(COOH)2) by modulating the surrounding pH. The CV peak currents of Fc(COOH)2 were quite large at pH 4.0 but significantly suppressed at pH 8.0, demonstrating reversible stimuli-responsive on-off behavior. The mechanism of stimuli-responsive property of the films was explored by comparative experiments and attributed to the different electrostatic interaction between the films and the probes at different pH. This stimuli-responsive films could be used to realize active/inactive electrocatalytic oxidation of glucose by GOD in the films and mediated by Fc(COOH)2 in solution, which may establish a foundation for fabricating novel stimuli-responsive electrochemical biosensors based on bioelectrocatalysis with immobilized enzymes

Development of novel tools for assisted reproductive technologies based on electrically switchable surfaces

A variety of stimuli have been explored in the last few decades to develop dynamic interfaces with biotechnological and biomedical applications, such as biosensors, point of care devices, cell behaviour control and tissue engineering. In this work, the use of an electrical stimulus was explored for the development of a smart switchable surface with the ability to, in an on-demand fashion, expose and conceal progesterone - an ovarian steroid hormone which plays a crucial role as a modulator of sperm function. In this system, an electric potential drives a conformational change in the surface bound peptide moiety with fast response time. Focus was given to the design of a device that could be used in assisted reproductive treatments and grown into a commercially marketable product. Whilst being developed for assessment of sperm quality and fertilizing potential, the application of this system can be widely extended as this approach can be applied to other relevant antigen-antibody systems, which have so far only been evaluated in static conditions. Fabrication of a micropatterned surface was performed and a novel method for orthogonal functionalisation of gold and glass was developed, where gold was functionalised with a polyethylene glycol thiol self-assembled monolayer (SAM) and glass was functionalised with a covalently bound poly-d-lysine layer for sperm cell attachment. In addition to the investigations on SAMs and mixed SAMs formed on gold, silicon and glass substrates, studies with fluospheres were also undertaken. These tools are aimed to be used for further studies with cells, namely the investigation of their response in terms of Ca2+ signalling, a key player in the regulation of sperm function