Localised hydrogen peroxide sensing for reproductive health

Abstract

The production of reactive oxygen species (ROS) is known to affect the developmental competence of embryos. Hydrogen peroxide (H₂O₂) an important reactive oxygen species, is also known to causes DNA damage and defective sperm function. Current techniques require incubating a developing embryo with an organic fluorophore which is potentially hazardous for the embryo. What we need is a localised ROS sensor which does not require fluorophores in solution and hence will allow continuous monitoring of H₂O₂ production without adversely affect the development of the embryo. Here we report studies on such a fibre-based sensor for the detection of H₂O₂ that uses a surface-bound aryl boronate fluorophore carboxyperoxyfluor-1(CPF1). Optical fibres present a unique platform due to desirable characteristics as dip sensors in biological solutions. Attempts to functionalise the fibre tips using polyelectrolyte layers and (3-aminopropyl)triethoxysilane (APTES) coatings resulted in a limited signal and poor fluorescent response to H₂O₂ due to a low tip surface density of the fluorophore. To increase the surface density, CPF1 was integrated into a polymer matrix formed on the fibre tip by a UV-catalysed polymerisation process of acrylamide onto a methacrylate silane layer. The polyacrylamide containing CPF1 gave a much higher surface density than previous surface attachment methods and the sensor was found to effectively detect H₂O₂. Using this method, biologically relevant concentrations of H₂O₂ were detected, enabling remote sensing studies into ROS releases from embryos throughout early development.