• Luminescent
• Micro-algae
• Miniemulsion polymerization
• Photophysics
• Polystyrene-based nanoparticles

Phosphorus is a main nutrient for all living species but inefficiently used, leading to environmental issues. Microalgae store phosphorus as polyphosphates, presenting a promising avenue for phosphorus recycling. Understanding the regulatory mechanisms of interplay between photosynthesis and polyphosphate production in algae would be essential for optimizing their biotechnological applications. This project aims to explore a novel platform of luminescent nanosensors to unravel this interplay. Not documented in current literature, they are localizable and possess a prolonged luminescence lifetime and they have been designed to interrogate several key analytes of photosynthetic organisms.

Three distinct methods were investigated for formulating these nanosensors using polystyrene-based nanoparticles. The first method employed commercially available carboxylate surface derivatized polystyrene nanoparticles loaded with different sensing probes via solvent penetration and subsequent trapping upon solvent removal. The second method involved nanoprecipitation, where sensing probes and a polystyrene copolymer were coprecipitated from a water-miscible organic solvent upon dilution in water. The third approach utilized miniemulsion polymerization to disperse sensing probes within styrene, which polymerized into nanoparticles under increased temperature. Experimental optimizations were conducted to evaluate these systems with five different sensing probes: PtOEP, NileRed, Methylene Blue, Gold Nanoclusters, and [L1Eu(hfac)3] complex. Comprehensive structural and functional characterization using various instrumental analysis methods preceded before their implementation in photosynthetic organisms. At the end, the internalization of promising nanoparticles into algae was investigated following thorough characterization. This research provides valuable insights into the potential applications of advanced nanosensors in understanding and enhancing the metabolic processes of microalgae.