The project ‘Hacking Photosynthesis: Biosensor for Herbicides and Beyond’ (B-FHAB) aims to develop a novel biosensor platform for detecting herbicides in water, addressing significant challenges in environmental monitoring. With the rising global population and increase in agrochemical activities, herbicide contamination in water sources has become a pressing issue. Traditional detection methods, such as liquid chromatography and mass spectrometry, are costly and complex. B-FHAB seeks to create an accessible biosensor that detects herbicides rapidly and with ease, thereby enhancing water monitoring frequency, safety and public health.
The proposed biosensor employs engineered photosynthetic proteins as biological recognition elements. These proteins serve a dual purpose: binding herbicides and transducing these binding events into an electrochemical signal. These signals are connected to an electrode via a redox polymer that also serves as a protein-immobilization matrix, preserving their function during prolonged and desiccated storage, and during continuous use. Herbicides inhibit the photoproteins' activities in a concentration-dependent manner, enabling the quantification of herbicide levels in a sample by monitoring changes in the electrochemical signal. Several challenges hinder the implementation of this accessible biosensing platform, including detection of herbicides below the EU's maximum residue limits, differentiating between various herbicide compounds, expanding the range of detectable compounds to cover the broad range of applied herbicides, and increasing the number of herbicide residues that can be detected on a single chip.
To overcome challenges in developing a herbicide biosensor, the project focuses on four primary objectives:
Objective 1 seeks to enhance sensitivity and selectivity of the biosensor through mutagenesis at the herbicide binding site of the photoprotein. This involves combining favorable point mutations into double or triple mutants, screening them in silico, constructing them in a wet-lab, and testing them using electrochemical means.
Objective 2 seeks to shift protein-herbicide binding from competitive to allosteric inhibition by taking mutagenesis out of the natural substrate-binding pocket and into a distally gating herbicide binding site, obviating inherent structural limitations in the current sensing modality. This will be accomplished via expansive computationally guided mutagenesis of residues at the periphery of the herbicide binding pocket.
Objective 3 aims to expand the biosensor application by docking large libraries of compounds to the photoprotein to discover novel biosensor targets that are outside of the range of our typical triazine-type herbicide pool.
Objective 4 seeks to demonstrate multi-compound sensing on a single test strip, by carefully engineering spectral and electronic triggers that activate herbicide specific detection.
The scientific impact of the B-FHAB project includes the validation of computational methods for guiding complex protein mutagenesis, thereby saving time and resources in experimental workflows. Economically, the project aims to provide cost-effective solutions for herbicide monitoring, driving growth in the environmental monitoring sector and creating new opportunities. Strategically, the project aligns with global environmental protection efforts and regulatory frameworks, contributing to sustainable development goals, particularly in clean water and responsible consumption.
