Field-deployable, lyophilized cell-free biosensor for robust and selective detection of inorganic arsenic in complex...

Current on-site arsenic monitoring is hindered by cold-chain dependence and biosafety risks. We developed a field-deployable cell-free protein synthesis (CFPS) biosensor for the rapid, selective detection of toxic inorganic arsenic in seaweed matrices (Sargassum fusiforme and Porphyra sp.). An ArsR-regulated genetic circuit enables effective discrimination between inorganic and organic arsenic species. A tailored lyophilization strategy eliminated the need for ultra-low temperature storage, retaining ∼70% activity over four weeks at room temperature. Notably, freeze-drying serendipitously suppressed leaky expression, reducing background noise by 8-fold compared to liquid controls. Validated through spike-and-recovery tests in real seaweed extracts, this cold-chain-free, highly sensitive platform represents a significant advancement for decentralized food safety monitoring and environmental screening.