Regenerable photonic aptasensor for detection of bacterial spores with stacks of GaAs–AlGaAs nanoheterostructures†

The reusability of biosensors is a crucial advancement in environmental monitoring and laboratory efficiency. In this study, we introduce the concept of a regenerable aptasensor based on digital photocorrosion (DIP) of a GaAs–AlGaAs biochip, designed with alternating nanolayers of GaAs (12 nm) and AlGaAs (10 nm). Each GaAs–AlGaAs bilayer acts as an independent sensing unit. By employing a specific thiolated aptamer, we achieve efficient detection of Bacillus thuringiensis spp. kurstaki spores. The interaction between the thiolated aptamers with the targeted spores leads to the formation of aptamer-spore hybrids, which bind to the GaAs surface. The GaAs–AlGaAs nanoheterostructure biochip supports multiple biosensing cycles. After consumption of the first GaAs–AlGaAs bilayer, a simple regeneration step with a high ionic strength buffer releases the bound spores and prepares subsequent nanolayers of the same biochip for reuse. The capability to regenerate and reuse individual nanolayers presents a novel and practical solution for reducing biosensor waste while improving operational efficiency. We further explore the conditions necessary for sustainable DIP operation in biochips containing multiple GaAs–AlGaAs nanolayer pairs, ensuring reliable performance over numerous biosensing cycles. Our findings establish a cost-effective and durable biosensing platform. This work marks a significant step toward quasi-autonomous biosensing technologies, paving the way for cost-effective and robust reusable biosensors suitable for remote and field applications.