Long‐Term and Continuous Plasmonic Oligonucleotide Monitoring Enabled by Regeneration Approach

Abstract The demand for continuous monitoring of biochemical markers for diagnostic purposes is increasing as it overcomes the limitations of traditional intermittent measurements. This study introduces a method for long‐term, continuous plasmonic biosensing of oligonucleotides with high temporal resolution. Our method is based on a regeneration‐based reversibility approach that ensures rapid reversibility in less than 1 minute, allowing the sensor to fully reset after each measurement. We investigated label‐free and AuNP enhancements for different dynamic ranges and sensitivities, achieving a limit of detection down to pM levels. We developed a regeneration‐based reversibility approach for continuous biosensing, optimizing buffer conditions using the Taguchi method to achieve rapid, consistent reversibility, ensuring reliable performance for long‐term monitoring. We detected oligonucleotides in buffered and complex solutions, including undiluted and unfiltered human serum, for up to 100 sampling cycles in a day. Moreover, we showed the long‐term stability of the sensor for monitoring capabilities in buffered solutions and human serum, with minimal signal value drift and excellent sensor reversibility for up to 9 days. Our method opens the door to new prospects in continuous biosensing by providing insights beyond intermittent measurements for numerous analytical and diagnostic applications.