From selection to sensing: recent advances in aptamer-based fluorescent and colorimetric platforms for illicit drug monitoring

Driven by the proliferation of opioids and new psychoactive substances, the global crisis of illicit drug abuse underscores an urgent need for rapid and portable detection tools for law enforcement and public health interventions. Recent advancements in aptamer-based fluorescent and colorimetric sensors offer a transformative alternative, combining their high sensitivity, specificity, and adaptability for on-site applications. This review critically highlights the aptamer selection advances for illicit drug small molecules, including breakthroughs in high-affinity molecular recognition and addressing screening challenges. Furthermore, the emerging optical sensing platforms and their innovations in signal transduction mechanisms and actual sample applications were highlighted. We also discuss emerging trends and future directions in aptamer-based optical sensors for illicit drug detection. The significance of this review lies in advancing the development of rapid and reliable sensing technologies for illicit drug detection, providing potential tools for roadside drug screening, border security, and forensic investigations.