Advances in Optical Nanoprobes for Bacterial Infection Diagnosis

Bacterial infections represent a major threat to global public health, and the rising prevalence of antibiotic resistance underscores the urgent need for early and accurate diagnosis. Optical imaging technologies, characterized by high sensitivity, spatiotemporal resolution, real-time monitoring capability, and noninvasiveness, have emerged as promising complementary and alternative approaches for bacterial infection diagnosis. This review comprehensively summarizes recent advances in optical nanoprobes for diagnosing bacterial infections. We first outline the structural and metabolic distinctions between bacteria and mammalian cells, along with the dynamic features of the infection microenvironment, which collectively provide a biological foundation for selective targeting and infection-specific imaging. We then detail the working principles, design strategies, and characteristics of various optical nanoprobes, including fluorescence, chemiluminescence, bioluminescence, photoacoustic, and Raman imaging probes, highlighting their applications in bacterial detection. Finally, we focus on in vitro diagnostic scenarios, categorizing and evaluating the performance, advantages, and challenges of optical nanoprobe-based technologies across clinical specimens such as blood, urine, and sputum. By offering a systematic perspective, this review aims to provide actionable insights for clinical translation and to promote the development of next-generation rapid diagnostic platforms for bacterial infections.