pH- and nitroreductase-responsive SERS acupuncture needles enabling ratiometric detection in both solution and tissue environments

The detection of pH and nitroreductase (NTR) in tissues plays a crucial role in assessing microenvironmental acid-base balance and diagnosing tumor hypoxia. However, most methods currently used for detecting substances in tissue samples require sample grinding for extraction, which compromises tissue integrity. Traditional Chinese medicine acupuncture needles offer a potential approach as they can be directly inserted into tissues, eliminating the need for destructive pretreatment procedures. In this work, we developed a novel acupuncture needles @ gold nanoparticles @ 5-mercapto-2-nitrobenzoic acid (ANs@Au NPs@MNBA) probe based on surface-enhanced Raman spectroscopy (SERS) technology, enabling simultaneous ratiometric detection of pH and NTR in both solution and intact tissue samples. The probe demonstrated excellent linear responses within pH ranges from 4.75 to 7.25 and NTR concentrations from 0 to 20.0 μg/mL. This innovative approach provides valuable insights into how tissue acid-base balance and NTR levels influence physiological functions and disease progression.