pH-responsive ratiometric photoacoustic imaging of polyaniline nanoparticle-coated needle for targeted cancer biopsy

Cancer microenvironment exhibits lower pH compared to healthy tissues, a characteristic which can be exploited using a pH-responsive needle to increase the accuracy of cancer biopsy. A needle, coated with pH-responsive polyaniline (PANI) nanoparticles (PANI-needle), is developed for the minimally invasive and quantitative pH analysis of tissue based on ratiometric photoacoustic (PA) imaging. The ratiometric PA signal from the PANIneedle within the 850-700 nm wavelength range shows a linear response as pH changes from 7.5 to 6.5. Owing to the high surface area of nanostructured PANI, the PA signal of PANI-needle exhibits a fast and reversible response of less than a few seconds. In a tissue-mimicking hydrogel phantom composed of two regions with different pH, PA ratios of PANI-needle successfully differentiate the local pH. The PANI-needle coupled with ultrasound-guided PA imaging is a promising technology for detection of malignant tissue through quantitative pH analysis during needle biopsy.

Automated summary

The cancer microenvironment has a lower pH than healthy tissues, which can be exploited for more accurate cancer biopsy. A needle coated with pH-responsive PANI nanoparticles is developed for minimally invasive and quantitative pH analysis using ratiometric PA imaging. The PANI-needle shows a linear response in the 850-700 nm wavelength range as pH changes from 7.5 to 6.5. Its high surface area allows for fast and reversible response in just a few seconds. The PANI-needle successfully differentiates local pH in a hydrogel phantom with different pH regions, making it a promising technology for malignant tissue detection during needle biopsy through quantitative pH analysis guided by ultrasound PA imaging.