Raman spectroscopy in renal analysis: Technologies, applications, and advancements

The advantage of Raman spectroscopy (RS) in renal analysis lies in its capacity to non-invasively acquire label-free molecular vibrational fingerprint information from biological samples. It characterizes alterations in diverse biomolecules, including proteins, lipids, nucleic acids, urates, oxalates, and cytochromes, facilitating the detection of molecular and metabolic abnormalities prior to the manifestation of morphological changes. The review explains how RS deciphers the molecular characteristics of various kidney diseases without using dyes. Comparisons are drawn among surface-enhanced Raman spectroscopy (SERS), tip-enhanced Raman spectroscopy (TERS), confocal Raman microscopy (CRM), and coherent Raman techniques to elucidate their applications in molecular mapping of urine, blood, kidney tissue, and individual cells. We also summarize the Raman spectral features of diverse biological samples for the molecular diagnosis of kidney diseases, with attention to the role of advanced analytical methods, including multivariate statistics, machine learning, and deep learning, in spectral interpretation and disease classification. Coupled with high-throughput instrumentation, miniaturized platforms, and artificial intelligence, RS holds potential for precision diagnostics and clinical translation in nephrology.