Terahertz spectra of proteinuria and non-proteinuria

Abstract

In clinical practice, proteinuria detection is of great significance in the diagnosis of kidney diseases. Dipstick analysis is used in most outpatient settings to semi-quantitatively measure the urine protein concentration. However, this method has limitations for protein detection, and alkaline urine or hematuria will cause false positive results. Recently, terahertz time-domain spectroscopy (THz-TDS) with strong hydrogen bonding sensitivity has been proven to be able to distinguish different types of biological solutions, which means that protein molecules in urine may have different THz spectral characteristics. In this study, we performed a preliminary clinical study investigating the terahertz spectra of 20 fresh urine samples (non-proteinuria and proteinuria). The results showed that the concentration of urine protein was positively correlated with the absorption of THz spectra at 0.5–1.2 THz. At 1.0 THz, the pH values (6, 7, 8, and 9) had no significant effect on the THz absorption spectra of urine proteins. The terahertz absorption of proteins with a high molecular weight (albumin) was greater than that of proteins with a low molecular weight (β2-microglobulin) at the same concentration. Overall, THz-TDS spectroscopy for the qualitative detection of proteinuria is not affected by pH and has the potential to discriminate between albumin and β2-microglobulin in urine.

Urinary Metabolic Biomarker Profiling for Cancer Diagnosis by Terahertz Spectroscopy: Review and Perspective

“…Xue et al compared the absorption spectra of proteinuria and non-proteinuria [49]. They first measured and calculated the THz absorption coefficient for water and urine samples (Figure 5a).…”

“…The introduction of metamaterials (MM) in the THz band has opened additional possibilities in the last ten years for new materials design that can sense bioactive substances such as proteins and nucleic acids [41][42][43][44][45][46][47][48]. THz radiation was already used for the protein concentration analysis considering non-proteinuria and proteinuria, which can indicate certain diseases, such as kidney disease [49]. Furthermore, glucose content in urine linked to diabetes [45] was also determined by THz radiation as well as nitriles in urine vapours during chemotherapy [50].…”

Terahertz Radiation Modulates Neuronal Morphology and Dynamics Properties

“…Terahertz waves have photonic and electronic properties, their photon energy is low, they do not ionize matter, and they have high penetration and fingerprint spectral properties [ 8 , 9 ]. Therefore, terahertz waves are widely used in security detection, superconducting materials, food, and medicine [ 10 , 11 , 12 , 13 ]. In addition, because many energy level jumps for macromolecular interactions are in the terahertz band, terahertz waves have a wide range of applications in biomedical imaging [ 14 , 15 ].…”