Correlation of surface-enhanced Raman spectroscopic fingerprints of kidney transplant recipient urine with kidney function parameters

Abstract

Routine monitoring of kidney transplant function is required for the standard care in post-transplantation management, including frequent measurements of serum creatinine with or without kidney biopsy. However, the invasiveness of these methods with potential for clinically significant complications makes them less than ideal. The objective of this study was to develop a non-invasive tool to monitor the kidney transplant function by using Surface-Enhanced Raman Spectroscopy (SERS). Urine and blood samples were collected from kidney transplant recipients after surgery. Silver nanoparticle-based SERS spectra of the urine were measured and evaluated using partial least squires (PLS) analysis. The SERS spectra were compared with conventional chemical markers of kidney transplant function to assess its predictive ability. A total of 110 kidney transplant recipients were included in this study. PLS results showed significant correlation with urine protein (R2 = 0.4660, p < 0.01), creatinine (R2 = 0.8106, p < 0.01), and urea (R2 = 0.7808, p < 0.01). Furthermore, the prediction of the blood markers of kidney transplant function using the urine SERS spectra was indicated by R2 = 0.7628 (p < 0.01) for serum creatinine and R2 = 0.6539 (p < 0.01) for blood urea nitrogen. This preliminary study suggested that the urine SERS spectral analysis could be used as a convenient method for rapid assessment of kidney transplant function.

Silver Nanoparticles-Based Substrate for Blood Serum Analysis under 785 nm Laser Excitation

“…Thus, the spectral bands and SERS characteristics of the serum obtained in the current study are similar to those reported in the studies of other authors. However, Huang et al and Feng et al [35,36] reported SERS bands at 702 cm -1 and 1383 cm -1 which were not observed in our study; these bands were assigned to the cytosine and CH3 domains respectively.…”

“…Silicon substrates were immersed in an Ag NP colloidal solution to allow Ag NPs to adhere to the surface. Huang et al and Zong et al [35,61] prepared colloids by adding NaOH solution to hydroxylamine hydrochloride solution and mixing the solution with AgNO3 aqueous solution at room temperature, until the formation of a milky-grey color. The Ag colloids were pelleted by centrifugation.…”

The Potential Applications of Raman Spectroscopy in Kidney Diseases

“…Second, SERS can distinguish multiple substances at the same time. Third, SERS may be a more convenient, less expensive, and faster tool than traditional techniques in clinical and biochemical laboratories [ 11 ]. On the other hand, the SERS technique has limitations in that (1) it requires intimate contact between the enhancing surface and the analyte, (2) the substrates degrade over time, resulting in a decrease in signal, (3) the substrates have limited selectivity for a given analyte, (4) the substrates have limited reusability, and (5) there are problems with homogeneity and reproducibility of the SERS signal within a substrate [ 12 ].…”

“…Research in the last decades has published several methods based on RS and SERS for the detection of urinary renal biomarkers, including urea peaks at 1004 cm −1 (symmetrical CN stretch) and 1161 cm −1 (attributed to NH 2 modes), creatinine peaks at 608 cm −1 (NCH 3 stretching, CO deformation and ring vibrations), 680 cm −1 (CNH 2 and CO stretching, ring vibrations), 846 cm −1 (CNH 2 deformation and ring vibrations), and 910 cm −1 (C–C–N stretching), glucose peak at 1128 cm −1 (C–O stretching), and protein peaks at 600, 850, 1060, and 1470 cm −1 (disulfide bonds, tyrosine, C–N bonds, and CH 2 and CH 3 angle bending) [ 23 , 24 , 25 , 26 ]. An overview of the most important findings of these studies is presented in Table 1 [ 11 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 ]. The applications of RS for the identification of uropathogens, urine crystals, and kidney stones are not included in this review.…”

“…Serum creatinine and urea are important biomarkers for diagnosing and monitoring kidney disease. Several studies have investigated the use of RS and SERS to detect these serum biomarkers rapidly and sensitively ( Table 2 ) [ 11 , 28 , 37 , 50 , 51 , 52 , 53 , 54 , 55 , 56 ].…”