Development of sarcosine quantification in urine based on enzyme-coupled colorimetric method for prostate cancer diagnosis

Circulating metabolite biomarkers: a game changer in the human prostate cancer diagnosis

PURPOSE

Prostate cancer (PCa) is the second most commonly diagnosed cancer in men in Western and Asian countries. Serum prostate-specific antigen (PSA) test has been the routine diagnostic method despite the tremendous research in diagnostic markers for early detection of PCa. A shift towards a promising and potential biomarker for PCa detection is through metabolomic profiling of biofluids, particularly the blood and urine samples. Finding reliable, routinely usable circulating metabolite biomarkers may not be a distant reality.

METHODS

We performed a PubMed-based literature search of metabolite biomarkers in blood and urine for the early detection of prostate cancer. The timeline of these searches was limited between 2007 and 2022 and the following keywords were used: 'metabolomics', 'liquid biopsy', 'circulating metabolites', 'serum metabolite', 'plasma metabolite', and 'urine metabolite' with respect to 'prostate cancer'. We focussed only on diagnosis-based studies with only the subject-relevant articles published in the English language and excluded all of the other irrelevant publications that included prostate tissue biomarkers and cell line biomarkers.

RESULTS

We have consolidated all the blood and urine-based potential metabolite candidates in individual as well as panels, including lipid classes, fatty acids, amino acids, and volatile organic compounds which may become useful for PCa diagnosis.

CONCLUSION

All these metabolome findings unveil the impact of different dimensions of PCa development, giving a promising strategy to diagnose the disease since suspected individuals can be subjected to repeated and largescale blood and urine testing.

Iron doped graphitic carbon nitride with peroxidase like activity for colorimetric detection of sarcosine and hydrogen peroxide

The successful synthesis is reported of Mn, Fe, Co, Ni, Cu-doped g-C₃N₄ nanoflakes via a simple one-step pyrolysis method, respectively. Among them, the Fe-doped g-C₃N₄ nanoflakes exhibited the highest peroxidase-like activity, which can be used for colorimetric detection of hydrogen peroxide (H₂O₂) and sarcosine (SA), within the detection ranges of 2-100 μM and 10-500 μM and detection limits of 1.8 μM and 8.6 μM, respectively. The catalytic mechanism of the Fe-doped g-C₃N₄ nanoflake was also explored and verified the generation of hydroxyl radical (•OH) through fluorescence method. It is believed that the Fe-doped g-C₃N₄ nanoflakes as enzyme mimics will greatly promote the practical applications in a variety of fields in the future including biomedical science, environmental governance, antibacterial agent, and bioimaging due to their extraordinary catalytic performance and stability. Graphical abstract.

A Rapid Method for the Detection of Sarcosine Using SPIONs/Au/CS/SOX/NPs for Prostate Cancer Sensing

BACKGROUND

Sarcosine is an amino acid that is formed by methylation of glycine and is present in trace amounts in the body. Increased sarcosine concentrations in blood plasma and urine are manifested in sarcosinemia and in some other diseases such as prostate cancer. For this purpose, sarcosine detection using the nanomedicine approach was proposed. In this study, we have prepared superparamagnetic iron oxide nanoparticles (SPIONs) with different modified surface area. Nanoparticles (NPs) were modified by chitosan (CS), and sarcosine oxidase (SOX). SPIONs without any modification were taken as controls. Methods and Results: The obtained NPs were characterized by physicochemical methods. The size of the NPs determined by the dynamic light scattering method was as follows: SPIONs/Au/NPs (100⁻300 nm), SPIONs/Au/CS/NPs (300⁻700 nm), and SPIONs/Au/CS/SOX/NPs (600⁻1500 nm). The amount of CS deposited on the NP surface was found to be 48 mg/mL for SPIONs/Au/CS/NPs and 39 mg/mL for SPIONs/Au/CS/SOX/NPs, and repeatability varied around 10%. Pseudo-peroxidase activity of NPs was verified using sarcosine, horseradish peroxidase (HRP) and 3,3',5,5'-tetramethylbenzidine (TMB) as a substrate. For TMB, all NPs tested evinced substantial pseudo-peroxidase activity at 650 nm. The concentration of SPIONs/Au/CS/SOX/NPs in the reaction mixture was optimized to 0⁻40 mg/mL. Trinder reaction for sarcosine detection was set up at 510 nm at an optimal reaction temperature of 37 °C and pH 8.0. The course of the reaction was linear for 150 min. The smallest amount of NPs that was able to detect sarcosine was 0.2 mg/well (200 µL of total volume) with the linear dependence y = 0.0011x - 0.0001 and the correlation coefficient r = 0.9992, relative standard deviation (RSD) 6.35%, limit of detection (LOD) 5 µM. The suggested method was further validated for artificial urine analysis (r = 0.99, RSD 21.35%, LOD 18 µM). The calculation between the detected and applied concentrations showed a high correlation coefficient (r = 0.99). NPs were tested for toxicity and no significant growth inhibition was observed in any model system (S. cerevisiae, S. aureus, E. coli). The hemolytic activity of the prepared NPs was similar to that of the phosphate buffered saline (PBS) control. The reaction system was further tested on real urine specimens. Conclusion: The proposed detection system allows the analysis of sarcosine at micromolar concentrations and to monitor changes in its levels as a potential prostate cancer marker. The whole system is suitable for low-cost miniaturization and point-of-care testing technology and diagnostic systems. This system is simple, inexpensive, and convenient for screening tests and telemedicine applications.

Simultaneous determination of sarcosine and its related metabolites by gas chromatography-tandem mass spectrometry for prostate cancer diagnosis

Shortly after sarcosine was delineated as a potential biomarker for prostate cancer in 2009, a variety of analytical methods for clinical application were developed. Moreover, higher uptake of glycine in the mitochondria also played a role in cancer proliferation. A major constraint in the accurate quantification of sarcosine was the interference of the two isomers, α-alanine and β-alanine, using chromatographic separation techniques. Accordingly, we aimed to develop an analytical method for determining sarcosine and its related metabolites (α- and β-alanine, glycine and creatinine) under the same conditions by gas chromatography-tandem mass spectrometry (GC-MS/MS). BSTFA + 1 % TMCS was used for silylation, and GC-MS/MS conditions were optimized for the target analytes. The unique transition ions of sarcosine, α- and β-alanine, glycine and creatinine set up in MRM acquisition were m/z 116 → 73, 190 → 147, 176 → 147, 176 → 147 and 100 → 73, respectively. This newly developed method was successfully validated to apply in clinical settings with low limits of detection (0.01 - 0.03 µg•mL-1), high correlations (R2 > 0.99), great accuracy (88 - 110 % recovery), and notable precision (RSD < 10 %). All TMS derivatives were > 80 % stable for up to 2 h after derivatization and analyzing during this period promises to achieve an accurate result. Monitoring the five-substance profile could enhance prospects for early diagnosis of prostate cancer.