Simultaneous determination of cellular adenosine nucleotides, malondialdehyde, and uric acid using HPLC

A ratiometric molecular imprinted electrochemiluminescence sensor based on enhanced luminescence of CdSe@ZnS quantum dots by MXene@NaAsc for detecting uric acid

An unlabeled ratiometric molecular imprinted electrochemiluminescence sensor was developed for the determination of trace uric acid, based on MXene@NaAsc nanocomposites, CdSe@ZnS quantum dots and molecularly imprinted polymer composites modified glass carbon electrode. MXene@NaAsc stably enhanced the electron transfer and improved electrochemiluminescence intensity by acting as a base platform and signal amplifier for CdSe@ZnS quantum dots. Specific molecular imprinting cavities based on electropolymerization with o-phenylenediamine were formed to specifically identify uric acid. Combining the good sensitivity of electrochemiluminescence and the excellent selectivity of molecularly imprinted polymer, the ratio of optical signal and electrical signal was used as a comprehensive signal to achieve the detection of uric acid. Based on this, uric acid was detected in the range from 1 × 10-10 to 1 × 10-4 mol/L with the LOD of 18.13 pmol/L (S/N = 3). The developed sensor with easy preparation, great selectivity and excellent sensitivity could successfully detect uric acid in human serum.

Enzymatic and Non-Enzymatic Uric Acid Electrochemical Biosensors: A Review

In recent years, the development of electrochemical biosensors for uric acid has made great achievements. Firstly, uric acid electrochemical biosensors were classified according to their reaction mechanism. Then, the reaction mechanism of the uric acid sensor and the application of nano-modified materials were deeply analyzed from the perspective of non-enzyme and enzymes. In this paper, the catalytic oxidation capacity, enzyme adsorption effect, conductivity, robustness, detection range, and detection limit of uric acid sensors were discussed and compared. Finally, the advantages of acid-sensitive electrochemical biosensors were summarized, and the constructive recommendations were proposed for improving the deficiencies of acid biosensors. The potential for further development in this area was also discussed.

Uric acid en route to gout

Gout and hyperuricemia (HU) have generated immense attention due to increased prevalence. Gout is a multifactorial metabolic and inflammatory disease that occurs when increased uric acid (UA) induce HU resulting in monosodium urate (MSU) crystal deposition in joints. However, gout pathogenesis does not always involve these events and HU does not always cause a gout flare. Treatment with UA-lowering therapeutics may not prevent or reduce the incidence of gout flare or gout-associated comorbidities. UA exhibits both pro- and anti-inflammation functions in gout pathogenesis. HU and gout share mechanistic and metabolic connections at a systematic level, as shown by studies on associated comorbidities. Recent studies on the interplay between UA, HU, MSU and gout as well as the development of HU and gout in association with metabolic syndromes, non-alcoholic fatty liver disease (NAFLD), and cardiovascular, renal and cerebrovascular diseases are discussed. This review examines current and potential therapeutic regimens and illuminates the journey from disrupted UA to gout.

Development of Optical-Based Molecularly Imprinted Nanosensors for Adenosine Detection

Adenosine nucleoside is an important molecule in human physiology. The levels of adenosine nucleoside in urine and plasma are directly or indirectly related to diseases such as neurodegenerative diseases and cancer. In the present study, adenosine-imprinted and non-imprinted poly(2-hydroxyethyl methacrylate-methacrylic acid) (poly(HEMA-MAA)) surface plasmon resonance (SPR) nanosensors were prepared for the determination of adenosine nucleoside. First, MAA/adenosine pre-polymerization complexes were prepared at different molar ratios using adenosine as a template molecule and methacrylic acid (MAA) as a monomer, and SPR nanosensor surfaces were optimized by determining the highest imprinting factor of the chip surfaces. The surfaces of adenosine-imprinted and non-imprinted SPR nanosensors were characterized by using atomic force microscopy, ellipsometry, and contact angle measurements. Kinetic analyses were made with different concentrations in the range of 0.5-400.0 nM for the detection range with a pH 7.4 phosphate buffer solution. The limit of detection in adenosine aqueous solutions, artificial plasma, and artificial urine was determined to be 0.018, 0.015, and 0.013 nM, respectively. In the selectivity analysis of the developed nanosensors, the selectivity of adenosine SPR nanosensors in solutions at different concentrations was determined by using guanosine and cytidine nucleosides. The relative selectivity coefficients of adenosine-imprinted SPR nanosensors for adenosine/cytidine and adenosine/guanosine are 3.836 and 3.427, respectively. Since adenosine-imprinted SPR nanosensors are intended to be used in medical analysis and research, adenosine analysis has also been studied in artificial urine and artificial plasma samples.

Association of traditional Chinese medicine body constitution and cold syndrome with leukocyte mitochondrial functions: An observational study

Body constitution in traditional Chinese medicine (TCM) refers to the holistic and relatively durable state of an individual, based on the qi and blood assessment, and TCM syndrome is defined as the theoretical abstraction of disease-symptom profiles. The biological basis as related to mitochondria, which produce most of the cellular energy, has not been well studied. This study aimed to elucidate the association of mitochondrial function with TCM body constitution and cold syndrome. Body constitution and cold syndrome in TCM were assessed using the Constitution in Chinese Medicine Questionnaire (CCMQ). The mitochondrial function of peripheral leukocytes was evaluated based on oxygen consumption rate (OCR) and enzyme activity; OCR reflects mitochondrial activity and the capacity to produce adenosine triphosphate (ATP). Cellular adenosine nucleotides and malondialdehyde levels were determined using high-performance liquid chromatography to assess the potential bioenergetic mechanisms. A total of 283 adults participated in this study. Leukocytes from subjects with a balanced constitution had higher OCRs than those with unbalanced constitutions. Yang deficiency and cold syndrome also demonstrated lower energy metabolism, as indicated by reduced basal metabolic rate and cellular levels of ATP and malondialdehyde. Decreased mitochondrial enzyme activity has been observed in individuals with the cold syndrome. Unbalanced body constitutions in TCM impair mitochondrial function in leukocytes, which may contribute to the high disease susceptibility. Cold syndrome is characterized by reduced mitochondrial mass, which may explain its symptoms of low-energy metabolism and cold intolerance.

A novel ratiometric fluorescence nanoprobe for sensitive determination of uric acid based on CD@ZIF-CuNC nanocomposites

A novel ratiometric fluorescence nanoprobe based on carbon dots (CDs) and Cu nanoclusters (CuNCs) was designed for the label-free determination of uric acid (UA). The metal-organic framework (MOF) encapsulated CuNCs (ZIF-CuNC), and nitrogen-doped CDs can self-assemble into well-defined spherical nanocomposites (CD@ZIF-CuNC) due to physical adsorption. Under the excitation wavelength of 360 nm, the CD@ZIF-CuNC nanocomposites exhibit two evident intrinsic emissions peaked at 460 nm (CDs) and 620 nm (ZIF-CuNC), respectively. In the presence of H₂O₂, the fluorescence of CD@ZIF-CuNC at 620 nm is quenched remarkably within 1 min, while little effect on the emission at 460 nm is observed. Therefore, taking the fluorescence at 620 nm as the report signal and 460 nm as the reference signal, ratiometric quantitative determination of H₂O₂ was achieved with a linear range of 1-100 μM and a detection limit of 0.30 μM. The CD@ZIF-CuNC nanoprobe was successfully applied to the determination of UA that is catalyzed by uricase to produce H₂O₂, obtaining the linear range of 1-30 μM and the detection limit of 0.33 μM. Eventually, this strategy has been successfully applied to the determination of UA in human urine samples. A novel and convenient CDs@ZIF-CuNCs-based nanoplatform was constructed for sensitive ratiometric fluorescence determination of UA.