A highly sensitive amperometric creatinine sensor

Electrochemical Creatinine (Bio)Sensors for Point-of-Care Diagnosis of Renal Malfunction and Chronic Kidney Disorders

In the post-pandemic era, point-of-care (POC) diagnosis of diseases is an important research frontier. Modern portable electrochemical (bio)sensors enable the design of POC diagnostics for the identification of diseases and regular healthcare monitoring. Herein, we present a critical review of the electrochemical creatinine (bio)sensors. These sensors either make use of biological receptors such as enzymes or employ synthetic responsive materials, which provide a sensitive interface for creatinine-specific interactions. The characteristics of different receptors and electrochemical devices are discussed, along with their limitations. The major challenges in the development of affordable and deliverable creatinine diagnostics and the drawbacks of enzymatic and enzymeless electrochemical biosensors are elaborated, especially considering their analytical performance parameters. These revolutionary devices have potential biomedical applications ranging from early POC diagnosis of chronic kidney disease (CKD) and other kidney-related illnesses to routine monitoring of creatinine in elderly and at-risk humans.

On-line 'protein shaker': A multicommutated flow analysis system for fluorometric creatinine determination in deproteinized serum

A fully mechanized multicommutated flow analysis (MCFA) system for fluorometric determination of creatinine in serum samples is introduced in this paper. The flow system was constructed with microsolenoid pumps and valves and with a 3D-printed flow cell. Fluorometric assay relied on creatinine reaction with 3,5-dinitrobenzoic acid and hydrogen peroxide in an alkaline environment. To overcome significant interference from protein, a flow reactor for serum deproteinization was designed and implemented in the flow system. The deproteinization was carried out by precipitation with trichloroacetic acid and the addition of sodium chloride facilitated the precipitate sedimentation. The supernatant representative sample was pumped out and subjected to fluorometric creatinine assay. The obtained linear range was from 1.6 to 500 μmol L^-1 and the precision, expressed as RSD, was below 3%. The proposed MCFA system was used to determine creatinine concentration in control serum samples. The results obtained with flow deproteinization correlated well with results obtained with conventional deproteinization (y = (0.91 ± 0.09) x + (37 ± 28)) with Pearson's r 0.979.

A review of recent advances in non-enzymatic electrochemical creatinine biosensing

Creatinine biosensing is a rapidly developing field owing to the clinical relevance of creatinine as a vital biomarker for several diseases associated with renal, thyroidal, and muscular dysfunctions. Over the years, we have observed numerous creatinine biosensing strategies, including the most widely studied enzymatic creatinine biosensors. Though the enzymatic approach provides excellent selectivity and reliability, it has certain drawbacks, which include high fabrication cost and poor storage stability (that is inherent to every enzyme-based biosensors). This has led to the development of non-enzymatic creatinine biosensors, of which electrochemical sensors are the most promising for point-of-care applications. However, only a limited number of studies have been conducted and there is a lack of reviews addressing the recent advances in this research area. Herein, we present for the first time, a review with a prime focus on the various strategies implemented in non-enzymatic electrochemical creatinine biosensing. We aim to offer a comprehensive context on the achievements and limitations of currently available non-enzymatic electrochemical creatinine biosensors and address the underlying factors pertaining to the interplay of modification/fabrication techniques with the sensitivity, selectivity, interferences, and long-term storage stability of the biosensor. We hope that this work shall prove to be seminal in the conception and advancement of future non-enzymatic electrochemical creatinine biosensors.

Trend in creatinine determining methods: Conventional methods to molecular‐based methods

Renal failure (RF) disease is ranked as one of the most prevalent diseases with severe morbidity and mortality. Early diagnosis of RF leads to subsequent control of disease to reduce the poor prognosis. The level of sera creatinine is considered as a significant biomarker for kidney biofunction, which is routinely detected by the Jaffe reaction. The normal range for creatinine in the blood may be 0.84‐1.21 mg/dL. Low accuracy, insufficient sensitivity, explosive and toxicity of picric acid, and pseudo‐interaction with nonspecific elements such as ammonium ions in the Jaffe method lead to the development of various techniques for precise detection of creatinine such as spectroscopic, electrochemical, and chromatography approaches and sensors based on enzymes, molecular imprinted polymer and nanoparticles, etc. Based on previously established results, they are trying to construct sensors with high accuracy, optimum sensitivity, acceptable linear/calibration range, and limit of detection, which are small in size and applicable by the patient him/herself (point‐of‐care testing). By comparing the results of research, a molecularly imprinted electrochemiluminescence‐based sensor with linear/calibration range of 5‐1 mMconcentration of creatinine and the detection limit of 0.5 nM has the best detectable resolution with 2 million measurable points. In this paper, we will review the recently developed methods for measuring creatinine concentration and renal biofunction.

Biosensing methods for determination of creatinine: A review

Creatinine is a metabolic product of creatine phosphate in muscles, which provides energy to muscle tissues. Creatinine has been considered as indicator of renal function specifically after dialysis, thyroid malfunction and muscle damage. The normal level of creatinine in the serum and its excretion through urine in apparently healthy individuals is 45-140 μM and 0.8-2.0 gm/day respectively. The level of creatinine reaches >1000 μM in serum during renal, thyroid and kidney dysfunction or muscle disorder. A number of conventional methods such as colorimetric, spectrophotometric and chromatographic are available for determination of creatinine. Besides the advantages of being highly sensitive and selective, these methods have some drawbacks like time-consuming, requirement of sample pre-treatment, high cost instrumental set-up and skilled persons to operate. The sensors/biosensors overcome these drawbacks, as these are fast, easy, cost effective and highly sensitive. This review article describes the classification, operating principles, merits and demerits of various creatinine sensors/biosensors, specifically nanomaterials based biosensors. Creatinine biosensors work optimally within 2-900 s, potential range 0.1-1.0 V, pH range 4.0-10.0, temperature range 25-35 °C and had linear range, 0.004-30000 µM for creatinine with the detection limit between 0.01.01 µM and 520 µM. These biosensors measured creatinine level in sera and urine samples and had storage stability between 4 and 390 days, while being stored dry at 4 °C. The future perspective for further improvement and commercialization of creatinine biosensors are discussed.

Novel electrochemical sensing platform based on magnetic field-induced self-assembly of Fe3O4@Polyaniline nanoparticles for clinical detection of creatinine

A novel electrochemical sensing platform based on magnetic field-induced self-assembly of Fe3O4@Polyaniline nanoparticles (Fe3O4@PANI NPs) has been for the first time fabricated for the sensitive detection of creatinine in biological fluids. The template molecule, creatinine, was self-assembled on the surface of Fe3O4@PANI NPs together with the functional monomer aniline by the formation of N-H hydrogen bonds. After pre-assembled, through the magnetic-induction of the magnetic glassy carbon electrode (MGCE), the ordered structure of molecularly imprinted polymers (MIPs) were established by the electropolymerization and assembled on the surface of MGCE with the help of magnetic fields by a simple one-step approach. The structural controllability of the MIPs film established by magnetic field-induced self-assembly was further studied. The stable and hydrophilic Fe3O4@PANI can not only provide available functionalized sites with which the template molecule creatinine can form hydrogen bond by the abundant amino groups in PANI matrix, but also afford a promoting pathway for electron transfer. The as-prepared molecularly imprinted electrochemical sensor (MIES) shows good stability and reproducibility for the determination of creatinine with the detection limit reached 0.35 nmol L(-1) (S/N=3). In addition, the highly sensitive and selective MIES has been successfully used for the clinical determination of creatinine in human plasma and urine samples. The average recoveries were 90.8-104.9% with RSD lower than 2.7%.

An Amperometric Enzyme Electrode for Creatine Determination Prepared by the Immobilization of Creatinase and Sarcosine Oxidase in Poly(vinylferrocenium)

A new enzyme electrode for the determination of creatine was developed by immobilizing creatinase (CI) and sarcosine oxidase (SO). The enzymes were co-immobilized in a poly(vinylferrocenium) matrix onto the surface of a platinum working electrode. Crosslinking with glutaraldehyte (GA) and bovine serum albumin (BSA) was selected as the best immobilization method for the enzymatic system. Determination of creatine was performed by the oxidation of enzymatically generated H2O2 at + 0.7 V vs. Ag/AgCl. The linear working range of the electrode was 2.0 x 10(-5) - 3.2 x 10(-4) M and the response time was about 50 s. The effects of pH, temperature, enzyme ratio and buffer concentration were investigated and optimum parameters were found to be 7.5, 37 degrees C, 2.5:1 (CI:SO) and 0.05 M, respectively. The stability and reproducibility of the enzyme electrode have been also studied.

An Amperometric Biosensor for Uric Acid Determination Prepared from Uricase Immobilized in Polypyrrole Film

In order to prepare a biosensor for the determination of uric acid, electropolymerization of pyrrole on Pt surface was carried out with an electrochemical cell containing pyrrole, ferrocene (as a electron mediator) and tetrabutylammonium tetrafluoroborat in acetonitrile by cyclic voltammetry between 0.0 and 1.0 V (vs. Ag/AgCl) at a scan rate of 50 mV/s upon Pt electrode. Uricase was immobilized by a glutaraldehyde/gelatine croslinking procedure on to polypyrrole film after the electropolymerization processes. The response of the biosensor against uric acid was measured after 330 seconds following the application of a constant potential of +0.7 V (vs. Ag/AgCl). The resulting biosensor exhibits excellent electrocatalysis for the uric acid. The amperometric determination is based on the electrochemical detection of H2O2, which is generated in enzymatic reaction of uric acid. The sensor responds to uric acid with a detection limit of 5.0 x 10(-7) M. The sensor remains relatively stable for 5 weeks. Interference effect were investigated on the amperometric response of the biosensor. Determination of uric acid was carried out in the biological fluids by biosensor.

Designing a molecularly imprinted polymer as an artificial receptor for the specific recognition of creatinine in serums

In this study, molecularly imprinted polymers (MIP) synthesized from two different functional monomers, beta-cyclodextrin (beta-CD) and 4-vinylpyridine (4-Vpy), were prepared. The crosslinkers used for these two monomers were epichlorohydrin (EPI) and divinylbenzene (DVB), respectively. It was attempted to adsorb the target molecule, creatinine, from its mixture solutions. A proper molar ratio of monomer/crosslinker for the preparation of the imprinted poly(beta-CD) was 1:10. Between both polymers mentioned above, the affinity of the imprinted poly(4-Vpy-co-DVB) towards creatinine was comparably superior. The imprinted poly(4-Vpy-co-DVB) for creatinine could reach a specific binding ratio of 3.11. The imprinted poly(4-Vpy-co-DVB) was further utilized to bind creatinine from human serum samples. The binding capacity of the imprinted poly(4-Vpy-co-DVB) for creatinine from the serum samples was plotted against the creatinine concentration. From the correlation, the feasibility of the imprinted poly(4-Vpy-co-DVB) thus prepared for the target analyte, creatinine, was experimentally confirmed.

Synthesis of creatinine-imprinted poly(β-cyclodextrin) for the specific binding of creatinine

An artificial receptor for creatinine was synthesized by the method of molecularly imprinted polymer (MIP). beta-Cyclodextrin was used as a monomer cross-linked with epichlorohydrin in the presence of creatinine, which was a template for the imprinting. Different molar ratios of monomer to template were used to synthesize the polymers so that better specific adsorption ability towards creatinine could be achieved. The results showed that to carry out the polymerization with a molar ratio of monomer to template of 3:2 and monomer to cross-linking agent of 1:10 was proper. N-hydroxysuccinimide and 2-pyrrolinidone were used as the analogues of creatinine in the adsorption experiments of multi-component solutions to reveal the specific recognition ability of the molecularly imprinted poly(beta-cyclodextrin) (poly(beta-CD)) for the template molecule, creatinine. One such detection interference of creatinine was creatine, which also co-exists in serum. Hence, adsorption experiments of creatinine/creatine binary mixture were also carried out to investigate and confirm the specific binding of the creatinine-imprinted poly(beta-cyclodextrin) towards creatinine. The hydroxyl groups of the imprinted poly(beta-CD) was further capped by chlorotrimethylsilane (CTMS) to investigate the interaction between creatinine and the imprinted poly(beta-CD). The adsorption resulting from the mixture solution by MIPs suggested that the creatinine-imprinted poly(beta-CD) demonstrated superior binding effect for the target molecule, creatinine, rather than creatine, N-hydroxysuccinimide and 2-pyrrolinidone.

Amperometric creatinine biosensor for hemodialysis patients

BACKGROUND

Creatinine is an important clinical laboratory parameter for the evaluation of kidney function. It is essential to determine its concentration in serum of patients suffering from renal insufficiency. During hemodialysis treatment, the measurement of creatinine in the effluent dialysate or ultrafiltrate may give additional information on the efficiency of the extracorporal procedure. Therefore, enzyme sensors with co-immobilized creatinine amidohydrolase, creatine amidinohydrolase and sarcosine oxidase have been used to determine creatinine.

METHODS

Enzymatically generated hydrogen peroxide has amperometrically been detected at a platinum-working electrode. To exclude electroactive compounds of the sample matrix, which might interfere with the electrochemical measurement, the sensors have additionally been modified by a Nafion membrane.

RESULTS

Such sensors showed a linear detection range of 0.06-1.7 mg/dl for creatinine. Diluting the sample with measuring buffer, it has also been possible to measure pathological creatinine concentrations up to 11 mg/dl. A good correlation between creatinine concentrations in serum, dialysate and ultrafiltrate determined by the presented enzyme sensors and those obtained by both, conventional colorimetric Jaffé and enzymatic measurements have been achieved.

CONCLUSION

Further developments will aim at the integration of this measuring principle into the concept to low-cost disposable planar sensors.

Creatinine biosensors: principles and designs

Creatinine biosensors, based on both potentiometric and amperometric devices, have been created. However, there are significant problems still to be addressed, including the balance between sensitivity and selectivity, interference rejection and sensor stability. In addition, many devices still rely on a dual-sensor approach for creatine and creatinine subtractive measurements. However, creatinine biosensors appear close to attaining the performance goals necessary for their widespread application. This article looks at the operating principle and design of both potentiometric and amperometric creatinine biosensors, and shows how the design of these devices affects their performance.

Biomedical application of immobilized enzymes

Reports on chemical immobilization of proteins and enzymes first appeared in the 1960s. Since then, immobilized proteins and enzymes have been widely used in the processing of variety of products and increasingly used in the field of medicine. Here, we present a review of recent developments in immobilized enzyme use in medicine. Generally speaking, the use of immobilized enzyme in medicine can be divided into two major categories: biosensors and bioreactors. A brief overview of the evolution of the biosensor and bioreactor technology, of currently existing applications of immobilized enzymes, of problems that researchers encountered, and of possible future developments will be presented.