A disposable non-enzymatic sensor for creatinine was developed by electrodepositing copper on screen printed carbon electrodes. The sensor was characterized using electrochemical and microscopic techniques. Electrochemical detection of creatinine was carried out in phosphate buffer solution of pH 7.4. The estimation was based on the formation of soluble copper-creatinine complex. The formation of copper-creatinine complex was established using the pseudoperoxidase activity of copper-creatinine complex. The sensor showed a detection limit of 0.0746 μM with a linear range of 6–378 μΜ. The sensor exhibited a stable response to creatinine and found to be free from interference from molecules like urea, glucose, ascorbic acid and dopamine. Real sample analysis was carried out with blood serum.

Fabrication of a disposable non-enzymatic electrochemical creatinine sensor

Colorimetric detection of hepatitis B virus (HBV) DNA based on DNA-templated copper nanoclusters.

Portable microfluidic system for determination of urinary creatinine.

Microfluidics has attracted considerable attention since its early development in the 1980s and has experienced rapid growth in the past three decades due to advantages associated with miniaturization, integration and automation. Urine analysis is a common, fast and inexpensive clinical diagnostic tool in health care. In this article, we will be reviewing recent works starting from 2005 to the present for urine analysis using microfluidic devices or systems and to provide in-depth commentary about these techniques. Moreover, commercial strips that are often treated as chips and their readers for urine analysis will also be briefly discussed. We start with an introduction to the physiological significance of various components or measurement standards in urine analysis, followed by a brief introduction to enabling microfluidic technologies. Then, microfluidic devices or systems for sample pretreatments and for sensing urinary macromolecules, micromolecules, as well as multiplexed analysis are reviewed, in this sequence. Moreover, a microfluidic chip for urinary proteome profiling is also discussed, followed by a section discussing commercial products. Finally, the authors' perspectives on microfluidic-based urine analysis are provided. These advancements in microfluidic techniques for urine analysis may improve current routine clinical practices, particularly for point-of-care (POC) applications.

Urine analysis in microfluidic devices

Background Albuminuria is a sensitive marker of renal derangement and has been included in a number of studies investigating chronic kidney diseases (CKDs). This study is aimed to evaluate the diagnostic performances of a strip for measuring the albumin/creatinine ratio (ACR) in the general population and to compare it with those found in a diabetic population. Methods Urine samples were obtained from 201 consecutive subjects enrolled in an epidemiological study and from 259 type 2 diabetic patients. Urine was tested for albumin and creatinine using the strip (Clinitek Microalbumin) and laboratory methods. A hundred samples were stored under various conditions to assess analyte stability. Results In the general population, the strip test reached a 90% sensitivity and 91% specificity, considering the laboratory method as the 'gold standard', sparing >80% of subjects the laboratory tests at the expense of a 1% false negative rate and an 8% false positive rate. Regarding sensitivity and specificity, the ACR test performs very similarly in the general population and in the diabetics. The stability study showed that storage at -20 degrees C induced a significant decrease in the albumin concentration with both methods, such that 5% of the samples were re-classified in the lower ACR class. Storage at -80 degrees C for up to 12 months did not affect the measurement with both methods. Conclusion Clinitek Microalbumin strips can be used for screening purposes in the general population since they correctly classify a significant percentage of subjects, particularly those with a normal albuminuria. Storage at -80 degrees C does not affect strip results. Screening with the strip and confirming positive results with a wet chemistry method are an efficient strategy for detecting albuminuria in the general population.

Lindsey D Bierbaum

Papers

Assay of creatinine using the peroxidase activity of copper-creatinine complexes.