Diagnosis of diabetes mellitus using sialic acid expression of erythrocyte and a microfluidic resistive temperature detector (micro-RTD)

Sialic acid (SA, N-acetylneuraminic acid), a negatively charged monosaccharide, is expressed less frequently in diabetes patients than in normal people. A simple method for differentiating abnormal erythrocytes from normal erythrocytes based on SA-expression can be a useful diagnostic tool for diabetes. This study developed such a system by first modifying a sensor surface with SA recognition molecules to capture SA-expressing erythrocytes. Second, the sensor surface was thoroughly washed to remove abnormal erythrocytes while the normal erythrocytes remained. The remaining cells from the patient's and normal samples were heated with a 532 nm wavelength laser and temperature changes were measured using a resistive temperature detector (RTD). Hemoglobin molecules in the erythrocytes absorb a specific wavelength of photons (532 nm), which is reflected as a temperature change. In total, 17 samples from diabetes patients and 9 samples from normal patients were applied to the study system. The average temperature difference (0.32 °C) between diabetics and non-diabetics was significant, indicating that the study system can be utilized for diagnosis of diabetes mellitus. Moreover, a microfluidic channel using PDMS (poly-dimethylsiloxane) was fabricated and integrated onto the RTD to precisely deliver the cells. The process described above was repeated and almost identical results were obtained, suggesting that the microfluidic RTD has promising clinical applications.