Rapid and Inexpensive Colorimetric Detection of Total Serum Protein Using Microzone Plates Wax-Printed on Polyester Films

This report describes a rapid and inexpensive colorimetric method based on biuret assay for total serum protein analysis using wax printed microzone plates and a desktop scanner. The colorimetric assay was performed in 96-microzone plates fabricated on polyester films through a wax printing protocol. The image scanning mode and the concentration of the biuret reagents were optimized to achieve the highest detectability levels. The best analytical response was obtained using the slide scanning mode as well as 4% CuSO4 and 150 mmol L-1 potassium sodium tartrate solutions. The proposed method offered linear relationship for the bovine serum albumin concentration range between 25 and 200 µmol L-1 with a limit of detection of 9.7 µmol L-1. The colorimetric approach revealed satisfactory precision (relative standard deviation values between 0.6 and 4.4%). The bioanalytical feasibility was demonstrated through the total protein analysis in serum samples collected from dogs previously diagnosed with kidney disease. The total serum protein concentrations varied from 960 ± 19 to 1661 ± 38 µmol L-1 and the achieved values revealed good accordance with those obtained through a reference method. Based on the reported results, wax printed microzone plates have demonstrated simplicity and potential to be adopted as alternative platforms for bioassays.

本研究报道了一种基于双缩脲法（biuret assay）的快速、低成本比色检测方案，可结合蜡印刷微区板（wax printed microzone plates）与台式扫描仪，用于血清总蛋白分析。该比色检测在通过蜡印刷工艺制备于聚酯薄膜（polyester films）上的96孔微区板（96-microzone plates）中完成。研究对图像扫描模式（image scanning mode）与双缩脲试剂浓度进行了优化，以实现最高检测灵敏度。最终最优分析响应条件为：采用玻片扫描模式，使用4%硫酸铜（CuSO4）溶液与150 mmol·L⁻¹酒石酸钾钠（potassium sodium tartrate）溶液。本方法对牛血清白蛋白（bovine serum albumin）的线性检测范围为25~200 µmol·L⁻¹，检测限（limit of detection）为9.7 µmol·L⁻¹。该比色方法展现出良好的精密度，相对标准偏差（relative standard deviation）介于0.6%~4.4%之间。研究通过对确诊肾病犬的血清样本进行总蛋白分析，验证了该生物分析方法的可行性。样本总血清蛋白浓度区间为960 ±19 至1661 ±38 µmol·L⁻¹，所得检测结果与参考方法（reference method）的测定值具有良好一致性。综上，蜡印刷微区板具备操作简便性与应用潜力，可作为生物检测的替代平台。