Department of Chemistry, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran.
Research and Technology Center of Biomolecules, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran.
Lab Chip. 2024 Apr 16;24(8):2298-2305. doi: 10.1039/d3lc00730h.
A volumetric bar-chart chip (V-chip) is a microfluidic device based on distance-based quantitative measurement that visualizes analyte concentration without the need for apparatus or data processing. This typically utilizes special receptors and catalysis parts that generate oxygen, so ink can be moved inside the channels, and enables instant visual quantitation of the analyte. However, the low stability of some macromolecules, the use of expensive catalysts, and difficulty in controlling the process cause inaccurate readings, and therefore, limit further development and the use of these systems. In this article, we introduced a novel approach that eliminates the use of catalysts in V-chips and provides an efficient and simple path in the design of biosensors. The product of the enzymatic reaction of urease with urea is bicarbonate, which turns into CO gas in an acidic environment. Therefore, the amount of gas produced is proportional to the amount of urea in the sample, and it can be quantitatively measured by visual detection from the amount of ink movement caused by CO gas pressure. This biosensor has a linear response range of 0 to 1000 μg ml and a detection limit of 3.6 μg ml in raw milk. The recovery of urea in raw milk at 100 and 400 μg ml concentrations was 96.5% and 98.9%, respectively. This volumetric chip shows potential for determining urea levels in real samples without requiring additional equipment. The combination of the sensitivity and specificity of enzymatic reactions, inherent gas-generating reactions, and the processability of microchips discussed in this paper can be the basis for the comprehensive development of volumetric chips, which can create a new path for the development of efficient and cheap biosensors.
一种基于体积的条形图芯片（V-chip）是一种基于距离的定量测量微流控设备，可在无需仪器或数据处理的情况下可视化分析物浓度。这通常利用特殊的受体和催化部分生成氧气，从而使墨水可以在通道内移动，并能够即时对分析物进行可视化定量。然而，一些大分子的稳定性低、昂贵的催化剂的使用以及难以控制该过程会导致读数不准确，因此限制了这些系统的进一步发展和应用。在本文中，我们介绍了一种新颖的方法，该方法可消除 V-chip 中催化剂的使用，并为设计生物传感器提供了一种高效且简单的途径。脲酶与尿素的酶反应产物是碳酸氢盐，在酸性环境下会转化为 CO 气体。因此，产生的气体量与样品中尿素的量成正比，并且可以通过 CO 气体压力引起的墨水移动量进行视觉检测进行定量测量。该生物传感器在原始牛奶中的线性响应范围为 0 至 1000 μg ml，检测限为 3.6 μg ml。在 100 和 400 μg ml 浓度的原始牛奶中，尿素的回收率分别为 96.5%和 98.9%。这种体积芯片具有无需额外设备即可确定实际样品中尿素水平的潜力。本文讨论的酶反应的灵敏度和特异性、固有的产气反应以及微芯片的可加工性的结合，可以为体积芯片的全面发展奠定基础，从而为高效、廉价的生物传感器的发展开辟新途径。
