Oswaldo Cruz Foundation (FIOCRUZ), Center for Technological Development in Health (CDTS)/National Institute of Science and Technology for Innovation in Neglected Populations Diseases (INCT-IDPN), Rio de Janeiro 21040-900, Brazil.
Electronic Languages and Electrochemical Sensors Laboratory, Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, São Paulo 05508-000, Brazil.
Biosensors (Basel). 2021 Nov 30;11(12):489. doi: 10.3390/bios11120489.
Diphtheria is a vaccine-preventable disease, yet immunization can wane over time to non-protective levels. We have developed a low-cost, miniaturized electroanalytical biosensor to quantify anti-diphtheria toxin (DTx) immunoglobulin G (anti-DTx IgG) antibody to minimize the risk for localized outbreaks. Two epitopes specific to DTx and recognized by antibodies generated post-vaccination were selected to create a bi-epitope peptide, biEP, by synthesizing the epitopes in tandem. The biEP peptide was conjugated to the surface of a pencil-lead electrode (PLE) integrated into a portable electrode holder. Captured anti-DTx IgG was measured by square wave voltammetry from the generation of hydroquinone (HQ) from the resulting immunocomplex. The performance of the biEP reagent presented high selectivity and specificity for DTx. Under the optimized working conditions, a logarithmic calibration curve showed good linearity over the concentration range of 10-10 IU mL and achieved a limit of detection of 5 × 10 IU mL. The final device proved suitable for interrogating the immunity level against DTx in actual serum samples. Results showed good agreement with those obtained from a commercial enzyme-linked immunosorbent assay. In addition, the flexibility for conjugating other capture molecules to PLEs suggests that this technology could be easily adapted to the diagnoses of other pathogens.
白喉是一种可通过疫苗预防的疾病，但随着时间的推移，免疫效力可能会减弱至无法提供保护的水平。我们开发了一种低成本、微型化的电化学生物传感器，用于定量检测抗白喉毒素（DTx）免疫球蛋白 G（anti-DTx IgG）抗体，以最大程度降低局部暴发的风险。选择了针对 DTx 的两个表位，这些表位是接种疫苗后产生的抗体所识别的，通过串联合成这些表位来创建双表位肽（biEP）。将 biEP 肽偶联到集成在便携式电极支架中的铅笔芯电极（PLE）表面。通过从生成的免疫复合物中生成对苯二酚（HQ），来测量捕获的抗 DTx IgG。biEP 试剂的性能对 DTx 具有高选择性和特异性。在优化的工作条件下，对数校准曲线在 10-10 IU mL 的浓度范围内表现出良好的线性，并实现了 5×10 IU mL 的检测限。最终的设备适用于检测实际血清样本中针对 DTx 的免疫水平。结果与商业酶联免疫吸附测定法（ELISA）获得的结果非常吻合。此外，将其他捕获分子偶联到 PLE 的灵活性表明，该技术可以轻松适应其他病原体的诊断。
