Fermentation Technology and Bioengineering Department, Central Food Technological Research Institute (A Constituent Laboratory of Council of Scientific and Industrial Research, New Delhi), Mysore 570020, India.
Biosens Bioelectron. 2012 Oct-Dec;38(1):411-5. doi: 10.1016/j.bios.2012.05.003. Epub 2012 May 19.
The routing of fluorescent signals from NADH to quantum dots (QDs) has been a subject of extensive research for FRET based applications. In the present study, the spectral cross talk of NAD(+)/NADH with QDs was used to monitor the reaction of NAD(+)-dependent dehydrogenase enzyme. CdTe QD may undergo dipolar interaction with NADH as a result of broad spectral absorption due to multiple excitonic states resulting from quantum confinement effects. Thus, non-radiative energy transfer can take place from NADH to CdTe QD enhancing QDs fluorescence. Energy routing assay of NADH-QD was applied for detection of formaldehyde as a model analyte in the range 1000-0.01 ng/mL by the proposed technique. We observed proportionate quenching of CdTe QD fluorescence by NAD(+) and enhancement in the presence of NADH formed by various concentrations of enzyme (0.028-0.4 U). Hence, it was possible to detect formaldehyde in the range 1000-0.01 ng/mL with a limit of detection (LOD) at 0.01 ng/mL and regression coefficient R(2)=0.9982. Therefore, a unique optical sensor was developed for the detection of the formaldehyde in sensitive level based on the above mechanism. This method can be used to follow the activity of NAD(+)-dependent enzymes and detection of dehydrogenases in general.
荧光信号从 NADH 到量子点 (QD) 的路由一直是基于 FRET 的应用的广泛研究课题。在本研究中，使用 NAD(+)/NADH 与 QD 的光谱串扰来监测 NAD(+)-依赖性脱氢酶的反应。由于量子限制效应导致的多个激子态引起的宽光谱吸收，CdTe QD 可能与 NADH 发生偶极相互作用。因此，非辐射能量可以从 NADH 转移到 CdTe QD，从而增强 QD 的荧光。通过所提出的技术，将 NADH-QD 的能量路由测定法应用于检测甲醛作为 1000-0.01ng/mL 范围内的模型分析物。我们观察到 NAD(+) 使 CdTe QD 荧光比例猝灭，并且在存在由各种浓度的酶（0.028-0.4U）形成的 NADH 的情况下增强。因此，有可能在 1000-0.01ng/mL 的范围内检测到甲醛，检测限（LOD）为 0.01ng/mL，回归系数 R(2)=0.9982。因此，基于上述机制，开发了一种用于检测灵敏水平甲醛的独特光学传感器。该方法可用于跟踪 NAD(+)-依赖性酶的活性以及一般脱氢酶的检测。
