Low-Cost Naked-Eye UVB and UVC Dosimetry Based on 3,3′,5,5′-Tetramethylbenzidine

Abstract

Ultraviolet radiation (UVR) is both useful to human beings and can cause irreversible harm of varying degrees (UVA, UVB, and UVC). Especially, in areas with excessive sunlight, the appearance of UVB results in an increased risk of skin cancer. On the other hand, UV lamps (254 nm, UVC) are widely used in disinfection (air, water, and factory food) and hospital sterilization; the leakage of UVC is thus sometimes inevitable, which may cause fatal injuries to the related staff. Therefore, low-cost UV dosimetry-based personal protective equipment (PPE) and industrial monitoring devices are of great importance. Here, for the first time, we found that 3,3′,5,5′-tetramethylbenzidine (TMB) could be rapidly oxidized upon UVB and UVC irradiation in a dose-dependent manner, in which TMB acts as a self-photosensitizer. Since TMB is a typical and widely used chromogenic substrate in enzyme-linked immunosorbent assay (ELISA), it is well-commercialized with low cost and vast availability worldwide, which permitted the development of low-cost naked-eye UVB and UVC dosimetry. A wearable bracelet mounted with TMB-loaded paper was developed for successful indication of whether the UVB exposure in the sunlight exceeded the minimum erythema dose (MED). In addition, we also developed a clock dial equipped with a TMB solution for unattended detection of UVC leakage from UVC disinfection lamps. The UVB-and UVC-selective coloration and low cost of TMB offered remarkable potential in facile detection of UVR in our daily life.

Long-Lived Phosphorescent Carbon Dots as Photosensitizers for Total Antioxidant Capacity Assay

“…The TMB (colorless) can be oxidized to oxTMB (blue color) by the highly oxidative oxygen species during the photosensitization process. Although the synthesized CDs have strong excitations at 220–260 nm (Figure c), the TMB could be photooxidized to a blue product by the high-energy UV light (typically 254 nm Hg lamp) irradiation . Therefore, the light-driven oxidation was performed using a commercialized 365 nm UV light LED.…”

“…Although the synthesized CDs have strong excitations at 220−260 nm (Figure 3c), the TMB could be photooxidized to a blue product by the high-energy UV light (typically 254 nm Hg lamp) irradiation. 29 Therefore, the light-driven oxidation was performed using a commercialized 365 nm UV light LED. As shown in Figure 4a, the addition of NPCDs and TMB into phosphate buffer (pH = 4) produced a distinct blue color with UV−vis absorption at 370 and 652 nm when they were irradiated under a 365 nm UV lamp.…”

Light-activated carbon dot nanozyme with scandium for a highly efficient and pH-universal bio-nanozyme cascade colorimetric assay

“…In addition, under UVB and UVC irradiation, TMB can be oxidized in a dose-dependent manner. 44 To investigate whether or not TMB is oxidized when exposed to UV light at 365 nm for 20 s (3 V, 3 W), solutions containing only TMB and the buffer solution were explored, as shown in Fig. S5 (ESI †), and irradiation (with buffer solutions as the blank group) showed no TMB oxidation.…”

A three-dimensional microfluidic flow cell and system integration for improved electrochemical substrate detection in HRP/TMB-based immunoassays

“…This improved signal stability, which is three times higher than the SNR for optical detection (SNR = 19), demonstrates that such an integrated platform can readily serve as an alternative to the optical detection mode for HRP/ H 2 O 2 /TMB-based immunoassays. Compared to existing or already published chromogenic detection methods for TMB, such as spectrometry, 37 optical microscopy, 38 fluorescence 39 or even naked-eye sensing, 40 this method allows for a shorter detection time with a higher signal-to-noise ratio. Also, compared to recent electrochemical sensor studies, the sensitivity and throughput of the developed method for TMB substrate detection is improved significantly.…”