Surface Plasmon-Coupled Dual Emission Platform for Ultrafast Oxygen Monitoring after SARS-CoV-2 Infection

Abstract

The outbreak of the COVID-19 pandemic has had a major impact on the health and well-being of people with its long-term effect on lung function and oxygen uptake. In this work, we present a unique approach to augment the phosphorescence signal from phosphorescent gold­(III) complexes based on a surface plasmon-coupled emission platform and use it for designing a ratiometric sensor with high sensitivity and ultrafast response time for monitoring oxygen uptake in SARS-CoV-2-recovered patients. Two monocyclometalated Au­(III) complexes, one having exclusively phosphorescence emission (λPL = 578 nm) and the other having dual emission, fluorescence (λPL = 417 nm) and phosphorescence (λPL = 579 nm), were studied using the surface plasmon-coupled dual emission (SPCDE) platform for the first time, which showed 27-fold and 17-fold enhancements, respectively. The latter complex having the dual emission was then used for the fabrication of a ratiometric sensor for studying the oxygen quenching of phosphorescence emission with the fluorescence emission acting as an internal standard. Low-cost poly (methyl methacrylate) (PMMA) and biodegradable wood were used to fabricate the microfluidic chips for oxygen monitoring. The sensor showed a high sensitivity with a limit of detection ∼ 0.1%. Furthermore, real-time oxygen sensing was carried out and the response time of the sensor was calculated to be ∼0.2 s. The sensor chip was used for monitoring the oxygen uptake in SARS-CoV-2-recovered study participants, to assess their lung function post the viral infection.

Metal–Dielectric Interfacial Engineering with Mesoporous Nano-Carbon Florets for 1000-Fold Fluorescence Enhancements: Smartphone-Enabled Visual Detection of Perindopril Erbumine at a Single-molecular Level

“…The conically graded mesopore-structure of NCF, resembling optical microcavities, creates nano-funnels that are appropriate for sustaining high electric field intensity (also called as hotspots). 12,14,16 Since NCF represents both morphologically and structurally unique materials, understanding its interaction with photons demands the creation of varied interfaces. This is achieved through three different configurations, namely (a) Spacer, where the NCF is pre-mixed in a polymeric matrix, and thus, the interaction between the NCF and the radiative dipoles of the emitter is mediated by the polymer, (b) Cavity, where the NCF and the fluorophore are mixed directly to enable direct coupling of the radiative dipoles with the electromagnetic hotspots of NCF, and Thus, both the NCF and the emitters experience vastly differing electromagnetic environments in these three configurations, which are expected to influence the nature and magnitude of SPCE enhancements.…”

“…The emission is captured using a smartphone, and the images are processed and analyzed using the Color Grab app (downloaded from the Google Play Store), in line with earlier works. 14,16,19,20 The methodology involved in the fabrication of the three nanointerfaces is shown in Figure S1b.…”

“…25−32 Furthermore, 118-fold SPCE enhancements have been demonstrated by minimizing Ohmic losses using high refraction index dielectrics in conjugation with metal nanostructures. 14 In spite of such significant advancements in both fundamental aspects and the applications thereof, the major challenges in SPCE enhancements using metallic nanostructures have been (i) inevitable Ohmic losses along with radiative damping, 12,14,17 (ii) poor chemical stability, especially in real-time applications, 16,19,22 and (iii) extensive isotropic photon scattering that compromises the magnitude of SPCE enhancements. 16−22 As opposed to the variety of metal, non-metallic, 33 dielectric, twodimensional, 34 and zero-dimensional substrates 35 that have been investigated for SERS, substrates for SPCE have been primarily restricted to metallic and their composites.…”

“…16−22 As opposed to the variety of metal, non-metallic, 33 dielectric, twodimensional, 34 and zero-dimensional substrates 35 that have been investigated for SERS, substrates for SPCE have been primarily restricted to metallic and their composites. 13,15,16 Thus, a ubiquitous platform that synergistically couples the plasmonic advantages of metallic nanostructures while simultaneously minimizing the Ohmic and radiative losses is desirable for improving the quality factor and reliability of SPCE, thereby transforming it into a powerful ultrasensitive analytical technique. 36−42 Achieving this would provide distinct opportunities for portable and mobile phone-based detection capabilities catering to the internet-of-things.…”

Microwave induced thermally assisted solvent-based bonding of biodegradable thermoplastics: an eco-friendly rapid approach for fabrication of microfluidic devices and analyte detection

“…These features make CA an ideal choice to be implemented in microfluidic applications and this study. Our previous experience comprises sustainable material based works 31 , 36 and now we are extending that knowledge to CA.…”