| Summary: |
Research will focus on developing optical sensors generated from organic waste for the analytical determination in wastewater of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is responsible for the pandemic of coronavirus disease 2019 (Covid-19). Our project aims to allow a wastewater-based epidemiology (WBE) approach to be used in early warning systems for Covid-19 outbreaks and to monitor the effects of public health interventions. This framework is also expected to be useful for WBE approaches focused on surveilling other viral diseases.
Covid-19 pandemic lead to a global emergency with nearly 7 million deaths, and is still a health concern. Importantly, it is known that virus carriers may present only slight symptoms or even be asymptomatic patients. Without being able to screen these carriers, they can increase disease transmission in an uncontrolled way. However, individual tracing can quickly overcome clinical testing capability. So, to be able to trace Covid-19 in a fast and and reliable manner is crucial for early stage prevention.
WBE is a promising approach for successful Covid-19 tracing and early stage prevention, as wastewater contains viruses excreted from symptomatic and asymptomatic individuals in a catchment. In fact, WBE has been shown to be useful for early warning of disease outbreaks, such as the ones relative to enteric virus. Furthermore, SARS-CoV-2 has already been detected in wastewater at wastewater treatment plants (WWTPs) and has been reported to remain infectious in sewage for days to weeks.
Nevertheless, for the successful WBE-tracing of SARS-CoV-2, reliable sensing techniques must be available. Nowadays, the reference method for SARS-CoV-2 sensing is reverse transcription polymerase chain reaction (RT-PCR). However, it demands high manpower and long processing times and can fail and report false-negative results on confirmed infection cases. Thus, more reliable sensing methods are needed.
Herei  |
Summary
Research will focus on developing optical sensors generated from organic waste for the analytical determination in wastewater of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is responsible for the pandemic of coronavirus disease 2019 (Covid-19). Our project aims to allow a wastewater-based epidemiology (WBE) approach to be used in early warning systems for Covid-19 outbreaks and to monitor the effects of public health interventions. This framework is also expected to be useful for WBE approaches focused on surveilling other viral diseases.
Covid-19 pandemic lead to a global emergency with nearly 7 million deaths, and is still a health concern. Importantly, it is known that virus carriers may present only slight symptoms or even be asymptomatic patients. Without being able to screen these carriers, they can increase disease transmission in an uncontrolled way. However, individual tracing can quickly overcome clinical testing capability. So, to be able to trace Covid-19 in a fast and and reliable manner is crucial for early stage prevention.
WBE is a promising approach for successful Covid-19 tracing and early stage prevention, as wastewater contains viruses excreted from symptomatic and asymptomatic individuals in a catchment. In fact, WBE has been shown to be useful for early warning of disease outbreaks, such as the ones relative to enteric virus. Furthermore, SARS-CoV-2 has already been detected in wastewater at wastewater treatment plants (WWTPs) and has been reported to remain infectious in sewage for days to weeks.
Nevertheless, for the successful WBE-tracing of SARS-CoV-2, reliable sensing techniques must be available. Nowadays, the reference method for SARS-CoV-2 sensing is reverse transcription polymerase chain reaction (RT-PCR). However, it demands high manpower and long processing times and can fail and report false-negative results on confirmed infection cases. Thus, more reliable sensing methods are needed.
Herein, we want to explore a nanotechnologic solution by developing optical sensors, based on photoluminescent and upconverting carbon dots (CDs). Optical sensors typically use concentration-dependent variations (exerted by the analyte) on the photoluminescence emitted by the sensing moiety to detect and quantify the target analyte. Photoluminescence spectroscopy has been extensively used for the direct sensing of different compounds due to its operational simplicity, high sensitivity and fast measurement procedure.
CDs are light-emitting carbon-based nanoparticles with strong light-emission, excellent stability, biocompatibility and low toxicity. Also, CDs can be mass produced by organic waste via sustainable hydrothermal and microwave synthesis routes. This is quite attractive, as the use of waste as a carbon source for CDs will favor a circular economy approach.
Herein, we will develop waste-based CDs with strong photoluminescence, which surface we will functionalize with DNA receptors that hybridize selectively with known RNA sequences of the SARS-CoV-2 virus. Sensing will then be possible by measuring the concentration-dependent effect on the photoluminescence of the CDs due to the selective binding of SARS-CoV-2 to the DNA receptor sequences.
To compensate for the typical UV-visible excitation of CDs, which is usually too energetic for complex matrixes as wastewater, we will provide to CDs upconversion luminescence. This optical process is particularly suitable for complex matrixes, as they can absorb low-energy photons (2 or more) in the near-infrared (NIR) region and emit one in the UV-visible zone. At NIR wavelength, autofluorescence is avoided and light scattering is reduced, generating a strong enhancement of the optical signal-to-noise. So, providing upconversion luminescence to the CDs will allow the creating of a powerful and sensing sensor for SARS-Cov-2.
Proof-of-concept will be provided by demonstrating analytical determination of SARS-CoV-2 in real wastewater matrix, to be provided by WWTPs of the Oporto (Portugal) municipal area, by using the proposed optical sensing waste-based CDs. Research efforts will focus on the optimization of the selectivity and on the decrease of the limits of detection and quantification toward the target SARS-CoV-2 RNA sequences.
This team is particularly suitable for this project as it, despite being composed by young researchers, combines years of hands-on experience on the development of photoluminescent CDs for different applications, including their use as optical nanosensors, being recognized for the excellence of their contributions to their fields of expertise. The suitability of the team for this project is increased by inclusion of Dr Algarra and Prof Dr Kumar as international consultants. The former is an expert in optical nanosensing, with focus on CDs, while the latter has experience in NIR-upconversion luminescence. Furthermore, all have collaborating with success in recent years.
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