No abstract

Oxidative stress is involved in many aging-related pathological disorders and is the result of a defective cellular management of redox reactions. Particularly, hydrogen peroxide, H2O2 is a major byproduct and a common oxidative stress biomarker. Monitoring H2O2 dynamics and a direct correlation to diseases remain still a challenge due to the complexity of redox reactions. Sensitivity and specificity are a major drawback for H2O2 sensors regardless their readout. Luminiscent boronate-based probes such as 4-MPBA are emerging as the most effective quantitation tool due to their specificity and sensitivity. Problems associated to these probes are limited intracellular sensing, water solubility, selectivity, and quenching. We have synthesized a boronate-based nanosensor with a SERS readout to solve these challenges. Furthermore, we found out that environmental pH gradients, as found in biological samples, affect the sensitivity of boronate-based sensors. When the sensor is in an alkaline environment, the oxidation promoted by H2O2 is more favored than in an acidic environment. This leads to different H2O2 measurements depending on pH. To solve this issue, we synthesized a multiplex nanosensor able to concomitantly quantify pH and H2O2. Our nanosensor first measures the local pH and based on this value, provide the amount of H2O2. It seems that this pH-dependent sensitivity effect applies to all boronic acid-based probes. We tested the multiplexing ability by quantitatively measuring intra-and extra-cellularly pH and H2O2 dynamics under physiological and pathological conditions on healthy cells and cells which H + and/or H2O2 homeostasis has been altered.

Oxidative stress is involved in many aging-related pathological disorders and is the result of defective cellular management of redox reactions. Particularly, hydrogen peroxide (H 2 O 2 ), is a major byproduct and a common oxidative stress biomarker. Monitoring its dynamics and a direct correlation to diseases remains a challenge due to the complexity of redox reactions. Sensitivity and specificity are major drawbacks for H 2 O 2 sensors regardless of their readout. Luminiscent boronate-based probes such as 3-mercaptophenylboronic acid (3-MPBA) are emerging as the most effective quantitation tool due to their specificity and sensitivity. Problems associated with these probes are limited intracellular sensing, water solubility, selectivity, and quenching. We have synthesized a boronate-based nanosensor with a surface-enhanced Raman spectroscopy (SERS) readout to solve these challenges. Furthermore, we found out that environmental pH gradients, as found in biological samples, affect the sensitivity of boronate-based sensors. When the sensor is in an alkaline environment, the oxidation of 3-MPBA by H 2 O 2 is more favored than in an acidic environment. This leads to different H 2 O 2 measurements depending on pH. To solve this issue, we synthesized a multiplex nanosensor capable of concomitantly quantifying pH and H 2 O 2 . Our nanosensor first measures the local pH and based on this value, provides the amount of H 2 O 2 . It seems that this pH-dependent sensitivity effect applies to all boronic acid based probes. We tested the multiplexing ability by quantitatively measuring intra-and extracellular pH and H 2 O 2 dynamics under physiological and pathological conditions on healthy cells and cells in which H + and/or H 2 O 2 homeostasis has been altered.

No abstract

Biosensors, especially those with a SERS readout, are required for an early and precise healthcare diagnosis. Unreproducible SERS platforms hamper clinical SERS. Here we report a synthetic procedure to obtain stabile, reproducible and robust highly-SERS performing nanocomposites for labelling. We controlled the NPs agglomeration and codification which resulted in an increased number of hot spots, thus exhibiting reproducible and superior Raman enhancement. We studied fundamental aspects affecting the plasmonic thiol bond resulting in pH exhibiting a determining role. We validated their biosensing performance by designing a SERS-based detection assay model for SARS-CoV-2. The limit of detection of our assay detecting the spike RBD was below 10 ng/mL.

Biosensors, especially those with a SERS readout, are required for an early and precise healthcare diagnosis. Unreproducible SERS platforms hampers the clinical translation of SERS. Here we report a synthetic procedure to obtain stabile, reproducible and robust highly-SERS performing nanocomposites for labelling. We control the NPs agglomeration and codification which results in an increased number of hot spots, thus exhibiting reproducible and superior Raman enhancement. We studied fundamental aspects affecting the plasmonic thiol bond resulting in pH exhibiting a determining role. We validated their biosensing performance by designing a SERS-based sandwich immunoassay against COVID-19. The limits of detection for the recombinant SARS-CoV-2 protein is below 0.01 ng/μL. We offered herein one nanostructure with robust and homogeneous SERS signal which can be potentially applied for biodiagnosis.

Biosensors, especially those with a SERS readout, are required for an early and precise healthcare diagnosis. Unreproducible SERS platforms hamper clinical SERS. Here we report a synthetic procedure to obtain stabile, reproducible and robust highly-SERS performing nanocomposites for labelling. We control the NPs agglomeration and codification which results in an increased number of hot spots, thus exhibiting reproducible and superior Raman enhancement. We studied fundamental aspects affecting the plasmonic thiol bond resulting in pH exhibiting a determining role. We validated their biosensing performance by designing a SERS-based ELISA SARS-CoV-2 detections assay which exhibits limits of detection below 0.01 ng/μL.