Covalent Surface Modification Effects on Single-Walled Carbon Nanotubes for Multimodal Optical Applications

Chio, Linda; Pinals, Rebecca L.; Goh, Natalie S.; Murali, Aishwarya; Landry, Markita P.

doi:10.1101/837278

Cited by 4 publications

(4 citation statements)

References 46 publications

(40 reference statements)

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“…Other studies focused more on covalent functionalization chemistry. 71 The data provided mechanistic insights into the sensing mechanism of SWCNT-based fluorescent sensors. We could rule out that energy transfer to vibrations of the solvent played a major role.…”

Section: ■ Discussionmentioning

confidence: 97%

Quantum Defects in Fluorescent Carbon Nanotubes for Sensing and Mechanistic Studies

et al. 2021

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Single-wall carbon nanotubes (SWCNT) fluoresce in the nearinfrared (NIR) region and have been assembled with biopolymers such as DNA to form highly sensitive molecular (bio)sensors. They change their fluorescence when they interact with analytes. Despite the progress in engineering these sensors, the underlying mechanisms are still not understood. Here, we identify processes and rate constants that explain the photophysical signal transduction by exploiting sp 3 quantum defects in the sp 2 carbon lattice of SWCNTs. As a model system, we use ssDNA-coated (6,5)-SWCNTs, which increase their NIR emission (E 11 , 990 nm) up to +250% in response to the important neurotransmitter dopamine. In contrast, SWCNTs coated with DNA but with a low number of NO 2 -aryl sp 3 quantum defects decrease both their E 11 (−35%) and defect-related E 11 * emission (−50%) at 1130 nm. Consequently, the interaction with the analyte does not change the radiative exciton decay pathway alone. Furthermore, the fluorescence response of pristine SWCNTs increases with SWCNT length, suggesting that exciton diffusion is affected. The quantum yield of pristine (6,5)-SWCNTs increases in response to the analyte from 0.6 to 1.3% and points to a change in non-radiative rate constants. These experimental results for dopamine and other analytes are explained by a Monte Carlo simulation of exciton diffusion, which supports a change in two non-radiative decay pathways together with an increase in exciton diffusion (three-rate constant model). The combination of such SWCNTs with defects and without defects enables the assembly of ratiometric biosensors with opposing responses at different wavelengths. In summary, we demonstrate how perturbation of a nanomaterial with quantum defects reveals the photophysical mechanism and reverses optical responses of biosensors.

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Section: ■ Discussionmentioning

confidence: 97%

Quantum Defects in Fluorescent Carbon Nanotubes for Sensing and Mechanistic Studies

et al. 2021

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“…Such strategies may include varying the antibiofouling polymers attached to the phospholipids, such as incorporating zwitterionic polymers, 35,48 or covalently linking polymers directly to the SWCNT surface. 49,50 Future work will also improve nanosensor sensitivity and selectivity to the CoV-2 S protein necessary for clinical application (comparisons in Table S2), potentially by incorporating a more specific sensing protein than ACE2, which serves as a receptor for other viral and endogenous proteins. 51 Such sensing proteins could include antibodies 52 or nanobodies, 53,54 as well as other viral biomarker binding moieties.…”

Section: ■ Conclusionmentioning

confidence: 99%

Rapid SARS-CoV-2 Spike Protein Detection by Carbon Nanotube-Based Near-Infrared Nanosensors

et al. 2021

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To effectively track and eliminate COVID-19, it is critical to develop tools for rapid and accessible diagnosis of actively infected individuals. Here, we introduce a single-walled carbon nanotube (SWCNT)-based optical sensing approach toward this end. We construct a nanosensor based on SWCNTs noncovalently functionalized with ACE2, a host protein with high binding affinity for the SARS-CoV-2 spike protein. The presence of the SARS-CoV-2 spike protein elicits a robust, 2-fold nanosensor fluorescence increase within 90 min of spike protein exposure. We characterize the nanosensor stability and sensing mechanism and passivate the nanosensor to preserve sensing response in saliva and viral transport medium. We further demonstrate that these ACE2-SWCNT nanosensors retain sensing capacity in a surface-immobilized format, exhibiting a 73% fluorescence turn-on response within 5 s of exposure to 35 mg/L SARS-CoV-2 virus-like particles. Our data demonstrate that ACE2-SWCNT nanosensors can be developed into an optical tool for rapid SARS-CoV-2 detection.

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“…Lastly, the fluorescence of SWCNTs is highly dependent on their surface composition. 55,123 Consequently, enzymatic reactions causing any alterations in the surface composition of SWCNTs are directly transduced into optical signals manifested in the modulation of the emitted fluorescence, enabling highly sensitive monitoring of enzyme activity. Due to these virtues, SWCNTs may be considered an ideal candidate for probing enzyme activity.…”

Section: Enzyme Activitymentioning

confidence: 99%

Monitoring Enzyme Activity Using Near-Infrared Fluorescent Single-Walled Carbon Nanotubes

Basu,

Hendler-Neumark,

Bisker

2024

ACS Sens.

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Enzymes serve as pivotal biological catalysts that accelerate essential chemical reactions, thereby influencing a variety of physiological processes. Consequently, the monitoring of enzyme activity and inhibition not only yields crucial insights into health and disease conditions but also forms the basis of research in drug discovery, toxicology, and the understanding of disease mechanisms. In this context, near-infrared (NIR) fluorescent single-walled carbon nanotubes (SWCNTs) have emerged as effective tools for tracking enzyme activity and inhibition through diverse strategies. This perspective explores the physicochemical attributes of SWCNTs that render them well-suited for such monitoring. Additionally, we delve into the various strategies developed so far for successfully monitoring enzyme activity and inhibition, emphasizing the distinctive features of each principle. Furthermore, we contrast the benefits of SWCNT-based NIR probes with conventional gold standards in monitoring enzyme activity. Lastly, we highlight the current challenges faced in this field and suggest potential solutions to propel it forward. This perspective aims to contribute to the ongoing progress in biodiagnostics and seeks to engage the wider community in developing and applying enzymatic assays using SWCNTs.

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Covalent Surface Modification Effects on Single-Walled Carbon Nanotubes for Multimodal Optical Applications

Cited by 4 publications

References 46 publications

Quantum Defects in Fluorescent Carbon Nanotubes for Sensing and Mechanistic Studies

Quantum Defects in Fluorescent Carbon Nanotubes for Sensing and Mechanistic Studies

Rapid SARS-CoV-2 Spike Protein Detection by Carbon Nanotube-Based Near-Infrared Nanosensors

Monitoring Enzyme Activity Using Near-Infrared Fluorescent Single-Walled Carbon Nanotubes

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