Carbon Dots for Intracellular pH Sensing with Fluorescence Lifetime Imaging Microscopy

Huang, Maojia; Liang, Xinyue; Zhang, Zixiao; Wang, Jing; Fei, Yiyan; Ma, Junjun; Qu, Songnan; Mi, Lan

doi:10.3390/nano10040604

Cited by 34 publications

(27 citation statements)

References 69 publications

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“…It is, however, not prone to photobleaching discrepancies limiting the use of conventional fluorophores, as these GQDs are known to exhibit high fluorescence stability under irradiation [ 36 ]. Concentration-independent lifetime measurements can circumvent the need for calibration, however, they are not considered for these in vitro experiments, as carbon based nanomaterials’ lifetimes are known to be strongly affected by a number of other environmental factors including the variations in intracellular pH [ 46 ].…”

Section: Resultsmentioning

confidence: 99%

Graphene Quantum Dots as Intracellular Imaging-Based Temperature Sensors

et al. 2021

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Non-invasive temperature sensing is necessary to analyze biological processes occurring in the human body, including cellular enzyme activity, protein expression, and ion regulation. To probe temperature-sensitive processes at the nanoscale, novel luminescence nanothermometers are developed based on graphene quantum dots (GQDs) synthesized via top-down (RGQDs) and bottom-up (N-GQDs) approaches from reduced graphene oxide and glucosamine precursors, respectively. Because of their small 3–6 nm size, non-invasive optical sensitivity to temperature change, and high biocompatibility, GQDs enable biologically safe sub-cellular resolution sensing. Both GQD types exhibit temperature-sensitive yet photostable fluorescence in the visible and near-infrared for RGQDs, utilized as a sensing mechanism in this work. Distinctive linear and reversible fluorescence quenching by up to 19.3% is observed for the visible and near-infrared GQD emission in aqueous suspension from 25 °C to 49 °C. A more pronounced trend is observed with GQD nanothermometers internalized into the cytoplasm of HeLa cells as they are tested in vitro from 25 °C to 45 °C with over 40% quenching response. Our findings suggest that the temperature-dependent fluorescence quenching of bottom-up and top-down-synthesized GQDs studied in this work can serve as non-invasive reversible/photostable deterministic mechanisms for temperature sensing in microscopic sub-cellular biological environments.

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Section: Resultsmentioning

confidence: 99%

Graphene Quantum Dots as Intracellular Imaging-Based Temperature Sensors

et al. 2021

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“…In in vitro cell imaging CQDs are used to enlighten specific structural elements or biological parameters. As an example, CQDs functionalized with both N and Cl based functional groups were utilized to detect the intracellular pH in HeLa cells [325]. As a matter of fact, such CQDs exhibit a fluorescence which decreases with increasing the pH of the medium.…”

Section: Carbon Dots Sensingmentioning

confidence: 99%

Carbon Nanomaterials: Synthesis, Functionalization and Sensing Applications

Speranza

2021

Nanomaterials

152

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Recent advances in nanomaterial design and synthesis has resulted in robust sensing systems that display superior analytical performance. The use of nanomaterials within sensors has accelerated new routes and opportunities for the detection of analytes or target molecules. Among others, carbon-based sensors have reported biocompatibility, better sensitivity, better selectivity and lower limits of detection to reveal a wide range of organic and inorganic molecules. Carbon nanomaterials are among the most extensively studied materials because of their unique properties spanning from the high specific surface area, high carrier mobility, high electrical conductivity, flexibility, and optical transparency fostering their use in sensing applications. In this paper, a comprehensive review has been made to cover recent developments in the field of carbon-based nanomaterials for sensing applications. The review describes nanomaterials like fullerenes, carbon onions, carbon quantum dots, nanodiamonds, carbon nanotubes, and graphene. Synthesis of these nanostructures has been discussed along with their functionalization methods. The recent application of all these nanomaterials in sensing applications has been highlighted for the principal applicative field and the future prospects and possibilities have been outlined.

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“…Carbon dots (CDs) based materials show great potential for bioimaging studies of intracellular pH sensing due to their stable optical properties, biocompatibility, and low toxicity. A pH-sensitive CD for intracellular pH sensing by fluorescence lifetime imaging microscopy was developed by L. Mi and coworkers [ 91 ]. This CD sensor presenting carboxyl, hydroxyl, and amide groups on the surface was prepared by a solvothermal reaction from citric acid and urea.…”

Section: Nano-sized Visual Ph Sensorsmentioning

confidence: 99%

“…This CD sensor presenting carboxyl, hydroxyl, and amide groups on the surface was prepared by a solvothermal reaction from citric acid and urea. The different groups on the CD surface undergo changes with the pH environments leading to different fluorescence lifetime values in the pH range of 2.6–8.6 inside HeLa cells microenvironment [ 91 ].…”

Section: Nano-sized Visual Ph Sensorsmentioning

confidence: 99%

Visual pH Sensors: From a Chemical Perspective to New Bioengineered Materials

Costanzo

Panunzi

2021

Molecules

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Many human activities and cellular functions depend upon precise pH values, and pH monitoring is considered a fundamental task. Colorimetric and fluorescence sensors for pH measurements are chemical and biochemical tools able to sense protons and produce a visible signal. These pH sensors are gaining widespread attention as non-destructive tools, visible to the human eye, that are capable of a real-time and in-situ response. Optical “visual” sensors are expanding researchers’ interests in many chemical contexts and are routinely used for biological, environmental, and medical applications. In this review we provide an overview of trending colorimetric, fluorescent, or dual-mode responsive visual pH sensors. These sensors include molecular synthetic organic sensors, metal organic frameworks (MOF), engineered sensing nanomaterials, and bioengineered sensors. We review different typological chemical entities of visual pH sensors, three-dimensional structures, and signaling mechanisms for pH sensing and applications; developed in the past five years. The progression of this review from simple organic molecules to biological macromolecules seeks to benefit beginners and scientists embarking on a project of pH sensing development, who needs background information and a quick update on advances in the field. Lessons learned from these tools will aid pH determination projects and provide new ways of thinking for cell bioimaging or other cutting-edge in vivo applications.

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Carbon Dots for Intracellular pH Sensing with Fluorescence Lifetime Imaging Microscopy

Cited by 34 publications

References 69 publications

Graphene Quantum Dots as Intracellular Imaging-Based Temperature Sensors

Graphene Quantum Dots as Intracellular Imaging-Based Temperature Sensors

Carbon Nanomaterials: Synthesis, Functionalization and Sensing Applications

Visual pH Sensors: From a Chemical Perspective to New Bioengineered Materials

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