Green and Near-Infrared Dual-Mode Afterglow of Carbon Dots and Their Applications for Confidential Information Readout

AbstractNear-infrared (NIR), particularly NIR-containing dual-/multi-mode afterglow, is very attractive in many fields of application, but it is still a great challenge to achieve such property of materials. Herein, we report a facile method to prepare green and NIR dual-mode afterglow of carbon dots (CDs) through in situ embedding o-CDs (being prepared from o-phenylenediamine) into cyanuric acid (CA) matrix (named o-CDs@CA). Further studies reveal that the green and NIR afterglows of o-CDs@CA originate from thermal activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) of o-CDs, respectively. In addition, the formation of covalent bonds between o-CDs and CA, and the presence of multiple fixation and rigid effects to the triplet states of o-CDs are confirmed to be critical for activating the observed dual-mode afterglow. Due to the shorter lifetime and insensitiveness to human vision of the NIR RTP of o-CDs@CA, it is completely covered by the green TADF during directly observing. The NIR RTP signal, however, can be readily captured if an optical filter (cut-off wavelength of 600 nm) being used. By utilizing these unique features, the applications of o-CDs@CA in anti-counterfeiting and information encryption have been demonstrated with great confidentiality. Finally, the as-developed method was confirmed to be applicable to many other kinds of CDs for achieving or enhancing their afterglow performances.

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A dual-mode colorimetric and fluorometric nanosensor for detection of uric acid based on N, P co-doped carbon dots and in-situ formation of Au/Ag core-shell nanoparticles

Microchemical Journal ◽

10.1016/j.microc.2020.105865 ◽

2021 ◽

Vol 162 ◽

pp. 105865

Author(s):

Tooba Hallaj ◽

Neda Azizi ◽

Mohammad Amjadi

Keyword(s):

Uric Acid ◽

Carbon Dots ◽

Core Shell ◽

Dual Mode ◽

Shell Nanoparticles ◽

In Situ Formation ◽

Doped Carbon Dots ◽

Core Shell Nanoparticles ◽

Co Doped

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Live cell bioimaging with carbon dots produced in situ by femtosecond laser from intracellular material

10.1101/455808 ◽

2018 ◽

Cited By ~ 1

Author(s):

Aleksander M. Shakhov ◽

Artyom A. Astafiev ◽

Alina A. Osychenko ◽

Maria S. Syrchina ◽

Viktor A. Nadtochenko

Keyword(s):

Femtosecond Laser ◽

Carbon Dots ◽

Near Infrared ◽

Laser Pulses ◽

Culture Cell ◽

Femtosecond Laser Pulses ◽

Live Cell ◽

Two Photon ◽

Two Photon Fluorescence

Owning to excellent optical properties and high biocompatibility carbon dots (CDs) have drawn increasing attention and have been widely applied as imaging agents for various bio-applications. Here we report a strategy for live-cell fluorescent bioimaging based on in situ synthesis of CDs within cells by tightly focused femtosecond laser pulses. Laser-produced carbon dots exhibit bright excitation-dependent fluorescence and are highly two-photon active under near infrared femtosecond excitation, thus demonstrating a potential for two-photon fluorescence imaging. The Raman spectra of fluorescent centers show strong D (1350 cm-1) and G (1590 cm-1) bands, thus suggesting that they are composed of carbon dots with sp2-hybridized core. Using Mouse GV oocytes as a model system we examine cytotoxicity and demonstrate the possibility of long-term fluorescent intracellular tracking of the laser-produced CDs. Created virtually in any point of the live cell, CD-based fluorescent μm-sized markers demonstrate high structural stability and retain bright fluorescence many hours after formation. Our results point to laser-produced fluorescent CDs as a highly-potent tool for cell cycle tracking, culture cell marking and probing intracellular movements.

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Near infrared spectroscopy of Eucalyptus pellita for foliar nutrients and the potential for real-time monitoring of trees in fertiliser trial plots

Journal of Near Infrared Spectroscopy ◽

10.1177/09670335211007971 ◽

2021 ◽

pp. 096703352110079

Author(s):

Agustan Alwi ◽

Roger Meder ◽

Yani Japarudin ◽

Hazandy A Hamid ◽

Ruzana Sanusi ◽

...

Keyword(s):

Near Infrared ◽

Acacia Mangium ◽

Nir Spectroscopy ◽

Nutrient Status ◽

Significant Loss ◽

Eucalyptus Pellita ◽

Operational Decision Making ◽

Fertiliser Application ◽

Planting Distance

Eucalyptus pellita F. Muell. has become an important tree species in the forest plantations of SE Asia, and in Malaysian Borneo in particular, to replace thousands of hectares of Acacia mangium Willd. which has suffered significant loss caused by Ceratocystis manginecans infection in Sabah, Malaysia. Since its first introduction at a commercial scale in 2012, E. pellita has been planted in many areas in the region. The species replacement requires new silvicultural practices to induce the adaptability of E. pellita to grow in the region and this includes relevant research to optimise such regimes as planting distance, pruning, weeding practices and nutrition regimes. In this present study, the nutritional status of the foliage was investigated with the aim to develop near infrared spectroscopic calibrations that can be used to monitor and quantify nutrient status, particularly total foliar nitrogen (N) and phosphorus (P) in the field. Spectra acquired on fresh foliage in situ on the tree could be used to predict N and P with accuracy suitable for operational decision-making regards fertiliser application. If greater accuracy is required, spectra acquired on dry, milled foliage could be used to predict N and P within a relative error of 10% (R2c, r2CV, RMSEP, RPD = 0.77, 0.71, 0.02 g 100/g, 1.9 for foliar P and = 0.90, 0.88, 0.21 g 100/g, 3.0 for foliar N on dry, milled foliage). The ultimate application of this is in situ nutrient monitoring, particularly to aid longitudinal studies in fertiliser trial plots and forest operations, as the non-destructive nature of NIR spectroscopy would enable regular monitoring of individual leaves over time without the need to destructively sample them. This would aid the temporal and spatial analysis of field data.

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