scholarly journals Temperature-sensitive carbon dots derived from poly(N-isopropylacrylamide) for fluorescence on–off properties

RSC Advances ◽  
2017 ◽  
Vol 7 (18) ◽  
pp. 11149-11157 ◽  
Author(s):  
Zihnil Adha Islamy Mazrad ◽  
Eun Bi Kang ◽  
Nuraeni Nuraeni ◽  
Gibaek Lee ◽  
Insik In ◽  
...  

Here, we report novel thermo-responsive fluorescent nanoparticles of carbonized poly(N-isopropylacrylamide) (PNIPAAm) through carbonization. The partial carbonized PNIPAAm (F-PNIPAAm) shows reversible capability based on fluorescence intensity.

2018 ◽  
Vol 15 (1) ◽  
pp. 47-55
Author(s):  
Xuebing Li ◽  
Haifen Yang ◽  
Ning Wang ◽  
Tijian Sun ◽  
Wei Bian ◽  
...  

Background: Morin has many pharmacological functions including antioxidant, anticancer, anti-inflammatory, and antibacterial effects. It is commonly used in the treatment of antiviral infection, gastropathy, coronary heart disease and hepatitis B in clinic. However, researches have shown that morin is likely to show prooxidative effects on the cells when the amount of treatment is at high dose, leading to the decrease of intracellular ATP levels and the increase of necrosis process. Therefore, it is necessary to determine the concentration of morin in biologic samples. Method: Novel water-soluble and green nitrogen and sulfur co-doped carbon dots (NSCDs) were prepared by a microwave heating process with citric acid and L-cysteine. The fluorescence spectra were collected at an excitation wavelength of 350 nm when solutions of NSCDs were mixed with various concentrations of morin. Results: The as-prepared NSCDs were characterized by transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The fluorescence intensity of NSCDs decreased significantly with the increase of morin concentration. The fluorescence intensity of NSCDs displayed a linear response to morin in the concentration 0.10-30 μM with a low detection limit of 56 nM. The proposed fluorescent probe was applied to analysis of morin in human body fluids with recoveries of 98.0-102%. Conclusion: NSCDs were prepared by a microwave heating process. The present analytical method is sensitive to morin. The quenching process between NSCDs and morin is attributed to the static quenching. In addition, the cellular toxicity on HeLa cells indicated that the as-prepared NSCDs fluorescent probe does not show obvious cytotoxicity in cell imaging. Our proposed method possibly opens up a rapid and nontoxic way for preparing heteroatom doped carbon dots with a broad application prospect.


Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1246
Author(s):  
Tengfei Wang ◽  
Hui Luo ◽  
Xu Jing ◽  
Jiali Yang ◽  
Meijun Huo ◽  
...  

Water-soluble fluorescent carbon dots (CDs) were synthesized by a hydrothermal method using citric acid as the carbon source and ethylenediamine as the nitrogen source. The repeated and scale-up synthetic experiments were carried out to explore the feasibility of macroscopic preparation of CDs. The CDs/Fe3+ composite was prepared by the interaction of the CDs solution and Fe3+ solution. The optical properties, pH dependence and stability behavior of CDs or the CDs/Fe3+ composite were studied by ultraviolet spectroscopy and fluorescence spectroscopy. Following the principles of fluorescence quenching after the addition of Fe3+ and then the fluorescence recovery after the addition of asorbic acid, the fluorescence intensity of the carbon dots was measured at λex = 360 nm, λem = 460 nm. The content of ascorbic acid was calculated by quantitative analysis of the changing fluorescence intensity. The CDs/Fe3+ composite was applied to the determination of different active molecules, and it was found that the composite had specific recognition of ascorbic acid and showed an excellent linear relationship in 5.0–350.0 μmol·L−1. Moreover, the detection limit was 3.11 μmol·L−1. Satisfactory results were achieved when the method was applied to the ascorbic acid determination in jujube fruit. The fluorescent carbon dots composites prepared in this study may have broad application prospects in a rapid, sensitive and trace determination of ascorbic acid content during food processing.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jisu Song ◽  
Jin Zhang

Abstract Carbon-dots (CDs), the emerging fluorescent nanoparticles, show special multicolor properties, chemical stability, and biocompatibility, and are considered as the new and advanced imaging probe in replacement of molecular fluorophores and semiconductor quantum dots. However, the requirement of external high power light source limits the application of fluorescent nanomaterials in bio-imaging. The present study aims to take advantage of bioluminescence resonance energy transfer mechanism (BRET) in creating self-illuminating C-dots. Renilla luciferase (Rluc) is chosen as the BRET donor molecule. Conjugation of Renilla luciferase and C-dots is necessary to keep their distance close for energy transfer. The optimal condition for achieving BRET is investigated by studying the effects of different factors on the performance of BRET, including the type of conjugation, concentration of carbon dots, and conjugation time. The linear relationship of BRET efficiency as a function of the amount of C-dots in the range of 0.20–0.80 mg/mL is observed. The self-illuminating carbon dots could be applied in bioimaging avoiding the tissue damage from the external high power light source.


Chemosensors ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 202
Author(s):  
Federico Calì ◽  
Valentina Cantaro ◽  
Luca Fichera ◽  
Roberta Ruffino ◽  
Giuseppe Trusso Sfrazzetto ◽  
...  

A bioinspired method of communication among biodevices based on fluorescent nanoparticles is herein presented. This approach does not use electromagnetic waves but rather the exchange of chemical systems—a method known as molecular communication. The example outlined was based on the fluorescence properties of carbon dots and follows a circular economy approach as the method involves preparation from the juice of lemon waste. The synthesis is herein presented, and the fluorescence properties and diffusion coefficient are evaluated. The application of carbon dots to molecular communication was studied from a theoretical point of view by numerically solving the differential equation that governs the phenomenon. The theoretical results were used to develop a prototype molecular communication platform that enables the communication of simple messages via aqueous fluids to a fluorescence-detecting biodevice receiver.


Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1171 ◽  
Author(s):  
Dan Zhao ◽  
Wenting Ma ◽  
Rong Wang ◽  
Xinzhou Yang ◽  
Jun Li ◽  
...  

Fluorescence/temperature-sensitive hydrogels, thanks to their properties in fluorescence and temperature sensitivity, have shown a promising outlook in the fields of drug delivery, cell imaging, etc., and thus become the focus of present research. This paper reports the preparation of green-fluorescence/temperature-sensitive hydrogels through one-step radical polymerization with green fluorescence-emissioned carbon dots as fluorescence probes and N-isopropylacrylamide as a monomer. UV-vis spectra, fluorescence spectra, and fluorescence microscope imaging have been used to characterize the prepared hydrogel, and to study their optical and temperature-sensitive properties. It was discovered that the emission of prepared hydrogel is excitation wavelength-dependent, pH responding, and excellent temperature-sensitive, as well as having good biocompatibility. The prepared hydrogel can also be applied as fluorescence ink in the fields of anti-counterfeit identification and appraisal.


2020 ◽  
Vol 96 (5) ◽  
pp. 1032-1040 ◽  
Author(s):  
Fatemeh Hashemi ◽  
Fatemeh Heidari ◽  
Nasrin Mohajeri ◽  
Farideh Mahmoodzadeh ◽  
Nosratollah Zarghami

RSC Advances ◽  
2016 ◽  
Vol 6 (89) ◽  
pp. 86012-86018 ◽  
Author(s):  
Mengmeng Li ◽  
Xiaoyan Song ◽  
Tingbin Zhang ◽  
Lintao Zeng ◽  
Jinfeng Xing

The fluorescence intensity change of TPE encapsulated in POSS–PNIPAM with a particular LCST (37.5 °C) with the temperature change.


NANO ◽  
2017 ◽  
Vol 12 (02) ◽  
pp. 1750024 ◽  
Author(s):  
Xiqing Liu ◽  
Xiao Wei ◽  
Yeqing Xu ◽  
Hongji Li ◽  
Kai Lu ◽  
...  

In this paper, a novel fluorescent nanoswitch based on carbon dots (CDs) was developed for the sensitive and selective determination of Hg[Formula: see text] and I[Formula: see text]. The CDs were obtained by simple hydrothermal process and had a strong fluorescence emission at 440[Formula: see text]nm. The fluorescence of the CDs can be selectively quenched by Hg[Formula: see text] ion, and then the I[Formula: see text] was added into the system, which can interact with Hg[Formula: see text] and recover fluorescence of the CDs. Under optimal conditions, the quenching fluorescence intensity on addition of Hg[Formula: see text] has obtained a satisfactory linear relationship covering the linear range of 0–50[Formula: see text][Formula: see text]M with the linear relationship ([Formula: see text]), and the limit of detection is 0.047[Formula: see text][Formula: see text]M. The additions of I[Formula: see text] could lead to the fluorescence intensity of the solution of CDs and Hg[Formula: see text] (50[Formula: see text][Formula: see text]M) recover rapidly, which is linearly related ([Formula: see text]) to the concentration of I[Formula: see text] in the range from 0 to 70[Formula: see text][Formula: see text]M, the detection limit for I[Formula: see text] was calculated to be 0.084[Formula: see text][Formula: see text]M. Moreover, the developed method to detect Hg[Formula: see text] and I[Formula: see text] was evaluated in real examples, and the fluorescence switching can sensitively and selectively detect Hg[Formula: see text] and I[Formula: see text] over some potentially interfering ions, the recoveries were up to 97.8–107.0% and 96.7–106.6%, respectively.


2019 ◽  
Vol 43 (11-12) ◽  
pp. 507-515 ◽  
Author(s):  
Ning Wang ◽  
Xuebing Li ◽  
Xuefang Yang ◽  
Zenglian Tian ◽  
Wei Bian ◽  
...  

Nitrogen-doped carbon dots were synthesized using citric acid monohydrate and glutathione as raw materials. The synthesized nitrogen-doped carbon dots were characterized by multiple analytical techniques, including transmission electron microscopy, Fourier transform infrared spectroscopy, ultraviolet–visible absorption spectroscopy, X-ray photoelectron spectroscopy, X-ray diffractometry, and fluorescence spectra. The fluorescence intensity of the nitrogen-doped carbon dots gradually quenched with different concentrations of Cu2+ ions. The effect of the pH value, the nitrogen-doped carbon dot concentration, and the reaction time on the fluorescence intensity of the N-CDs-Cu2+ system was investigated, and the experimental conditions were optimized. A rapid and sensitive method for the determination of Cu2+ ions was established that exhibited a good linearity in the concentration range 0.20–200.0 μM with a detection limit of 0.27 nM. Meanwhile, the fluorescence quenching mechanism of the interaction between nitrogen-doped carbon dots and Cu2+ was preliminarily discussed. The method was used to detect trace Cu2+ in tap water and lake water, with recoveries ranging from 98.1% to 102.0%. Furthermore, due to low cytotoxicity and good biocompatibility, nitrogen-doped carbon dots as a probe were also successfully used in bioimaging.


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