Resonance Energy Transfer Strategy Research Articles

A novel fluorescent probe for ratiometric detection of formaldehyde in real food samples, living tissues and zebrafish.

Herein, a two-photon (TP) ratiometric fluorescent probe (NpFA) was developed for detecting formaldehyde (FA) in real food samples, living onion tissues and zebrafish by fluorescence resonance energy transfer (FRET) strategy. Specifically, a TP fluorophore as the donor and a FA turn-on naphthalimide fluorophore as the acceptor were connected by a non-conjugated linker to construct the TP-FRET-based NpFA, which exhibited a target-modulated ratiometric fluorescence response to FA rapidly with high selectivity and sensitivity during 65s, and a large ratio ~5-fold enhancement at I550/I410 after addition of FA, displaying ~60-fold enhancement at 550nm and a quite low DOC of 5.8±0.2nM. Moreover, NpFA has a good imaging resolution and depth of deep tissue penetration. Therefore, based on the above results, NpFA has the capability to be a useful tool for investigating FA in real samples application, and we also hope NpFA will further study of the physiological and pathological function of FA.

A novel dark resonance energy transfer-based fluorescent probe with large Stokes shift for the detection of pH and its imaging application

Herein, we design and synthesize a pH-dependent turn-on fluorescent probe based on the dark resonance energy transfer (DRET) strategy. A silacyclopentadiene (silole) derivative with aggregation-induced emission (AIE) properties is selected as dark energy donor and a rhodamine B derivative with spirocyclic structure as energy acceptor. Attributed to the non-emissive character of silole in solution, fluorescence leakage from the donor is eliminated. Binding with H+ turns on the DRET process and energy of donor is converted to the acceptor's fluorescence output before non-radiative decay. The probe responds to pH variation from 2.75 to 5 in buffer solutions with a Stokes shift up to 220 nm. In addition, imaging experiments suggest that the probe is capable of determining pH fluctuations in live cells with good cell membrane permeability and low cytotoxicity.

A TAT peptide-based ratiometric two-photon fluorescent probe for detecting biothiols and sequentially distinguishing GSH in mitochondria

Although biothiols, including cysteine (Cys), glutathione (GSH), and homocysteine (Hcy) can be used to diagnose many diseases and research physiological metabolism in many physiological processes, in situ real-time detection and differentiation of biothiols is still challenging because their similar chemical properties and molecular structures. Herein, we utilized the native chemical ligation (NCL) reaction mechanism to develop a Förster resonance energy transfer (FRET) strategy for designing a cell penetration peptide TAT-modified ratiometric two-photon biothiols probe (TAT-probe). The TAT-probe can not only rapidly enter into mitochondria assisted by TAT peptide, but also simultaneously detect biothiols and sequentially distinguish GSH. When the TAT-probe was excited with 404/820 nm wavelength light, it showed a change in the ratio of fluorescence after adding biothiols, including a quenched red fluorescence intensity (λem = 585 nm) and an enhanced signal in green fluorescence intensity (λem = 520 nm). Excitingly, the TAT-probe excited at 545 nm could display a red fluorescence (λem = 585 nm) towards GSH and a quenched signal towards Hcy or Cys. This specific fluorescence response indicated the TAT-probe could effectively detect biothiols and differentiate GSH from Cys/Hcy in mitochondria. This work pioneered a new approach to design and synthesize biothiol-probes based on peptides and NCL reaction mechanism.

Sensitive electrochemiluminescence aptasensor for chlorpyrifos detection based on resonance energy transfer between MoS2/CdS nanospheres and Ag/CQDs

A "signal on" aptasensor was fabricated for chlorpyrifos detection by a highly efficient electrochemiluminescence resonance energy transfer (ECL-RET) strategy between MoS2/CdS nanospheres and silver/carbon quantum dots (Ag/CQDs). Compared with the conventional MoS2/CdS nanosheets, the MoS2/CdS nanospheres have a larger specific surface area and electron density, which makes the catalytic effect on K2S2O8 stronger and has higher luminescence intensity. As a receptor, through the synergistic effect of Ag NPs and CQDs, it has a very wide absorption band between 300 and 600 nm. The absorption band and the emission spectrum of MoS2/CdS completely overlap, and the high quantum yield of Ag/CQDs can achieve efficient energy resonance transfer. The proposed ECL aptasensor provided a linear range from 10 nM to 1.0 fM for chlorpyrifos detection and the detection limit of 0.35 fM (S/N = 3) under optimal experimental conditions. The method was successfully applied to the detection of chlorpyrifos in fruit and vegetable samples with satisfactory results.

Ultrasensitive Fluorescent miRNA Biosensor Based on a "Sandwich" Oligonucleotide Hybridization and Fluorescence Resonance Energy Transfer Process Using an Ln(III)-MOF and Ag Nanoparticles for Early Cancer Diagnosis: Application of Central Composite Design.

Herein, a novel, rapid, highly sensitive, and selective fluorescent biosensor is presented, which is designed based on "sandwich-type" hybridization of oligonucleotides and the fluorescence resonance energy transfer (FRET) strategy. It senses and determines the MicroRNA-155 (miRNA-155) expression levels as a cancer biomarker. In this study, a modified La(III)-metal-organic framework(MOF) and silver nanoparticles (Ag NPs) were used as the energy donor-acceptor pairs in fluorescence quenching through the FRET process. La(III)-MOF was synthesized and then modified by glutaraldehyde as a cross-linking agent. The Ag NPs were also prepared, and then, the surface of both was conjugated with different 5'-amino-labeled ssDNA strands (aptamers). These prepared nanoprobes were characterized by various physicochemical techniques such as X-ray diffraction, energy-dispersive X-ray spectrometry, Fourier transform infrared, field emission scanning electron microscopy, UV-vis spectroscopy, elemental mapping, and gel electrophoresis. To optimize the detection conditions, several factors affecting biosensor performance were assessed by one variable-at-a-time and central composite design methods. Under optimum conditions, this "turn-off" fluorescent biosensor could detect and determine as low as 0.04 ppb (ng. mL-1) or 5.5 fM of the miRNA-155 biomarker. Therefore, this biosensor provides highly promising potential for lung and breast cancer diagnosis.

A progesterone biosensor derived from microbial screening

Bacteria are an enormous and largely untapped reservoir of biosensing proteins. We describe an approach to identify and isolate bacterial allosteric transcription factors (aTFs) that recognize a target analyte and to develop these TFs into biosensor devices. Our approach utilizes a combination of genomic screens and functional assays to identify and isolate biosensing TFs, and a quantum-dot Förster Resonance Energy Transfer (FRET) strategy for transducing analyte recognition into real-time quantitative measurements. We use this approach to identify a progesterone-sensing bacterial aTF and to develop this TF into an optical sensor for progesterone. The sensor detects progesterone in artificial urine with sufficient sensitivity and specificity for clinical use, while being compatible with an inexpensive and portable electronic reader for point-of-care applications. Our results provide proof-of-concept for a paradigm of microbially-derived biosensors adaptable to inexpensive, real-time sensor devices.

Magnetic resonance energy transfer for in vivo glutathione susceptibility weighted imaging

Glutathione (GSH) plays a vital role in maintaining biological redox homeostasis. Accordingly, accurate imaging of glutathione in vivo is of great significance. Herein, we propose a magnetic resonance energy transfer (MRET) strategy based on a distance-dependent magnetic exchange coupling effect (MECE), which can realize GSH detection within tumors in vivo by susceptibility weighted imaging (SWI). Fe3O4 nanoparticles (NPs) and CoFe2O4 NPs linked with cystamine (Fe3O4–S–S–CoFe2O4) have been successfully designed as SWI nanoprobes. After the disulfide bonds are broken by excess GSH in the tumor, the increase in the distance between Fe3O4 NPs and CoFe2O4 NPs will induce a decrease of MECE and magnetic susceptibility. As a result, the changes in the SWI signals are used for tumor GSH detection in vivo. Experimental results in vitro and in vivo demonstrate that the Fe3O4–S–S–CoFe2O4 SWI nanoprobe can sensitively detect concentrations of GSH in tumors. Hence, this strategy not only improves the sensitivity of the GSH response in SWI but also provides a powerful basis for the design of other responsive functional MRI nanoprobes.

An efficient TP-FRET-based lysosome-targetable fluorescent probe for imaging peroxynitrite with two well-resolved emission channels in living cells, tissues and zebrafish

Peroxynitrite (ONOO−), an important role of reactive oxygen species (ROS) in vivo, and studies showed abnormal of ROS can induce lysosomal membrane permeabilization (LMP) and lead to the death of cells. Thus, it is of great significance for designing an effective method for investigating relationship between physiology and pathology between ONOO− and lysosome. Herein, for the first time, we adopted a Förster resonance energy transfer (FRET) strategy to construct a lysosome-targetable small molecular ratiometric two-photon (TP) fluorescent probe (NpRh-ONOO) for detecting ONOO− in living cells, tissues and zebrafish. Specifically, a TP fluorophore and a rhodamine B fluorophore are directly connected by a flexible piperidine linker to form the TP-FRET-scaffold, a hydrazide as ONOO− reactive set, and a dimethylamino as lysosome targeting-group, which shows a target-modulated ratiometric TP fluorescence response, two well-resolved emission peaks separated by 73 nm, rapid response (<10 s), high selectivity and sensitivity with the detection limit is as low as 3.3 nM for ONOO−. These prominent features of probe were then applied for ratiometric bioimaging both exogenous and endogenous peroxynitrite in living cells, tissues and zebrafish, demonstrating it can be used as a powerful tool for biological research of lysosomal peroxynitrite in biological systems.

Electrochemiluminescence Double Quenching System Based on Novel Emitter GdPO4:Eu with Low-Excited Positive Potential for Ultrasensitive Procalcitonin Detection.

Nowadays, the electrochemiluminescence (ECL) immunosensor with the unique superiority of tunable luminescence and ultrahigh sensitivity has become one of the most promising immunoassay techniques, especially for low-abundance biomarkers analysis. However, the use of signal probes with high excited potential and applied emitters which owned good intensity but biotoxicity limited its application. Herein, an ECL resonance energy transfer strategy was developed based on protein bioactivity protection utilizing europium-doped phosphoric acid gadolinium (GdPO4:Eu) as novel low-potential luminophor (donor) and Pd@Cu2O as the quenching probe (acceptor). Specifically, GdPO4:Eu was first prepared by using the hydrothermal synthesis method to apply in ECL, and when it coexisted with K2S2O8, cathode, a strong ECL signal would be generated at a low potential of -1.15 V (vs Ag/AgCl), where the immunocompetence of antigens and antibodies can be maintained well. Electrical pair Eu3+/Eu2+, as the coreactant promoter, produced by potential excitation could produce more SO4•- to accelerate the oxidation process of GdPO4:Eu. Meanwhile, Cu2O coated onto Pd (Pd@Cu2O), as a dual-quencher, enhanced the quenching effect of Pd alone and controlled the ECL intensity of the "signal on" state within a reasonable range. As a result, the proposed biosensor for detection of trace procalcitonin, a biomarker of systemic inflammatory response syndrome, exhibited a far low detection limit, 0.402 fg/mL (S/N = 3). Importantly, this work not only utilized a promising ECL emitter for biosensing platform construction but also had momentous potential in biomarker detection of disease diagnosis and clinical analysis.

An effective FRET-based two-photon ratiometric fluorescent probe with double well-resolved emission bands for lysosomal pH changes in living cells and zebrafish.

In cells, lysosome is an acidic organelle (approximately pH 4.5-5.5), whose pH changes plays a key role in mediating various biological processes. To address this issue, a lot of fluorescent probes have been developed and prepared for tracking lysosomal pH changes. However, few of these probes can realize the imaging of lysosomal pH changes in biosystems. Herein, a new two-photon (TP) ratiometric fluorescent probe (NpRhLys-pH) by adopting the fluorescence resonance energy transfer (FRET) strategy has been developed for imaging of lysosomal pH changes in living cells and zebrafish. In this probe NpRhLys-pH, constructed by conjugating a TP fluorophore (D-Π-A-structured naphthalimide derivative) with a rhodamine B fluorophore via a non-conjugated flexible linker, the morpholine moiety serves as a targeting unit for anchoring lysosomes, and the xanthane derivative shows a pH-modulated open/close form of the spirocycle. Such a scaffold affords the NpRhLys-pH is a reliable and specific probe for anchoring lysosomes in living cells and zebrafish with dual-channel emission peaks separated by 85 nm, and responds to lysosomal pH rapidly and reversibly with high selectivity and sensitivity, demonstrating it can be used as a powerful tool for the biological research of the relationship between physiology and pathology and lysosomal pH changes in biological systems.

A new ratiometric fluorescent probe for sensing lysosomal HOCl based on fluorescence resonance energy transfer strategy.

In this paper, ratiometric imaging of lysosomal HOCl was realized with a molecular probe (CR-Ly) based on fluorescence resonance energy transfer by using coumarin as the donor and rhodamine as acceptor. CR-Ly showed high sensitivity and fast response to HOCl. Moreover, CR-Ly exhibited excellent selectivity and sensitivity for HOCl over other biologically relevant species. Furthermore, it was successfully utilized to image the endogenous HOCl with low cytotoxity. And CR-Ly was capable of targeting lysosomes and monitoring lysosomal hypochlorous acid changes owing to the presence of the morpholine moiety. We believe that probe CR-Ly would be helpful to further research on the HOCl-associated diseases in lysosomes.

A chemiluminescence resonance energy transfer strategy and its application for detection of platinum ions and cisplatin.

A novel chemiluminescence resonance energy transfer (CRET) system was developed and combined with a structure-switching aptamer for the highly sensitive detection of platinum. Platinum was chosen as a model analyte to demonstrate the generality of the new CRET system. This aptameric platform consisted of a streptavidin labeled aptamer against platinum and a streptavidin-coated magnetic bead for the selective separation of platinum-bound aptamer. The platinum-aptamer probe contained several guanine (G) bases bound to the 3,4,5-trimethoxyphenyl-glyoxal (TMPG) donor group at the 5' end, a fluorescent acceptor (6-carboxy-2',4,7,7'-tetrachlorofluorescein, TET) at the 3' end, and a streptavidin aptamer sequence in which several base pairs were replaced by the G-G mismatch to induce the platinum-oligonucleotide coordination. The chemiluminescence (CL) generated by TMPG/G bases is transferred to the acceptor (TET). In the presence of platinum, the platinum-aptamer probe was folded such that the G bases at the 5' end and TET at the 3' were in close proximity. The complex was separated using streptavidin-coated magnetic beads by the addition of TMPG to form the TMPG/G bases complex. The ultraweak CL from the TMPG/G bases was strongly enhanced by TET. This novel CRET-based method can be easily performed with high limit of detection (50ng·mL-1) and selectivity over other metal ions. This technique provides a novel method for simple, fast, and convenient point-of-care diagnostics for monitoring proteins and metal ions. Graphical abstract Schematic presentation of chemiluminescence resonance energy transfer (CRET) detection of platinum(II) by Pt-base pair coordination to the aptamer. TMPG: 3,4,5-trimethoxyphenyl-glyoxal, fluorophore TET: 6-carboxy-2',4,7,7'-tetrachlorofluorescein.

Aptasensor for multiplex detection of antibiotics based on FRET strategy combined with aptamer/graphene oxide complex

The development of a multiplexed sensing platform is necessary for highly selective, sensitive, and rapid screening of specific antibiotics. In this study, we designed a novel multiplex aptasensor for antibiotics by fluorescence resonance energy transfer (FRET) strategy using DNase I-assisted cyclic enzymatic signal amplification (CESA) method combined with aptamer/graphene oxide complex. The aptamers specific for sulfadimethoxine, kanamycin, and ampicillin were conjugated with Cyanine 3 (Cy3), 6-Carboxyfluorescein (FAM), and Cyanine 5 (Cy5), respectively, and graphene oxide (GO) was adopted to quench the fluorescence of the three different fluorophores with the efficiencies of 94.36%, 93.94%, and 96.97% for Cy3, FAM, and Cy5, respectively. CESA method was used for sensitive detection, resulting in a 2.1-fold increased signal compared to those of unamplified method. The aptasensor rapidly detected antibiotics in solution with limit of detection of 1.997, 2.664, and 2.337 ng/mL for sulfadimethoxine, kanamycin, and ampicillin, respectively. In addition, antibiotics dissolved in milk were efficiently detected with similar sensitivities. Multiplexed detection test proved that the fluorescently modified aptamers could work separately from each other. The results indicate that the aptasensor offers high specificity for each antibiotic and enables simultaneous and multicolor sensing for rapid screening of multiple antibiotics at the same time.

A dual-site modulated FRET-based two-photon ratiometric fluorescent probe for tracking lysosomal pH changes in living cells, tissues and zebrafish

Lysosomal pH plays an essential role in mediating various biological processes such as immunization, cell metabolism and enzyme activity. Herein, by utilizing the fluorescence resonance energy transfer (FRET) strategy, a two-photon (TP) ratiometric fluorescent probe (NpLys-pH) has been developed for tracking of lysosomal pH changes in living cells, tissues, and zebrafish. NpLys-pH was constructed by conjugating a pH turn-on TP fluorophore 1 (D-π-A-structured naphthalene derivative) with a pH turn-off naphthalimide fluorophore 2via a non-conjugated linker. Meanwhile, NpLys-pH has two potential pH response sites that modulate the fluorescence signal by ICT and PET, respectively. The FRET process exists between the TP fluorophore 1 and naphthalimide fluorophore 2. In addition, NpLys-pH respond to pH rapidly and reversibly with high selectivity and sensitivity and has been applied for tracking lysosomal pH changes in living cells, tissues and zebrafish. We expect that the new probe present here can prompt the development of a wide variety of TP ratiometric fluorescent probes which can find application in detecting other important analytes in biological systems.

Electrochemiluminescence resonance energy transfer for both “turn-off” detection of 2,4,6-trinitrophenol and “turn-on” detection of lidocaine hydrochloride using luminol-doped silica nanoparticles

It is the first time to develop electrochemiluminescence resonance energy transfer (ECRET) strategy using luminol-doped silica nanoparticles (luminol-SiNPs) for both “turn-off” detection of 2,4,6-trinitrophenol (TNP) and “turn-on” detection of anesthetic drug lidocaine hydrochloride (LDC). The spectral overlap of ECL emission of luminol-SiNPs with the absorption of TNP triggers ECRET from luminol-SiNPs to TNP and results in the decreased ECL signals. Besides, the specific interaction between TNP and LDC consumes TNP, accordingly prevents ECRET from luminol-SiNPs to TNP and achieves increasing ECL signals. The proposed ECRET strategy using luminol-SiNPs exhibits fast response (within 10 min), high sensitivity with LOD of 22.4 nM for TNP and 92.5 nM for LDC, respectively. It is also successfully applied in ECRET detection of TNP in lake water, LDC in human serum and commercial drug sample detections with satisfactory recoveries. More importantly, ECL of luminol-SiNPs is measured via linear sweep voltammetry by electrochemical reduction of dissolved oxygen at negative potential (– 1 V) and in no need of adding hydrogen peroxide (H2O2). Reactive oxygen species be generated in situ and make luminol-SiNPs system emit ECL, which makes ECL of the whole luminol-SiNPs system more stable than luminol-H2O2 system.

Glutaraldehyde non-conjugated chitosan polymer fluorophores for selective determination of picric acid via fluorescence resonance energy transfer strategy

Water-dispersed glutaraldehyde (GA) non-conjugated chitosan polymer fluorophores (GCPF) with quantum yield of 16% is synthesized by stirring chitosan and GA for 6 h at room temperature in the present work. It is a facile and mild method and fluorescent GCPF can be stabled for two months. Owing to the spectral overlap of fluorescent spectrum of GCPF and absorption spectrum of picric acid (PA), a novel sensitive fluorescent method using fluorescent GCPF for PA detection from 10 nM to 50 μM via fluorescence resonance energy transfer (FRET) strategy is established. The distance between donor of GCPF and acceptor of PA (R0 value) is calculated to be 3.5 nm. FRET method using fluorescent GCPF possesses high sensitivity (LOD of 2.8 nM), and selectivity and fast response within 2 min. Moreover, fluorescent GCPF is also utilized in visual analysis of PA using cotton swabs. Fluorescence quenching effect can be observed by eyes irradiated with 365 nm ultraviolet light at cotton swabs and using GCPF solid on quartz glasses, which paves an effect and wide way for the application of fluorescent GCPF in our daily life.

Hydrogenated Titanium Oxide Decorated Upconversion Nanoparticles: Facile Laser Modified Synthesis and 808 nm Near-Infrared Light Triggered Phototherapy

With multiphoton excited upconversion nanoparticles (UCNPs) as energy transducer, ultraviolet (UV) light responsive titanium dioxide (TiO2) can be triggered indirectly by near-infrared (NIR) light for deep-tissue photodynamic therapy (PDT) through the fluorescence resonance energy transfer (FRET) strategy. Compared to pristine TiO2, absorption of hydrogenated black TiO2 (H-TiO2) in visible (vis) and NIR regions presents a marked improvement in performance, which leads H-TiO2 to enhance its overall activity. Owing to the light absorption enhancement, the single component H-TiO2 can be served as vis-driven photosensitizers (PSs) for PDT as well as NIR-triggered photothermal agents (PTAs) for photothermal therapy (PTT) simultaneously. Herein, H-TiO2 decorated Nd3+-sensitized-UCNPs (Nd:UCNPs@H-TiO2) nanocomposites (NCs) were synthesized by Nd:Y3Al5O12 (Nd:YAG) pulsed-laser irradiation of Nd:UCNPs@TiO2 precursors in suspended aqueous solution. Pulsed-laser modified synthesis is the optimum selection for prepar...

A photoelectrochemical aptasensor for aflatoxin B1 detection based on an energy transfer strategy between Ce-TiO2@MoSe2 and Au nanoparticles.

In this work, a novel photoelectrochemical (PEC) aptasensor was developed for the sensitive detection of aflatoxin B1 (AFB1) based on a resonance energy transfer strategy between the Ce-TiO2@MoSe2 heterostructure and Au nanoparticles (AuNPs). The Ce-TiO2@MoSe2 composite was obtained by growing MoSe2 nanosheets on a TiO2 nanocube doped by the Ce element with a facile hydrothermal method. The composite effectively extended the absorption of TiO2 to the visible region and avoided the self-aggregation of MoSe2 nanosheets, leading to the excellent photocurrent response under visible light excitation. The PEC aptasensor was then fabricated by immobilizing the Ce-TiO2@MoSe2 composite on an ITO electrode, followed by the modification of the aminated AFB1 aptamer. An AuNP-labeled DNA sequence was subsequently hybridized with the aptamer to fabricate a sandwich structure, which was destroyed after the introduction of AFB1, decreasing the amount of the energy acceptor (AuNPs) at the electrode surface. Accordingly, the photocurrent was increased with the increase of AFB1 concentration. Under the optimal conditions, the PEC aptasensor showed a wide linear range of 0.03-200 ng mL-1 and a low detection limit of 0.01 ng mL-1 for AFB1 determination.

Drug screening assay based on the interaction of intact Keap1 and Nrf2 proteins in cancer cells.

The Nrf2-Keap1 interaction is the major regulatory pathway for cytoprotective responses against oxidative and electrophilic stresses. Keap1, a substrate protein of a Cul3-dependent E3 ubiquitin ligase complex, is a negative regulator of Nrf2. The use of chemicals to regulate the interaction between Keap1 and Nrf2 has been proposed as a strategy for the chemoprevention of degenerative diseases and cancers. The interactions between Keap1 and Nrf2 in vitro and in vivo were investigated using fluorescence resonance energy transfer (FRET) and bimolecular fluorescence complementation (BiFC) strategies in our study. Nrf2 with its N-terminal fused to eGFP and Keap1 with its C-terminal fused to mCherry were expressed and purified in vitro. When purified eGFP-Nrf2 and Keap1-mChrry proteins were mixed together, a strong FRET signal could be detected, indicating an efficient energy transfer from eGFP to mCherry. Moreover, the FRET was detected in vivo using confocal microscopy in colon cancer HCT-116 cells that were co-transfected with eGFP-Nrf2 and Keap1-mCherry. Finally, using an eGFP BiFC approach, the Keap1-Nrf2 interaction was also detected in MCF7 cells by transfecting eGFP N-terminal fused to Nrf2 (eN158-Nrf2) and eGFP C-terminal fused to Keap1 (eC159-Keap1). Using the BiFC and FRET systems, we demonstrated that the prototypical Nrf2-activiting compound tBHQ and the antitumor drug F-dUrd might interfere with the intracellular interaction between Keap1 and Nrf2 whereas the 5-Fu have little role in activating the protective response of Nrf2 pathway in cancer cells. By analyzing the perturbation of the energy transfer between the donor and acceptor fluorophores and the bimolecular fluorescence complementation of eGFP, we can screen potential inhibitors for the interaction between Keap1 and Nrf2.

Simultaneous biosensing of CA125 and CA15-3 tumor markers and imaging of OVCAR-3 and MCF-7 cells lines via bi-color FRET phenomenon using dual blue-green luminescent carbon dots with single excitation wavelength

Here, we developed a facile route to synthesize two CDs with the maximum emission locates at 326 nm and 443 nm under 230 nm excitation. The absolute photoluminescence quantum yield (QY) is as high as 29% and 52% for CD-1 and CD-2 with strong blue-green fluorescence, respectively. The functionalized CDs (CDs-NH2, CDs-COOH) conjugated with antibodies used for simultaneous detection of two tumor-markers using fluorescence resonance energy transfer (FRET) strategy, when MoS2 nanosheets functionalized with ssDNA related aptamers applied as quencher. The response of sensor enhanced gradually with increasing of targets at range 0.05–8 pg/mL with detection limit (DL) 5.0 fg/mL for CA125, while for CA15-3 concentration range was 1.0–35 pg/mL and DL was 0.5 pg/mL. This strategy revealed a stable analytical performance for the detection of OVCAR-3 and MCF-7 cells lines ranging from 1000 to 10,000 cells/mL with DL 2–3 cells in 10 μL of injected sample. When the CDs-Ab was used in selective imaging of MCF-7 and OVCAR-3 cancer cells, a strong PL emission was observed. After incubation times, both the cells size and shape clearly remained without any change. The results demonstrate that the CDs are a potentially excellent bioimaging component in pathological diagnosis, biomedicine research and management of cancer diseases.