Photoinduced Electron Transfer Effect Research Articles

Novel self-assembled spirochiral nanofluorescent probe for fipronil detection efficiently by PET mechanism

A novel spirochiral compound S-SPINOL-Y1 (S-6,6′ −bis (thiophen-2-yl)-2,2′, 3,3′ −tetrahydro-1,1′-spirobis[indinee]-7,7′ −diol) was synthesized via a Suzuki reaction and self-assembled into nanospheres in ethanol solution. Nano or micron vesicles could be formed by changing the concentration of ethanol solvent. The resulting nanoprobe demonstrated rapid and effective recognition of fipronil (FIP) through the photoinduced electron transfer effect (PET mechanism), as evidenced by complete fluorescence quenching. Concurrently, the spiral chiral S-SPINOL-Y1 and FIP co-assembled into vein-like nanotubes within the ethanol solution by covalent bonding and intermolecular hydrogen bonding.

A Smartphone-Integrated Ratiometric Fluorescence Sensor for the Ultrasensitive and Selective Detection of 5-Heneicosylresorcinol in Whole Wheat Foods.

Precise on-site monitoring of alkylresorcinols, a vital biomarker, is crucial for verifying whole wheat foods and accurately quantifying the whole wheat content in various consumer and industrial products. Herein, for the first time, we introduce a novel ratiometric fluorescence sensor (CDs@ZIF-8/CdTe@MIP) for ultrasensitive and selective detection of alkylresorcinols. 5-Heneicosylresorcinol (C21:0 AR), the primary alkylresorcinol homologue in whole wheat grains, was selected as the target analyte. This analyte was specifically and selectively recognized by the incorporation of a molecularly imprinted polymer (MIP) layer. Within this nanoreactor, blue-emitting carbon dots embedded in zeolitic imidazolate framework-8 (CDs@ZIF-8) and orange-emitting CdTe quantum dots served as the self-calibration signal and response signal, respectively. Exploiting a photoinduced electron transfer effect between CdTe and C21:0 AR, the established fluorescence sensor exhibited remarkable sensing performance, offering wide linear responses in 0.005-1 μg·mL-1 and 1-80 μg·mL-1 concentration ranges, and achieving a low detection limit of 1.14 ng·mL-1. The proposed assay effectively detected C21:0 AR in real samples, including 8 whole wheat foods and 19 whole wheat grains, demonstrating good recoveries and relative standard deviation. Furthermore, an intelligent sensing platform was established by integrating CDs@ZIF-8/CdTe@MIP with a smartphone-assisted device, thus validating the feasibility of visual and on-site monitoring of C21:0 AR. Because of its rapid response, portability, cost-effectiveness, superior sensitivity, and high selectivity, the proposed sensor serves as a reliable method for the analysis of C21:0 AR, thus having substantial potential for on-site monitoring of whole wheat foods.

Enhancement of sensitivity for moxifloxacin spectrofluorimetric analysis through photoinduced electron transfer inhibition. Green assessment with application to pharmaceutical eye drops

A green, simple, rapid, selective, and highly sensitive fluorimetric protocol has been established for quantitative analysis of the antibacterial drug moxifloxacin in its pure form and pharmaceutical dosage form. Owing to photoinduced electron transfer, moxifloxacin exhibits low native fluorescence in neutral media. Based on that, the developed fluorimetric protocol depends on inhibiting the photoinduced electron transfer effect of the nitrogen atom presented on the pyrrolidine ring in moxifloxacin by suitable adjusting of pH of the medium surrounding it, leading to its protonation. It is simply achieved by using 0.5 M acetic acid. This protonation enhances the native fluorescence of moxifloxacin, turning it into a stronger one. This fluorescence was measured at 498 nm after excitation at 295 nm with a linearity range from 10 to 60 ng mL−1 and a high correlation coefficient value of 0.9998. The fluorimetric approach could be applied for moxifloxacin detection with a limit of 0.89 ng mL−1 and a quantification limit of 2.69 ng mL−1. The developed method has been validated according to ICH guidelines, indicating high accuracy and excellent precision. Furthermore, the developed fluorimetric protocol was applied successfully for moxifloxacin analysis in pharmaceutical eye drops. As a result, the proposed protocol could be easily applied for quality control of moxifloxacin in different laboratories all over the world.

Synthesis of an Antipyrine-Based Fluorescent Probe with Synergistic Effects for the Selective Recognition of Zinc Ion

A novel fluorescent probe containing an imine structure was synthesized through a condensation reaction based on the skeleton of antipyrine. Due to the synergistic effect of photoinduced electron transfer (PET), excited-state intramolecular proton transfer (ESIPT), and E/Z isomerization, the probe itself has weak fluorescence. When zinc ions are added to the ethanol solution of the probe, the formed complex inhibits PET, ESIPT, and E/Z isomerization while activating chelation-enhanced fluorescence (CHEF), resulting in fluorescent “turn-on” at 462 nm. Under optimal detection conditions, the probe can rapidly respond to zinc ions within 3 min, with a linear range of 60–220 μM and a lower limit of detection (LOD) of 0.63 μM. It can also specifically identify zinc ions in the presence of 13 common metal ions.

Fluorescence Sensing Properties of a Bibranched Cyanostilbene Derivative Containing -NH2 for Trace Water and Picric Acid Determination.

In order to design organic small molecule fluorescent materials with multiple sensing, a bibranched -NH2 modified cyanostilbene derivative (AM) was synthesized. It exhibits solvent and aggregation-induced emission effects, with a solid-state quantum yield of 28%, which is seven times higher than that in THF. The synthesized sample AM demonstrated high sensitivity to trace water via a fluorescence "turn-off" response, achieving a low detection limit of 0.41 µM in THF and 0.80 µM in EtOH. AM also exhibits a "turn-off" response to picric acid, attributed to the photo-induced electron transfer effect it induces. The recognition of picric acid by AM demonstrates specificity and resistance to interference from nitro explosives, with a detection limit of 300 ppb and a linear relationship (R2 = 0.9981) at the range of 0-4 equivalents AM. Such acid recognition can facilitate the design of qualitative test papers and safety inks. Additionally, AM can function as a temperature sensor with a linear relationship (R2 = 0.9976) within the temperature range of 25-110°C. Leveraging these unique characteristics, a series of methods were proposed for the direct quantitative determination of trace water in nonaqueous solvents, picric acid, and temperature.

A Novel Multi-Effect Photosensitizer for Tumor Destruction via Multimodal Imaging Guided Synergistic Cancer Phototherapy.

How to ingeniously design multi-effect photosensitizers (PSs), including multimodal imaging and multi-channel therapy, is of great significance for highly spatiotemporal controllable precise phototherapy of malignant tumors. Herein, a novel multifunctional zinc(II) phthalocyanine-based planar micromolecule amphiphile (ZnPc 1) was successfully designed and synthesized, in which N atom with photoinduced electron transfer effect was introduced to enhance the near-infrared absorbance and nonradiative heat generation. After simple self-assembling into nanoparticles (NPs), ZnPc 1 NPs would exhibit enhanced multimodal imaging properties including fluorescence (FL) imaging (FLI) /photoacoustic (PA) imaging (PAI) /infrared (IR) thermal imaging, which was further used to guide the combined photodynamic therapy (PDT) and photothermal therapy (PTT). It was that under the self-guidance of the multimodal imaging, ZnPc 1 NPs could precisely pinpoint the tumor from the vertical and horizontal boundaries achieving highly efficient and accurate treatment of cancer. Accordingly, the integration of FL/PA/IR multimodal imaging and PDT/PTT synergistic therapy pathway into one ZnPc 1 could provide a blueprint for the next generation of phototherapy, which offered a new paradigm for the integration of diagnosis and treatment in tumor and a promising prospect for precise cancer therapy.

Multidimensional detection of roxarsone via AIE-based sulfates

Improper abuse of roxarsone (ROX) in industrial production leads to harmful effects on water, soil, food, and living creatures. It is significant to detect its concentration in the environment and biosystem. Herein, two aggregation-induced emission (AIE)-active fluorescence probes, TPE-TPE and TPE-TPE-CN, are successfully synthesized via a sulfur (VI) fluoride exchange (SuFEx) click reaction and first employed to detect ROX in the environment and living 3T3 cells. These two probes can selectively detect ROX in water due to the synergistic effect of photoinduced electron transfer (PET) and fluorescence resonance energy transfer (FRET) between the probes and ROX. The detection limit of TPE-TPE and TPE-TPE-CN is 0.154 and 0.385 μmol/L, respectively, much lower than the safety concentration stipulated by the World Health Organization (WHO). In addition, with the aid of a color discrimination application in a smartphone, these two probes can also detect ROX in real samples (such as water, soil, and cabbage), demonstrating their excellent potential for monitoring ROX in a practical environment.

Hydrogen-bond tuned conjugated architectures for nitric oxide sensing in single-benzene framework: Advances and mechanistic insights

In contrast to the conventional fluorescence enhancement resulting from the cessation of the photoinduced electron transfer effect upon capturing nitric oxide (NO) by o-phenylenediamine, we found an interesting fluorescence quench within small molecule fluorophores characterized by intramolecular hydrogen bonding. Herein, the integration of a push-pull electron system with intramolecular hydrogen bonding onto an ultra-small fluorophore was employed to fabricate a hydrogen bond-tuned single benzene core fluorescent probe with an exceptional fluorescence quantum yield of 26 %, denoted as HSC-1. By virtue of its small size and low molecular weight (mere 192 g/mol), it demonstrated superior solubility and biocompatibility. Given the optimized conditions, HSC-1 manifested extraordinary linearity in detecting NO concentrations ranging from 0.5 to 60 μM, with an outstanding detection limit of 23.8 nM. Theoretical calculations unraveled the photophysical properties of hydrogen bonding-related probe molecules and highlighted the NO sensing mechanism. This pioneering work offers an important platform for the design of small fluorescence probes only with a single benzene core applied to NO sensing, which will potentially emerge as a new frontier in the area.

A lysosome-targeted fluorescent probe for fluorescence imaging of hypochlorous acid in living cells and in vivo

Lysosomes, as crucial acidic organelles in cells, play a significant role in cellular functions. The levels and distribution of hypochlorous acid (HOCl) within lysosomes can profoundly impact their biological functionality. Hence, real-time monitoring of the concentration of HOCl in lysosomes holds paramount importance for further understanding various physiological and pathological processes associated with lysosomes. In this study, we developed a bodipy-based fluorescent probe derived from pyridine and phenyl selenide for the specific detection of HOCl in aqueous solutions. Leveraging the probe's sensitive photoinduced electron transfer effect from phenyl selenide to the fluorophore, the probe exhibited satisfactory high sensitivity (with a limit of detection of 5.2 nM and a response time of 15 s) to hypochlorous acid. Further biological experiments confirmed that the introduction of the pyridine moiety enabled the probe molecule to selectively target lysosomes. Moreover, the probe successfully facilitated real-time monitoring of HOCl in cell models stimulated by N-acetylcysteine (NAC) and lipopolysaccharide (LPS), as well as in a normal zebrafish model. This provides a universal method for dynamically sensing HOCl in lysosomes.

Lignin based water-soluble fluorescent macromolecular probes for the detection of Fe3+ ion

Lignin is an abundant biomass material in the natural world, its application value and application scope ought to be enlarged. In this work, dealkalized lignin with good water-solubility was used to combine with water-insoluble boron-dipyrromethene (BODIPY) fluorophore to obtain readily water-soluble macromolecular probes. Firstly, a small molecular fluorescent BODIPY probe with two amino groups (-NH2) and another small molecular fluorescent probe with two chlorine groups (-Cl) were synthesized. Secondly, the small-molecular fluorescent probe with two -NH2 groups reacted with carbonyl groups in the lignin by Schiff base formation reaction. Meanwhile, the small-molecular fluorescent probe with two -Cl groups reacted with hydroxyl groups in the lignin by Williamson ether formation reaction. Eventually, two lignin-based fluorescent probes were obtained. The molecular weights of the two probes reached 22.4 kDa and 20.1 kDa. Moreover, these two fluorescent probes were readily soluble in H2O and DMF. Both of the fluorescent macromolecules have good recognition ability for Fe3+, with detection limits of 2.1 × 10−7 mol/L and 1.1 × 10−7 mol/L respectively. Fe3+ interacts with the fluorescent probe, and the imine bond (-CN-) reacts with Fe3+ to cause fluorescence response. The photo-induced electron transfer effect is enhanced, and the photo-induced electron transfer (PET) mechanism causes the fluorescent quenching. This work expands the application scope of lignin as a biomass material and lays a foundation for the development of lignin materials.

A bimetallic organic framework based fluorescent aptamer probe for the detection of zearalenone in cereals

In this work, a bimetallic organic framework (Cu/UiO-66) based “turn on” fluorescent aptamer probe was designed for the high-efficiency detection of zearalenone (ZEN). In the probe, the 6-carboxyfluorescein-labeled aptamer (FAM-Apt) was used as the recognition element, and the electrostatic interaction, coordination effect, and photoinduced electron transfer effect between FAM-Apt and Cu/UiO-66 caused fluorescence quenching. When ZEN existed, FAM-Apt recognized ZEN specifically, causing FAM-Apt to separate from the surface of Cu/UiO-66 and recovery of fluorescence. Under the optimal conditions, the probe had a linear detection range of 0.5 ng/mL–60 ng/mL, and the detection limit was 0.048 ng/mL. The application potential of the probe was verified by real detection of various cereals and their products, with a standard recovery from 83.67 %–106.8 %. The development of this efficient, rapid, and sensitive ZEN detection method provides a new platform for the quality control of cereals and their products.

Fluorescent Features and Applicable Biosensing of a Core-Shell Ag Nanocluster Shielded by a DNA Tetrahedral Nanocage.

The DNA frame structure as a natural shell to stably shield the sequence-templated Ag nanocluster core (csAgNC) is intriguing yet challenging for applicable fluorescence biosensing, for which the elaborate programming of a cluster scaffold inside a DNA-based cage to guide csAgNC nucleation might be crucial. Herein, we report the first design of a symmetric tetrahedral DNA nanocage (TDC) that was self-assembled in a one-pot process using a C-rich csAgNC template strand and four single strands. Inside the as-constructed soft TDC architecture, the template sequence was logically bridged from one side to another, not in the same face, thereby guiding the in situ synthesis of emissive csAgNC. Because of the strong electron-repulsive capability of the negatively charged TDC, the as-formed csAgNC displayed significantly improved fluorescence stability and superb spectral behavior. By incorporating the recognizable modules of targeted microRNAs (miRNAs) in one vertex of the TDC, an updated TDC (uTDC) biosensing platform was established via the photoinduced electron transfer effect between the emissive csAgNC reporter and hemin/G-quadruplex (hG4) conjugate. Because of the target-interrupted csAgNC switching in three states with the spatial proximity and separation to hG4, an "on-off-on" fluorescing signal response was executed, thus achieving a wide linear range to miRNAs and a limit of detection down to picomoles. Without complicated chemical modifications, this simpler and more cost-effective strategy offered accurate cell imaging of miRNAs, further suggesting possible therapeutic applications.

Fluorescence turn-off strategy for sensitive detection of DNA methyltransferase activity based on DNA-templated gold nanoclusters

DNA methylation results in a variety of human diseases and the DNA methylation process is mediated by DNA methyltransferases, which have therefore become potential targets for disease treatment. In this study, a turn-off nanogold biological probe system was successfully created for determining the activity of DNA methyltransferases (M.SssI MTase). A dumbbell-shaped DNA probe with a site-recognizable region of M. SssI MTase and a fluorescent signal probe based on a DNA-templated gold nanocluster (DNA-AuNC) probe combined for the quantitative detection of M. SssI MTase. This dumbbell-shaped DNA probe was methylated by M. SssI MTase, and the dumbbell-shaped DNA probe with a methyl group was recognized by an endonuclease (GlaI) and cleaved into hairpin DNA. The dGTP was added to the 3′-OH terminus of hairpin DNA fragments in the presence of terminal deoxynucleotidyl transferase (TdT), and the hairpin DNA was extended with a G-rich sequence that can be used as an inactivation probe. When the inactivation probe was combined with the signal probe, the fluorescent signal disappeared due to the photoinduced electron transfer effect. Methyltransferase activity was then detected based on the turn-off principle of the fluorescence signal from the DNA-AuNCs. The bioprobe enabled sensitive detection of M. SssI MTase with a detection limit of 0.178 U mL−1 and good specificity. The bioprobe demonstrated good detection efficiency in both human serum and cell lysates, and its unique fluorescence turn-off mechanism provided good resistance to interference, thus increasing its potential application in complex biological samples. Moreover, it is suitable for screening and assessing the inhibitory activity of M. SssI MTase inhibitors, and therefore has significant potential for disease diagnosis and drug discovery.

Concentration-regulated multi-color fluorescent carbon dots for the detection of rifampicin, morin and Al3+

Carbon dots have many new and interesting phenomena, and the concentration dependent luminescence wavelength is an intriguing one. Herein, nitrogen-sulfur co-doped carbon dots (NSCDs) diluted to different concentrations, the high concentration of G-NSCDs (0.2 mg mL−1) with green fluorescence and the low-concentration of B-NSCDs (0.01 mg mL−1) with blue fluorescence were obtained. Further, it was found that the detection behaviors are different for different concentrations. The “turn-off” fluorescent sensor of G-NSCDs can specifically recognize rifampicin in a linear range of 0.2–20 μM with a detection limit of 56.6 nM employing the mutual effect of photo-induced electron transfer and dynamic quenching. Meanwhile, a “turn-off” B-NSCDs fluorescence sensor was constructed to effectively identify morin based on the internal filtration effect and static quenching, achieving a suitable linearity of 0.2–30 μM and a detection limit of 51.2 nM. Due to the strong chelation of morin and Al3+, a “turn-on” fluorescent probe for sequential detection Al3+ was fabricated based on B-NSCDs-morin system, obtaining a good linearity of 0.1–2.0 μM with a satisfactory detection limit of 45.8 nM. These interesting behaviors indicate that NSCDs are expected to become novel sensing materials for the monitoring of rifampicin, morin and Al3+ in organisms, which is beneficial for our health.

A naphthalimide-based fluorescent probe for rapid detection of nitrite and its application in food quality monitoring

Nitrite (NO2−) is a widely used food additive and long-term aging of cooked leftovers may also contribute to the formation of NO2−, excessive consumption of NO2− is harmful to human health. Developing an effective sensing strategy for on-site monitoring of NO2− has attracted considerable attention. Herein, a novel colorimetric and fluorometric probe ND-1 based on photoinduced electron transfer effect (PET) was designed for highly selective and sensitive detection of nitrite (NO2−) in foods. The probe ND-1 was strategically constructed by employing naphthalimide as the fluorophore and o-phenylendiamine as the specific recognition site for NO2−. The triazole derivative ND-1-NO2- could be produced exclusively by reacting with NO2−, leading to a visible colorimetric change from yellow to colorless accompanied by a significantly enhanced fluorescence intensity at 440 nm. The probe ND-1 exhibited promising sensing performances towards NO2− including high selectivity, rapid response time (within 7 min), low detection limit (47.15 nM) and wide quantitative detection range (0–35 μM). In addition, probe ND-1 was capable of quantitative detecting of NO2− in real food samples (including pickled vegetables and cured meat products) with satisfactory recovery rates (97.61%–103.08%). Moreover, the paper device loaded by probe ND-1 could be utilized for visual monitoring of NO2− levels variation of stir-fried greens. This study provided a feasible method for the accurate, traceable and rapid on-site monitoring NO2− in foods.

Fluorescence sensitively sensing on antibiotic and nitrobenzene of two diverse 2D Zn-organic networks

Two 2D luminous zinc(II) coordination polymers have been synthesized hydrothermally with the formulas of [Zn(4-HDBB)(3-bibz)](1) and [Zn2(4-DBB) (OH)(4,4′-bbpy)1.5]·2H2O(2) (4-H3DBB = 4-(3,5-dicarboxylatobenloxy) benzoic acid, 3-bibz = 3-bis(imidazole-l-ylmethyl) benzene and 4,4′-bbpy = 4,4′-bis (imidazolyl) biphenyl), and characterized by single crystal X-ray diffraction, IR, TG and PXRD technologies. Structural analyses exhibit both of them crystallize in P-1 space group of triclinic crystal system with 2D network structures. 1 possesses the interpenetration of 2D (4,4) networks based on the cross of two kinds of 1D chains. The 2D networks of 2 featuring 1D tube-like structure are linked by the six-number-ring H-bonds clusters. Fluorescence sensing properties on antibiotic of two complexes display 1 could detect of chloramphenicol (LOD = 6.64 × 10−7 mol⋅ L-1) and the detection limit of polymer 2 for tetracycline is 1.22 × 10−7 mol⋅ L-1. Solvents detection show that nitrobenzene in water was completely quenched by all of them, and display the highly sensitive sensing for nitrobenzene with the limit of detection of 5.0 × 10−8 mol L-1(1) and 2.14 × 10−7mol·L-1(2), respectively. Through theoretical calculation, it is found that the sensing mechanism of two complexes on nitrobenzene could be mainly attributed to the photo-induced electron transfer effect (PET). The fact shows that the two complexes can be used multi-functional sensors in the future.

Enhancement of Coloring and Bleaching Rates of Photochromic WO<sub>3</sub> Composite Films by Adding Polyethylene Glycol

WO3-based photochromic composite films were fabricated using a translucent urethane resin and a peroxoisopolytungstic acid - methanol solution as raw materials. Moreover, and polyethylene glycol (PEG, molecular weight 1000) was added to the composite as a sensitizer. The WO3 mean particle sizes in the obtained composite were 46–55 nm, which implies that by PEG addition caused a slight reduction in the particle size. Additionally, the coloring/bleaching rate and the transmittance module of the composite films were drastically increased by PEG addition. These improvements in photochromic properties were previously considered to be due to the effect of the particle size of WO3 particles in the composite, but were mainly assumed the effect of photoinduced electron transfer, which is caused by the presence of PEG in the composites.

Red-emissive carbon dots based fluorescent and smartphone-integrated paper sensors for sensitive detection of carbendazim

Trace detection of carbendazim (CBZ), a worldwide used pesticide, in crops and foods is important and urgent to reduce risks to human health. Herein, newly red-emissive carbon dots (R-CDs) based fluorescent and smartphone-integrated paper sensors were developed for highly-selective, and -sensitive rapid sensing of CBZ. R-CDs were synthesized from citric acid and urea via a DMF solvothermal method, which showed excellent analytical performance due to abundant carboxyl groups on the surface and long emission wavelength to avoid autofluorescence interference of matrix. According to the red fluorescence quenching by CBZ via π-π interaction and photoinduced electron-transfer effect, the newly fluorescent nano sensor could realize CBZ sensing within 3 min with high selectivity out of the other six interfering pesticides, as well as fascinating sensitivity with an ultralow detection limit of 3.5 ng/mL. The practicable application in the spiked medicinal Lotus seeds samples exhibited satisfactory recoveries of 95.5%-108.3%. The portable paper-based sensor fabricated by depositing R-CDs on the filter paper enabled quantitative readout of test strip results assisted with a smartphone, providing a rapid on-site tool for CBZ detection in medicinal foods. This is the first report of a novel, sensitive, and portable R-CDs based sensing platform for simple, cost-effective, and rapid on-site detection of CBZ in the field of food safety with great application potential.

Application of a Dual-Probe Coloading Nanodetection System in the Process Monitoring and Efficacy Assessment of Photodynamic Therapy: An In Vitro Study.

The oxygen-consuming property of photodynamic therapy (PDT) affects its effects and aggravates tumor hypoxia, thus upregulating the vascular endothelial growth factor (VEGF) to exacerbate tumor metastasis and lead to treatment failure. Therefore, it is necessary to monitor the dynamic changes in the factors related to PDT and tumor development trends in real time, thus helping to improve PDT efficiency. This study fabricated a fluorescent probe, TPE-2HPro, and a fluorescein-labeled aptamer probe, FAM-AptamerVEGF, to detect hydrogen peroxide (H2O2) and VEGF through the photoinduced electron-transfer effect and the specific affinity of the aptamer to VEGF, respectively. The two probes were loaded into the inner pores and absorbed on the surface of polydopamine coating-wrapped mesoporous silica nanoparticles (MSN@PDA) to construct the dual-probe-loaded system, MSNTH@PDAApt, which was kept stable in fetal bovine serum (FBS) solution and achieved pH-responsive release behavior, thus helping to increase the accumulation of the two probes in tumor cells. The dichloroacetic acid-mediated in vitro antitumor tests showed that the changing trends of H2O2 and VEGF levels were consistent with the results of related mechanism studies and could be monitored by MSNTH@PDAApt. The in vitro chlorin e6 (Ce6)-mediated PDT treatment demonstrated that when the illumination condition was 650 nm, 50 mW/cm2 for 10 min, cells were more inclined to metastasis and invasion rather than death due to a substantial increase in VEGF expression at the low Ce6 concentrations. With the increase of the Ce6 concentration, the growth of the H2O2 level gradually exceeded that of VEGF, and the reactive oxygen species (ROS)-mediated cell death dominated when the Ce6 concentration was about 2 times its IC50 values. Besides, hypoxia also affected the H2O2 and VEGF changes. These results demonstrated that MSNTH@PDAApt could precisely monitor and assess the tumor development trends during PDT treatment, thus helping improve the treatment effect.

A highly efficient molecularly imprinted fluorescence sensor for assessing whole wheat grains by the rapid and sensitive detection of alkylresorcinols

To differentiate whole wheat foods from refined wheat foods is still challenging grain industry and confusing consumers. Alkylresorcinols (ARs), as biomarkers of whole wheat grains, can serve for assessing the authenticity of whole wheat foods. Herein, a highly efficient fluorescence sensing platform (CDs@MIP) for rapid and sensitive analysis of ARs was explored, using carbon dots (CDs) as fluorophores and 5-heneicosylresorcinol (C21:0 AR) as template molecules embedded in a molecularly imprinted polymer (MIP) coating. Benefiting from the specific cavities in the probe and a photo-induced electron transfer effect, the fluorescence intensity of CDs@MIP was significantly quenched in the presence of C21:0 AR, exhibiting a superior binding efficiency and selectivity. As a result, the fabricated optical sensor delivered a wide linear range of C21:0 AR from 0.015 to 60 μg mL−1 with an ultralow detection limit of 4 ng mL−1. It was noteworthy that the sensor was successfully applied for the rapid detection of C21:0 AR in commercial whole-wheat foods as well as visualization analysis on the test paper, comprehensively validating the practicality and efficacy of CDs@MIP based fluorescence assay. The study provides a rapid and sensitive detection method of C21:0 AR, paving a new way for guiding grain industry to effectively qualify the authenticity and to quantify the content of whole wheat in wheat-based foods.