Asparagus officinalis Herb-Derived Carbon Quantum Dots: Luminescent Probe for Medical Diagnostics.

The utilization of natural materials for the synthesis of highly fluorescent carbon quantum dots (CQDs) presents a sustainable approach to overcome the challenges associated with traditional chemical precursors. Here, we report the synthesis of novel S,N-self-doped CQDs (S,N@CQDs) derived from asparagus officinalis herb. These S,N@CQDs exhibit 16.7 % fluorescence quantum yield, demonstrating their potential in medical diagnostics. We demonstrate the efficacy of S,N@CQDs as luminescent probes for the detection of anti-pathogenic medications metronidazole (MTZ) and nitazoxanide (NTZ) over concentration ranges of 0.0-180.0 µM (with a limit of detection (LOD) of 0.064 µM) and 0.25-40.0 µM (LOD of 0.05 µM), respectively. The probes were successfully applied to determine MTZ and NTZ in medicinal samples, real samples, and spiked human plasma, with excellent recovery rates ranging from 99.82 % to 103.03 %. Additionally, S,N@CQDs demonstrate exceptional efficacy as diagnostic luminescent probes for hemoglobin (Hb) detection over a concentration range of 0-900 nM, with a minimal detectability of 9.24 nM, comparable to commercially available medical laboratory diagnostic tests. The eco-friendly synthesis and precise detection limits of S,N@CQDs meet necessary analytical requirements and hold promise for advancing diagnostic capabilities in clinical settings. This research signifies a significant step towards sustainable and efficient fluorescence-based medical diagnostics.

Carbon dots as fluorescent nanoprobes for assay of some non-fluorophoric nitrogenous compounds of high pharmaceutical interest.

Background: Carbon dots, CDs, have excellent photoluminescence properties, good biocompatibility, low toxicity and good light stability. The optical, magnetic and electronic properties of CDs make them a hugely relevant tool to be used in pharmaceutical analysis, bioimaging, drug delivery, and other fields. The fluorescence of carbon nanodots makes it suitable for assay of some nitrogenous compounds of high pharmaceutical interest. In this work, we develop simple, fast and green spectrophotometric methods for quantification of Azithromycin and Rasagiline mesilate using synthesized fluorescent CDs from garlic peels. Results: The spectrometric methods depend on stoichiometric reactions of both drugs with fluorescent CDs. Carbon dots exhibit a declared absorption peak λmax at 238 nm and potent fluorimetric emission at λem 528 nm, upon excitation at λex 376 nm. Drugs' concentrations in ppm are efficiently calculated using Stern-Volmer Equation. Decrease in fluorescence (ΔF = F o - F) and the F-ratio values are linearly correlated to molar concentration of each quencher (drug). A significant linear diminish in the dots' measured absorbance and fluorimetric emission values was observed. Validation of all the developed methods was according to the ICH guidelines. Conclusions: In a new way, this work successfully indicates, spectrometric methods for rapid detection of two non-fluorophoric nitrogenous compounds using potent carbon nanodots. Consequently, these green developed methods offer several benefits as simplicity, ease of quantification, accuracy and precision that encourage the application of the developed methods in routine analysis of Azithromycin and Rasagiline mesilate in quality control laboratories as analytical tool. Supplementary Information: The online version contains supplementary material available at 10.1186/s43088-023-00346-z.

Dinuclear Lanthanide Compound as a Promising Luminescent Probe for Al3+ Ions.

Luminescent probes have wide applications in biological system analysis and environmental science. Here, one novel luminescent dinuclear europium compound with a crown ether analogous ligand was synthesized through a solvent-thermal reaction. Through transformation, upon the addition of Al3+ ions to the N,N'-dimethyl formamide solution of the europium compound, the luminescent intensity of the characteristic emission of Eu3+ decreased, and a new emission peak appeared at 346 nm and increased rapidly. The luminescent investigation indicated that it could act as a highly sensitive and selective luminescent probe for Al3+ ions. Moreover, mass spectrometry and single-crystal X-ray diffraction confirmed the formation of a new more stable trinuclear aluminium compound during the sensing process.

An Overview on Coinage Metal Nanocluster-Based Luminescent Biosensors via Etching Chemistry.

The findings from the synthetic mechanism of metal nanoclusters yield the etching chemistry based on coinage metal nanoclusters. The utilization of such chemistry as a tool that can alter the optical properties of metal nanoclusters has inspired the development of a series of emerging luminescent biosensors. Compared with other sensors, the luminescent biosensors have the advantages of being more sensitive, saving time and saving cost. We reviewed topics on the luminescent sensors based on the etching of emissive coinage metal nanoclusters. The molecules possessing varied etching ability towards metal nanoclusters were categorized with discussions of corresponding etching mechanisms. The understanding of etching mechanisms favored the discussions of how to use etching methods to detecting biochemical molecules. The emerging luminescent biosensors via etching chemistry also provided challenges and new opportunities for analytical chemistry and sensors.

A Patient-Ready Wearable Transcutaneous CO2 Sensor.

Continuously monitoring transcutaneous CO2 partial pressure is of crucial importance in the diagnosis and treatment of respiratory and cardiac diseases. Despite significant progress in the development of CO2 sensors, their implementation as portable or wearable devices for real-time monitoring remains under-explored. Here, we report on the creation of a wearable prototype device for transcutaneous CO2 monitoring based on quantifying the fluorescence of a highly breathable CO2-sensing film. The developed materials are based on a fluorescent pH indicator (8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt or HPTS) embedded into hydrophobic polymer matrices. The film's fluorescence is highly sensitive to changes in CO2 partial pressure in the physiological range, as well as photostable and insensitive to humidity. The device and medical-grade films are based on our prior work on transcutaneous oxygen-sensing technology, which has been extensively validated clinically.

Inexpensive bioluminescent genosensor for sensitive determination of DNA damage induced by some commonly used sunscreens.

Sunscreens (SSs) are highly applied all over the world on large areas of human body. Benzophenone chemical group constitute a major part in most SSs. Benzophenones are reported to induce changes in nucleic acids upon UV-irradiation. These alterations may potentially lead to DNA mutation, cell apoptosis, and eventually skin cancer. This work compares the kinetics of the induced DNA damage by some SSs after UV-irradiation. Six commonly used SSs; 4-t-butyl-4-methoxy dibenzoyl methane, 4-methoxycinnamic acid, 2-hydroxy-4-methoxybenzophenone (BZ-3), Dibenzoyl methane, 2,2'-dihydroxy-4-methoxy benzophenone (BZ-8) and p-methylbenzoic acid; are investigated. In this work, terbium chloride bioluminescent genosensor is used for sensitive, simple and inexpensive determination of induced DNA-damage. Results reveal that only BZ-3 and BZ-8 induced DNA-damage upon UV-irradiation that are confirmed by both absorption spectroscopy and viscosity measurements. Moreover, viscosity studies indicated the possible intercalation of the SS into DNA prior to initiation of DNA damage. Furthermore, the potency of BZ-3 and BZ-8 to induce DNA damage upon UVA irradiation was assessed on calf thymus DNA. The low cost of the proposed bioluminescent genosensor allows it to be an automatic simple process for the investigation of any DNA-drug interactions without the need of coupling with other analytical methods.

A dual-function luminescent probe for copper(II) ions and pH detection based on ruthenium(II) complex.

A new ruthenium complex-based luminescent probe Ru-impa for Cu2+ and pH detection has been synthesized and characterized. Ru-impa could rapidly and selectively detect Cu2+ in aqueous solutions and the working pH ranges from weakly acidic to alkaline. The detection limit calculated using the S/N and S/B ratio was 24.7 nM and 3.4 µM, respectively. The test strips for practical detecting application were also prepared and the actual detection limit in drinking water was found to be 3 µM, which is lower than the WHO-guided drinking water limit (30 µM) and the upper limit of human serum free copper content (1.7-3.9 µM). Luminescence imaging study showed that Ru-impa could monitor Cu2+ level fluctuation in the cells. In addition, Ru-impa also shows a sensitive on-off luminescence response when pH > 10, indicating that it can also be used as a pH sensor under extremely alkaline conditions.

Luminescent determination of propineb fungicide by using a carbon quantum dots-europium ions system.

We propose a modification of lanthanide-sensitized luminescence (LSL) to increase the selectivity and sensitivity of analytical methods based on this detection. LSL consists in the formation of complexes of lanthanide ions and organic compounds. Then, an intramolecular energy transfer occurs from the excited state of the ligand (organic analyte) to the emitting level of the lanthanide. The utilization of luminescent nanoparticles (carbon quantum dots, CQDs) in LSL systems can enhance their sensitivity and selectivity. CQDs can react with lanthanide ions through their carboxylic groups. These systems can thus be used as time-resolved luminescent probes. Propineb (PPN), a well-known dithiocarbamate fungicide, has been selected as the target analyte to show the advantages of using CQDs in LSL systems. The method proposed is based on the quenching produced by PPN in europium-CQDs luminescence, obtaining a detection limit of 0.03 µg mL-1 PPN and a method detection limit of 3 mg kg-1 in capers (bud and fruit), fulfilling the maximum residue limit in these samples (25 mg kg-1). The results showed that the use of nanoparticles in LSL systems may provide novel and simple analytical methods for the screening of contaminants in the agri-food sector.

Ultrasound-Assisted Synthesis of Luminescent Micro- and Nanocrystalline Eu-Based MOFs as Luminescent Probes for Heavy Metal Ions.

The luminescent coarse-, micro- and nanocrystalline europium(III) terephthalate tetrahydrate (Eu2bdc3·4H2O) metal-organic frameworks were synthesized by the ultrasound-assisted wet-chemical method. Electron micrographs show that the europium(III) terephthalate microparticles are 7 µm long leaf-like plates. According to the dynamic light scattering technique, the average size of the Eu2bdc3·4H2O nanoparticles is equal to about 8 ± 2 nm. Thereby, the reported Eu2bdc3·4H2O nanoparticles are the smallest nanosized rare-earth-based MOF crystals, to the best of our knowledge. The synthesized materials demonstrate red emission due to the 5D0-7FJ transitions of Eu3+ upon 250 nm excitation into 1ππ* state of the terephthalate ion. Size reduction results in broadened emission bands, an increase in the non-radiative rate constants and a decrease in both the quantum efficiency of the 5D0 level and Eu3+ and the luminescence quantum yields. Cu2+, Cr3+, and Fe3+ ions efficiently and selectively quench the luminescence of nanocrystalline europium(III) terephthalate, which makes it a prospective material for luminescent probes to monitor these ions in waste and drinking water.

A Portrait of the OPE as a Biological Agent.

Oligophenylene ethynylenes, known as OPEs, are a sequence of aromatic rings linked by triple bonds, the properties of which can be modulated by varying the length of the rigid main chain or/and the nature and position of the substituents on the aromatic units. They are luminescent molecules with high quantum yields and can be designed to enter a cell and act as antimicrobial and antiviral compounds, as biocompatible fluorescent probes directed towards target organelles in living cells, as labelling agents, as selective sensors for the detection of fibrillar and prefibrillar amyloid in the proteic field and in a fluorescence turn-on system for the detection of saccharides, as photosensitizers in photodynamic therapy (due to their capacity to highly induce toxicity after light activation), and as drug delivery systems. The antibacterial properties of OPEs have been the most studied against very popular and resistant pathogens, and in this paper the achievements of these studies are reviewed, together with almost all the other roles held by such oligomers. In the recent decade, their antifungal and antiviral effects have attracted the attention of researchers who believe OPEs to be possible biocides of the future. The review describes, for instance, the preliminary results obtained with OPEs against severe acute respiratory syndrome coronavirus 2, the virus responsible for the COVID-19 pandemic.

A Unique Multifunctional Luminescent Probe for Self-Monitoring Photodynamic Therapy by Detecting H2S in Cancer Cells.

With the increasing interest in photodynamic therapy (PDT), the assessment of the level of reactive oxygen species produced during PDT has also become increasingly important. However, most of the fluorescent probes for reactive oxygen species (ROS) evaluation were separated from photosensitizers in the PDT process, resulting in ex situ and asynchronous treatment feedback. Additionally, the consumption of ROS by these fluorescent probes themselves will inevitably affect the therapeutic effect. Herein, inspired by the redox balance in the cell, we developed a multifunctional hydrogen sulfide (H2S) probe Ru-NBD for reporting the therapeutic effect during the PDT process by detecting hydrogen sulfide. The probe Ru-NBD could not only serve as an effective PDT reagent both before and after H2S activation but could also be used for real-time and in situ monitoring of the therapeutic effect via restored luminescence during the PDT process. As the phototherapy process progresses, the luminescent signal of Ru-NBD changes accordingly. The experimental results show that there is a certain correlation between the luminescence intensity and the cell inhibition rate; thus, we can monitor the phototherapy process by detecting the changes in the probe's luminescent signal. This study provides an idea for the design and adjustment of PDT.

Synthsis and characterization of Tb3+/Eu3+ complexes based on 2,4,6-tris-(4-carboxyphenyl)-1,3,5-triazine ligand for ratiometric luminescence temperature sensing.

By choosing C3 symmetric 2,4,6-tris-(4-carboxyphenyl)-1,3,5-triazine (TCTZ) as the ligand, a series of lanthanide metal-origanic complexes Tb1-xEux-TCTZ(DMF)·2H2O(x = 0, 0.01, 1) have been successfully synthesized via solvothermal reaction. The complexes present intense emission although with coordinationofwater molecules. The temperature-dependent photoluminescent (PL) properties of Tb-TCTZ is investigated both in terms of emission intensity and lifetime in order to establish their potentials as luminescent themometers. It shows excellent responseto temperature from 303 to 403 K and exhibits the maximum relative sensitivity(Sr) as high as 5.36% K-1 at 403 K. Tb0.99Eu0.01-TCTZ is evaluated for application as ratiometric luminescence thermometers, which exhibits high sensitivity to temperature in range of 303-403 K, with the maximum absolute sensitivity (Sa) and Sr as 5.16% and 3.22% K-1 respectively. The obtained maximum sensitivities in this study is superior to many materials reported. Moreover, the emission color changes from green at 303 K to red at 403 K, so that it is also suitable to act as colorimetric luminescent probes.

New luciferin-based probe substrates for human CYP26A1.

Activity of human CYP26A1 towards six proluciferin probe substrates and their ester derivatives was monitored. These included three monofluorobenzyl ether isomers and three five-membered heterocycles. Overall, luciferin substrates with a free acid group gave higher activities than the ester compounds. Also, luciferin derivatives with six-ring structures were better metabolized than those with five-rings. The best substrates identified in this study are Luciferin 6' 3-fluorobenzyl ether (Luciferin-3FBE) and its methyl ester (Luciferin-3FBEME). Taken together, we describe eleven new probe substrates for CYP26A1 and demonstrate for the first time that CYP26A1 does not only accept acid substrates but can also metabolize esters.

Design and synthesis of two new terbium and europium complex-based luminescent probes for the selective detection of zinc ions.

Zinc plays a key role in many physiological processes and has implications for the environment. Consequently, detection of chelatable zinc ion (Zn2+ ) has attracted widespread interest from the research community. Lanthanide-based luminescent probes offer particular advantages, such as high water solubility, long luminescence lifetimes and a large Stokes' shift, over common organic dye-based fluorescent sensors. Here, we report the synthesis of terbium and europium complex-based probes, Tb-1 and Eu-1, for sensitive and selective detection of Zn2+ in water. These probes featured the incorporation of bis(2-pyridylmethyl)]amine (DPA) receptor for Zn2+ chelation and the 1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane (DO3A) ring to chelate lanthanide (Ln3+ ). Tb-1 and Eu-1 displayed high selectivity for Zn2+ ions over a wide range of competing ions, with limits of detection of 0.50 ± 0.1 µM and 1.5 ± 0.01 µM, respectively. Density functional theory simulations were in good agreement with experimental observations, displaying high Zn2+ selectivity compared with most competing ions. In the competing ions experiments, the luminescence response of Tb-1 and Eu-1 was moderately quenched by some ions such as Cu2+ , this was linked to the comparable binding abilities of these ions for the receptor of the probe.

Core-shell upconversion nanoparticles of type NaGdF4:Yb,Er@NaGdF4:Nd,Yb and sensitized with a NIR dye are a viable probe for luminescence determination of the fraction of water in organic solvents.

Lanthanide-doped core-shell upconversion nanoparticles (UCNPs) of type NaGdF4:Yb,Er@NaGdF4:Yb,Nd were prepared by the co-precipitation method. The luminescence intensity was further enhanced by adding the sensitizer dye IR-808. If water is added to organic solvents [such as N,N-dimethylformamide (DMF), dimethyl sulfoxide, methanol, acetone, acetonitrile, and ethanol] containing the probe, its luminescence intensity peaking at 545 nm is reduced. The decrease is linearly related to the percentage of water in the respective organic solvent. Water fractions ranging from 0.05% to 10% (volume %) can be sensitively detected, and the detection limit is 0.018% of water in DMF. The detection scheme is mainly attributed to the fact that the transfer of energy from the near-infrared light (NIR) dye to the UCNPs is strongly reduced in the presence of traces of water. Graphical abstract The near infrared dye (IR-808) transfer efficiency to NaGdF4:Yb, Er@NaGdF4:Yb, Nd upconversion nanoparticles in water is far less than that in organic phase. Several methods for determination of trace water in organic solvents were developed by using this effect.

Photoexcitation-controlled self-recoverable molecular aggregation for flicker phosphorescence.

Chemical systems with external control capability and self-recoverability are promising since they can avoid additional chemical or energy imposition during the working process. However, it remains challenging to employ such a nonequilibrium method for the engineering of optoelectronic function and for visualization. Here, we report a functional molecule that can undergo intense conformational regulation upon photoexcitation. It enables a dynamical change in hydrophobicity and a follow-up molecular aggregation in aqueous media, accordingly leading to an aggregation-induced phosphorescence (AIP) behavior. This successive performance is self-recoverable, allowing a rapid (second-scale cycle) and long-standing (>103 cycles) flicker ability under rhythmical control of the AIP. Compared with traditional bidirectional manipulations, such monodirectional photocontrol with spontaneous reset profoundly enhances the operability while mostly avoiding possible side reactions and fatigue accumulation. Furthermore, this material can serve as a type of luminescent probe for dynamically strengthening visualization in bioimaging.

In vitro tracking of phospholipase A2 from snake venom conjugated with magic-sized quantum dots.

Phospholipases A2 represent a family of enzymes with important application in medicine. However, direct tracking is difficult due to the absence of a stable, effective and specific marker for these enzymes. Magic-sized quantum dots (MSQDs) are inorganic semiconducting nanocrystals with unique physical properties. They have the ability to conjugate to proteins, making them excellent markers for biological systems. In this work, we labelled phospholipase A2 from Bothrops alternatus snake venom with Cadmium selenide (CdSe)/cadmium sulphate (CdS) MSQDs-a biocompatible and luminescent probe-. Bioconjugation was confirmed using infrared spectra and fluorescence microscopy, which demonstrated that the CdSe/CdS MSQDs interact with phospholipase A2 without interfering with its activity. This probe may be an important tool for the elucidation of many biological mechanisms, because it allows the pathway of phospholipase A2 to be tracked from its entry through the plasma membrane until its incorporation into the nucleus of myoblasts.

Luminescence determination of microRNAs based on the use of terbium(III) sensitized with an enzyme-activated guanine-rich nucleotide.

A method is reported for the fluorometric quantitation of microRNA. It is making use of a luminescent probe deribed from terbium(III) ion whose fluorescence is sensitized with a guanine-rich (G-rich) nucleotide. The probe has a large Stokes' shift and strong and sharp emission bands. The assay relies on the wide substrate specificity of terminal deoxynucleotidyl transferase (TdTase), which catalyzes the formation of long G-rich nucleotides when using microRNA primer as a trigger to start the polymerization. The addition of Tb(III) induces the formation of a G-quadruplex from the G-rich nucleotide, and this strongly enhances the green fluorescence of Tb(III) (peaking at 545 nm upon photoexcitation at 290 nm). Specifically, microRNA-21 was chosen as the analyte. The fluorescence intensity of Tb(III) increases linearly in the 1 pM to 1 nM microRNA concentration range, and the detection limit is as low as 0.11 pM. The method can distinguish between family members of microRNA and performs excellently even when applied to extracts of cancer cells. Graphical abstract A fluorometric technique is reported for the determination of microRNA. It is based on signal enhancement based on the sensitization of terbium(III) via a guanine-rich nucleotide sequence. Klenow Fragment exo- (KFexo-) generates DNA sequence at the 3'-OH of microRNA, and terminal deoxynucleotidyl transferase (TdTase) catalyzes the formation of long G-rich nucleotides.

Solvo-thermal synthesis of a unique alkaline earth-transition Ba-Cd micro-porous coordination framework as hetero-metallic luminescent sensor for Cu2+ and real-time detection of benzaldehyde.

In this work a unique hetero-metallic alkaline earth-transition Ba-Cd luminescent micro-porous metal-organic framework {[BaCd(µ6-tp)1.5(µ2-Cl)(H2O) (DMF)2]·0.75H2O}n (H2tp=terephthalic acid) (1) has been prepared under solvo-thermal conditions. In 1 infinite 1D {Ba-X-Cd} (X=O, Cl) inorganic chains are linked via these full de-pronated tp2- ligands forming a unique 3D I1O2 type micro-porous coordination framework. PXRD patterns of 1 have been determined confirming pure phases of 1. Luminescence investigations suggested that 1 exhibits highly selective and sensitive sensing for trace amounts of benzaldehyde in ethanol, which provides a facile method for real-time detection of benzaldehyde. Meanwhile 1 also exhibits highly selective and sensitive sensing for Cu2+ over other cations with high quenching efficiency Ksv value 1.15×104L·mol-1. As far as we know, 1 represents the first example of alkaline earth-transition hetero-metallic Ba-Cd micro-porous coordination framework as bi-functional luminescent probes for Cu2+ and benzaldehyde.

Uranyl tris nitrato as a luminescent probe for trace water detection in acetonitrile.

Uranyl tris nitrato i.e. [UO2 (NO3 )3 ]- was formed by adding tetramethylammonium nitrate to uranyl nitrate in acetonitrile medium. The luminescence features of this complex in acetonitrile are very sensitive to water content, which could lead to the use of it as a luminescent probe for water present in acetonitrile. The luminescence intensity ratio of 507 to 467 nm peak of uranyl tris nitrato showed a linear response in the range 0-5% (v/v) water content in acetonitrile. The present method was applied for three synthetic samples of acetonitrile for water detection and the results obtained were compared using Karl Fischer titration. There was a good agreement in the values obtained by both the methods.