A novel coumarin-fluorescein-based fluorescent probe for ultrafast and visual detection of H2S in a Parkinson's disease model

Hydrogen sulfide (H2S) has a crucial impact on diverse biological processes and has been shown to be related to various diseases. Many probes have been developed to detect intracellular H2S by fluorescent imaging. However, the development of rapid, highly selective and sensitive H2S probes remains a challenge. Herein, two fluorogenic probes, CNS and FCS, are designed and synthesized for the ultrafast detection of H2S with fluorescein and coumarin fluorophores. The results show that both probes can be applied to monitor and image endogenous H2S in cervical cancer HeLa cells and live zebrafish, and FCS shows a higher sensitivity, selectivity and fluorescence intensity. We then further applied FCS in a Parkinson's disease Drosophila model, and the results show that FCS can precisely indicate the level of H2S in the Parkinson's disease model. Thus, FCS will likely to be applied for the early diagnosis of Parkinson's disease.

Real-time visualization the pH fluctuations of living cells with a ratiometric near-infrared fluorescent probe

In situ real-time quantitative monitoring pH fluctuation in complex living systems is vitally significant. In the current work, a ratiometric near-infrared (NIR) probe (MCyOH) was developed to confront this challenge. MCyOH exhibited good sensitivity, photostability, reversibility, and an ideal pKa (pKa = 6.65). Ratiometric character of MCyOH is beneficial to accuracy detect the pH fluctuations in living cells under different stimulation. The observations showed that intracellular pH was decreased when HepG2 cells under oxidative stress or starvation conditions. In particular, HepG2 cells was acidulated after addition of ethanol, however, the acidification phenomenon was attenuated or disappeared when HepG2 cells preincubated with disulfiram or fomepizole. Finally, MCyOH was successfully applied to observe the increasement of intracellular pH when HepG2 cells treated with fomepizole individually. Overall, MCyOH would be a practical candidate to explore pH-associated physiological and pathological varieties.

Exchangeable Self-Assembled Lanthanide Antennas for PLIM Microscopy

Lanthanides have unique photoluminescence (PL) emission properties, including very long PL lifetimes. This makes them ideal for biological imaging applications, especially using PL lifetime imaging microscopy (PLIM). PLIM is an inherently multidimensional technique with exceptional advantages for quantitative biological imaging. Unfortunately, due to the required prolonged acquisitions times, photobleaching of lanthanide PL emission currently constitutes one of the main drawbacks of PLIM. In this study, we report a small aqueous-soluble, lanthanide antenna, 8-methoxy-2-oxo-1,2,4,5-tetrahydrocyclopenta[de]quinoline-3-phosphonic acid, PAnt, specifically designed to dynamically interact with lanthanide ions, serving as exchangeable dye aimed at mitigating photobleaching in PLIM microscopy in cellulo. Thus, self-assembled lanthanide complexes that may be photobleached during image acquisition are continuously replenished by intact lanthanide antennas from a large reservoir. Remarkably, our self-assembled lanthanide complex clearly demonstrated a significant reduction of PL photobleaching when compared to well-established lanthanide cryptates, used for bioimaging. This concept of exchangeable lanthanide antennas opens new possibilities for quantitative PLIM bioimaging.

Carbazole-based mitochondria-targeted fluorescent probes for in vivo viscosity and cyanide detection in cells and zebrafish

Cells of most eukaryotic species contain mitochondria, which play a role in physiological processes such as cellular senescence, metabolism, and autophagy. Viscosity is considered a key marker for many illnesses and is involved in several crucial physiological processes. Cyanide (CN-) can target cytochrome-c oxidase, disrupting the mitochondrial electron transport chain and causing cell death through asphyxiation. In this study, a fluorescent probe named HL-1, which targets mitochondria and measures viscosity and CN- levels, was designed and synthesized. HL-1 is viscosity-sensitive, with a linear correlation coefficient of up to 0.992. In addition, HL-1 was found to change color substantially during a nucleophilic addition reaction with CN-, which has a low detection limit of 47 nM. HL-1 not only detects viscosity and exogenous CN- in SKOV-3 cells and zebrafish but also monitors viscosity changes during mitochondrial autophagy in real time. Furthermore, HL-1 has been used successfully to monitor changes in mitochondrial membrane potential during apoptosis. Endogenous CN- in plant samples was quantified. HL-1 provides new ideas for studying viscosity and CN-.

Synthesis of an aggregation-induced emission (AIE) dye with pH-sensitivity based on tetraphenylethylene-pyridine for fluorescent nanoparticles and its applications in bioimaging and in vitro anti-tumor effect

In this contribution, a novel AIE monomers 2-(4-styrylphenyl)- 1,2-diphenylvinyl)styryl)pyridine (SDVPY) with smart fluorescent pH-sensitivity basing on tetraphenylethylene-pyridine were successfully synthesized for the first time, subsequently, a series of amphiphilic copolymers PEG-PY were achieved by reversible addition-fragmentation chain transfer (RAFT) polymerization of SDVPY and poly(ethylene glycol) methacrylate (PEGMA), which would self-assemble in water solution to form core-shell nanoparticles (PEG-PY FONs) with about 150 nm diameter. The PEG-PY FONs showed obvious fluorescence response to Fe3+, HCO3- and CO32- ions in aqueous solution owing to their smart pH-sensitivity and AIE characteristics, and their maximum emission wavelength could reversibly change from 525 nm to 624 nm. The as-prepared PEG-PY FONs showed also prospective application in cells imaging with the variable fluorescence for different pH cells micro-environment. When PEG-PY copolymers self-assembled with the anti-tumor drug paclitaxel (PTX), the obtained PY-PTX FONs could effectively deliver and release PTX with pH-sensitivity, and could be easily internalized by A549 cells and located at the cytoplasm with high cytotoxicity, which was further confirmed by the Calcein-AM/PI staining of dead and alive A549 cells. Moreover, the flow cytometry results indicated that the PY-PTX FONs could obviously induce the apoptosis of A549 cells, which further showed the great potential of PY-PTX FONs in the application of tumors therapy.

Old trees bloom new flowers, lysosome targeted near-infrared fluorescent probe for ratiometric sensing of hypobromous acid in vitro and in vivo based on Nile red skeleton

Hypobromous acid (HOBr), one of the significant reactive oxygen species (ROS) that acts as an important role in human immune system, however the increasing level of HOBr in human body can cause the disorder of eosinophils (EPO), leading to oxidative stress in organelles, and further causing a series of diseases. In this study, a ratiometric fluorescent probe DMBP based on Nile red skeleton was developed to detect HOBr specifically by the electrophilic substitution with HOBr. DMBP emits near-infrared (NIR) fluorescence at 653 nm, after reacting with HOBr, the emission wavelength of DMBP shifted blue and a new peak appeared at 520 nm, realizing a ratiometric examination of HOBr with a limit of detection of 89.00 nM. Based on its sensitive and specific response to HOBr, DMBP was applied in the visual imaging of HOBr in HepG2 cells and zebrafish. Foremost, probe DMBP has excellent lysosome targeting ability and NIR emission reduced the background interference of biological tissues, providing a potential analytical tool to further investigate the role of HOBr in lysosome.

Recent progress of near-infrared fluorescent probes in the determination of reactive oxygen species for disease diagnosis

Reactive oxygen species (ROS), a chemically defined group of reactive molecules derived from molecular oxygen, are involved in a variety of physiological and pathological processes, including immune defense, cellular metabolism, and other physiological processes. To access their detailed function in these processes, it is critical to establish rapid, accurate and in situ assays for these species in vivo. Among the potential assays, fluorescent probes are considered as the most promising candidate to monitor the biological ROS in vivo with great spatial and temporal resolution and are extensively used as an excellent tool in modern redox biology discovery. Recently, abundant fluorescent probes have been successively developed for in vitro or intracellular detection of ROS, but most of them could not be used for in vivo imaging due to their intrinsic shortcomings such as short emission wavelengths, phototoxicity and poor tissue penetration. Recent development of fluorescent ROS probes with near-infrared emission aim to address these concerns to develop practical assays. Herein, we review recent developments of ROS-sensitive near-infrared fluorescent probes, with an emphasis on the design, synthesis, characteristics of fluorescent probes, as well as their applications. We hope this review will aid the development of a new generation of efficient, sensitive and biocompatible fluorescent probes for in vivo ROS detection.

Ultrasound activated probe for disease imaging and therapy In-Vivo

Sonodynamic therapy (SDT) is the use of ultrasound (US) to excite sonosensitizers to produce reactive oxygen species (ROS) to induce tumor cell death, thereby achieving therapeutic purposes. Based on the strong tissue penetration ability of ultrasound, SDT can realize the treatment of deeper tumors, and it is targeted, can be specifically concentrated at the tumor site, and has little impact on surrounding normal tissues. It has broad clinical transformation prospects. Therefore, sonosensitizers are the key to SDT, and the exploration of sonosensitizers with excellent therapeutic performance has received great attention. We reviewed the development of ultrasound-inspired sound sensitizers for imaging and treatment. First, different types of sonosensitizers are introduced, the construction and performance of inorganic, organic and hybrid types of sonosensitizers are evaluated, followed by a review of different image-guided SDT, and finally the key problems and solutions in this field are discussed in detail.

A turn-on fluorescent probe for detecting and bioimaging of HOCl in inflammatory and liver disease models

Hypochlorous acid (HOCl) is a common reactive oxygen species (ROS) associated with the development of liver, tumor, inflammatory, and other diseases. In this work, the turn-on fluorescent probe named (WZ-HOCl) with a naphthalimide structure was designed and synthesized to detect endogenous HOCl in disease models. WZ-HOCl can achieve a fast response to HOCl with good linearity in the range of 0-45 μM (LOD = 147 nM). The application of WZ-HOCl in bioimaging was investigated by constructing a series of cellular disease models, and the results showed that WZ-HOCl could sensitively detect endogenous HOCl in inflammatory and liver disease models. It can also be used to differentiate between hepatocytes and hepatoma cells. WZ-HOCl will provide new methods and ideas for fluorescent probes in detecting drug-induced liver injury, alcoholic and non-alcoholic steatohepatitis, and some inflammation-related diseases.

A D-π-A-based near-infrared fluorescent probe with large Stokes shift for the detection of cysteine in vivo

D-π-A dyes are an ideal strategy for building near-infrared fluorescent probes that have a large Stokes shift due to their excellent properties of adjustable emission wavelength and Stokes shift. Developing a near-infrared (NIR) fluorescent probe (JTPQ-Cys) capable of detecting cysteine (Cys) was the aim of this study. In JTPQ-Cys, julolidine served as the electron donor (D) and quinoline as the electron acceptor (A), with 3,4-ethylenedioxythiophene as the π-bridge. The π-conjugation and vibrational/rotational activity of the molecule were increased by the introduction of 3,4-ethylenedioxythiophene, causing the molecule to exhibit NIR emission and a large Stokes shift. When JTPQ-Cys was used to detect Cys, a clear fluorescence turn-on signal was observed at 741 nm, together with a Stokes shift of 268 nm. The limit of detection of JTPQ-Cys for Cys is 24 nM. Moreover, JTPQ-Cys has been utilized successfully for imaging studies of Cys in cells and zebrafish because it has good photostability, low cytotoxicity, and a high signal-to-noise ratio. Overall, our findings demonstrate the potential of JTPQ-Cys to be one of the best choices for detecting Cys in biological systems, and JTPQ is an ideal fluorophore to construct fluorescence dyes for bioimaging.

Time-gated luminescent probes for lysosomal singlet oxygen: Synthesis, characterizations and bioimaging applications

BACKGROUD

Single oxygen (1O2), the molecular oxygen at its excited state, plays a crucial role in the photodynamic therapy (PDT) of some diseases owing to its strong oxidizing property to destroy malignant cells. Although the fluorescent probe technique has proven its powerful application abilities for detection of 1O2 in biological systems, most of the reported fluorescent probes suffered from the interference of background autofluorescence of biological samples. It is clear that the real-time and in situ, background-free fluorescent detection of 1O2 generated in live cells, especially in some organelles, is of great significance for understanding the action mechanism of PDT drugs.

RESULTS

By introducing a lysosome-anchoring motif, a morpholine moiety, into a 1O2-specifically-reactive terpyridine polyacid ligand, [4'-(9-anthryl)-2,2':6',2″-terpyridine-6,6″-diyl] bis(methylenenitrilo) tetrakis (acetic acid) (ATTA), and chelating with lanthanide ions (Eu3+ or Tb3+), two lanthanide complex-based "turn-on" luminescent probes that can be used for the background-free time-gated luminescent (TGL) detection of lysosomal 1O2, Lyso-ATTA-Eu3+ and Lyso-ATTA-Tb3+, have been developed. The probes exhibit fast luminescence responses (within 2.5 min) towards 1O2 with high selectivity and sensitivity (<0.75 μM) in a wide pH range (4-11). And the excellent lysosome-localization performance of the probes allowed them to be used for the monitoring of endogenous 1O2 in lysosomes, which enabled the variability of lysosomal-1O2 concentrations induced by different photosensitizers to be successfully discriminated. Furthermore, by doping Lyso-ATTA-Eu3+ into the polyethylene glycol (PEG) hydrogel, the smart luminescent sensor film, PEG-Lyso-ATTA-Eu3+, was prepared, and successfully used for the detection of the on-site 1O2 production during the PDT process of psoriatic disease in model mice.

SIGNIFICANT

Two lysosome-targetable background-free TGL probes for 1O2 were firstly reported. The developed smart luminescent sensor film could be a powerful tool for the clinical monitoring of PDT on skin diseases without using sophisticated and expensive instruments.

Design, synthesis and cell imaging of a new 3-thiolflavone fluorescent probe for biothiols

Abnormal levels of intracellular biothiol species, including glutathione (GSH), homocysteine (Hcy), and cysteine (Cys), are closely relevant to a variety of diseases. In this study, we first report the design and synthesis of a 3-thiolflavone-based probe 3-STF with an S-S linkage both as the fluorescence quenching agent and the recognition site. Upon treatment with biothiols, the S-S linkage was cleaved by nucleophilic attack of RS-, and 3-STF exhibited a specific "turn-on" fluorescence response at 543.8 nm upon 390 nm excitation. Meanwhile, 3-STF was proved to be highly sensitive and selective for the detection of biothiols over other nucleophiles such as amino acids and H2S. The sensing mechanism was further verified by 1H NMR and ESI-MS analysis. In addition, 3-STF with low cytotoxicity can be successfully applied to detect endogenous and exogenous biothiols in HepG-2 cells.

A novel pathway for ratiometric hydrazine sensing in environmental samples and the detection of intracellular viscosity by a mitochondria-targeted fluorescent sensor

Mass and signal transfer, dispersion of reactive metabolites in living cells, and interactions between biomacromolecules are greatly affected by viscosity inside the cells. It is crucial to accurately determine viscosity for reliable results because of the complexities of live cells. Herein, we introduce a new fluorescence probe based on the cyanobiphenyl and benzothiazolium units. This probe not only responds to intracellular viscosity but also detects hydrazine, a widely used chemical that poses significant environmental and toxic risks to organisms. The proposed sensing mechanism provides a new pathway that includes intramolecular cyclization with hydrazine, which differs from other sensing mechanisms. A weak emission (at 590 nm) of the probe under excitation at 365 nm resulted in 25-fold higher emission at 488 nm after the addition of N2H4. The quantum yield of the probe (Φ = 0.089) increased to Φ = 0.199 with the addition of N2H4. In addition, the probe demonstrated 45-fold emission enhancement at 560 nm in viscous media, with a color change from non-fluorescence to yellow fluorescence. Good hydrazine sensing features with high adaptability, selectivity, sensitivity, ratiometric and fast response (90 s), low cytotoxicity (more than 90% of cell viability), low detection limit (86.0 nM), good linearity in the range of 0-35.0 μM, and high signal-to-noise ratio sensing capability were achieved. The hydrazine-sensing capability of the mitochondria-targetable probe in living cells makes it a strong candidate for various biological and environmental applications, including intracellular tracking and imaging. These results suggest that the present probe shows significant potential for the effective fluorescence detection of hydrazine.

A fluorescent probe for bioimaging of GSH in cancer cells

A fluorescent probe CTP2-IMC was designed for bioimaging of glutathione (GSH) in cancer cells with indomethacin (IMC), coumarin and bromide as the targeting group, fluorophore and receptor, respectively. Due to the π-π interaction between coumarin and IMC, CTP2-IMC mainly exists in the form of folded state in aqueous solution. The non-radiative transitions caused by the photo-induced electron transfer (PET) process from IMC to the fluorophore as well as the heavy-atom effect led to non-fluorescent of CTP2-IMC. The substitution of Br by GSH and unfolded conformation induced by IMC acceptor on cancer cells resulted in significant fluorescence enhancement, which enabled CTP2-IMC to bioimage GSH in cancer cells rather than in normal one.

Xanthene-based Hg2+ fluorescent probe for detection of Hg2+ in water/food samples, as well as imaging of live cells, zebrafish and tobacco seedlings

In this paper, an Hg2+ detection probe, HOS, was prepared with a xanthene as the parent fluorophore. Hg2+-initiated thioacetal deprotection reaction is the detection mechanism of this probe. After testing, the probe HOS was able to accurately determine Hg2+ with a detection limit of 36 nM. It was successfully applied to the detection of Hg2+ in different water samples and shrimp samples, meanwhile, the filter paper strips prepared by HOS were obviously changed from light yellow to dark yellow under daylight, and from green to yellow under 365 nm UV light. Furthermore, probe HOS enabled Hg2+ bioimaging experiments on HepG2 cells, zebrafish and tobacco seedlings under laser confocal microscopy.

Promises of anionic calix[n]arenes in life science: State of the art in 2023

Because they hold together molecules by means of non-covalent interactions - relatively weak and thus, potentially reversible - the anionic calixarenes have become an interesting tool for efficiently binding a large range of ligands - from gases to large organic molecules. Being highly water soluble and conveniently biocompatible, they showed growing interest for many interdisciplinary fields, particularly in biology and medicine. Thanks to their intrinsic conical shape, they provide suitable platforms, from vesicles to bilayers. This is a valuable characteristic, as so they mimic the biologically functional architectures. The anionic calixarenes propose efficient alternatives for overcoming the limitations linked to drug delivery and bioavailability, as well as drug resistance along with limiting the undesirable side effects. Moreover, the dynamic non-covalent binding with the drugs enables predictable and on demand drug release, controlled by the stimuli present in the targeted environment. This particular feature instigated the use of these versatile, stimuli-responsive compounds for sensing biomarkers of diverse pathologies. The present review describes the recent achievements of the anionic calixarenes in the field of life science, from drug carriers to biomedical engineering, with a particular outlook on their applications for the diagnosis and treatment of different pathologies.

A multi-signal mitochondria-targeted fluorescent probe for simultaneously distinguishing biothiols and realtime visualizing its metabolism in cancer cells and tumor models

Biothiols and its metabolite SO2 derivatives play vital roles in various physiological processes. Although a few probes have been designed for monitoring the metabolism of biothiols, developing multi-signal fluorescent probes with practicability for simultaneously distinguishing biothiols (GSH, Cys and Hcy) and real-time visualizing SO2 derivatives is an enormous challenge. To better visualize biothiols metabolism in vitro and vivo, we developed a novel multi-signal NIR fluorescent probe (probe 2) with mitochondria-targeted for distinguishing biothiols and its metabolism, based on an ICT-PET synergetic mechanism. Probe 2 with dual recognition sites distinguishing detected Cys/Hcy (Red-Green), GSH (Green) and SO32- (Blue) via three channels. First probe 2 distinguished Cys and GSH to estimate main biothiols in living cells through the ratio changes of two well-defined emission bands (Red-Green), and then imaged its metabolite SO2 with ratiometric fluorescence (Red-Blue), eliminating the interference by different biothiols. Notably, probe 2 exhibits satisfactory sensitivity (detection limit: 0.21, 0.13, 0.14 and 3.06 μM for Cys, Hcy, GSH and SO32-, respectively), high selectivity, reliability at physiological pH, and rapid fluorescence response (within 10 min). Given these advantages, probe 2 has been successfully applied to the real-time monitor GSH metabolic process in MCF-7 cells and biothiols metabolism in breast cancer, suggesting biothiols metabolic changes might be a diagnostic indicator during cancer treatment. So probe 2 is a convenient and efficient tool for understanding the physiological functions of biothiols and its metabolism.

A chromogenic diarylethene-based probe for the detection of Cu2+ in aqueous medium in Drosophila for early diagnosis of Alzheimer

A diarylethene-based probe (Z)-N'-((2-amino-5-chlorophenyl)(phenyl)methylene)-2-hydroxy benzohydrazide (KBH) has been proficiently developed and its structure has been confirmed by single crystal X-ray diffraction technique. It displays a selective and sensitive colorimetric sensing of Cu2+ ions in aqueous medium with a naked eye colour change from colourless to yellow. It exhibits a significantly low limit of detection as 1.5 nM. A plausible binding mechanism has been proposed using Job's plot, FT-IR, 1H NMR titration, HRMS and DFT studies. The chemosensor is effectively reversible and reusable with EDTA. Test strip kit and real water sample analysis have been shown to establish its practical applicability. Further, the potential of KBH for the early diagnosis of Cu2+ ion-induced amyloid toxicity has been investigated in eye imaginal disc of Alzheimer's disease model of Drosophila 3rd instar larvae. The in-vivo interaction of KBH with Cu2+ in gut tissues of Drosophila larvae establishes its sensing capability in biological system. Interestingly, the in-vivo detection of Cu2+ has been done using bright field imaging which eliminates the necessity of a fluorescent label, hence making the method highly economical.

Lipid Droplets Specific Fluorophore for Demarcation of Normal and Diseased Tissues

Using high-fidelity, permeable, lipophilic, and bright fluorophores for imaging lipid droplets (LDs) in tissues holds immense potential in diagnosing conditions such as diabetic or alcoholic fatty liver disease. In this work, we utilized linear and Λ-shaped polarity-sensitive fluorescent probes for imaging LDs in both cellular and tissue environments, specifically in rats with diabetic and alcoholic fatty liver disease. The fluorescent probes possess several key characteristics, including high permeability, lipophilicity, and brightness, which make them well-suited for efficient LD imaging. Notably, the probes exhibit a substantial Stokes shift, with 143 nm for DCS and 201 nm for DCN with selective targeting of the lipid droplets. Our experimental investigations successfully differentiated morphological variations between diseased and normal tissues in three distinct tissue types: liver, adipose, and small intestine. They could help provide pointers for improved detection and understanding of LD-related pathologies.

3D-printed colorimetric copper ion detection kit and portable fluorescent sensing device using smartphone based on ratiometric fluorescent probes

Copper ion (Cu2+) is not only a transition metal ion but also a significant environmental pollutant. The imbalance of Cu2+ content will threaten the safety of the environment and even life. The portable detection devices based on ratiometric fluorescent probes have garnered increasing attention and acclaim because of their reliable analysis parameters. Therefore, two Cu2+ ratiometric fluorescent probes (RH-1 and RH-2) were developed, which exhibit pronounced fluorescence changes, high sensitivity, excellent selectivity, and large Stokes shift. Both probes are capable of detecting Cu2+ in water and milk samples. It is worth noting that a 3D-printed fluorescence sensing device was constructed using RH-1, and a new 3D-printed copper ion detection kit was developed based on RH-2, enabling on-the-spot estimation of Cu2+ concentration. These devices significantly facilitate Cu2+ detection in daily life. RH-2 has been successfully employed for imaging Cu2+ in living cells and zebrafish. In conclusion, this work provides, for the first time, the 3D-printed ideal tools for detecting Cu2+. It also provides valuable insights for the establishment of on-site portable detection methods for other important substances.

Polyethylenimine-protected green-emission copper nanoclusters as highly effective fluorescent and colorimetric nanoprobe for selective cobalt ions and temperature sensing

Excessive uptake of Co2+ is harmful to one's physical health and should not be ignored. Herein, a polyethylenimine (PEI) protected hydrophilic copper nanoclusters (PEI-CuNCs) with strong green fluorescence emission around 510 nm was apace synthesized employing a one-pot method without hyperthermia. Interestingly, the as-prepared water-soluble PEI-CuNCs can be specifically quenched by Co2+ at pH 6.0, with a wide detection range (0-500 μM) and a sensitive detection limit of 14.9 nM, which was lower than the maximum level in the body. Besides, the colorimetric detection of Co2+ could be additionally realized based upon the typical yellow color of PEI-CuNCs changed to baby-pink color of the PEI-Co2+ complex. Furthermore, the PEI-CuNCs was employed in fabrication portable test strip for visual detection of Co2+ by capturing the change in fluorescence color, which can be ascribed to the coordination interaction between Co2+ and amine groups in PEI, and also the aggregated quenching of large PEI-CuNCs-Co2+ particles formation. Moreover, the PEI-CuNCs displayed excellent reversible thermo-responsive within a temperature range of 20-65 °C. It is worth mentioning that the PEI-CuNCs exhibited low bio-toxicity and excellent cell permeability when selectively detecting Co2+ in living cells by fluorescence microscopy imaging. Armed with these engaging properties, the sensing system paved a new avenue for the effective development of a convenient fluorescence colorimetry sensor for general assessment of potential risks and specific assessment of human security.

A review of innovative electrochemical strategies for bioactive molecule detection and cell imaging: Current advances and challenges

Cellular heterogeneity poses a major challenge for tumor theranostics, requiring high-resolution intercellular bioanalysis strategies. Over the past decades, the advantages of electrochemical analysis, such as high sensitivity, good spatio-temporal resolution, and ease of use, have made it the preferred method to uncover cellular differences. To inspire more creative research, herein, we highlight seminal works in electrochemical techniques for biomolecule analysis and bioimaging. Specifically, micro/nano-electrode-based electrochemical techniques enable real-time quantitative analysis of electroactive substances relevant to life processes in the micro-nanostructure of cells and tissues. Nanopore-based technique plays a vital role in biosensing by utilizing nanoscale pores to achieve high-precision detection and analysis of biomolecules with exceptional sensitivity and single-molecule resolution. Electrochemiluminescence (ECL) technology is utilized for real-time monitoring of the behavior and features of individual cancer cells, enabling observation of their dynamic processes due to its capability of providing high-resolution and highly sensitive bioimaging of cells. Particularly, scanning electrochemical microscopy (SECM) and scanning ion conductance microscopy (SICM) which are widely used in real-time observation of cell surface biological processes and three-dimensional imaging of micro-nano structures, such as metabolic activity, ion channel activity, and cell morphology are introduced in this review. Furthermore, the expansion of the scope of cellular electrochemistry research by innovative functionalized electrodes and electrochemical imaging models and strategies to address future challenges and potential applications is also discussed in this review.

Influence of surface modification and size of lanthanide-doped upconverting nanoparticles on wheat seedlings

In recent years, nanotechnology has found widespread applications in environmental monitoring, medical applications, plant fertilisers, cosmetics and others. Therefore, it is important to study nanomaterials' influence and subsequent risks to the environment and organisms (from production to disposal). Therefore, in the present study, the toxic effects of two surface modifications (poly (ethylene glycol)-neridronate, PEG-Ner and poly (acrylic acid), PAA) in comparison to unmodified, 26 nm- and 52 nm-sized core@shell lanthanide-doped upconverting nanoparticles (UCNPs, NaYF4:Yb3+,Er3+@NaYF4) were analysed. Wheat seedlings (Triticum aestivum L.) were chosen as a model organism since this species is one of the most widely cultivated crops. The influence of UCNPs (at concentrations of 0, 10, 50, and 100 μg/mL) on germination percentage, germination rate and growth was studied based on morphological parameters such as root number, root and hypocotyl length, and root and hypocotyl mass. In addition, an assay based on Evans blue staining was conducted to analyse damaged cell membranes and cell death. The type, size and concentration of UCNPs influenced the growth but not the germination of wheat. 52-nm-sized ligand-free UCNPs and the 26-nm-sized UCNPs/PAA decreased plant growth. Moreover, the ligand-free 26-nm-sized UCNPs interacted with the root cell membranes of seedlings. No significant changes were observable regarding viability (tetrazolium chloride reduction assay), oxidative stress and electrolyte leakage from root cells in plants incubated with ligand-free 26-nm-sized UCNPs. Overall, we have shown that the ligand-free UCNPs (of both sizes) had the strongest toxic effect; PAA-modified UCNPs were toxic only at smaller sizes and PEG-Ner-modified UCNPs had no toxic impact. Therefore, PEG-Ner was identified as the safest surface compound among the UCNPs investigated in the study, which may neutralise the harmful effects of nanoparticles on plants.

Distribution of molybdenum in soft tissues and blood of rats after intratracheal instillation of molybdenum(IV) sulfide nano- and microparticles

There is still little literature data on the toxicity and safety of the commonly used molybdenum (Mo) disulfide which is present in the working as well as living environments. Thus, an experiment was carried out involving rats, with single and repeated intratracheal exposure (in the latter case, 7 administrations at 2-week intervals with the analysis performed after 90 days) to lower (1.5 mg Mo kg-1 b.w.) and higher (5 mg Mo kg-1 b.w.) doses of molybdenum(IV) sulfide nanoparticles (MoS2-NPs) and microparticles (MoS2-MPs). The analysis of Mo concentrations in the tail and heart blood as well as in soft tissues (lung, liver, spleen, brain), after mineralization and bioimaging, was meant to facilitate an assessment of its accumulation and potential effects on the body following short- and long-term exposure. The multi-compartment model with an exponential curve of Mo concentration over time with different half-lives for the distribution and elimination phases of MoS2-MPs and MoS2-NPs was observed. After 24 h of exposure, a slight increase in Mo concentration in blood was observed. Next, Mo concentration indicated a decrease in blood concentration from 24 h to day 14 (the Mo concentration before the second administration), below the pre-exposure concentration. The next phase was linear, less abrupt and practically flat, but with an increasing trend towards the end of the experiment. Significantly higher Mo concentrations in MoS2-NPs and MoS2-MPs was found in the lungs of repeatedly exposed rats compared to those exposed to a single dose. The analysis of Mo content in the liver and the spleen tissue showed a slightly higher concentration for MoS2-NPs compared to MoS2-MPs. The results for the brain were below the calculated detection limit. Results were consistent with results obtained by bioimaging technique.

Diketopyrrolopyrrole-based fluorescent probe for visualizing over-expressed carboxylesterase in fever via ratiometric imaging

Fever is the result of inflammation and the innate self-defense response of organisms, can cause abnormal changes in the activity of many enzymes in organisms, including the important carboxylesterase (CE). Monitoring the activity changes of CE in vivo during a fever will help to understand heat-related pathological mechanisms. In this paper, we designed diketopyrrolopyrrole-based ratiometric fluorescent probes DPP-FBC-P and DPP-FBO-P containing alkyl chain and diethylene glycol monomethyl ether chain respective for detection of CE. Both probes could realized fast response to CE and displayed good selectivity and high sensitivity. Compared with DPP-FBO-P, DPP-FBC-P had better biocompatibility, larger signal to noise ratio (225-fold vs 125-fold) and lower detection limit (1.6 × 10-5 U/mL vs 4.2 × 10-5 U/mL). Moreover, the probe DPP-FBC-P had been successfully applied to image the endogenous CE in HepG2 cells and solid tumors, and also visualized the over expressed CE in fever cells. Most importantly, the changes of CE level in the liver of fever mice model induced by LPS were monitored with the assistance of DPP-FBC-Pvia dual channel ratio imaging for the first time. In addition, fluorescence color signal in solution was captured by smart phone, and the linear relationship between RGB ratio (G/R) and CE concentration was established. This work will provide a potential approach for investigating the physiological and pathological processes of heat related diseases.

Photocatalytic, Antibacterial, Cytotoxic and Bioimaging Applications of Fluorescent CdS Nanoparticles Prepared in DNA Biotemplate

Synthesizing nanoparticles in biotemplates has been cited as one of the most promising way to obtain monodispersed inorganic nanoparticles. In this method, uniform voids in porous materials serve as hosts to confine the synthesized nanoparticles. DNA template can be described as a smart glue for assembling nanoscale building blocks. Here we investigate the photocatalytic, antibacterial, cytotoxic, and bioimaging applications of DNA capped CdS. XRD, SEM, TEM, UV-visible absorption, and photoluminescence spectra were used to study structural, morphological, and optical properties of CdS nanoparticles. Prepared CdS nanoparticles exhibit visible fluorescence. The photocatalytic activity of CdS towards Rhodamine 6G and Methylene blue are 64% and 91% respectively. A disc-diffusion method is used to demonstrate antibacterial screening. It was shown that CdS nanoparticles inhibit Gram-positive bacteria and Gram-negative bacteria effectively. DNA capped CdS shows higher activity than uncapped CdS nanoparticles. MTT cell viability assays were carried out in HeLa cells to investigate the cytotoxicity for 24 h. At a concentration 2.5 µg/ml, it shows 84% cell viability and 43% viability at 12.5 µg/ml. The calculated LC50 value is equal to 8 µg/ml. These DNA capped CdS nanoparticles were taken for an in-vitro experiment with HeLa cells to exhibit the possibility of bioimaging applications. The present study suggests that the synthesized CdS nanoparticles could be a potential photocatalyst, antibacterial agent, and biocompatible nanoparticle for bioimaging applications.

Metallosurfactant aggregates: Structures, properties, and potentials for multifarious applications

Metallosurfactants offer important scientific and technological advances due to their novel interfacial properties. As a special class of structures formed by the integration of metal ions into amphiphilic surfactant molecules, these metal-based amphiphilic molecules possess both organometallic and surface chemistries. This review critically examines the structural transitions of metallosurfactants from micelle to vesicle upon metal coordination. The properties of a metallosurfactant can be changed by tuning the coordination between the metal ions and surfactants. The self-assembled behavior of surfactants can be controlled by selecting transition-metal ions that enhance their catalytic efficiency in environmental applications by applying a hydrogen evolution reaction or oxygen evolution reaction. We present the different scattering techniques available to examine the properties of metallosurfactants (e.g., size, shape, structure, and aggregation behavior). The utility of metallosurfactants in catalysis, the synthesis of nanoparticles, and biomedical applications (involving diagnostics and therapeutics) is also explored.

Synthesis and Application of Carbon Quantum Dots Derived from Carbon Black in Bioimaging

Carbon quantum dots (CQDs) are a new type of fluorescent QDs that consists mainly of carbon atoms. In this research, CQDs were synthesized through harsh oxidizing conditions applied on carbon black and subsequent N-doping using hexamethylenetetramine (Hexamine) and polyethyleneimine (PEI). The synthesized CQDs were characterized using FTIR, AFM, UV-Visible spectroscopy, photoluminescence (PL) spectroscopy, and fluorescence imaging respectively. The AFM images showed that the dots are in the range of 2-8 nm. N-doping of the CQDs increased the PL intensity. The PL enhancement for the CQDs that were N-doped with PEI was higher compared to those N-doped with hexamine. The shift in PL by changing the excitation wavelength has been attributed to the nano-size of the CQDs, functional groups, defect traps, and quantum confinement effect. The in vitro fluorescence imaging revealed that N-doped CQDs can internalize into the cells and be used for fluorescent cell imaging.

An aggregation-induced emission-based ratiometric fluorescent chemosensor for Hg(II) and its application in Caenorhabditis elegans imaging

A chromone-based ratiometric fluorescent probe L2 was developed for the selective detection of Hg(II) in a semi-aqueous solution based on aggregation-induced emission (AIE) and chelation-enhanced fluorescence (CHEF) effect. The probe L2 fluoresced significantly at 498 nm in its aggregated state, and when chelated with Hg(II), the soluble state fluoresced 1-fold higher. In addition, Job's plot reveals that the probe forms a 1:1 stoichiometry complex with Hg(II) with an association constant of 9.10 × 103M-1 estimated by the BH plot. The probe L2 detects Hg(II) down to 22.47 nM without interference from other interfering ions. The FTIR, ESI mass, and DFT-based computational studies investigated the binding mechanism of probe L2 with Hg(II). Taking advantage of its AIE characteristics, the probe L2 was successfully applied for bio-capability analysis in Caenorhabditis elegans (a nematode worm) imaging of Hg(II) in a living model.

A rationally designed fluorescent probe for sulfur dioxide and its derivatives: applications in food analysis and bioimaging

Exogenous sulfur dioxide (SO2) and its derivatives (SO32-/HSO3-) have been extensively utilized in food preservation and endogenous SO2 is recognized as a significant gaseous signaling molecule that can mediate various physiological processes. Overproduction and/or extensive intake of these species can trigger allergic reactions and even tissue damage. Therefore, it is highly desirable to monitor SO2 and its derivatives effectively and quantitatively both in vitro and in vivo. Herein, a new mitochondria-targeted fluorescent probe (PIB) had been constructed, which could ratiometrically recognize SO2 and its derivatives with excellent sensitivity (DL = 15.9 nM) and a fast response time (200 s). The obtained high selectivity and good adaptability of this SO2-specific probe in a wide pH range (6.5-10.0) allowed for quantitatively tracking of SO2 and its derivatives in real food samples (granulated sugar, crystal sugar, and white wine). In addition, PIB could locate at mitochondrion and was capable of imaging exogenous/endogenous SO2 in the cells and zebrafish. In particular, our findings represented one of the rare examples that have demonstrated endogenous SO2 is closely related with the apoptosis of cells. Importantly, probe PIB was successfully employed for in situ metabolic localization in mouse organs, implying the potential applications of our probe in further exploration on SO2-releated pathological and physiological processes.

A novel sensitive fluorescent probe with double channels for highly effective recognition of biothiols

Biothiols play a crucial role in maintaining redox balance in organisms, and anomalous levels of biothiols in human organs can lead to various sicknesses and biological disorders. This work developed a novel sensitive fluorescent probe TZ-NBD with double channels for highly efficient recognition of biothiols. TZ-NBD adopts 4-Chloro-7-nitrobenzofurazan (NBD-Cl) as the recognition moiety with simultaneous fluorescence output. By incorporating NBD-Cl with the other fluorophore, benzothiazole dihydrocyclopentachromene derivative (TZ-OH), the dual-channel sensitive fluorescence probe TZ-NBD was built. The existence of Cys/ Hcy could significantly trigger both the green and red fluorescent emissions, which were derived from fluorophores amine-substituted NBD and TZ-OH, respectively. While exposing to GSH, only the red-channel fluorescence signal could be detected, indicating the release of TZ-OH. The phenomena was mainly attributed to the fact that sulfur-substituted NBD has nearly no fluorescence, while amine-substituted NBD shows obvious green fluorescence. In our study, TZ-NBD exhibited dual-channel sensitivity, fast response, and excellent selectivity to biothiols in vitro. Moreover, TZ-NBD was favorably utilized for recognition of biothiols in vivo. We believe that the sensitive fluorescence probe with double channels can afford an alternate approach for monitoring biothiols in organisms and would be useful for studying diseases associated with biothiols.

Applications of human and bovine serum albumins in biomedical engineering: A review

Serum albumin, commonly recognized as a predominant major plasma protein, is ubiquitously distributed among vertebrates, demonstrating versatility and widespread accessibility. Numerous studies have discussed the composition and attributes of human and bovine serum albumin; nonetheless, few systematic and comprehensive summaries on human and bovine serum albumin exist. This paper reviews the applications of human and bovine serum albumin in biomedical engineering. First, we introduce the differences in the structure of human and bovine serum albumin. Next, we describe the extraction methods for human and bovine serum albumin (fractionation process separation, magnetic adsorption, reverse micellar (RM) extraction, and genetic engineering) and the advantages and disadvantages of recently developed extraction methods. The characteristics of different processing forms of human and bovine serum albumin are also discussed, concomitantly elucidating their intrinsic properties, functions, and applications in biomedicine. Notably, their pivotal functions as carriers for drugs and tissue-engineered scaffolds, as well as their contributions to cell reproduction and bioimaging, are critically examined. Finally, to provide guidance for researchers in their future work, this review summarizes the current state of human and bovine serum albumin research and outlines potential future research topics.

Rhodamine-based Fluorescent Probe With Quick Response and High Selectivity for Imaging Labile Ferrous Iron in Living Cells and Zebrafish

The transition between its various oxidation states of Iron plays a crucial part in various chemical transformation of cells. Misregulation of iron can give rise to the iron-catalyzed reactive oxygen species disorder which have been linked to a variety of diseases, so it is crucial to monitor the labile iron pool in vivo for clinical diagnosis. According to iron autoxidation and hydrogen abstraction reaction, we reported a novel "off-on" fluorescent probe to response to ferrous (Fe2+) both in solutions and biological systems. The probe responds to Fe2+ with good selectivity toward competing metal ions. What's more, the probe presents significant fluorescent enhancement to Fe2+ in less than 1 min, making real-time sensing in biological system possible. The applications of the probe in bioimaging revealed the changes in labile iron pool by iron autoxidation or diverse stimuli.

Development of Simple Fluorescence Analytical Strategy for the Detection of Triazophos Using Greenish-Yellow Emissive Carbon Dots Derived from Curcuma longa

This study describes a new method for synthesizing water-soluble carbon dots (CDs) using "Curcuma longa" (green source) named CL-CDs via a single-step hydrothermal process. The as-synthesized CL-CDs exhibited greenish-yellow fluorescence at 548 nm upon excitation at 440 nm. It shows good water stability and exhibits a quantum yield of 19.4%. The developed probe is utilized for sensing triazophos (TZP) pesticide via a dynamic quenching mechanism, exhibiting favorable linearity ranging from 0.5-500 μM with a limit of detection of 0.0042 μM. The as-prepared CL-CDs probe was sensitive and selective towards TZP. Lastly, the successful application of the CL-CDs-based fluorescent probe in water and rice samples highlights its potential as a reliable and efficient method for the detection of TZP in various real sample matrices. Eventually, bioimaging and biocompatibility aspects of CL-CDs have been assessed on Saccharomyces cerevisiae (yeast) cell and lung cancer (A549) cell lines, respectively.

An activatable small-molecule fluorogenic probe for detection and quantification of beta-amyloid aggregates

Extracellular accumulation of β amyloid (Aβ) peptides in the brain is thought to be a pathological hallmark and initial event before the symptom starts of Alzheimer's patients. Herein, we developed two series of benzo[d]thiazole-based small-molecule compounds (BM1-BM4, BPM1-BPM4) with a donor-acceptor (D-A) or donor-π-acceptor (D-π-A) architecture, respectively, based on structure-activity relationship. Among them, the optimized BPM1 not only displayed the highest binding affinity to Aβ aggregates over other proteins or Aβ monomers, but was readily activated its fluorescence with 10-fold fluorescence enhancement, allowing for specifically and sensitively detecting Aβ aggregates. BPM1 also exhibits several other advantages including low molecular weight, low cytotoxicity and excellent biological stability. Besides, cell staining results confirmed that SK-N-BE(2) cells can be fluorescently lighted up as well as cell permeability and damage when treated with BPM1-bound Aβ1-42 aggregates.

Bioimaging of a chromenoquinoline-based ratiometric fluorescent probe for detecting ClO. Spectrochim Acta A Mol Biomol Spectrosc 2023;303:123256. [PMID: 37579661 DOI: 10.1016/j.saa.2023.123256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Hypochlorous acid (HClO) is a reactive oxygen species and a relatively strong antibacterial substance in the immune defense system. The normal concentration of HClO in the human body is approximately 200 μM, and its high concentration can cause tissue damage and some diseases. Herein, a chromenoquinoline-based ratiometric fluorescent probe was developed to detect and quantify HClO. The developed Probe 1 exhibited the advantages of large Stokes shift (137 nm), high synthetic yield (84.7 %), simple synthesis method, short response time (<4 min), low detection limit (5.1 nM), and low toxicity. The probe was successfully validated in live cells and zebrafish.

Cellstitch: 3D cellular anisotropic image segmentation via optimal transport

BACKGROUND

Spatial mapping of transcriptional states provides valuable biological insights into cellular functions and interactions in the context of the tissue. Accurate 3D cell segmentation is a critical step in the analysis of this data towards understanding diseases and normal development in situ. Current approaches designed to automate 3D segmentation include stitching masks along one dimension, training a 3D neural network architecture from scratch, and reconstructing a 3D volume from 2D segmentations on all dimensions. However, the applicability of existing methods is hampered by inaccurate segmentations along the non-stitching dimensions, the lack of high-quality diverse 3D training data, and inhomogeneity of image resolution along orthogonal directions due to acquisition constraints; as a result, they have not been widely used in practice.

METHODS

To address these challenges, we formulate the problem of finding cell correspondence across layers with a novel optimal transport (OT) approach. We propose CellStitch, a flexible pipeline that segments cells from 3D images without requiring large amounts of 3D training data. We further extend our method to interpolate internal slices from highly anisotropic cell images to recover isotropic cell morphology.

RESULTS

We evaluated the performance of CellStitch through eight 3D plant microscopic datasets with diverse anisotropic levels and cell shapes. CellStitch substantially outperforms the state-of-the art methods on anisotropic images, and achieves comparable segmentation quality against competing methods in isotropic setting. We benchmarked and reported 3D segmentation results of all the methods with instance-level precision, recall and average precision (AP) metrics.

CONCLUSIONS

The proposed OT-based 3D segmentation pipeline outperformed the existing state-of-the-art methods on different datasets with nonzero anisotropy, providing high fidelity recovery of 3D cell morphology from microscopic images.

A simple indanone-based red emission fluorescent probe for the rapid detection of cysteine in vitro and in vivo

Cysteine is a vital biothiols that plays an important role in numerous physiological and pathological processes. The development of simple molecule tools for detection and analysis Cys in subcellar environment is significant for further exploring their pathophysiological. In this work, a simple but activated fluorescent probe AMIA was constructed with a donor-π-accepter (D- π -A) structure, which using an indanone as the electron-withdrawing unit acting as the fluorophore, dimethylamino group attached to the position 4 of the benzene ring as the electron-donating, two double bonds as the linker group, and the acryloyl ester group as the trigger and response unit. This probe AMIA was exhibited highly selective and sensitive response to Cys over other amino acids and ions under physiological conditions. It was found that AMIA showed a red turn-on fluorescence response at 630 nm towards Cys with a large stroke shift of 170 nm and a very low detection limit of 26.3 nM. HRMS, 1H NMR and TD-DFT calculation further confirmed that the response mechanism is the Cys triggered the addition-cyclization reaction between AMIA' acryloyl group and Cys' sulfhydryl and amino unit, leading to the release of a red fluorescent dye AMIA-OH, which can be identified by naked eyes. Furthermore, AMIA was successfully applied for simultaneous determination of Cys in living cells and zebrafish with lower cytotoxicity and good cell permeability. We hope that this novel indanone-based probe AMIA will provide a new reference for visualized Cys in other complex biological system.

AIEE activated Pyrene-Dansyl coupled FRET probe for discriminating detection of lethal Cu2+ and CN-: Bio-Imaging, DNA binding studies and prompt prognosis of Menke's disease

In present work a pyrene-dansyl dyad functionalized chemoreceptor, DPNS is unveiled towards ultrasensitive chromo-fluorogenic detection of heavy and transition metal ions (HTMs) like Cu2+ and pernicious CN-. It demonstrated distinct chromogenic responses; colorless to faint yellow (Cu2+), intense yellow (CN-) from contaminant aqueous sources. Cu2+ instigated alteration in DPNS fluorescence from feeble emission to sparkling green with LOD: 37.75 × 10-9 M, cyan emission for CN- having LOD 61.51 × 10-8M. In particular, chemical scaffold of DPNS consists of -C = N, O = S = O donor entitities that escalates overall polarity thereby providing an excellent binding pocket for simultaneous Cu2+ and CN- recognition with distinct photophysical signaling. Impressively, presence of two fluorophoric moieties triggers FRET, CHEF phenomenon. The conceivable host:guest interactive pathway is manifested by LMCT- FRET-PET-CHEF, C = N isomerization for Cu2+ and ICT-H-bonding for CN-. An exquisite experimental and theoretical corroboration further strengthened the recognition phenomenon. In addition owing to pyrene excimer formation, DPNS exhibits AIEE with increasing water fraction. Notably, DPNS could successfully undergo intracellular tracking of Cu2+ in Tecoma Stans, Peperomia Pellucida. DPNS•••Cu2+ adduct displayed significant intercalative DNA binding activity rationalized by spectral investigation, competitive EB binding, viscosity study. The overall findings, excellent properties endows DPNS a potential contender towards discriminative detection of Cu2+ and CN- like toxic industrial contaminants.

Fluorescent probe for sensitive discrimination of GSH and Hcy/Cys with single-wavelength excitation in biological systems via different emission

Biothiols (GSH, Hcy, Cys) are important active sulfur substances in biological systems and widely participate in various physiological processes. The three kinds of biothiols have similar chemical structures, including the sulfhydryl group (-SH) and an amino group (-NH2), so distinguishing two or more of them simultaneously is an important challenge. Herein, a nopinone-based fluorescent probe 3-(3-((4-nitrobenzoxadiazole vinyl) nopinyl difluoride (NF-NBD) was designed to distinguish GSH and Hcy/Cys by generating different fluorescence channels with a single excitation wavelength. The nitrobenzodioxazole (NBD) was introduced in the fluorescent probe by ether bounds that can quench fluorescence and selectively discriminate GSH and Hcy/Cys. After reacting with GSH and Hcy/Cys, NF-NBD exhibited strong fluorescence (green for GSH and yellow for Hcy/Cys). NF-NBD displayed a wide linear range, low detection limit, a rapid response time, and superior selectivity for biothiols. Furthermore, NF-NBD was applied to image and distinguish different biothiols in living cells and zebrafish via different fluorescence signals at a single excitation wavelength.

[An updated review on Emerging recent advances and biomedical application of silver nanocluster]

Silver nanoclusters (AgNCs) have emerged as versatile nanomaterials with immense potential in theranostic applications, combining therapeutic and diagnostic functions in a single platform. This review provides a comprehensive overview of recent advancements in the synthesis, characterization, and utilization of AgNCs for theranostics. The synthesis of AgNCs has witnessed significant progress, with numerous strategies such as chemical reduction, green synthesis, and templated approaches being employed to control size, shape, and stability. Their unique optical properties, including strong fluorescence and surface-enhanced Raman scattering (SERS) signals, make AgNCs ideal candidates for bioimaging and diagnostic purposes. Additionally, the surface chemistry of AgNCs allows for facile functionalization with targeting ligands and therapeutic agents, enhancing their specificity and efficacy. In the realm of diagnostics, AgNCs have been employed for various imaging modalities, including fluorescence imaging, photoacoustic imaging, and SERS-based sensing. Their excellent photostability and biocompatibility make them suitable for in vitro and in vivo imaging applications, enabling the real-time monitoring of disease progression and treatment response.

Sustainable synthesis of lignin-derived carbon dots with visible pH response for Fe3+ detection and bioimaging

Synthesis of lignin-based carbon dots (LCDs) with high quantum yield (QY), stable fluorescence properties and biocompatibility has been a challenge. Here, we propose an improved two-step strategy for producing high-quality LCDs from enzymatic hydrolysis lignin (EHL). The p-aminobenzenesulfonic acid used in the strategy not only provides nitrogen and sulfur elements, but also tailors the disordered three-dimensional structure of EHL. The successful co-doping of N and S elements favors the reduction of the optical energy bandgap (Eg), resulting in a high QY of 45.05% for LCDs. The LCDs exhibited superior selectivity and sensitivity for Fe3+ with a limit of detection (LOD) of 0.15 μM when Fe3+ concentration was 50-500 μM. In addition, LCDs demonstrated significant fluorescence in HepG2 cells and HepG2 cells loaded with LCDs at a concentration of 80 μg/mL showed good viability, suggesting that they are suitable for in vivo applications. The luminescent centers of LCDs change during pH regulation and thus show a special visual response to pH changes, making them have great potential for detecting metabolism in living cells. This work provides a novel and low-cost method for fabricating sustainable fluorescent probes for chemical sensing and bioimaging.

Multicolor emission-based nitrogen, sulfur and boron co-doped photoluminescent carbon dots for sequential sensing of Fe3+ and cysteine: RGB color sensor and live cell imaging

Herein, a simple hydrothermal synthesis is used to prepare multiple heteroatom-doped photoluminescent carbon dots (CDs) from thiourea (N and S source) and boric acid (B source) as precursors. The optical and physicochemical properties of the as-synthesized NSB-CDs were studied using UV-Vis, photoluminescence, TEM, FT-IR, XRD, Raman, and XPS analyses. The NSB-CDs exhibited excellent stability, high photostability, pH, and ionic strength tolerance; they retained their excellent stability independent of excitation. The NSB-CDs featured small sizes of approximately 3.2 ± 0.4 nm (range: 2.0-5.0 nm) as evidenced using TEM measurements. The NSB-CDs were used as a photoluminescent sensing platform to detect Fe3+ as well as cysteine (Cys) molecules. The competitive binding of Cys to Fe3+ resulted in NSB-CDs that retained their photoluminescence. For the rapid identification and quantification of Fe3+ and Cys, NSB-CDs were developed as a "switch-on" dual-function sensing platform. The linear detection range of Fe3+ was 0-20 μM (limit of detection [LOD]: 54.4 nM) and that of Cys was 0-50 μM (LOD: 4.9 nM). We also introduced a smartphone RGB analysis method for detecting low-concentration solutions based on digital images. The NSB-CDs showed no toxicity at 100 μg/mL. Photoluminescent probes for multicolor live-cell imaging can be used with NSB-CDs at this concentration, suggesting that NSB-CDs may be promising photoluminescent probes.

A NIR ratiometric fluorescence probe for rapid, sensitive detection and bioimaging of hypochlorous acid

Hypochlorous acid (HClO) is a condition where there is not enough oxygen in body tissues due to an imbalance between oxygen supply and consumption for cellular functions. In order to comprehend the biological functions of HClO within cells, the development of an effective and selective detection method is of great crucial. In this paper, a near-infrared ratiometric fluorescent probe (YQ-1) for detecting HClO was exploited based on a benzothiazole derivative. YQ-1's fluorescence shifted from red to green with a large blue shift (165 nm) in the presence of HClO, and the solution's color changed from pink to yellow. YQ-1 quickly detected HClO (within 40 s) with a low detection limit (4.47 × 10-7 mol/L) and was not affected by other interferences. The mechanism of YQ-1's response to HClO was confirmed by HRMS, 1H NMR and density functional theory (DFT) calculations. Moreover, due to its low toxicity, YQ-1 successfully utilized for fluorescence imaging for HClO both endogenous and exogenous in cells.

Easily synthesizable molecular probe for the nanomolar level detection of Cd2+ in near aqueous media: Theoretical investigations and live cell imaging

The present investigation highlights a quinoline-based small molecule probe (DEQ) for the detection of Cd2+ among other metal ions in near-aqueous media. The probe DEQ and its Cd2+ complex (DEQ-Cd) have been synthesized and characterized by all possible spectroscopic methods. The weakly emissive DEQ showed its strong emission in the presence of Cd2+, which is attributed to the photoinduced electron transfer (PET) along with the chelation-enhanced fluorescence (CHEF) mechanism. The 1:1 binding mode between ligand and Cd2+ is confirmed by single crystal XRD analysis, which is further supported by Job's plot and HRMS. The detection limit of the probe to recognize Cd2+ was found to be as low as 89 nM. Furthermore, DEQ can act as a reversible fluorescence probe with the off-on-off mechanism by the alternative addition of Cd2+ and EDTA. DFT and TD-DFT studies exposed the proposed mechanism after Cd2+ insertion and the obtained results for electronic spectra are in line with the experimental results. The response towards pH was quite interesting and allowed us to study its application in live cell imaging. With all the positive results, the proposed ligand DEQ can be used as a potential probe for the detection of Cd2+ in real-life applications.

Biological Interaction and Imaging of Ultrasmall Gold Nanoparticles

The ultrasmall gold nanoparticles (AuNPs), serving as a bridge between small molecules and traditional inorganic nanoparticles, create significant opportunities to address many challenges in the health field. This review discusses the recent advances in the biological interactions and imaging of ultrasmall AuNPs. The challenges and the future development directions of the ultrasmall AuNPs are presented.

Hodgkin Lymphoma: A disease shaped by the tumor micro- and macroenvironment

The tumor microenvironment (TMicroE) and tumor macroenvironment (TMacroE) are defining features of classical Hodgkin lymphoma (cHL). They are of critical importance to clinicians since they explain the common signs and symptoms, allow us to classify these neoplasms, develop prognostic and predictive biomarkers, bioimaging and novel treatments. The TMicroE is defined by effects of cancer cells to their immediate surrounding and within the tumor. Effects of cancer cells at a distance or outside of the tumor define the TMacroE. Paraneoplastic syndromes are signs and symptoms due to effects of cancer at a distance or the TMacroE, which are not due to direct cancer cell infiltration. The most common paraneoplastic symptoms are B-symptoms, which manifest as fevers, chills, drenching night sweats, and/or weight loss. Less common paraneoplastic syndromes include those that affect the central nervous system, skin, kidney, and hematological autoimmune phenomena including hemophagocytic lymphohistiocytosis (HLH). Paraneoplastic signs such as leukocytosis, lymphopenia, anemia, and hypoalbuminemia are prognostic biomarkers. The neoplastic cells in cHL are the Hodgkin and Reed Sternberg (HRS) cells, which are preapoptotic germinal center B cells with a high mutational burden and almost universal genetic alterations at the 9p24.1 locus primarily through copy gain and amplification with strong activation of signaling via PD-L1, JAK-STAT, NFkB, and c-MYC. In the majority of cases of cHL over 95% of the tumor cells are non-neoplastic. In the TMicroE, HRS cells recruit and mold non-neoplastic cells vigorously via extracellular vesicles, chemokines, cytokines and growth factors such as CCL5, CCL17, IL6, and TGF-β to promote a feed-forward inflammatory loop, which drives cancer aggressiveness and anti-cancer immune evasion. Novel single cell profiling techniques provide critical information on the role in cHL of monocytes-macrophages, neutrophils, T helper, Tregs, cytotoxic CD8+ T cells, eosinophils, mast cells and fibroblasts. Here, we summarize the effects of EBV on the TMicroE and TMacroE. In addition, how the metabolism of the TMicroE of cHL affects bioimaging and contributes to cancer aggressiveness is reviewed. Finally, we discuss how the TMicroE is being leveraged for risk adapted treatment strategies based on bioimaging results and novel immune therapies. In sum, it is clear that we cannot effectively manage patients with cHL without understanding the TMicroE and TMacroE and its clinical importance is expected to continue to grow rapidly.

Functional fluorescent nanomaterials for the detection, diagnosis and control of bacterial infection and biofilm formation: Insight towards mechanistic aspects and advanced applications

Infectious diseases resulting from the high pathogenic potential of several bacteria possesses a major threat to human health and safety. Traditional methods used for screening of these microorganisms face major issues with respect to detection time, selectivity and specificity which may delay treatment for critically ill patients past the optimal time. Thus, a convincing and essential need exists to upgrade the existing methodologies for the fast detection of bacteria. In this context, increasing number of newly emerging nanomaterials (NMs) have been discovered for their effective use and applications in the area of diagnosis in bacterial infections. Recently, functional fluorescent nanomaterials (FNMs) are extensively explored in the field of biomedical research, particularly in developing new diagnostic tools, nanosensors, specific imaging modalities and targeted drug delivery systems for bacterial infection. It is interesting to note that organic fluorophores and fluorescent proteins have played vital role for imaging and sensing technologies for long, however, off lately fluorescent nanomaterials are increasingly replacing these due to the latter's unprecedented fluorescence brightness, stability in the biological environment, high quantum yield along with high sensitivity due to enhanced surface property etc. Again, taking advantage of their photo-excitation property, these can also be used for either photothermal and photodynamic therapy to eradicate bacterial infection and biofilm formation. Here, in this review, we have paid particular attention on summarizing literature reports on FNMs which includes studies detailing fluorescence-based bacterial detection methodologies, antibacterial and antibiofilm applications of the same. It is expected that the present review will attract the attention of the researchers working in this field to develop new engineered FNMs for the comprehensive diagnosis and treatment of bacterial infection and biofilm formation.

IR-775 - Hyptis loaded bioactive nanoparticles for enhanced phyto-photothermal therapy of breast cancer cells

Photo-responsive therapy is an emerging treatment modality due to its bioimaging and therapeutic properties. Phototherapy induces localized hyperthermia and selectively eradicates cancer cells. The current study showed that multifunctional biodegradable liposome nanosystem (HIL NPs) containing Hyptis suaveolens bioactive molecules and IR-775, a NIR dye showed efficient bioavailability to cancer ells and allowed tumor ablation upon NIR laser irradiation. The resulting entities present in the nanosystem, i.e., bioactive molecules of Hyptis, serve as an anticancer agent, and IR-775 helps in the photothermal ablation of highly metastatic breast cancer cells. Hyptis suaveolens is a weed that grows rampantly, impeding the growth of neighboring plants; nonetheless, its bioactive compounds have demonstrated therapeutic benefits. The obtained HIL NPs, photothermally active liposome nanosystem showed a high fluorescence absorption peak in the NIR range and delivered a photothermal conversion efficiency of 55.20 % upon NIR laser irradiation. TEM and particle size analyzer revealed that HIL NPs have a size of 141 ± 30 nm with a spherical shape. The results of in-ovo (zebrafish) experiments have shown efficient bioimaging capabilities with minimal concentrations of HIL NPs compared to respective controls. Furthermore, in-vitro studies of HIL NPs against triple-negative breast cancer (4T1) indicated effective anticancer activity by a combined cytotoxic effect and hyperthermia. Tumor ablation was facilitated by reactive oxygen species production and hyperthermia, leading to DNA damage and apoptosis due to overexpression of ɣ-H2AX, Cathepsin B, and p53, which halted cancer cell proliferation. Therefore, HIL NPs demonstrated effective anticancer effects induced by combined phyto-photothermal therapy when evaluated against an in-vitro breast cancer model.

Molecular engineering and bioimaging applications of C2-alkenyl indole dyes with tunable emission wavelengths covering visible to NIR light

As an important member of dyes, small-molecule fluorescent dyes show indispensable value in biomedical fields. Although various molecular dyes have been developed, full-color dyes covering blue to red region derived from a single chromophore are still in urgent demand. In this work, a series of dyes based on C2-alkenyl indole skeleton were synthesized, namely AI dyes, and their photophysical properties, cytotoxicity, and imaging capacity were verified to be satisfactory. Particularly, the maximal emission wavelengths of these dyes could cover a wide range from visible to NIR light with large Stokes shifts. Besides, the optical and structural discrepancies between the C2- and C3- alkenyl AI dyes were discussed in detail, and the theoretical calculations were conducted to provide insights on such structure-activity relationship. Finally, as a proof-of-concept, a fluorescent probe AI-Py-B capable of imaging endogenous ONOO- was presented, demonstrating the bioimaging potentials of these alkenyl indole dyes. This work is anticipated to open up new possibilities for developing dye engineering and bio-applications of natural indole framework.