During multicellular development, specification of distinct cell fates is often regulated by the same transcription factors operating differently in distinct cis-regulatory modules, either through ...different protein complexes, conformational modification of protein complexes, or combinations of both. Direct visualization of different transcription factor complex states guiding specific gene expression programs has been challenging. Here we use in vivo FRET-FLIM (Förster resonance energy transfer measured by fluorescence lifetime microscopy) to reveal spatial partitioning of protein interactions in relation to specification of cell fate. We show that, in Arabidopsis roots, three fully functional fluorescently tagged cell fate regulators establish cell-type-specific interactions at endogenous expression levels and can form higher order complexes. We reveal that cell-type-specific in vivo FRET-FLIM distributions reflect conformational changes of these complexes to differentially regulate target genes and specify distinct cell fates.
Water-soluble perylenediimides (PDIs) with high fluorescence intensity, photostability and biocompatibility have been successfully prepared and applied in the biological field. In this tutorial ...review, we briefly focus on the synthetic strategies for the preparation of water-soluble PDIs by incorporating ionic or non-ionic substituents with multiple polar groups into the bay-region, imide- or ortho-positions of PDIs. These ionic/non-ionic substituents can suppress π-π aggregation and shield the inner perylene chromophores, thus contributing to the water solubility which is essential for biological applications. The optical properties, absorption and emission maxima above 500 nm, minimize the autofluorescence background of cells and provide access to imaging in living cells. The biological applications of water-soluble PDIs are discussed from simple (basic) to complex (advanced) processes, including biosensing
in vitro
studies, imaging and gene/drug delivering in living cells, tissues and the whole body. The promising future of designed multi-functional water-soluble PDIs will be highlighted in this review.
Water-soluble perylenediimides (PDIs) with high fluorescence intensity, photostability and biocompatibility have been successfully prepared and applied in the biological field.
We developed an ultrasensitive fluorescence resonance energy transfer (FRET) aptasensor for kanamycin detection, using upconversion nanoparticles (UCNPs) as the energy donor and graphene as the ...energy acceptor. Oleic acid modified upconversion nanoparticles were synthesized through a hydrothermal process followed by a ligand exchange with hexanedioic acid. The kanamycin aptamer (5'-NH2-AGATGGGGGTTGAGGCTAAGCCGA-3') was tagged to UCNPs through an EDC–NHS protocol. The π–π stacking interaction between the aptamer and graphene brought UCNPs and graphene in close proximity and hence initiated the FRET process resulting in quenching of UCNPs fluorescence. The addition of kanamycin to the UCNPs–aptamer–graphene complex caused the fluorescence recovery because of the blocking of the energy transfer, which was induced by the conformation change of aptamer into a hairpin structure. A linear calibration was obtained between the fluorescence intensity and the logarithm of kanamycin concentration in the range from 0.01nM to 3nM in aqueous buffer solution, with a detection limit of 9pM. The aptasensor was also applicable in diluted human serum sample with a linear range from 0.03nM to 3nM and a detection limit of 18pM. The aptasensor showed good specificity towards kanamycin without being disturbed by other antibiotics. The ultrahigh sensitivity and pronounced robustness in complicated sample matrix suggested promising prospect of the aptasensor in practical applications.
•An aptasensor is constructed to detect kanamycin based on upconversion fluorescence resonance energy transfer.•The conformation change of kanamycin aptamer into a hairpin structure after interacting with the target is accompanied by the alteration of energy-transfer efficiency.•The aptasensor for kanamycin detection is ultrasensitive.•The aptasensor is robust in human serum samples indicating its prospect of practical applications.
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is spreading around the globe since December 2019. There is an urgent need to develop sensitive and online methods for on-site ...diagnosing and monitoring of suspected COVID-19 patients. With the huge development of Internet of Things (IoT), the impact of Internet of Medical Things (IoMT) provides an impressive solution to this problem. In this paper, we proposed a 5G-enabled fluorescence sensor for quantitative detection of spike protein and nucleocapsid protein of SARS-CoV-2 by using mesoporous silica encapsulated up-conversion nanoparticles (UCNPs@mSiO2) labeled lateral flow immunoassay (LFIA). The sensor can detect spike protein (SP) with a detection of limit (LOD) 1.6 ng/mL and nucleocapsid protein (NP) with an LOD of 2.2 ng/mL. The feasibility of the sensor in clinical use was further demonstrated by utilizing virus culture as real clinical samples. Moreover, the proposed fluorescence sensor is IoMT enabled, which is accessible to edge hardware devices (personal computers, 5G smartphones, IPTV, etc.) through Bluetooth. Medical data can be transmitted to the fog layer of the network and 5G cloud server with ultra-low latency and high reliably for edge computing and big data analysis. Furthermore, a COVID-19 monitoring module working with the proposed the system is developed on a smartphone application (App), which endows patients and their families to record their medical data and daily conditions remotely, releasing the burdens of going to central hospitals. We believe that the proposed system will be highly practical in the future treatment and prevention of COVID-19 and other mass infectious diseases.
Suitable labels are at the core of Luminescence and fluorescence imaging and sensing. One of the most exciting, yet also controversial, advances in label technology is the emerging development of ...quantum dots (QDs)--inorganic nanocrystals with unique optical and chemical properties but complicated surface chemistry--as in vitro and in vivo fluorophores. Here we compare and evaluate the differences in physicochemical properties of common fluorescent labels, focusing on traditional organic dyes and QDs. Our aim is to provide a better understanding of the advantages and limitations of both classes of chromophores, to facilitate label choice and to address future challenges in the rational design and manipulation of QD labels.
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•NearIR(NIR) absorbing dyes for Photodynamic therapy was reviewed.•NIR absorbing chromophore BODIPY, cyanine, porphyrin, phthalocyanine, nano assemblies and etc., were ...covered.•Performance of the NIR dyes on selective ablation of tumors were discussed.•Photodynamic mechanism of these dyes were covered.•Potential of Photosensitizers selectively targeting sub-cellular organelles were discussed.
Photo Dynamic Therapy (PDT) is regarded as an effective therapeutic approach for cancer, which employs light and photosensitizing chemical substances. The successful demonstration of this technique by Dougherty et al. paved a new way for tumor treatment. Since then the technique has been continuously evolving to keep up its promises in medical science. The basic idea of PDT is to administer photoactive small molecules within tumor cells. The photoactive molecules, well known as Photosensitizers (PS) absorb light from external light source depending on its absorption property and goes to excited state. In this excited state they react with molecular oxygen of the living tissues and forms reactive oxygen species (ROS). These ROS are very toxic to the cells as they instantly oxidize important biomolecules such as proteins and nucleic acids (DNA, RNA), which leads to the dysfunction of the cells and eventually results in the cell death. In this context, PS which absorb broad region of energy ranging to Near Infrared Region (NIR) is desired as NIR, with better penetration efficiency into deep tissues as compared to visible light. One single review would be inadequate to consolidate all aspects of PDT on its design and efficacy. Each step needs a lot of standardizations and efforts and every step is equally important. This review is an attempt to give a comprehensive overview about the recent advancement in NIR absorbing dyes such as BODIPYs, Keio Fluors, Aza-BODIPY, Chorin, Phthalocyanines, Cyanine dyes, and Nano particles based NIR photosensitizers and their potential in PDT. Herein, we have also given deep insights into the recent trends in this field which emphasizes the potential of this technique to become a first line of treatment for tumours of diverse range.
Food analysis is essential in monitoring food quality for risk assessment regarding public health. Traditional techniques can meet the requirement of routine food analysis in laboratory. However, ...serious food safety situations urgently demand rapid, time-saving, low-cost analysis methods even on-site, portable and household testing kits. Fluorescence analysis exhibits immense potential for food safety owing to its remarkable advantages of high sensitivity, ease of operation, low cost and rapid result outputs.
Carbon dots (CDs) are novel 0D carbonic nanomaterials recently emerging as potential substitutes for traditional fluorescent materials. Compared with the conventional fluorescent materials, e.g. organic fluorescent dyes, metal nanoparticles/nanoclusters and quantum dots (QDs), CDs possess many appealing merits such as ease of preparation, low cost, non-blinking, low cytotoxicity, excellent biocompatibility and high resistance to photo-bleaching. As a result CDs-based fluorescence sensing provides excellent analysis platforms for monitoring food-related analytes. This review provides a comprehensive overview of the state-of-the-art synthesis methods and the fluorescence properties of CDs along with the sensing mechanisms and designing principles of CDs-based fluorescent sensors for food analysis. Possible challenges and appealing prospects of CDs-based fluorescent sensors are also discussed.
CDs have been widely applied in bio-imaging, sensing, drug delivery, catalysis and optronics. Integration of CDs into food science and engineering for food safety control and risk assessment exhibits a bright future.
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•Fluorescence properties for reducing interferences to food safety screening.•Fluorescence response mechanisms of CDs-based fluorescent sensors.•Designing and analysis principles of CDs sensors for food analysis.•Selectivity improving and interference reducing for practical applications.•New trends in material, ligands and portable sensors designing.
The remote detection of water stress in a citrus orchard was investigated using leaf-level measurements of chlorophyll fluorescence and
Photochemical Reflectance Index (PRI) data, seasonal ...time-series of crown temperature and PRI, and high-resolution airborne imagery. The work was conducted in an orchard where a regulated deficit irrigation (RDI) experiment generated a gradient in water stress levels. Stomatal conductance (Gs) and water potential (Ψ) were measured over the season on each treatment block. The airborne data consisted on thermal and hyperspectral imagery acquired at the time of maximum stress differences among treatments, prior to the
re-watering phase, using a miniaturized thermal camera and a micro-hyperspectral imager on board an unmanned aerial vehicle (UAV). The hyperspectral imagery was acquired at 40
cm resolution and 260 spectral bands in the 400-885
nm spectral range at 6.4
nm full width at half maximum (FWHM) spectral resolution and 1.85
nm sampling interval, enabling the identification of pure crowns for extracting radiance and reflectance hyperspectral spectra from each tree. The FluorMOD model was used to investigate the retrieval of chlorophyll fluorescence by applying the
Fraunhofer Line Depth (FLD) principle using three spectral bands (FLD3), which demonstrated that fluorescence retrieval was feasible with the configuration of the UAV micro-hyperspectral instrument flown over the orchard. Results demonstrated the link between seasonal PRI and crown temperature acquired from instrumented trees and field measurements of stomatal conductance and water potential. The sensitivity of PRI and Tc–Ta time-series to water stress levels demonstrated a time delay of PRI vs Tc–Ta during the recovery phase after
re-watering started. At the time of the maximum stress difference among treatment blocks, the airborne imagery acquired from the UAV platform demonstrated that the crown temperature yielded the best coefficient of determination for Gs (r
2
=
0.78; p
<
0.05) and Ψ (r
2
=
0.34; p
<
0.001). Among the narrow-band indices calculated, the PRI
515 index (reference band
=
515
nm) obtained better results than PRI
570, with r
2
=
0.59 (p
<
0.01) for Gs, and r
2
=
0.38 (p
<
0.001) for Ψ. The BGI1 index calculated from the blue (R
400) and green (R
550) bands resulted on the highest significance levels (p
<
0.001) for both Gs (r
2
=
0.62) and Ψ (r
2
=
0.49). Out of the structural indices assessed, RDVI, MTVI1 and TVI showed greater sensitivity for Gs (r
2
=
0.6; p
<
0.01) and Ψ (p
<
0.001) than NDVI. Chlorophyll fluorescence calculated from the micro-hyperspectral imagery with the FLD3 method tracked stress levels, obtaining r
2
=
0.67 (p
<
0.05) with stomatal conductance, and r
2
=
0.66 (p
<
0.001) with water potential. The work presented in this manuscript demonstrates the feasibility of thermal, narrow-band indices and fluorescence retrievals obtained from a micro-hyperspectral imager and a light-weight thermal camera on board small UAV platforms for stress detection in a heterogeneous tree canopy where very high resolution is required.
► Water stress was investigated using a micro-hyperspectral imager on board an UAV. ► A link between PRI and crown temperature was demonstrated over the entire season. ► Seasonal variation of PRI and Tc-Ta demonstrated a time delay of PRI during recovery. ► Best indicators of stress were crown Tc, F (FLD method) and the BGI1 index. ► It demonstrates the F retrieval using micro-hyperspectral imagers on board UAVs.
•Smartphones' ubiquitous distribution and international connectivity is changing the concept of mobile health.•Smartphones are exploited as both portable detectors and instrumental ...interfaces.•Smartphone-based devices have great potential as point-of-care platforms for healthcare, food safety, environmental monitoring, and biosecurity.
The ubiquitous distribution and international connectivity of smartphones is changing the concept of mobile health and promising to reshape the biosensor market. Smartphone-based biosensors have been explored using different approaches, either using the smartphone as detector or as instrumental interface. Smartphone-based biosensors have great potential as point-of-care and point-of-need platforms for healthcare, food safety, environmental monitoring, and biosecurity, especially in remote and rural areas. Here, we critically review the most recent papers on the use of smartphones as analytical devices and biosensors. We focus on analytical performance and on prospects for commercialization.
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