Excitation Light Source Research Articles

Study on the Identification of Brown Rice Storage Year Based on Fluorescence Spectral Fusion Technique

The storage time of rice determines its quality and nutritional value, and the longer the storage time, the greater the impact. In this study, different excitation wavelengths (405 nm, 365 nm, 310 nm) were used to detect the fluorescence spectrum of “Dongdao 12” brown rice. Support vector machine (SVM), K-nearest neighbor (KNN), and wide neural network (WNN) were used for modeling and analysis. Under the excitation of 310 nm, the accuracy of WNN classification is up to 99.2%. In order to reduce the scattering effect and other interference in the data, multiplicative scatter correction (MSC), standard normal variable (SNV), and Savitzky–Goray smoothing (SG) preprocessing methods were used. The results showed that SG + KNN classification achieved an accuracy of 99.3% under 310 nm excitation. In order to further improve the classification accuracy, the original spectrum and the preprocessed spectrum under different excitation light sources were fused. The classification accuracy of all methods was improved, and the original data fusion was combined with the WNN model to reach 100%. It shows that fluorescence spectroscopy has excellent potential in identifying rice storage years.

Identification of peripheral nerve functional fascicles in Sprague-Dawley rats by the carbon quantum dot-Annexin V antibody complex

To explore a method to identify the sensory and motor fascicles of the peripheral nerve to achieve accurate peripheral nerve functional fascicle suture. The peripheral nerve Sunderland V injury model, muscle branch of the femoral nerve and saphenous nerve were established in the bilateral femoral nerves of Sprague-Dawley (SD) rats. The specific samples were grouped as follows: the main trunk of the femoral nerve was exposed bilaterally and cut with microscopic scissors in the main trunk of the femoral nerve to prepare a model of Sunderland V injury in the mixed fascicle of peripheral nerves; the muscle branch of the femoral nerve was exposed bilaterally and cut in the middle section of the muscle branch of the femoral nerve to prepare a model of Sunderland V injury in the motor fascicle of peripheral nerves; the saphenous nerve was exposed bilaterally and cut at 1 cm below the patella to prepare a model of Sunderland V injury to the sensory fascicle of the peripheral nerves. A carbon quantum dot (CD)-annexin V antibody complex was prepared and applied to the distal and proximal nerve stumps of the peripheral nerve Sunderland V injury model groups of SD rats. Under the excitation light source of a 380 nm uv lamp, fluorescence color development was observed under a fluorescence microscope after 5, 10, 15, and 20 min. At 5 min, sections of the bilateral femoral nerve trunk, muscular branches of the femoral nerve, and Sunderland V lesion of the saphenous nerve in SD rats were only dark in color under the microscope, and there was no difference in fluorescence. The intensity of the staining increased significantly for 10–20 min. The sensory fascicles and saphenous nerves of the femoral nerve trunk showed blue fluorescence under the CD-Annexin V antibody complex staining, while the motor fascicles and muscle branches of the femoral nerve trunk showed no fluorescence. Fluorescence intensity gradually decreased after 20 min of staining. There was no significant difference in the staining intensity at 5, 10, 15, and 20 min in each group. Our results suggest that the CD-Annexin antibody complex can be used to identify functional fascicles of peripheral nerves in SD rats.

Recent Advances in Thermally Activated Delayed Fluorescence-Based Organic Afterglow Materials.

Thermally activated delayed fluorescence (TADF)-based materials are attracting widespread attention for different applications owing to their ability of harvesting both singlet and triplet excitons without noble metals in their structures. As compared to the conventional fluorescence and room-temperature phosphorescence pathways, TADF originates from the reverse intersystem crossing process from the excited triplet state (T1) to the singlet state (S1). Therefore, TADF emitters enabling activated and long lifetime T1 excitons are potential candidates for generating long-lived afterglow emission, an effect that can still be observed for a while by the naked eye after the removal of the excitation light source. Recently, TADF-based organic afterglow materials featuring high photoluminescence quantum yields and long lifetimes above 100 ms under ambient conditions, have emerged for advanced information security, high-contrast biological imaging, optoelectronic devices, and intelligent sensors, whereas the related systematic review is still lacking. Herein, the recent progress in TADF-based organic afterglow materials is summarized and an overview of the photophysical mechanism, design strategies, and the performances for relevant applications is given. In addition, the challenge and perspective of this area are given at the end of the review.

A Sodium Metal-Organic Framework with Deep Blue Room-Temperature Phosphorescence.

It is a great challenge to manufacture room-temperature blue long afterglow phosphorescent materials adapted to environmental conditions. Herein, an Na-based metal-organic framework (MOF) was constructed using Na+ and 1H-1,2,4-triazole-3,5-dicarboxylic acid, which exhibits long-lived of 378.9 ms, deep blue and room-temperature phosphorescence, meanwhile possesses the visible blue afterglow for 3~6 seconds after removing excitation light source. The three-dimensional coordination bonds network provided by Na-based MOF protects the organic ligands intrinsic hydrogen bond network, resulting in the phosphor lifetime and residual color remaining unchanged in different gas atmospheres. Furthermore, first-principles time-dependent density functional theory reveals that the rigid Na-based MOF structure can limit the rotation and vibration of the room-temperature phosphorescent organic ligands. This limitation results in the suppression of non-radiative decay for both singlet and triplet excitons, promotes intersystem crossing, and increases the rate of radiative decay, ultimately achieving long-lived room-temperature phosphorescence.

Perovskite polycrystal for optically tuning terahertz interference fringes

We optically tuned the terahertz interference fringe using a perovskite polycrystal. Specifically, we used CH3NH3PbI3 polycrystals with different morphologies that were annealed at different temperatures. The largest modulations depth (23 %) was obtained for the CH3NH3PbI3 polycrystal drop-coated at 130 °C; this was also greater than that of a spin-coated CH3NH3PbI3 thin film. We demonstrated that the combination of a drop-coated CH3NH3PbI3 polycrystal with a metasurface allows modulation of terahertz waves. Using the interference formed by partial-through measurement and the shift of the periodic peak in the terahertz time-domain spectroscopy system, we experimentally verified that the perovskite polycrystal can redshift the terahertz-band interference fringes by 50 GHz by changing the optical power density of the external excitation light source. This provides a new idea and possibility for the development of novel terahertz modulation devices.

Controllable multicolored optical glass-ceramics based on nanostructure strategies and dopants

Novel functional materials that integrate multiple tunable luminescence modes hold significant scientific and application potential. In this study, nanostructure strategies were employed to fabricate a series of microcrystalline glasses doped with rare-earth and transition-metal ions. The crystallization behavior of the nanocrystals (NCs) was revealed through high-resolution transmission electron microscopy (HRTEM), and the photoluminescence spectra of the samples were systematically investigated, demonstrating the achievement of independent and efficient visible light emission. With the further addition of the dopant Mn2+, it can occupy different sites to generate efficient energy transfer for ions, effectively improve the luminous efficiency, and changing the Mn2+ concentration can achieve a wide tunable color gamut. In addition, by exciting the glass samples with different excitation light sources, tunable emission of both red and blue was achieved. The results demonstrated the significant potential of the experimental samples as new multifunctional materials for optical dynamic anti-counterfeiting applications.

An all-in-one smartphone-assisted ratiometric fluorescent device for visual and quantitative detection of glutathione

The daily consumption of foods abundant in Glutathione (GSH) can be supplemented to maintain the homeostasis of GSH in human health and alleviate pathologies resulting from abnormal GSH levels. The fluorescence-based visual determination of GSH has gradually attracted the attention of researchers due to its robust performance and versatile implementation. However, the current GSH visual strategy primarily relies on variations in fluorescence intensity at a single emission wavelength, which poses challenges for naked-eye and portable readout, as well as distorted signals caused by complex matrix effects in real samples. Herein, a ratiometric fluorescence sensor based on carbon dots (CDs) combined with an all-in-one 3D-printed smartphone-based device was successfully developed for low-cost, visual and rapid detection of GSH without the need for an external excitation light source. The ratiometric fluorescent materials were synthesized by conjugating blue carbon dots (B-CDs) with yellow carbon dots (Y-CDs) through the utilization of selected Cu2+ ions. The resulting mechanism demonstrated that the coordination interaction between Cu2+ and residual aromatic amino groups in Y-CDs (Y-CDs-Cu2+) contributed to a newly emitted peak at 580 nm, thereby inducing fluorescence resonance energy transfer from B-CDs to Y-CDs-Cu2+. A linear correlation was found between GSH concentrations and R/B values in the range of 10–100 μM, with a limit of detection observed at 4.8 μM. By utilizing this portable device in combination with RGB analysis, the quantitative detection of GSH can be achieved even in complex food matrices such as tomatoes and grapes. The universality of this all-in-one device was further validated by pre-spraying CDs onto a paper strip for visual measurement of GSH. This work offers a portable, visual, and accessible approach to evaluating food safety and nutrition, thereby demonstrating significant economic value and holding profound implications for human health.

Near-infrared light induced cathodic photoelectrochemical biosensor for duplex-specific nuclease mediated detection of miRNA166-a

The photoelectrochemical (PEC) biosensor is a new sensing platform which has the merits of low background signal, low cost, easy miniaturization and so on. However, at present, most PEC biosensors utilize visible light or ultraviolet light as the excitation light source. This type of light has high energy and may cause some light damage to the detected object and some photoelectric materials, thus limiting its application scope. Herein, based on NaYF4:Yb,Tm/BiOBr0.8I0.2 a cathode PEC biosensor that can be excited by near-infrared light was constructed to avoid the occurrence of anode false positives and light damage. Through two cycles of the miRNA cycle assisted by Duplex-Specific Nuclease (DSN) and the dissolved oxygen cycle assisted by gold nanoparticles during the detection process, the detection signal was amplified and miRNA166-a was sensitively detected. By using up-conversion materials, the near-infrared light of 980 nm can be converted into ultraviolet light and visible light, thus exciting the photogenerated carriers of BiOBr0.8I0.2. The photocurrent reaction shows a positive correlation with the quantity of gold nanoparticles present on the electrode surface, which are derived from the reporter molecules produced by the hybridization of miRNA166-a and H1. It has a good linear relationship and selectivity towards miRNA166-a, and the detection limit is 0.32 fM. This sensing method provides a cathode PEC biosensor, which can be excited by near-infrared light. The overall light damage of the system is low, and the possibility of false positive of anode PEC biosensor can be avoided, which has certain significance.

Investigation into NSAW excitation and modulation utilizing the grating mask technique

Narrowband surface acoustic wave (NSAW) method is a promising ultrasonic detection technique, with its laser-induced excitation technology offering the advantages of non-contact and flexible regulation. This paper proposes an NSAW excitation and modulation system based on the grating mask method to detect the nonlinear characteristics of the spectra caused by the variation in material surface properties. According to Doyer’s sharp line excitation theory, a strip line source array excitation model formed by superposition principle is established, and the effects of duty ratios of the masks on NSAW spectra amplitude characteristics are interpreted. An NSAW excitation and B-scan experimental system that can realize line source spacing changes is developed, and the effects of cylindrical lens height and masks with different duty ratios on NSAW spectra modulation are studied. The experimental results show that the amplitude ratios (the ratio of the double frequency amplitude to the second harmonic amplitude) are consistent with the results of the Doyer superimposed strip line source array excitation model in which the excitation light source energy is evenly distributed. The second-order nonlinear coefficients extracted from the experimental spectra can effectively characterize the surface properties of 6061 aluminum alloy at different annealing temperatures.

Evaluation of Thermal Transport Characteristics of Three-Dimensional Self-Ordered Multilayered Silicon-Germanium Nanodots

1. Background and purpose Silicon-germanium (SiGe) alloys have much lower thermal conductivity than Si and Ge single crystals and are expected to be candidates for next-generation thermoelectric device materials of internet of things society. It is important to achieve both high carrier mobility and low thermal conductivity on the basis of the dimensionless figure of merit [1]. There are several studies on the thermoelectric properties of SiGe with low-dimensional structures such as superlattice and nanodots [2,3] to dramatically decrease thermal conductivity. However, the relationship between the nanoscale thermal properties and the phonon scattering mechanism of self-ordered multilayer SiGe nanodots with high uniformity grown by Stranski-Krastanov [4] mode is unclear. In this study, we demonstrated the thermal transport characteristics of the self-ordered multilayer SiGe nanodots. 2. Experiments Si/SiGe superlattice and nanodots samples were fabricated by reduced pressure chemical vapor deposition. We set to 20 cycles of Si0.65Ge0.35 / Si superlattice, the staggered Si0.65Ge0.35 nanodots (alternately stacked) and the dot-on-dot Si0.65Ge0.35 nanodots (vertically stacked) by changing growth temperature and precursors for Si spacer growth [4], as shown in Fig. 1. Thermal properties were evaluated by the Time Domain Thermoreflectance (TDTR) method. The strain states and Ge fraction were evaluated by Raman spectroscopy. The focal length and wavenumber resolution of the Raman spectrometer were 2,000 mm and 0.1 cm-1, respectively. The excitation light source was a green laser (wavelength: 532 nm). We obtained the Raman spectra of Si-Si, Si-Ge, and Ge-Ge vibrational modes derived from the SiGe regions. 3. Results and discussion Figure 2 shows the thermal conductivity for the SiGe region of the superlattice and nanodots (dot-on-dot and staggered structures) obtained by TDTR method. We found that the SiGe nanodots with the dot-on-dot structure have the highest thermal conductivity, while the SiGe nanodots with the staggered structure and SiGe superlattice have almost the same thermal conductivity. We consider that the heat flow easily penetrates from the top (surface) to the bottom (Si substrate interface) in the dot-on-dot structures. On the other hand, it is possible that the staggered SiGe nanodots can play a sufficient role as a phonon scatterer compared to the dot-on-dot structures since the superlattice structure and the staggered SiGe nanodots have almost the same thermal properties. In conclusion, we demonstrated the possibility of controlling phonon scattering by changing the arrangement of the self-ordered multilayer SiGe nanodots. Acknowledgement This work was supported by JSPS KAKENHI Grant Number 21K14201, Japan.

High sensitive ratiometric optical thermometer based on different multi-photon processes of upconversion luminescence in scheelite Ca1-xMgxWO4:Er3+/Yb3+ phosphors

The relative fluorescence intensity from different multi-photon processes is affected by the excitation light source fluctuation, which reduces the anti-interference and sensitivity of thermometers based on fluorescence intensity ratio (FIR) in upconversion (UC) luminescence. Ca1-xMgxWO4: Yb3+, Er3+ phosphors with scheelite structure were synthesized to investigate their anti-interference and higher temperature sensitivity. With x increasing from 0 to 1, the Bragg angle shifted toward higher angle, indicating that the larger disorders were introduced into the phosphors. The emissions assigned to Er3+ were enhanced with Mg2+ concentration increasing, attributed to oxygen vacancies according to the results of electron paramagnetic resonance. The photon numbers of upconversion luminescence assigned to 2H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions of Er3+ were three- and two-photon processes, respectively. The ratio between the cube of 4S3/2 and the square of 2H11/2 emissions revealed higher temperature sensing performance and anti-interference on the excitation source power than the that between 4S3/2 and 2H11/2. The maximum relative sensitivity was 0.66 % K−1 at 300 K based on the common optical ratiometric thermometry. The maximum relative sensitivity based on the emissions assigned to different multi-photon processes was 7.2 % K−1 at 573 K. The dopants of Mg2+ composited of oxygen vacancies in CaWO4 crystals improved the luminous intensity and temperature sensing performance. This suggested the potential application of optical ratiometric thermometers based on different multi-photons of UC luminescence in temperature sensing field.

Fluorescence microscopy for brain activity imaging: one-photon microscopy and its application to pharmacological research

The development of genetically-encoded fluorescent probes for the detection of intracellular calcium ions and various neurotransmitters has progressed significantly in recent years, and there is a growing need for techniques that rapidly and efficiently image these signals in the living brain for pharmacological studies of the central nervous system. In this article, we discuss one-photon fluorescence microscopy techniques used for brain activity imaging, particularly wide-field imaging and head-mounted miniaturized microscopy, and introduce their basic principles, recent advances, and applications in pharmacological research. Wide-field calcium imaging is suitable for mesoscopic observation of cortical activity during behavioral tasks in head-fixed awake mice, while head-mounted miniaturized microscopes can be attached to the animal's head to image brain activity associated with naturalistic behaviors such as social behavior and sleep. One-photon microscopy allows for the development of a simple and cost-effective imaging system using an affordable excitation light source such as a light-emitting diode. Its excitation light illuminates the entire field of view simultaneously, making it easy to perform high-speed imaging using a high-sensitivity camera. In contrast, the short wavelength of the excitation light limits the field of observation to areas on or near the brain surface due to its strong light scattering. Moreover, the out-of-focus fluorescence makes it difficult to obtain images with a high signal-to-noise ratio and spatial resolution. The use of one-photon microscopy in brain activity imaging has been limited compared to two-photon microscopy, but its advantages have recently been revisited. Therefore, this technique is expected to become a useful method for pharmacologists to visualize the activity of the living brain.

Structural Coloration and Up/Down‐Conversion Photoluminescence of Carbon Nanotube Fibers for Ultraviolet Detection

AbstractCarbon nanotubes (CNTs) are in great demand in many fields because of their unique properties such as high conductivity, chemical stability, lightweight, and high strength. They also received much attention in optical‐related fields because of the super‐black characteristics under visible light and the photothermal effect of infrared light. Recently, the coloration of CNTs under visible light is realized by a simple liquid phase method with the help of silica photonic crystal (PC) coatings. However, the response modulation such as the photoluminescence (PL) property of CNTs to the infrared and ultraviolet (UV) bands is not yet studied. Herein, silane functionalized carbon dots (SiCDs) are introduced into silica PCs, and successfully realized the structural coloration and PL of CNT fibers (CNTFs). The optical and fluorescence visualization of single CNTs and suspended CNT networks (SCNTNs) is also realized with the assistance of SiCDs droplets. These SiCDs‐decorated SiPCs‐coated CNTFs (SiCDs@SiPCs‐CNTFs) exhibit an up/down‐conversion PL response, and the excitation light source can be UV light, visible light, and near‐infrared laser. The structural coloration and the development of new PL properties will promote the wide applications of PL carbon hybrid materials in many fields such as smart displays, intelligent textiles, anti‐counterfeiting, etc.

Chromophore-Assisted Light Inactivation for Protein Degradation and Its Application in Biomedicine.

The functional investigation of proteins holds immense significance in unraveling physiological and pathological mechanisms of organisms as well as advancing the development of novel pharmaceuticals in biomedicine. However, the study of cellular protein function using conventional genetic manipulation methods may yield unpredictable outcomes and erroneous conclusions. Therefore, precise modulation of protein activity within cells holds immense significance in the realm of biomedical research. Chromophore-assisted light inactivation (CALI) is a technique that labels photosensitizers onto target proteins and induces the production of reactive oxygen species through light control to achieve precise inactivation of target proteins. Based on the type and characteristics of photosensitizers, different excitation light sources and labeling methods are selected. For instance, KillerRed forms a fusion protein with the target protein through genetic engineering for labeling and inactivates the target protein via light activation. CALI is presently predominantly employed in diverse biomedical domains encompassing investigations into protein functionality and interaction, intercellular signal transduction research, as well as cancer exploration and therapy. With the continuous advancement of CALI technology, it is anticipated to emerge as a formidable instrument in the realm of life sciences, yielding more captivating outcomes for fundamental life sciences and precise disease diagnosis and treatment.

Enrichment-enhanced photoacoustic spectroscopy based on vertical graphene

This manuscript proposes a method to improve the gas detection sensitivity of the photoacoustic spectroscopy (PAS) by the enrichment of the concentration of a gas species based on vertical graphene (VG). This is accomplished by exploiting the characteristics of vertical graphene grown on Ni foam to adsorb gas molecules and subsequently desorb them at high temperatures. After the adsorption by the VG material, the enrichment cell is heated to 150 ℃; then the enriched gas is collected and passed into the PAS cell. A DFB-QCL laser tuned at 5263 nm was used as the excitation light source of the PAS sensor for NO detection. The experimental results showed that at a gas pressure of 760 torr and with a signal integration time of 1 s, the ultimate detection limit of traditional photoacoustic spectroscopy for NO gas is 14 ppb, while that of enrichment-enhanced photoacoustic spectroscopy is 1.3 ppb, proving that this method can increase the sensitivity of one order of magnitude.

P-EcStat: A Versatile Design of Photoelectrochemical and Electrochemical Sensing System with Smartphone Interface via Bluetooth Low Energy

Electrochemical and photoelectrochemical sensors are a rapidly developing field in analytical chemistry. However, commercial systems often lack versatility and affordability, hindering wider adoption. Additionally, the absence of integrated excitation light sources limits their application in photoelectrochemical sensing. Here, we present a highly precise, versatile, affordable measurement system for both electrochemical and photoelectrochemical sensing applications. The system incorporates a three-electrode potentiostat with a synchronized excitation light source. This design enables the system to perform conventional electrochemical measurements like cyclic voltammetry, chronoamperometry, and photoelectrochemical amperometric measurements with controlled light excitation. The developed measurement system operates within a voltage range suitable for a measurable current range of 1 nA to 18 mA, with a high precision of 99%. The excitation source is a monochromatic LED system offering seven distinct wavelengths with digitally controlled intensity via a digital-to-analog converter. Furthermore, an Android-based user interface allows wireless system control via Bluetooth Low Energy. The report also details the construction of a photoelectrochemical experiment using copper (II) oxide nanorods synthesized by the hydrothermal process as the photoactive material employed to test the experiment on a potassium ferricyanide/potassium ferrocyanide solution. This user-friendly system allows broader exploration of electrochemical and photoelectrochemical sensing applications.

Compact three-dimensional fluorescence spectroscopy and its application in food safety

Three-Dimensional fluorescence spectroscopy is an indispensable tool for identification of substances by virtue of its ability to supply abundant characteristic information and high spectral resolution. In this work, we present a compact three-dimensional fluorescence spectrometer utilizing 18 different wavelength LEDs as excitation light source, instead of the conventional bulky multi-wavelength illumination strategy. This spectrometer can in situ obtain the spectral information accurately and fast, while reducing the weight and volume of system. To show its broad biochemical utility, we utilize the compact spectrometer to measure four types of vegetable oil samples from different origins, and analyzed their spectral characteristics. Moreover, we construct a deep learning model based on the 2D-CNN network to detect sesame oil adulteration qualitatively and quantitively. The Compact fluorescence spectrometer proposed has the potential to classify and grade food oils in situ, addressing the problem of sesame oil adulteration on the market.

New 3-D Fluorescence Spectral Indices for Multiple Pigment Inversions of Plant Leaves via 3-D Fluorescence Spectra

High-sensitivity fluorescence monitoring has been widely used in agriculture and environmental science. However, the active fluorescence detection information of leaf segments mainly focuses on total chlorophyll, and the fluorescence information of chlorophyll a, chlorophyll b, and some other pigments has not been explored. This only considers the fluorescence spectrum characteristics at a single wavelength or the fluorescence integral from a range of wavelength regions and does not completely consider the linkage relation between the excitation, emission, and interference information. In this paper, the three-dimensional fluorescence spectrum, containing the excitation and emission fluorescence spectra, and the corresponding multiple pigment characteristics from the upgraded LOPEX_ZJU database were collected. The linkages of excitation and emission of the three-dimensional fluorescence spectra of these pigments were analyzed for the newly built multiple pigment 3-D fluorescence spectral indices (3-D FSIs), including those of chlorophyll a, chlorophyll b, carotenoid, anthocyanin, and flavonoid 3-D FSIs. Then, these pigment inversion models were established and validated. The results show that the 3-D FSIs performances for the photosynthetic pigment content inversion (including chlorophyll a and b, and carotenoids) were much better than those for the photo-protective pigments (including anthocyanins and flavonoids) from the 3-D fluorescence spectra of these plant leaves. Here, the 3-D fluorescence normalization index (FNI ((F430,690-F430,763)/(F430,690+F430,763))) for the chlorophyll a inversion model has a high accuracy, the RMSE is 2.96 μg/cm2, and the 3-D fluorescence reciprocal difference index (FRI (F650,704/F650,668) for the chlorophyll b model has an encouraging RMSE (2.01 μg/cm2). The RMSE of the 3-D fluorescence ratio index (FRI (F500,748/F500,717)) for the carotenoid inversion is 3.77 μg/cm2 RMSE. Only FRI (F370,615/F370,438) was selected for the modeling and validating evaluation of the leaf Flas content inversion, but the evaluation metrics were not good, with an RMSE (151.13 μg/cm2). For Ants, although there was a 3-D FSI (FRDI (1/F540,679-1/F540,557)), and its evaluation metrics, with an RMSE (2.8 μg/cm2), were at or over 0.05 level, the validating evaluation metric VC (98.3577%) was not encouraging. These results showed that fluorescence, as a nondestructive and efficient detection method, could determine the contents of chlorophyll a, chlorophyll b, and carotenoid in plant leaves, providing a new method to detect plant information. It can also provide a potential chance for the fluorescence images of fine photo-protective pigments, especially chlorophyll a and b, using the special active fluorescence excitation light source and a few fluorescence imaging channels from the optimal FSIs.

High Color Conversion Efficiency Realized in Graphene‐Connected Nanorod Micro‐LEDs Using Hybrid Ag Nanoparticles and Quantum Dots

AbstractIn this paper, a uniform nanorod (NR) array is etched onto the surface of Micro‐Light‐Emitting‐Diodes (µLEDs) and mix Ag nanoparticles (NPs) with QDs to fill the gaps between the nanorods. Simultaneously, the study utilizes graphene to connect individual nanorods and enhance current spreading. The nanorod array's structure significantly reduces the distance between the QDs and the quantum well (QW), reducing energy loss from the excitation light source through a non‐radiative energy transfer (NRET) mechanism. Additionally, the Ag NPs function as localized surface plasmons (LSPs), further enhancing the CCE of QDs via the absorption resonance. In this study, the effects of two types of Ag NPs are compared with different absorption resonance peaks on device performance. The results demonstrate that Ag NPs with absorption resonance peaks matching the emission wavelength of QDs play a more crucial role in the system. This configuration achieves a CCE of 77.78% for µLEDs with nanorod arrays, operating at a current of 10 mA. Compared to the conventional µLED structure with QDs only on the surface, the proposed method improves the CCE of µLEDs by an impressive 86.5%. This outcome underscores the significant contribution of the NR structure and LSPs in enhancing the CCE of QD‐µLEDs.

Functional Green-Emitting Mn2+-doped Zinc Germanate Persistent Luminescent Nanoparticles for Dual-Mode Immunochromatographic Detection.

Immunochromatography is a commonly used immediate detection technique, using signal labels to generate detection signals for rapid medical diagnosis. However, its detection sensitivity is affected by background fluorescence caused by the excitation light source. We have developed an immunochromatographic test strip using Zn2GeO4:Mn2+ (ZGM) persistent luminescent nanoparticles (PLNPs) for immediate fluorescence detection and highly sensitive persistent luminescence (PersL) detection without background fluorescence interference. ZGM emits a strong green light when exposed to ultraviolet (UV) excitation, and its green PersL can persist for over 30 min after the excitation light is turned off. We modified the surface of ZGM with heparin-binding protein (HBP) antibodies to create immunochromatographic test strips for the detection of HBP as the target analyte. Under UV excitation, the chromatography test paper can be visually observed at concentrations as low as 25 ng/mL. After the excitation light source is switched off, PersL can achieve a detection limit of 4.7 ng/mL without background interference. This dual-mode immunochromatographic detection, based on ZGM, shows great potential for in vitro diagnostic applications.