Persistent Luminescence Nanoparticles Research Articles

Single-laser excitation synergistic photo- and chemodynamic therapy system based on persistent luminescence nanoparticles

Photodynamic and photothermal therapy (PDT and PTT) have been widely used in tumor treatment researches owe to its advantages of spatiotemporal controlliability and non-invasiveness. Combining two phototherapy strategies together and/or with chemodynamic therapy (CDT) could achieve better therapeutic efficiency, but the resulting inconvenient dual-laser irradiation and the potential skin toxicity limit its development. Moreover, the lack of tumor-specificity causes side-effects to normal tissues. Therefore, shortening the irradiation time, or integrating two lasers, and increasing tumor specificity are necessary to reduce side effects. Herein, we developed a tumor microenvironment responsive one-laser-excited PDT/PTT/CDT synergistic therapeutic nanosystem ZPPSC (refers to ZGGC-PDA-PEI-Si-Pc-Cu) for precise tumor phototherapy. In this nanosystem, the simultaneous PTT and PDT activation using a single laser, enhancing phototherapy efficiency while reducing phototoxicity were achieved. Specifically, persistent luminescence nanoparticle ZnGa1.6Ge0.2O4:Cr (ZGGC) is coated with polydopamine (PDA) through self-polymerization of dopamine, modified with polyethyleneimine (PEI), Si-Pc, and adsorbed with Cu2+. Cu2+ quenches the persistent luminescence (PersL) in physiological environment, and could be reduced to Cu+ under the excess GSH in tumor cells, resulting in removing from nanosystem. Whereafter, PersL is restored, and Fenton-like reaction between Cu+ and overexpressed H2O2 is triggered to generate ·OH for CDT therapy. Under single 808-nm irradiation, PDA will be irradiated to perform PTT, and the opening persistent luminescence could irradiate photosensitizers for PDT and continues to stimulate them even after the laser stops, reducing external excitation time. The in vivo results shown that ZPPSC exhibit ideal PDT performance, and increased local temperature close to 60 °C. Most importantly, the tumor inhibition rate by combined PTT, PDT, CDT with 5-min 808-nm laser irradiation is 99%, and even one mouse was completely cured with the bearing tumor completely disappeared. By using this nanosystem, PDT and PTT were achieved by only on laser with relatively short irradiation time. Moreover, the weak tissue penetration of the 660-nm PS excitation source was also addressed. Our design achieves tumor-specific one-laser three-mode phototherapy with shortened irradiation time, enhancing therapy effectiveness while minimizing side effects. These results exhibit great therapeutic outcomes of ZPPSC for precious tumor phototherapy.

Folic Acid‐Modified Nanoprobe for In Vivo‐Targeted Persistent Luminescence Imaging and pH‐Responsive Antibiotic Therapy of Bacterial Infection

AbstractLow antibiotic utilization and inability to achieve real‐time monitoring of pathological status and treatment processes often result in unsatisfactory performance against bacterial infection. Developing a targeting antibacterial nanoprobe combining imaging with stimulus‐response antibiotic release is a promising strategy to precisely recognize lesions and enhance therapeutic efficacy for bacterial infection. In this work, we report a pH‐responsive theragnostic nanoplatform for targeted imaging and local drug release at the bacterial infection site. The nanoplatform consists of the core‐shell structure with persistent luminescence nanoparticles (PLNPs) as the core for autofluorescence‐free luminescence imaging and zeolitic imidazolate framework‐8 (ZIF‐8) as the shell to act as a carrier for antibiotics cefazolin. The core‐shell nanostructure is further conjugated with folic acid to facilitate the uptake and accumulation of the nanoparticles, and realize the autofluorescence‐free targeted imaging of the infection site. The acidic microenvironment at the bacterial infection site enables ZIF‐8 to decompose for specific drug release improve the performance in bacterial infection treatment. The developed pH‐responsive nanotheranostic probe is promising for autofluorescence‐free targeted imaging and therapy of bacterial infection.

Optical Determination of Tryptophan Using Persistent Luminescence Nanoparticles (PLNPs)

Tryptophan is an essential amino acid that is an important part of the human diet. In this work, label-free photoluminescence sensing based upon persistent luminescent nanoparticles (PLNPs) Zn0.8Ga2O4: Cr3+ is reported to determine tryptophan. Following 254 nm excitation, the PLNPs released luminescence after storing the absorbed light. Compared to the standard fluorescence, the persistent afterglow of the PLNPs was used for detection and imaging without external illumination, thereby eliminating autofluorescence and scattered light generated by biological substrates. For tryptophan concentrations from 4 to 240 µM, a linear relationship was described by F/F 0 = 0.9416 − 0.0024 [Trp] with a correlation coefficient of 0.9911 and a detection limit of 0.19 µM. The recoveries of analyzed samples were between 97.9 and 101.9% providing good accuracy and simple methodology.

Red/NIR/SWIR multi-band persistent luminescent nanoparticles as ultrasensitive multi-channel tracers in water and crude oil/water emulsions

Red/NIR/SWIR multi-band persistent luminescent nanoparticles as ultrasensitive multi-channel tracers in water and crude oil/water emulsions

Ultrabright Fluorescent Nanorod-Based Immunochromatographic with Low Background for Advancing Detection Performance.

Nanomaterials-based immunochromatographic assays (ICAs) are of great significance in point-of-care testing (POCT), yet it remains challenging to explore low background platforms and high chromogenic intensity probes to improve detection performance. Herein, we reported a low interference and high signal-to-noise ratio fluorescent ICA platform based on ultrabright persistent luminescent nanoparticles (PLNPs) Zn2GeO4: Mn, which could produce intense photoluminescence at 254 nm excitation to reduce background interference from ICA substrates and samples. The prepared immunosensor was successfully applied in T-2 toxin detection with a remarkable limit of detection of 0.025 ng/mL, which was 22-fold more sensitive compared with that of traditional gold nanoparticles. Ultimately, a portable 3D-printed detection device equipped with a smartphone analyzing application was fabricated for quantitative readout in POCT, achieving favorable recoveries in practical sample detection. This work provides a creative attempt for ultrabright PLNP-based low background ICA, and it also guarantees its feasibility in practical POCT.

From synthesis to fabrication: Engineering thin translucent films with green persistent luminescent nanoparticles

Green-emitting ZnGa2O4:Mn2+ persistent luminescent nanoparticles were synthesized via a solvothermal method followed by a microwave-assisted sintering at 1150 °C. The obtained cubic-like particles averaged 62 ± 16 nm by Transmission Electron Microscopy (TEM) and presented afterglow for up to 2 h after a 5 min excitation in the UV. By Electron Paramagnetic Resonance (EPR), it was observed that the Mn2+ dopant replaces uniquely Zn2+ sites during synthesis. The obtained particles were dispersed with hydroxypropyl methylcellulose (HPMC) in water to create thin films by drop-casting. The films with different concentrations of nanoparticles (1 g/m2, 10 g/m2 and 100 g/m2) had average visible transmittances between 20% and 24%, and presented persistent luminescence after UV excitation, with longer duration by increasing nanoparticle concentration. By synchrotron X-ray Fluorescence (XRF) nanomapping of these films it is possible to see clusters of up to 6 μm of the nanoparticles in the film due to water pockets during film-casting. The X-ray Excited Optical Luminescence (XEOL) showed only Mn2+ emission and the XEOL-XRF mapping proved the integrity of the nanoparticles after film fabrication. By combining the solvothermal method, microwave-assisted sintering, and drop casting, this study establishes a promising pathway for the development of advanced flexible and translucent persistent luminescent composites.

Trap engineering in LiInSi2O6:Cr,Pr by excess cristobalite silica for X-ray activated near-infrared persistent luminescence imaging in vivo

Chromium-doped persistent luminescence nanoparticles (PLNPs) have promising biomedical applications in X-ray charged near-infrared (NIR) luminous imaging. The persistent luminescence (PersL) property was usually adjusted by co-doping with other ions. Impurity phases were thought to be adverse to the PersL. In this study, a composite material, LiInSi2O6:Cr,Pr·2SiO2 (LICP-S), was synthesized with a PersL peak at 800 nm after being charged by 1 Gy X-ray while LiInSi2O6:Cr (LIC) and LiInSi2O6:Cr,Pr (LICP) possessed no or very weak PersL. Distinctively, excess metastable cristobalite silica was found essential for the much more intense PersL of LICP-S than LICP and LIC. Thermostimulated luminescence spectra studies indicated that cristobalite adjusted the Pr-related traps from deep traps to shallow ones, which facilitated the room temperature PersL. The low dose X-ray charged PersL of LICP-S was applied to demonstrate the luminous labeling of a medical silicone prosthesis that was supposed to be imbedded in body for years via X-ray activated PersL imaging in vitro and in vivo. This work not only provides a kind of PLNPs with 800 nm emission suitable for low dose X-ray activation, but also an unusual strategy for trap engineering in PersL materials by designing multi-phase composites.

Enhanced up-conversion persistent luminescence of Zn2GeO4:Mn phosphors by non-equivalent doping and sensitization of up-conversion nanocrystals

Up-conversion persistent luminescence (UCPL) nanoparticles have captured tremendous attention due to their unique optical operating performance such as the absence of auto-fluorescence and the charging capacity of near-infrared (NIR) light. However, the weak afterglow intensity as well as low duration limits their practical applications including multimode anti-counterfeiting and biological imaging, etc. Herein, typical green persistent luminescence (PersL) and photo-stimulated luminescence (PSL) of Zn2GeO4:Mn2+ phosphors were enhanced via non-equivalent Li+ co-doping, in which the preferred site selection of Mn2+ and Li + have been verified by using the first-principles theory. The possible luminescent enhancement mechanisms were proposed based on improving the oxygen vacancy density and promoting the formation of Mn4+ defect energy level in bandgap structure by non-equivalent doping of Li+. Interestingly, UCPL of Zn2GeO4:Mn2+,Li + can be achieved after charging of Vis to NIR light. It is worth noting that this UCPL can be further enhanced by the sensitization of NaYF4:Yb,Tm nanoparticles via simply mixing Zn2GeO4:Mn2+,Li+ and NaYF4:Yb,Tm under 980 laser stimulation. As a result, Zn2GeO4:Mn2+,Li+ phosphor exhibits the enhanced quintuple-mode luminescence including photoluminescence, PersL, PSL, photo-stimulated persistent luminescence and UCPL. In particular, the achieved NIR rechargeable UCPL hybrid phosphors exhibit enormous potential for higher order anti-counterfeiting and rewriteable data encryption and decryption applications.

Bimodal persistent luminescence for autofluorescence-free ratiometric biosensing.

In optical biosensing, analyte-independent factors such as autofluorescence interference and excitation source fluctuation decrease the sensitivity and accuracy. Herein, we reported a bimodal persistent luminescence strategy to design dual-emissive persistent luminescence nanoparticles (PLNPs) with built-in self-calibration to preclude interference from analyte-independent factors in biosensing. As a proof of concept, ZnGa2O4:Cr PLNPs with emissions at both 490 nm and 695 nm were designed. The I490/I695 ratio of ZnGa2O4:Cr was readily adjusted by simply changing the doping concentration of Cr3+. The ZnGa2O4:Cr PLNPs were employed for the ratiometric detection of urinary mesna. A good linear relationship between the I490/I695 ratio of ZnGa2O4:Cr-based nanoprobe and the concentration of mesna was obtained in the range of 0-40 μM. The limit of detection was about 0.40 μM. Results showed that autofluorescence interference from urine was totally eliminated by collecting the persistent luminescence signal of ZnGa2O4:Cr after excitation ceased. Moreover, the built-in self-calibration feature of the ratiometric ZnGa2O4:Cr PLNPs efficiently suppressed the interference from fluctuations in instrumental parameters during urinary mesna detection. The recovery rates of mesna in the spiked urine samples are in the range of 99.1~109.0%, showing the reliability of the ratiometric ZnGa2O4:Cr PLNPs in urinary mesna detection. ZnGa2O4:Cr can further be expanded to the detection of other analytes in complex matrices. This study may open new opportunities for the design of dual-emissive PLNPs with tunable ratios of emission intensity, and it can further promote the applications of optical biosensing in disease diagnosis, food safety, and environmental monitoring.

The improved size distribution and NIR luminescence of ZGGO:Cr3+ nanoparticles induced by Y3+ doping

Zn2Ga2.98-xYxCr0.02Ge0.75O8 (ZGGO:Cr0.02,Yx) persistent luminescent nanoparticles (PLNPs) with different concentrations were synthesized by a hydrothermal method combined with a vacuum heat treatment. With increasing Y3+ concentration from 0 to 0.05, the average size reduces from 53 to 28 nm and the particle shape changes from irregular to nearly spherical due to Y3+ doping leading to the suppressed growth rate of nanocrystals via surface charge modification. On the basis of spectral analyses and the first-principles calculation, the near infrared (NIR) emission peaks at 703 and 743 nm originate from the 4T2→4A2 transition of Cr3+ occupying octahedral Ga3+ sites and the 4A2→4T1 transition of Cr3+ occupying tetrahedral Ga3+ sites, respectively. Meanwhile, it is found that Y3+ ions are more likely to occupy tetrahedral Ga3+ sites and it leads to not only the creation of more anti-site defect pairs and the enhanced afterglow intensity but also the increased rigidity and the improved dispersibility of PLNPs in different simulated body fluids induced by complete surface modification (i.e. SiO2 coating). The above results indicate that ZGGO: Cr0.02,Y0.03@SiO2 PLNPs have potential applications in bioimaging.

H2 O2 -Induced Persistent Luminescence Signal Enhancement Applied to Biosensing.

Persistent luminescence nanoparticles (PLNPs) are innovative materials able to emit light for a long time after the end of their excitation. Thanks to this property, their detection can be separated in time from the excitation, making it possible to obtain images with a high signal-to-noise ratio. This optical property can be of particular interest for the development of in vitro biosensors. Here, wereport the unexpected effect of hydrogen peroxide (H2 O2 ) on the signal intensity of ZnGa2 O4 :Cr3+ (ZGO) nanoparticles. In the presence of H2 O2 , the signal intensity of ZGO can be amplified. This signal amplification can be used to detect and quantify H2 O2 in various media, using non-functionalized ZGO nanoparticles. This small molecule can be produced by several oxidases when they react with their substrate. Indeed, the quantification of glucose, lactic acid, and uric acid is possible. The limit of detection could be lowered by modifying the nanoparticles synthesis route. These optimized nanoparticles can also be used as new biosensor to detect larger molecules such as antigen, using the appropriate antibody. This unique property, i.e., persistent luminescence signal enhancement induced by H2 O2 , represents a new way to detect biomolecules which could lead to a very large number of bioassay applications.

Nonstoichiometric Nanocubes with a Controllable Morphology and Persistent Luminescence for Autofluorescence-Free Biosensing.

Persistent luminescence nanoparticles (PLNPs) have shown special advantages in areas such as bioimaging, cancer therapy, stress sensing, and photo-biocatalysis. However, the lack of methods for controllable synthesis of PLNPs with uniform morphologies and strong persistent luminescence has seriously hindered the applications of PLNPs. Herein, we reported that modifying the electronic structures of zinc gallogermanate (ZGGO) PLNPs by nonstoichiometric reactions can produce highly uniform nanocubes with controllable size and persistent luminescence. By nonstoichiometric increase of the Ge/Ga ratio in ZGGO, the ZGGO PLNPs were transformed from a mixture of nanocubes and small nanospheres into highly symmetrical and uniform large nanocubes, accompanied by the enhancement of persistent luminescence intensity by about 3.7 times. Moreover, we found that ZGGO PLNPs were responsive to reactive oxygen species (ROS), that is, the persistent luminescence of ZGGO can be quenched by ROS. Autofluorescence-free serum ROS detection was achieved with the developed PLNPs. Further, a biosensing assay for glucose oxidase (GOx) was designed based on the responsiveness of ZGGO PLNPs to H2O2. This study may pave a new way for better control of PLNPs' size, morphology, and persistent luminescence, and it can further promote the applications of PLNPs in areas ranging from theranostics to solar energy utilization.

Ultrasound-Chargeable Persistent Luminescence Nanoparticles to Generate Self-Propelled Motion and Photothermal/NO Therapy for Synergistic Tumor Treatment.

Cancer phototherapy indicates advantages in ease of manipulation, negligible drug resistance, and spatiotemporal control but is confronted with challenges in tumor cell accessibility and intermittent light excitation. Herein, we propose a strategy with persistent luminescence (PL)-excited photothermal therapy (PTT), concurrent thermophoresis-propelled motion, and PL-triggered NO release, where PL emission is chargeable by ultrasonication for readily applicable to deep tumors. Mechanoluminescent (ML) nanodots of SrAl2O4:Eu2+ (SAOE) and PL nanodots of ZnGa2O4:Cr3+ (ZGC) were deposited on mesoporous silicates to obtain mSZ nanoparticles (NPs), followed by partially coating with polydopamine (PDA) caps and loading NO donors to prepare Janus mSZ@PDA-NO NPs. The ML emission bands of SAOE nanodots overlap with the excitation band of ZGC, and the persistent near-infrared (NIR) emission could be repeatedly activated by ultrasonication. The PL emission acts as an internal NIR source to produce a thermophoretic force and NO gas propellers to drive the motion of Janus NPs. Compared with the commonly used intermittent NIR illumination at both 660 and 808 nm, the persistent motion of ultrasound-activated NPs enhances cellular uptake and long-lasting PTT and intracellular NO levels to combat tumor cells without the use of any chemotherapeutic drugs. The ultrasound-activated persistent motion promotes intratumoral accumulation and tumor distribution of PTT/NO therapeutics and exhibits significantly higher tumor growth inhibition, longer animal survival, and larger intratumoral NO levels than those who experience external NIR illumination. Thus, this study demonstrates a strategy to activate PL emissions and construct PL-excited nanomotors for phototherapy in deep tissues.

Energy recruitment via lanthanide-chelate to boost the persistent luminescence of nanophosphor for contrast-enhanced tumor navigation

Persistent luminescence (PersL) nanoparticles (PLNPs) with excitation-afterglow emission separation character, have brought luciferous prospect for ultrasensitive optical detection to circumvent the weakness of clinical fluorescence modality, benefiting from the strengths of autofluorescence-free, low phototoxicity and superior photostability. Nevertheless, small dimensions of PLNPs (<200 nm, suitable for in vivo diagnosis) synthesized via current procedures are inevitably accompanied with PersL brightness sacrifice. Whereas the past few years have witnessed advances to promote the performance of nanophosphor, proposing a versatile and sustainable approach to boost the excitation absorption capacity, thus amplifying the PersL is of industrywide urgency. Here, we first report a “lanthanide-chelate sensitization” strategy involving Eu-DOTA as strong photon harvester and Zn2SnO4: Cr3+, Eu3+ (ZSCE) PLNPs as matched acceptor to steadily augment the intensity of obtained ZDE PLNPs via efficacious Förster-type energy transfer. Photobleaching resistant ZDE PLNPs with different DOTA-Eu substitutions enable maximal 3.9-fold luminous brightness and 1.4-fold decay lifetime over bare PLNPs. Cladded with hyaluronic acid (HA), ZDE@HA PLNPs performed high signal-to-noise ratio imaging and accurate tumors boundary depicting which facilitates PersL-guided breast tumors excision. Strikingly, the “Ln-chelate sensitization” concept could serve as an extensible approach to optimize existing PLNPs, which lightens up new perspectives for ultra-contrastive malignancy navigation.

The role of Li+ and Yb3+ in modulating the electronic structure and luminescence of MgGeO3:Mn2+ nanoparticles

Inorganic persistent luminescence (PersL) nanoparticles (NPs) emitting at the deep-red and near-infrared (NIR) are promising candidates for applications in the biomedical field, such as optical imaging, sensing and therapy. The emission wavelength is closely related to the identity of the light activators (i.e. metal ion dopant), and the local environment they occupy in the host crystal lattice. In this paper, PersL nanoparticles with dual emission bands based on MgGeO3 was investigated. These nanoparticles exhibit one emission band at the deep-red region when doped with Mn2+. Introducing Yb3+ as a second dopant enables a deep-red-to-NIR energy transfer, producing dual-emission at both deep-red and NIR. The NIR emission can be further enhanced by the addition of Li+. A detailed spectroscopy study is performed to investigate the local structure around the light activators Mn2+ and Yb3+, and how it is influenced by the Li+ co-dopant. We found that adding the Yb3+ and Li+ changes the preferred site of occupancy for Mn2+, and when Mn2+ is shifted to a site that emits deep-red less efficiently, it acts as an electron trap to extend the PersL of the NIR-II emission. The mechanism for the deep-red-to-NIR energy transfer is proposed.

Near-Infrared Persistent Luminescence Nanoprobe for Ultrasensitive Image-Guided Tumor Resection.

Near-infrared (NIR) fluorescence imaging poses significant superiority over traditional medical imaging for tumor resection, thus having attracted widely attention. However, for tiny tumor residues, it requires relative high sensitivity to determine. Here, based on persistent luminescence nanoparticles (PLNPs), an ultrasensitive nanoprobe with extraordinary tumor imaging result is developed to guide surgical removal. Persistent luminescence (PersL) is quenched in normal tissue by the outer layer of MnO2 , and is recovered due to the degradation of MnO2 in tumor microenvironment, significantly improving the sensitivity of tumor imaging. Combined with the absence of background fluorescence in imaging of PLNPs, ultrahigh sensitivity is achieved. In orthotopic breast cancer model, the intraoperative tumor-to-normal tissue (T/NT) signal ratio of the nanoprobe is 58.8, about 9 times that of downconversion nanoparticles. The T/NT ratio of residual tumor (<2mm) remains 12.4, considerably high to distinguish tumor tissue from normal tissue. Besides, multiple-microtumor, 4T1 liver-implanted tumor and lung metastasis models are built to prove that this ultrasensitive nanoprobe is feasible to recognize tumor residues. Notably, PersL imaging takes only 1.5min, appropriate to be applied for intraoperative imaging. Overall, an ultrasensitive and convenient imaging for recognizing residual tumor tissue is introduced, holding promise for complete surgical removal.

Clinical radiation dose verification by topographic persistent luminescence dosimetry

Radiation dose verification in radiotherapy is essential to determine the dose delivered to irradiated tissue while minimizing normal tissue toxicity. However, the challenge remains in determining topographic radiation dose profiles due to limitations in conventional dosimeters. Herein, we report a robust technique for visualizing and verifying clinical doses based on reusable, flexible scintillating films comprising lanthanide-doped persistent luminescent nanoparticles. These nanoparticle-based films outperform commercially available radiochromic films in terms of linear response to irradiation doses between 0 and 25 Gy. We demonstrate topographic persistent luminescence dosimetry for radiotherapy of mice and rabbits with malignant tumors. Our data show a higher signal-to-background ratio, especially at lower (<0.1 Gy) and higher (>10 Gy) X-ray doses. We also demonstrate that topographic persistent luminescence dosimetry can record complex clinical dose distributions for dose verification and radiotherapy planning.

Light Conversion Nanomaterials for Wireless Phototherapy.

ConspectusPhototherapy including optogenetics, photodynamic therapy (PDT), photothermal therapy (PTT), and photoimmunotherapy (PIT) has been proven to be effective against different diseases. However, as the name suggests, phototherapy requires light irradiation, thus its therapeutic efficiency is often restricted by limited depth of light penetration within biological tissue. This light penetration limitation is significantly adverse to PDT and optogenetics because both therapies are usually activated with UV and visible light of very poor tissue penetration efficiency. Current light delivery methods usually involve cumbersome setups and require optical fiber or catheter insertion, which not only restrict the movement of patients but also impose incompatibility issues with chronic implantation. To address the existing challenges, wireless phototherapy was developed through various approaches over recent years, which usually relies on implantable wireless electronic devices. However, the application of wireless electronic devices is limited by invasion during implantation, unwanted heat generation, and adverse immunogenicity of these devices.Over the recent years, applying light conversion nanomaterials as light transducers for wireless phototherapy has garnered much interest. Compared with implantable electronic devices and optical fiber, nanomaterials can be easily injected into the body with minimal invasiveness and can also be surface functionalized to increase their biocompatibility and cell accumulation efficiency. Commonly applied light conversion nanomaterials include upconversion nanoparticles (UCNPs), X-ray nanoscintillators, and persistent luminescence nanoparticles (PLNPs). UCNPs and X-ray nanoscintillators can respectively convert near-infrared (NIR) light and X-ray, which have good tissue penetration efficiency, to UV or visible light, which is suitable for activating phototherapy. PLNPs can be excited by external light such as X-rays and NIR light and retain long afterglow luminescence after the removal of the excitation light source. As a result, applying PLNPs in phototherapy can potentially reduce irradiation time from external light sources, thus minimizing tissue photodamage. This Account aims to briefly discuss (i) the mechanisms of different phototherapies, (ii) the development and mechanisms of light conversion nanomaterials, (iii) the application of light conversion nanomaterials in wireless phototherapy, highlighting how they relieve current challenges in phototherapy, and (iv) perspectives for future development of light conversion nanomaterials for wireless phototherapy.

Competitive ELISA based on pH-responsive persistent luminescence nanoparticles for autofluorescence-free biosensor determination of ochratoxin A in cereals.

An accurate and sensitive competitive enzyme-linked immunosorbent assay (ELISA) based on persistent luminescence nanoparticles Zn2GeO4:Mn2+, Eu3+ (ZGME) was developed for detecting ochratoxin A (OTA), a powerfully toxic mycotoxin usually found in grains. As a signal output element of autofluorescence-free biosensors, ZGME can be integrated into ELISA with glucose oxidase (GOx)-binding OTA molecules due to its excellent pH-responsive persistent luminescence. In the absence of OTA, the OTA-GOx conjugate was captured by the anti-OTA monoclonal antibody (anti-OTA mAb) pre-coated on the 96-well plate. The results indicate a decrease in the pH value of the solution, which triggered the quenching of ZGME luminescence due to GOx-dependent gluconic acid production. The presence of OTA inhibited the binding of OTA-GOx on the plate, thus decreasing the production of gluconic acid and increasing the persistent luminous intensity of ZGME. Under the optimized concentrations of anti-OTA mAb and OTA-GOx, quantitative determination of OTA was achieved by plotting the increase or decrease in persistent luminescence intensity of ZGME at 535nm. In this study, the linear range was from 0.1μg L-1 to 63μg L-1, and the limit of detection (LOD) was as low as 0.045μg L-1. In five food samples (corn grit, brown rice, soybean, rice, and wheat), the results exhibited good stability and repeatability, with a recovery range from 81.3% to 94.4% and a relative standard deviation (RSD) of less than 4.2%. Hence, the established method provides a sensitive, accurate, and autofluorescence-free approach for the determination of OTA in different grain samples.

Bright, small sizes and hydro-dispersive NIR persistent luminescence nanoparticles modified with Si and amino groups for enhanced bioimaging

Near-infrared (NIR) persistent luminescence nanoparticles (PLNPs) with high brightness, small sizes, good hydro-dispersivity, and intrinsic surface-functional groups are desirable in biological applications. In this work, Cr3+-doped zinc gallogermanates Zn1+x Ga2−2x Ge x O4:Cr (ZGGC) PLNPs were hydrothermally synthesized via 3-aminopropyltriethoxysilane (APTES) as an additive, or APTES and cetyltrimethylammonium bromide (CTAB) as two co-additives. Addition of APTES not only dramatically enhances the 696 nm NIR luminescence intensity, but also obviously decreases the particle size and introduces amino groups. In particular, the x = 0.1 series ZGGC (ZGGC0.1) with the addition of n moles equivalent APTES (ZGGC0.1-nA) had smaller particle sizes than the x = 0.2 counterpart (ZGGC0.2-nA). The NIR afterglow intensities increased with the APTES introduction. The ZGGC0.2-2.5A sample (also named as ZGGC, Si, -NH2) exhibited maximum luminescence intensities both in solid and aqueous states. With APTES, Si atom is doped and –NH2 groups are modified, the trap depth and density become larger, and the afterglow intensities and decay time are significantly enhanced. More notably, co-addition of CTAB (ZGGC0.2-2.5A-C) (also named as ZGGC, Si, −NH2’) further enhances hydro-dispersivity and luminescence intensity, decreases particle sizes, and results in more prominent amino groups. The trap density is drastically higher than that without CTAB (i.e. ZGGC0.2-2.5A). Change of Cr3+ microenvironment in the crystal and more defects introduction contribute to the enhanced brightness. As expected, the ZGGC,Si,-NH2’ PLNPs possess excellent biocompatibility, deep tissue penetration and distinguished bioimaging properties, and rechargeability with orange LED light. The ZGGC,Si,-NH2’ PLNPs should provide to be an excellent nanomaterial for various functionalization and bioimaging applications.