Fluorescence Resonance Energy Transfer Inhibition Assay for α-Fetoprotein Excreted during Cancer Cell Growth Using Functionalized Persistent Luminescence Nanoparticles

Size-independent boosting of near-infrared persistent luminescence in nano-phosphors via a magnesium doping strategy

Near-infrared (NIR)-emitting persistent luminescence nanoparticles (PLNPs) are ideal optical imaging contrast reagents characterized by autofluorescence-free optical imaging for their frontier applications in long-term bioimaging. Preparation of uniform small-sized PLNPs with excellent luminescence performance is crucial for biomedical applications, but challenging. Here, we report a facile magnesium doping strategy to achieve size-independent boost of NIR persistent luminescence in typical and most concerned ZnGa2O4:Cr3+ PLNPs. This strategy relies on the doping of Mg2+ ions that with similar size of Zn2+ ions in the host lattice matrix, and concomitant to the electron traps tailoring tuned by varying the feed ratio of Mg2+. The optimum Mg2+-doped PLNPs give a long afterglow time (signal-to-noise ratio (SNR) = 31.6 at 30 d) without changing the desirable uniform sub-10 nm size of the original nanocrystals. The appropriate increase of the depth and concentration of electron trap contribute jointly to the enhancement of lifetime (488 % longer, 20.57 s) and afterglow time for 700 nm persistent luminescence. Meanwhile, these PLNPs keep the original excellent rechargeability and promote over 60 times increase of SNR in renewable in vivo imaging. This simple strategy provides a basis for new opportunities to address the critical challenge of effective optical performance boost in small-sized PLNPs.

Persistent Luminescence Lifetime-Based Near-Infrared Nanoplatform via Deep Learning for High-Fidelity Biosensing of Hypochlorite

In light of deep tissue penetration and ultralow background, near-infrared (NIR) persistent luminescence (PersL) bioprobes have become powerful tools for bioapplications. However, the inhomogeneous signal attenuation may significantly limit its application for precise biosensing owing to tissue absorption and scattering. In this work, a PersL lifetime-based nanoplatform via deep learning was proposed for high-fidelity bioimaging and biosensing in vivo. The persistent luminescence imaging network (PLI-Net), which consisted of a 3D-deep convolutional neural network (3D-CNN) and the PersL imaging system, was logically constructed to accurately extract the lifetime feature from the profile of PersL intensity-based decay images. Significantly, the NIR PersL nanomaterials represented by Zn1+xGa2-2xSnxO4: 0.4 % Cr (ZGSO) were precisely adjusted over their lifetime, enabling the PersL lifetime-based imaging with high-contrast signals. Inspired by the adjustable and reliable PersL lifetime imaging of ZGSO NPs, a proof-of-concept PersL nanoplatform was further developed and showed exceptional analytical performance for hypochlorite detection via a luminescence resonance energy transfer process. Remarkably, on the merits of the dependable and anti-interference PersL lifetimes, this PersL lifetime-based nanoprobe provided highly sensitive and accurate imaging of both endogenous and exogenous hypochlorite. This breakthrough opened up a new way for the development of high-fidelity biosensing in complex matrix systems.

Molecularly Targeted Lanthanide Nanoparticles for Cancer Theranostic Applications

Injectable colloidal solutions of lanthanide oxides (nanoparticles between 10 and 100 nm in size) have demonstrated high biocompatibility and no toxicity when the nanoparticulate units are functionalized with specific biomolecules that molecularly target various proteins in the tumor microenvironment. Among the proteins successfully targeted by functionalized lanthanide nanoparticles are folic receptors, fibroblast activation protein (FAP), gastrin-releasing peptide receptor (GRP-R), prostate-specific membrane antigen (PSMA), and integrins associated with tumor neovasculature. Lutetium, samarium, europium, holmium, and terbium, either as lanthanide oxide nanoparticles or as nanoparticles doped with lanthanide ions, have demonstrated their theranostic potential through their ability to generate molecular images by magnetic resonance, nuclear, optical, or computed tomography imaging. Likewise, photodynamic therapy, targeted radiotherapy (neutron-activated nanoparticles), drug delivery guidance, and image-guided tumor therapy are some examples of their potential therapeutic applications. This review provides an overview of cancer theranostics based on lanthanide nanoparticles coated with specific peptides, ligands, and proteins targeting the tumor microenvironment.

Nanoparticle-Based Bioaffinity Assays: From the Research Laboratory to the Market

Advances in the development of new biorecognition elements, nanoparticle-based labels as well as instrumentation have inspired the design of new bioaffinity assays. This review critically discusses the potential of nanoparticles to replace current enzymatic or molecular labels in immunoassays and other bioaffinity assays. Successful implementations of nanoparticles in commercial assays and the need for rapid tests incorporating nanoparticles in different roles such as capture support, signal generation elements, and signal amplification systems are highlighted. The limited number of nanoparticles applied in current commercial assays can be explained by challenges associated with the analysis of real samples (e.g., blood, urine, or nasal swabs) that are difficult to resolve, particularly if the same performance can be achieved more easily by conventional labels. Lateral flow assays that are based on the visual detection of the red-colored line formed by colloidal gold are a notable exception, exemplified by SARS-CoV-2 rapid antigen tests that have moved from initial laboratory testing to widespread market adaption in less than two years.

Ultra-Sensitive Portable Visual Paper-Based Viral Molecularly Imprinted Sensor without Autofluorescence Interference

Detection of the virus is the primary factor to discover and block the occurrence and development of the virus epidemic. Here, an ultrasensitive paper-based virus molecular imprinting sensor is developed to detect two viruses simultaneously in which the detection limit of the influenza virus (H5N1) is 16.0 aM (9.63 × 103 particles/mL) while that of the Hepatitis B Virus (HBV) is 129 fM (7.77 × 107 particles/mL). This paper-based sensor is low cost and is easy to cut, store, and carry. In addition, the visual semiquantitative detection of two viruses is achieved by using two aptamer-functionalized persistent luminescent nanoparticles as signal probes. These probes and the imprinted cavities on the paper-based material formed sandwich-type double recognition of the target viruses. This sensor has extremely high sensitivity to the H5N1 virus, which is of great value to solve the influenza epidemic with the most outbreaks in history, and also opens up a new way for the prevention and control of other virus epidemics. This cheap and portable visual sensor provides the possibility for self-service detection and can greatly reduce the pressure on medical staff and reduce the risk of virus infection caused by the concentration of people to be tested.

Persistent luminescent nanophosphors for applications in cancer theranostics, biomedical, imaging and security

The extraordinary and unique properties of persistent luminescent (PerLum) nanostructures like storage of charge carriers, extended afterglow, and some other fascinating characteristics like no need for in-situ excitation, and rechargeable luminescence make such materials a primary candidate in the fields of bio-imaging and therapeutics. Apart from this, due to their extraordinary properties they have also found their place in the fields of anti-counterfeiting, latent fingerprinting (LPF), luminescent markings, photocatalysis, solid-state lighting devices, glow-in-dark toys, etc. Over the past few years, persistent luminescent nanoparticles (PLNPs) have been extensively used for targeted drug delivery, bio-imaging guided photodynamic and photo-thermal therapy, biosensing for cancer detection and subsequent treatment, latent fingerprinting, and anti-counterfeiting owing to their enhanced charge storage ability, in-vitro excitation, increased duration of time between excitation and emission, low tissue absorption, high signal-to-noise ratio, etc. In this review, we have focused on most of the key aspects related to PLNPs, including the different mechanisms leading to such phenomena, key fabrication techniques, properties of hosts and different activators, emission, and excitation characteristics, and important properties of trap states. This review article focuses on recent advances in cancer theranostics with the help of PLNPs. Recent advances in using PLNPs for anti-counterfeiting and latent fingerprinting are also discussed in this review.

Time-resolved fluorescence nanoprobe of acetylcholinesterase based on ZnGeO:Mn luminescence nanorod modified with metal ions

A novel time-resolved fluorescence nanoprobe (PBMO, PLNR-BSA-Mn2+-OPD) is fabricated for the label-free determination of acetylcholinesterase (AChE). The ZnGeO:Mn persistent luminescence nanorod (PLNR) and Mn(II) are, respectively, exploited as the signal molecule and quencher to construct the PBMO nanopobe using bovine serum albumin (BSA) as the surface-modified shell and o-phenylenediamine (OPD) as the reducing agent. In the presence of H2O2, the persistent luminescence of PBMO at 530 nm is enhanced remarkably within 30 s due to the oxidation of Mn(II). H2O2 can react with thiocholine (TCh), which is produced through the enzymatic degradation of acetylcholine (ATCh) by AChE. The PBMO nanoprobe is successfully applied to the determination of AChE in the linear range of 0.08-10 U L-1, with a detection limit of 0.03 U L-1 (3σ/s). The practicability of this PBMO nanoprobe is confirmed by accurately monitoring AChE contents in human serum samples, giving rise to satisfactory spiking recoveries of 96.2-103.6%.

Particle Adsorption Using a Quartz Crystal Microbalance with Dissipation by Applying a Kelvin-Voigt-Based Viscoelastic Model and the Gauss-Newton Method

The use of a quartz crystal microbalance with dissipation (QCM-D) to study the adsorption of particles larger than 100 nm, such as liposomes, viruses, and nano/micro-plastics, remains challenging owing to the lack of appropriate models for data evaluation. This study presents a method for quantifying the adsorption of negatively charged polystyrene latex (100 nm-1 μm) at the solid-liquid interface. The validity of a viscoelastic model based on Kelvin-Voigt theory was assessed, and the model was used to evaluate particle adsorption data obtained from QCM-D measurements. The Gauss-Newton method was used to fit the data; the values obtained were larger than results from atomic force microscopy, indicating that the viscoelastic model combined with the Gauss-Newton method can quantify the adsorption of large polystyrene particles and the surrounding water around them. We suggested that QCM-D, in combination with an appropriate viscoelastic model, is applicable to estimate adsorption at the solid-liquid interface even for soft particles larger than 1 μm, which are out of the range of applications to the hydrodynamics model. Furthermore, we successfully showed that the recorded dissipation reflects the viscoelastic properties of the layer. The viscoelastic model allowed quantification of the rheological properties of the layer. The ratio of the viscous and elastic contributions was characterized by using loss tangent (tan δ) values that were extracted from the experimental data by applying the viscoelastic model. These values were lower for the adsorption of the negatively charged polystyrene particles on a positive surface than on a negative surface. This suggests that tan δ reflects the strength of the contact between the particle and substrate.

Phosphorescent Carbon Dots as Long-Lived Donors To Develop an Energy Transfer-Based Sensing Platform

Employing long-lived luminescent materials to design a chemical sensing platform can eliminate real-time excitation and background fluorescence. However, the realization of long-lived emissions in aqueous media was limited to transition-metal complexes, doped quantum dots, organic crystals, and inorganic persistent phosphors, which suffer from the drawbacks of large size, expensive elements, and poor dispersibility. In this work, phosphorescent carbon dots (CDs) were covalently immobilized in a silica matrix (CDs@SiO₂) to achieve afterglow emission in an aqueous dispersion. CDs@SiO₂ with long lifetime (∼1.6 s) was utilized as an energy donor to fabricate nonradiative energy transfer systems with various organic dyes through the surface micelle self-assembly method. Benefiting from the high energy transfer efficiency between CDs@SiO₂ and organic dyes, multicolor afterglow emissions were successfully obtained in aqueous media. As a proof of concept, a ratiometric phosphorescent probe using CDs@SiO₂ as a donor and Hg²⁺-responsive rhodamine derivative as an acceptor was designed. Hg²⁺ triggered the energy transfer process between the donor-acceptor pair, leading to the sensitive detection of Hg²⁺ ions. The work presented here provides opportunities to develop chemical sensors with low background interferences and easily recognizable signals.

Achieving Persistent Luminescence Performance Based on the Cation-Tunable Trap Distribution

Deep-red persistent luminescence (PersL) materials have promising applications in fluorescence labeling and tracking. PersL spectral range and PersL duration are considered to be the key factors driving the development of high-performance deep-red PersL materials. To address these two key issues, the performance of PersL materials was continually optimized by doping with cations (Si⁴⁺ and Al³⁺ ions), relying on the material of Li₂ZnGe₃O₈:Cr³⁺ from the previous work of our group, and a 4.8-fold increase in PersL radiation spectrum intensity and more than twice the PersL duration was achieved (PersL duration up to 47 h). Ultimately, the obtained PersL materials are used to demonstrate their potential use in multi-level anti-counterfeiting, tracking and localization, respectively. This study provides a unique and novel entry point for achieving high-performance PersL materials by optimizing the PersL material host to modulate the electronic structure.

Research progress on near-infrared long persistent phosphor materials in biomedical applications

After excitation is stopped, long persistent phosphor materials (LPPs) can emit light for a long time. The most important feature is that it allows the separation of excitation and emission in time. Therefore, it plays a vital role in various fields such as data storage, information technology, and biomedicine. Owing to the unique mechanism of storage and luminescence, LPPs can avoid the interference of sample autofluorescence, as well as show strong tissue penetration ability, good afterglow performance, and rich spectral information in the near-infrared (NIR) region, which provides a broad prospect for the application of NIR LPPs in the field of biomedicine. In recent years, the development and applications in biomedical fields have been advanced significantly, such as biological imaging, sensing detection, and surgical guidance. In this review, we focus on the synthesis methods and luminescence mechanisms of different types of NIR LPPs, as well as their applications in bioimaging, biosensing detection, and cancer treatment in the field of biomedicine. Finally, future prospects and challenges of NIR LPPs in biomedical applications are also discussed.

Fate and biological impact of persistent luminescence nanoparticles after injection in mice: a one-year follow-up

Persistent luminescence nanoparticles (PLNPs) are attracting growing interest for non-invasive optical imaging of tissues with a high signal to noise ratio. PLNPs can emit a persistent luminescence signal through the tissue transparency window for several minutes, after UV light excitation before systemic administration or directly in vivo through visible irradiation, allowing us to get rid of the autofluorescence signal of tissues. PLNPs constitute a promising alternative to the commercially available optical near infrared probes thanks to their versatile functionalization capabilities for improvement of the circulation time in the blood stream. Nevertheless, while biodistribution for a short time is well known, the long-term fate and toxicity of the PLNP's inorganic core after injection have not been dealt with in depth. Here we extend the current knowledge on ZnGa_1.995O₄Cr_0.005 NPs (or ZGO) with a one-year follow-up of their fate after a single systemic administration in mice. We investigated the organ tissue uptake of ZGO with two different coatings and determined their intracellular processing up to one year after injection. The biopersistence of ZGO was assessed, with a long-term retention, quantified by ICP-MS, mostly in the liver and spleen, parallel with a loss of their luminescence properties. The analysis of the toxicity related to combining an animal's weight, key hematological and metabolic markers, histological observations of liver tissues and quantification of the expression of 31 genes linked to different metabolic reactions did not reveal any signs of noxiousness, from the macro scale to the molecular level. Therefore, the ZGO imaging probe has been proven to be a safe and relevant candidate for preclinical studies, allowing its long term use without any in vivo disturbance of the general metabolism.

Non-autofluorescence Detection of H5N1 Virus Using Photochemical Aptamer Sensors Based on Persistent Luminescent Nanoparticles

Fluorescence sensing is limited in practical applications owing to multiple autofluorescent substances in complex biological samples such as serum. In this paper, the luminescence decay effect of persistent luminescent nanoparticles (PLNPs) was used to avoid the interference of autofluorescence in complex biological samples, and a non-autofluorescence molecularly imprinted polymer aptamer sensor (MIP-aptasensor) was designed to detect H5N1 virus. The proposed MIP-aptasensor consists of a magnetic MIP and aptamer-functionalized persistent luminescent nanoparticle Zn₂GeO₄:Mn²⁺-H5N1 aptamer (ZGO-H5N1 Apt). Upon simultaneous recognition of H5N1 virus, strong persistent luminescent signal changes were produced. Using the unique luminescent characteristics of PLNPs and the high selectivity of imprinted polymers and aptamers, the designed MIP-aptasensor effectively eliminates the autofluorescence background interference of serum samples and realizes the non-autofluorescence detection of H5N1 virus with high sensitivity (a limit of detection of 0.0128 HAU mL^-1, 1.16 fM) and selectivity (the imprinting factor for the target H5N1 virus was 6.72). This tool provides a strategy for the design of sensors and their application in complex biological samples.

Manipulation of time-dependent multicolour evolution of X-ray excited afterglow in lanthanide-doped fluoride nanoparticles

External manipulation of emission colour is of significance for scientific research and applications, however, the general stimulus-responsive colour modulation method requires both stringent control of microstructures and continously adjustment of particular stimuli conditions. Here, we introduce pathways to manipulate the kinetics of time evolution of both intensity and spectral characteristics of X-ray excited afterglow (XEA) by regioselective doping of lanthanide activators in core-shell nanostructures. Our work reported here reveals the following phenomena: 1. The XEA intensities of multiple lanthanide activators are significantly enhanced via incorporating interstitial Na⁺ ions inside the nanocrystal structure. 2. The XEA intensities of activators exhibit diverse decay rates in the core and the shell and can largely be tuned separately, which enables us to realize a series of core@shell NPs featuring distinct time-dependent afterglow colour evolution. 3. A core/multi-shell NP structure can be designed to simultaneously generate afterglow, upconversion and downshifting to realize multimode time-dependent multicolour evolutions. These findings can promote the development of superior XEA and plentiful spectral manipulation, opening up a broad range of applications ranging from multiplexed biosensing, to high-capacity information encryption, to multidimensional displays and to multifunctional optoelectronic devices.

X-ray activated afterglow nanomaterials are desirable components for advanced optoelectronic applications. Here, the authors present pathways to modulate the stimulus-responsive color emissions in lanthanide-doped fluoride core-shell nanoparticles.

Enzyme-controllable just-in-time production system of copper hexacyanoferrate nanoparticles with oxidase-mimicking activity for highly sensitive colorimetric immunoassay

Nanozymes are a series of elaborately designed nanomaterials that can mimic the catalytic sites of natural enzymes for reactions. Bypassing the tedious design and preparation of nanomaterial, in this work, we report on a novel just-in-time production system of copper hexacyanoferrate nanoparticles (CHNPs), which act as an oxidase-mimicking nanozyme. This system can rapidly produce CHNPs nanozyme on demand by simply mixing Cu(II) with potassium hexacyanoferrate(III) (K₃[Fe(CN)₆]). It is found that once K₃[Fe(CN)₆] is reduced to K₄[Fe(CN)₆], the formation of CHNPs is inhibited. Therefore, the just-in-time production system of CHNPs was coupled with alkaline phosphatase (ALP) to construct an enzyme-controllable just-in-time production (ECJP) system, in which ALP could inhibit the production of by catalyzing the hydrolysis of ascorbic acid 2-phosphate (AAP) to generating ascorbic acid (AA). The ECJP system is then used to probe the activity of ALP by employing 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) as the chromogenic substrate, and a detection limit of 0.003 U L^-1 was achieved. Moreover, by adapting ALP as the enzyme label, an ECJP system-based colorimetric immunoassay protocol was established for sensitive detection of aflatoxin B₁ (AFB₁), and a detection limit as low as 0.73 pg mL^-1 was achieved. The developed immunoassay method is successfully applied to the detection of AFB₁ in peanut samples. The operation of ECJP system is quite simple and the coupling of ALP with CHNPs nanozyme can arouse dual enzyme-like cascade signal amplification. So, we believe this work can offer a new perspective for the development of nanozymes-based biodetection methods and colorimetric immunoassay strategies.

Gold Nanowires Array-Based Closed Bipolar Nanoelectrode System for Electrochemiluminescence Detection of α-Fetoprotein on Cell Surface

Inspired by the promising applications of a closed bipolar electrodes (c-BPEs) system in electrochemiluminescence (ECL) detection of cell adhesion and disease-related biomarkers, here, a gold nanowires array-based c-BPEs system was constructed for cell surface protein detection. Regular and uniform gold nanowires array were prepared by intermittent potentiostatic deposition. Then, two poly(dimethylsiloxane) (PDMS) chips with a hole diameter of 2 mm as a reservoir were placed at both sides of Au nanowires array to construct c-BPEs system. Thionine-functionalized silicon dioxide nanoparticles conjugated to antibody (Ab2-Th@SiO₂) were used as the electrochemical probe, while [Ru(bpy)₃]²⁺-wrapped SiO₂ nanoparticles (Ru(II)@SiO₂) were employed as the ECL signal readout. Taking α-fetoprotein (AFP) as model, the gold nanowires array-based c-BPEs system allowed sensitive detection of AFP at a linear range from 0.002 to 50.0 ng/mL and at least 6 living cells ascribing to the synergetic amplification effect at both sensing and reporting chambers. Besides, the amount of AFP expressed by HepG2 cells was calculated to be 6.71 pg/cell. The presented strategy with high sensitivity provided a promising and universal platform for the detection of other cancer cells and disease-related biomarkers (such as proteins, glycan, miRNA).

Persistent Production of Reactive Oxygen Species with Zn2GeO4:Cu Nanorod-Loaded Microneedles for Methicillin-Resistant Staphylococcus Aureus Infectious Wound Healing

Skin wound infection caused by methicillin-resistant Staphylococcus aureus (MRSA) is an urgent concern. Photodynamic therapy has emerged as a promising means of combating bacterial infection. However, continuous or repeated in situ light excitation is required for photosensitizers to produce reactive oxygen species (ROS), and most photosensitizers need sufficient oxygen to produce singlet oxygen (¹O₂), which greatly limits their clinical application. In this work, we report the preparation of Zn₂GeO₄:Cu²⁺ (ZGC) persistent luminescence nanorods with excellent ability for persistent ROS production after stopping excitation for MRSA infectious wound healing. The prepared ZGC nanorods were loaded into dissolvable microneedles (MNs) (ZGC@MNs) to penetrate biofilms and treat MRSA-infected wounds in a minimally invasive manner. ZGC showed a long-persistent photocatalytic effect to constantly produce multiple ROS (¹O₂, hydroxyl radical, and superoxide radical) accompanied by persistent luminescence after a pre-illumination. The MN tips of ZGC@MNs were rapidly dissolved to release ZGC for the continuous production of multiple ROS for at least 48 h with no need for in situ excitation and no special requirement on the amount of oxygen for eliminating MRSA biofilms. The developed ZGC@MN patches exhibited excellent antibacterial activity and biocompatibility for effectively reducing inflammation and promoting wound healing in vivo.

Designing Next Generation of Persistent Luminescence: Recent Advances in Uniform Persistent Luminescence Nanoparticles

Persistent luminescence is a unique optical process where long-lasting afterglow persists after the cessation of excitation. Nanoscale persistent luminescent materials are getting increased research interest from various fields due to their unique optical property. In recent years, inspiring achievements have been made to produce uniform persistent luminescence nanoparticles (PLNPs) in a controllable manner, unleashing their fascinating potential, surpassing other types of luminescent materials in a wide variety of application such as high-contrast bioimaging and high-resolution X-ray detection. In this review, the evolution of uniform PLNPs, from their bulk phosphor counterparts, to the "top-down" preparation of nanoscale persistent luminescent materials, to the recent "bottom-up" synthesis of uniform PLNPs is first summarized. The respective milestones of uniform PLNPs prepared by templated synthesis, aqueous synthesis, and colloidal synthesis are highlighted. The key optical properties that can be enhanced in uniform PLNPs, including increasing the persistent luminescence intensity, tuning the excitation irradiance, as well as the emission wavelengths are then analyzed. Detailed strategies to enhance each optical property are also discussed in various sections. Finally, future challenges are highlighted with respect to the perspectives on the development of next-generation PLNPs with novel applications.

Facile and Controllable Synthesis of the Renal-Clearable "Luminous Pearls" for in Vivo Afterglow/Magnetic Resonance Imaging

To date, the strategic exploration of a synthetic approach to afford persistent luminescent nanoparticles (PLNPs) integrated with precisely controlled size/monodispersity and renal-clearable capability remains extremely challenging. Herein, we report a facile synthetic process with an elucidated mechanism to fine-tune the size for acquiring renal-clearable PLNPs, using mesoporous silica nanoparticles (MSNs) as a template. This strategy relies on the controlled crystallization of the precursor ions in the pore channels of MSNs at a high temperature, leading to the formation of monodispersed PLNPs with an average diameter as small as 2.5 nm after complete removal of MSN templates. The as-prepared ultrasmall PLNPs coated with polyethylene glycol exhibit uniform size, excellent water-dispersibility, good persistent luminescence, and high T₁ relaxivity (17.6 mM^-1·S^-1), ensuring their suitability for afterglow/magnetic resonance dual-modality imaging and subsequent in vivo renal clearance. Thus, our study provides a strategy to inspire the controlled synthesis of diverse PLNPs by using MSN templates, simultaneously addressing the critical issues of precise adjustment of size and body clearance for versatile biomedical applications.

Afterglow Implant for Arterial Embolization and Intraoperative Imaging

Transcatheter arterial embolization (TAE) is wildly used in clinical treatments. However, the online monitoring of the thrombosis formation is limited due to the challenges of the direct visualization of embolic agents and the real-time monitoring of dynamic blood flow. Thus, we developed a photochemical afterglow implant with strong afterglow intensity and a long lifetime for embolization and imaging. The liquid pre-implant injected into the abdominal aorta of mice was rapidly transformed into a hydrogel in situ to embolize the blood vessel. The vascular embolism position can be observed by the enhanced afterglow of the fixed implant, and the long lifetime of afterglow can also be used to monitor the effect of embolization. This provides an excellent candidate in bio-imaging to avoid the autofluorescence interference from continuous light excitation. The study suggests the potential usefulness of the implant as an embolic agent in TAE and artery imaging during a surgical procedure.

Molecular Probes for Autofluorescence-Free Optical Imaging

Optical imaging is an indispensable tool in clinical diagnostics and fundamental biomedical research. Autofluorescence-free optical imaging, which eliminates real-time optical excitation to minimize background noise, enables clear visualization of biological architecture and physiopathological events deep within living subjects. Molecular probes especially developed for autofluorescence-free optical imaging have been proven to remarkably improve the imaging sensitivity, penetration depth, target specificity, and multiplexing capability. In this Review, we focus on the advancements of autofluorescence-free molecular probes through the lens of particular molecular or photophysical mechanisms that produce long-lasting luminescence after the cessation of light excitation. The versatile design strategies of these molecular probes are discussed along with a broad range of biological applications. Finally, challenges and perspectives are discussed to further advance the next-generation autofluorescence-free molecular probes for in vivo imaging and in vitro biosensors.

AIEgen-Based Lifetime-Probes for Precise Furin Quantification and Identification of Cell Subtypes

Biochemical sensing probes based on aggregation-induced-emission luminogens (AIEgens) are widely used in biological imaging and therapy, chemical sensing, and material sciences. However, it is still a great challenge to quantify the targets through fluorescence intensity of AIEgen probes due to their undesirable aggregations. Here, a PyTPA-ZGO probe with three lifetime signals for precise quantification of furin is constructed: the lifetime signal 1 and signal 2 comes from AIEgen PyTPA-P (τ_Pn ) and inorganic nanoparticles Zn₂ GeO₄ :Mn²⁺ -NH₂ (τ_Zn ), respectively, while the lifetime signal 3 is marked as the composite dual-lifetime signal (CDLS_n , C D L S n = τ Z n τ P n ). In contrast, the fluorescence intensity signal of PyTPA-P shows defectively quantitative performance. Furthermore, it is found that the CDLS_n exhibits higher significant differences than the two other lifetime signals (τ_Pn and τ_Zn ) thanks to its wide range between the maximum and minimum signal values and small standard deviation. Therefore, CDLS_n is further used to accurately identify cell subtypes based on the specific concentration of furin in each subtype. The lifetime criterion can realize precise quantification, and it should be a promising direction of AIEgen-based quantitative analysis in the future.

Photoluminescent Nanoparticles for Chemical and Biological Analysis and Imaging

Research related to the development and application of luminescent nanoparticles (LNPs) for chemical and biological analysis and imaging is flourishing. Novel materials and new applications continue to be reported after two decades of research. This review provides a comprehensive and heuristic overview of this field. It is targeted to both newcomers and experts who are interested in a critical assessment of LNP materials, their properties, strengths and weaknesses, and prospective applications. Numerous LNP materials are cataloged by fundamental descriptions of their chemical identities and physical morphology, quantitative photoluminescence (PL) properties, PL mechanisms, and surface chemistry. These materials include various semiconductor quantum dots, carbon nanotubes, graphene derivatives, carbon dots, nanodiamonds, luminescent metal nanoclusters, lanthanide-doped upconversion nanoparticles and downshifting nanoparticles, triplet-triplet annihilation nanoparticles, persistent-luminescence nanoparticles, conjugated polymer nanoparticles and semiconducting polymer dots, multi-nanoparticle assemblies, and doped and labeled nanoparticles, including but not limited to those based on polymers and silica. As an exercise in the critical assessment of LNP properties, these materials are ranked by several application-related functional criteria. Additional sections highlight recent examples of advances in chemical and biological analysis, point-of-care diagnostics, and cellular, tissue, and in vivo imaging and theranostics. These examples are drawn from the recent literature and organized by both LNP material and the particular properties that are leveraged to an advantage. Finally, a perspective on what comes next for the field is offered.

Functional Micro-/Nanomaterials for Multiplexed Biodetection

When analyzing biological phenomena and processes, multiplexed biodetection has many advantages over single-factor biodetection and is highly relevant to both human health issues and advancements in the life sciences. However, many key problems with current multiplexed biodetection strategies remain unresolved. Herein, the main issues are analyzed and summarized: 1) generating sufficient signal to label targets, 2) improving the signal-to-noise ratio to ensure total detection sensitivity, and 3) simplifying the detection process to reduce the time and labor costs of multiple target detection. Then, available solutions made possible by designing and controlling the properties of micro- and nanomaterials are introduced. The aim is to emphasize the role that micro-/nanomaterials can play in the improvement of multiplexed biodetection strategies. Through analyzing existing problems, introducing state-of-the-art developments regarding relevant materials, and discussing future directions of the field, it is hopeful to help promote necessary developments in multiplexed biodetection and associated scientific research.

Persistent luminescence nanoparticles for cancer theranostics application

Persistent luminescence nanoparticles (PLNPs) are unique optical materials that emit afterglow luminescence after ceasing excitation. They exhibit unexpected advantages for in vivo optical imaging of tumors, such as autofluorescence-free, high sensitivity, high penetration depth, and multiple excitation sources (UV light, LED, NIR laser, X-ray, and radiopharmaceuticals). Besides, by incorporating other functional molecules, such as photosensitizers, photothermal agents, or therapeutic drugs, PLNPs are also widely used in persistent luminescence (PersL) imaging-guided tumor therapy. In this review, we first summarize the recent developments in the synthesis and surface functionalization of PLNPs, as well as their toxicity studies. We then discuss the in vivo PersL imaging and multimodal imaging from different excitation sources. Furthermore, we highlight PLNPs-based cancer theranostics applications, such as fluorescence-guided surgery, photothermal therapy, photodynamic therapy, drug/gene delivery and combined therapy. Finally, future prospects and challenges of PLNPs in the research of translational medicine are also discussed.

A dual-colored persistent luminescence nanosensor for simultaneous and autofluorescence-free determination of aflatoxin B1 and zearalenone

Mycotoxins contamination in agricultural products poses a serious threat to human and animal health, so rapid and sensitive nanosensors for simultaneous determination of multiple mycotoxins in food samples are highly desirable for food safety monitoring. Herein, we report the fabrication of functional dual-colored persistent luminescence nanoparticles (PLNPs) in conjunction with Fe₃O₄ magnetic nanoparticles as a nanosensor for the simultaneous biosensing of aflatoxin B₁ (AFB₁) and zearalenone (ZEN) in food samples. Two types of PLNPs with a single excitation wavelength, Zn₂GeO₄:Mn²⁺ and Zn_1.25Ga_1.5Ge_0.25O₄:Cr³⁺,Yb³⁺,Er³⁺, are employed as the signal units, and aptamers with high affinity and specificity to the corresponding mycotoxins are used as the recognition units. The nanosensor was fabricated by hybridizing the aptamer modified PLNPs with the complementary DNA modified Fe₃O₄. The developed nanosensor offers the integrated merits of autofluorescence-free detection of persistent luminescence, the high specificity of aptamer and the high speed of magnetic separation, allowing highly sensitive and selective detection of AFB₁ and ZEN in food samples with the limits of detection of 0.29 pg mL^-1 for AFB₁ and 0.22 pg mL^-1 for ZEN and the recoveries of 93.6%-103.2% for AFB₁ and 94.7%-105.1% for ZEN. This work also provides a novel universal PLNPs-based optical platform for the simultaneous detection of multiple contaminants in complex samples.

A dual-rotator fluorescent probe for analyzing the viscosity of mitochondria and blood

A novel mitochondria-targeting molecular rotator FD was designed to visualize changes in viscosity under hypoxic conditions in vitro and in vivo. Importantly, FD can be used to detect changes in the blood viscosity of liver cancer and liver cirrhosis patients, and also rehabilitation of liver disease.

Persistent luminescence-polypyrrole nanocomposite for dual-modal imaging and photothermal therapy of mammary cancer

Multifunctional nanocomposites that possess imaging and high-performance therapeutic features are experiencing a surge in interest in the precision clinical anticancer treatment. In this work, we reported the fabrication and bio-application of a novel persistent luminescence-polypyrrole nanocomposite (LPLNP@SPP) for photoacoustic/persistent luminescence (PA/PL) dual-modal imaging guided photothermal therapy (PTT). The construction of LPLNP@SPP avoids the PL quenching of LPLNP-OH by the polypyrrole-coating, and thus enables the combination of PL and PTT. The LPLNP@SPP shows excellent biocompatibility, long lasting near-infrared (NIR) PL emitting without in situ excitation and high-contrast PA signals. Meanwhile, this nanocomposite exhibits strong NIR absorbance and exceptional photothermal conversion capability, which provides notable potential for imaging-guided antitumor therapy. Thus, our work highlights the dual-functional core-shell LPLNP@SPP as a feasible theranostic nanoplatform for cancer diagnosis and therapy.

Persistent luminescence nanorod based luminescence resonance energy transfer aptasensor for autofluorescence-free detection of mycotoxin

Serious ochratoxin A (OTA) contamination necessitates the development of rapid, sensitive and selective analytical methods for its determination in food safety. Herein, we report a persistent luminescence resonance energy transfer (LRET) based aptasensor for the autofluorescence-free detection of OTA. OTA aptamer functionalized persistent luminescence nanorod (PLNR) Zn₂GeO₄:Mn²⁺ and the aptamer complementary DNA modified gold nanoparticle (AuNP) were used as the donor and the acceptor, respectively. The developed LRET aptasensor integrated the advantages of the long-lasting persistent luminescence of PLNR, the high selectivity of aptamer and the low probe background of LRET sensors, allowing autofluorescence-free detection of OTA in biological samples with high sensitivity and selectivity. The developed LRET aptasensor gave an excellent linearity in the range of 0.01-10 ng mL^-1, the detection limit of 3 pg mL^-1 and the precision of 2.7% (RSD, n = 11) at 1 ng mL^-1 level. The applicability of the developed aptasensor was demonstrated by analyzing beer samples for OTA with the recoveries of 92.3%-104%.

Recent Advances of Persistent Luminescence Nanoparticles in Bioapplications

Persistent luminescence phosphors are a novel group of promising luminescent materials with afterglow properties after the stoppage of excitation. In the past decade, persistent luminescence nanoparticles (PLNPs) with intriguing optical properties have attracted a wide range of attention in various areas. Especially in recent years, the development and applications in biomedical fields have been widely explored. Owing to the efficient elimination of the autofluorescence interferences from biotissues and the ultra-long near-infrared afterglow emission, many researches have focused on the manipulation of PLNPs in biosensing, cell tracking, bioimaging and cancer therapy. These achievements stimulated the growing interest in designing new types of PLNPs with desired superior characteristics and multiple functions. In this review, we summarize the works on synthesis methods, bioapplications, biomembrane modification and biosafety of PLNPs and highlight the recent advances in biosensing, imaging and imaging-guided therapy. We further discuss the new types of PLNPs as a newly emerged class of functional biomaterials for multiple applications. Finally, the remaining problems and challenges are discussed with suggestions and prospects for potential future directions in the biomedical applications.

Degradation of ZnGa2O4:Cr3+ luminescent nanoparticles in lysosomal-like medium

The ultimate goal of in vivo imaging is to provide safe tools to probe the inside of a body in order to obtain pathological information, monitor activities, and examine disease progression or regression. In this context zinc gallate doped with chromium III (ZGO) nanoparticles with persistent luminescence properties have been previously developed, and their biodistribution as well as in vitro toxicity were evaluated. However, to date, nothing is known about their potential transformations in biological media, which may hinder their biomedical applications. In order to know if these nanoparticles could degrade, the present work consists of studying their fate over time depending on both their coating and the aqueous media in which they are dispersed. ZGO nanoparticles have been dispersed in three different aqueous solutions for up to 90 days and characterized by numerous techniques. Among the evaluated dispersion media, Artificial Lysosomal Fluid (ALF) mimicking the intracellular lysosome environment elicited significant degradation of ZGO nanoparticles. The chelating agents present in ALF have proved to play a major role in the degradation of the ZGO, by stabilizing the nanoparticles and increasing the contact. An important time decrease of the luminescence properties has also been observed, which correlated with the release of ions from ZGO nanoparticles as well as their decreasing size. This information is valuable since it indicates, for the first time, the long-term degradation of persistent luminescent nanoprobes in an in vivo like model medium. Therefore, possible elimination of the imaging probes after in vivo preclinical applications could be foreseen.

Determination of Hydrogen Sulfide in Wines Based on Chemical-Derivatization-Triggered Aggregation-Induced Emission by High-Performance Liquid Chromatography with Fluorescence Detection

A chemical-derivatization-triggered aggregation-induced emission (AIE) method for the highly selective determination of hydrogen sulfide (H₂S) in wine matrices by high-performance liquid chromatography with fluorescence detection (HPLC-FLD) was developed. The detection strategy was developed based on the chemical derivatization of H₂S using a low-cost AIE-active fluorescence derivatization reagent, N-(3-iodine-2-oxopropyl)pyrene methamine (NIPM), to trigger specific AIE at 475 nm, which was red-shifted sharply to the maximum emission wavelength as compared with NIPM monomers of 375 nm, effectively quenching the interference from other thiol-containing compounds. With the aid of specific AIE and the effective separation of HPLC, the proposed method showed high selectivity and sensitivity toward H₂S. The limits of detection (LODs) at the sub-nM level of 0.25 nmol/L in the wine-beer sample and 0.30 nmol/L in red wine sample were obtained. To certify its applicability, this proposed strategy was successfully applied for the determination of H₂S in wine matrices.

Recent advancements in polyethyleneimine-based materials and their biomedical, biotechnology, and biomaterial applications

Precise-synthesis strategies and integration approaches of bioinspired PEI-based systems, and their biomedical, biotechnology and biomaterial applications.

Application of a Y-type-DNA-functionalized nanogold probe featuring specific telomerase recognition and doxorubicin release in cancer cells

A Y-type-DNA-functionalized nanogold probe was synthesized to identify telomerase and trigger drug release in cancer cells.

A simple chemiluminescent aptasensor for the detection of α-fetoprotein based on iron-based metal organic frameworks

MIL-100 (Fe) was used to construct a chemiluminescent aptasensing platform based on the electrostatic adsorption of MIL-100 (Fe) and aptamers.

Fast Affinity Induced Reaction Sensor Based on a Fluorogenic Click Reaction for Quick Detection of Protein Biomarkers

Despite numerous biosensors currently available, the routine biomarker detection still largely relies on traditional ELISA and Western blot. Those standard techniques are labor intensive and time-consuming. Herein we introduce a fast affinity induced reaction sensor (FAIRS) that overcomes a few limitations of traditional and emerging biosensors. FAIRS is a general, one-step method and is naturally specific in detection. FAIRS probes are composed of a sandwich ELISA antibody pair that is conjugated with two fluorogenic click chemicals. This technology leverages significant differences of antibody affinity and chemical reaction rate, which are characterized to guide probe design. The stability, sensitivity, detection range, and response time are fully characterized. Application to IL-6 detection using blood serum and cell culture medium demonstrates that FAIRS can quantify IL-6 with high sensitivity in one step. With the unique features, FAIRS probes may find broad applications in medical sciences and clinical diagnostics, where quick detection of biomarkers is demanded.

Dual-modal aptasensor for the detection of isocarbophos in vegetables

An aptamer-based colorimetric-phosphorescent assay was developed for the detection of isocarbophos. The colorimetric assay relied on the aggregation of gold nanoparticles (AuNPs) caused by the competitive binding of aptamer between isocarbophos and AuNPs in the presence of a high salt concentration. The further addition of persistent luminescence nanorods (PLNRs) into the system showed the phosphorescence sensitively proportional to the concentration of isocarbophos, due to the inner filter effect between PLNRs and AuNPs. The assay showed good linearity within 50-500 μg/L and 5-160 μg/L, and limit of detection of 7.1 μg/L and 0.54 μg/L in colorimetry and phosphorescence mode, respectively. The feasibility of this approach for food analysis was demonstrated with the sensitive and selective determination of isocarbophos residues in vegetables.

Nanohoneycomb Surface-Enhanced Raman Spectroscopy-Active Chip for the Determination of Biomarkers of Hepatocellular Carcinoma

Overexpression of the Lens culinaris agglutinin-reactive fraction of alpha-fetoprotein (AFP-L3) is an essential biomarker for early diagnosis of hepatocellular carcinoma (HCC). In this study, we designed a new surface-enhanced Raman spectroscopy active chip for the detection of AFP with high sensitivity and excellent repeatability. This chip was composed of a honeycomb gold nanostructure array with strong electromagnetic field coupling due to the special cavity geometric characteristics of the honeycomb structure. The honeycomb structure exhibited extraordinary performance for the specific detection of AFP in the range of 0.003-3 ng/mL and also determined the proportion of AFP-L3 with a high degree of accuracy, which has shown great potential for application in the clinical diagnosis of HCC.