Strategies to engineer various nanocarrier-based hybrid catalysts for enhanced chemodynamic cancer therapy.

Chemodynamic therapy (CDT) is a newly developed cancer-therapeutic modality that kills cancer cells by the highly toxic hydroxyl radical (˙OH) generated from the in situ triggered Fenton/Fenton-like reactions in an acidic and H2O2-overproduced tumor microenvironment (TME). By taking the advantage of the TME-activated catalytic reaction, CDT enables a highly specific and minimally-invasive cancer treatment without external energy input, whose efficiency mainly depends on the reactant concentrations of both the catalytic ions and H2O2, and the reaction conditions (including pH, temperature, and amount of glutathione). Unfortunately, it suffers from unsatisfactory therapy efficiency for clinical application because of the limited activators (i.e., mild acid pH and insufficient H2O2 content) and overexpressed reducing substance in TME. Currently, various synergistic strategies have been elaborately developed to increase the CDT efficiency by regulating the TME, enhancing the catalytic efficiency of catalysts, or combining with other therapeutic modalities. To realize these strategies, the construction of diverse nanocarriers to deliver Fenton catalysts and cooperatively therapeutic agents to tumors is the key prerequisite, which is now being studied but has not been thoroughly summarized. In particular, nanocarriers that can not only serve as carriers but are also active themselves for therapy are recently attracting increasing attention because of their less risk of toxicity and metabolic burden compared to nanocarriers without therapeutic capabilities. These therapy-active nanocarriers well meet the requirements of an ideal therapy system with maximum multifunctionality but minimal components. From this new perspective, in this review, we comprehensively summarize the very recent research progress on nanocarrier-based systems for enhanced CDT and the strategies of how to integrate various Fenton agents into the nanocarriers, with particular focus on the studies of therapy-active nanocarriers for the construction of CDT catalysts, aiming to guide the design of nanosystems with less components and more functionalities for enhanced CDT. Finally, the challenges and prospects of such a burgeoning cancer-theranostic modality are outlooked to provide inspirations for the further development and clinical translation of CDT.

Tissue Engineering of JAK Inhibitor-Loaded Hierarchically Biomimetic Nanostructural Scaffold Targeting Cellular Senescence for Aged Bone Defect Repair and Bone Remolding.

Cell senescence or apoptosis contributes to self-failure and functional loss in specialized cells, leading to incapacity of the body to repair specific damages. Senescent bone marrow mesenchymal stem cells (BMSCs) lose their proliferative abilities and secrete senescence-associated secretory phenotype (SASP), hindering their participation in bone defect repair. Hence, the effective suppression of cell senescence is crucial to restore the self-repair capacity of body to treat bone defects. Since the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway is associated with SASP secretion, herein, a new strategy is proposed to inhibit this pathway to suppress SASP secretion and enhance osteoblast activity based on a novel hierarchically biomimetic nanostructural electrospun scaffold with JAK inhibitors (JAKi, Ruxolitinib) loaded. As validated by in vitro and in vivo experiments, the JAKi loaded scaffold reduces SASP expression effectively and alleviates senescent cell burden, creating a pro-regeneration microenvironment that enhances osteoblast function and mineralization activity as well as rejuvenating the bone repair capacity. These findings offer insights into the regulatory role of cellular senescence in bone aging and provide a new and effective strategy to treat age-related bone defects by delivery of JAKi to locally aging bone defect sites.

Engineering of a NIR-activable hydrogel-coated mesoporous bioactive glass scaffold with dual-mode parathyroid hormone derivative release property for angiogenesis and bone regeneration.

Osteogenesis, osteoclastogenesis, and angiogenesis play crucial roles in bone regeneration. Parathyroid hormone (PTH), an FDA-approved drug with pro-osteogenic, pro-osteoclastogenic and proangiogenic capabilities, has been employed for clinical osteoporosis treatment through systemic intermittent administration. However, the successful application of PTH for local bone defect repair generally requires the incorporation and delivery by appropriate carriers. Though several scaffolds have been developed to deliver PTH, they suffer from the weaknesses such as uncontrollable PTH release, insufficient porous structure and low mechanical strength. Herein, a novel kind of NIR-activable scaffold (CBP/MBGS/PTHrP-2) with dual-mode PTHrP-2 (a PTH derivative) release capability is developed to synergistically promote osteogenesis and angiogenesis for high-efficacy bone regeneration, which is fabricated by integrating the PTHrP-2-loaded hierarchically mesoporous bioactive glass (MBG) into the N-hydroxymethylacrylamide-modified, photothermal agent-doped, poly(N-isopropylacrylamide)-based thermosensitive hydrogels through assembly process. Upon on/off NIR irradiation, the thermoresponsive hydrogel gating undergoes a reversible phase transition to allow the precise control of on-demand pulsatile and long-term slow release of PTHrP-2 from MBG mesopores. Such NIR-activated dual-mode delivery of PTHrP-2 by this scaffold enables a well-maintained PTHrP-2 concentration at the bone defect sites to continually stimulate vascularization and promote osteoblasts to facilitate and accelerate bone remodeling. In vivo experiments confirm the significant improvement of bone reparative effect on critical-size femoral defects of rats. This work paves an avenue for the development of novel dual-mode delivery systems for effective bone regeneration.

Dual "Unlocking" Strategy to Overcome Inefficient Nanomedicine Delivery and Tumor Hypoxia for Enhanced Photodynamic-Immunotherapy.

Lacking blood vessels is one of the main characteristics of most solid tumors due to their rapid and unrestricted growth, which thus causes the inefficient delivery efficiency of nanomedicine and tumor hypoxia. Herein, a dual "unlocking" strategy to overcome these obstacles is proposed by combining engineered hybrid nanoparticles (named ZnPc@FOM-Pt) with dexamethasone (DXM). It is verified that pretreatment of tumors with DXM can increase intratumorally micro-vessel density (delivery "unlocking") to enhance the tumor delivery efficiency of ZnPc@FOM-Pt and decrease HIF-1α expression. Correspondingly, more Pt can catalyze tumor-overexpressed H2 O2 to produce oxygen to further cause hypoxia "unlocking," ultimately achieving boosted ZnPc-based photodynamic therapy in vivo (tumor inhibition rate: 99.1%). Moreover, the immunosuppressive tumor microenvironment is efficiently reversed and the therapeutic effect of anti-PD-L1-based immunotherapy is promoted by this newly designed nanomedicine. This dual "unlocking" strategy provides an innovative paradigm on simultaneously enhancing nanomedicine delivery efficacy and hypoxia relief for tumor therapy.

GSH-Responsive Organosilica Hybrid Nanosystem as a Cascade Promoter for Enhanced Starvation and Chemodynamic Therapy.

Glucose oxidase (GOD)-mediated starvation therapy (ST) that causes intratumoral glucose depletion is a promising strategy for tumor treatment. However, the ultimate efficacy is inevitably limited by tumor hypoxia, as oxygen is a key component in the consumption of glucose by GOD. In this study, a kind of glutathione (GSH)-responsive organosilica hybrid micelles loaded with Mn3 O4 and GOD (denoted as Mn3 O4 @PDOMs-GOD) is ingeniously designed for enhanced ST and chemodynamic therapy (CDT). Specifically, the internalized Mn3 O4 @PDOMs-GOD in tumor cells consumes intracellular glucose and oxygen (O2 ) under the catalysis of GOD to generate hydrogen peroxide (H2 O2 ), which is subsequently decomposed by Mn3 O4 to liberate O2 . This cyclically regenerated O2 will form a virtuous cycle of O2 and H2 O2 compensation to enhance the ST outcome. Meanwhile, Mn3 O4 can oxidize and deplete the overexpressed GSH in the tumor microenvironment (TME) to release Mn2+ , which then catalyzes H2 O2 into highly toxic hydroxyl radicals (·OH) to accomplish chemodynamic therapy (CDT). Both in vitro and in vivo experiment results demonstrate the significant antitumor efficacy of Mn3 O4 @PDOMs-GOD by the cooperatively enhanced ST and CDT, suggesting the feasibility to develop promising therapeutic platforms with higher treatment efficacies.

Engineered Organosilica Hybrid Micelles for Photothermal-enhanced Starvation Cancer Therapy.

Glucose oxidase (GOD)-based starvation therapy (ST), which inhibits the growth and proliferation of cancer cells by consuming glucose, has attracted intensive attention as an emerging non-invasive method for fighting cancers. However, the enzyme activity of GOD is greatly limited in vivo because of its optimal catalytic activity in the temperature range of 43-60 °C. Herein, a photothermal-enhanced starvation strategy is developed based on our engineered organosilica hybrid micelles (TiO2-x @POMs-GOD), in which the fluoride-doped TiO2-x with photothermal properties is encapsulated in the cores of organosilica cross-linked micelles and GOD is immobilized on the carboxyl groups of PAA segments. With its internalization by cancer cells, the conjugated GOD can effectively deplete glucose to achieve the ST effect, which can be remarkably enhanced by the loaded fluoride-doped TiO2-x with NIR laser irradiation, thus cooperatively contributing to the efficient treatment of TiO2-x @POMs-GOD on various cancer cells. This suggests great potential for TiO2-x @POMs-GOD in photothermal-enhanced ST in vivo.

One-pot fabrication of a polydopamine-based nanoplatform for GSH triggered trimodal ROS-amplification for cancer therapy.

Reactive oxygen species (ROS) based nanoplatforms have been considered as attractive and feasible candidates for cancer therapy. However, the activated endogenous antioxidant defense of cancer cells in response to the ROS attack greatly hinders their therapeutic efficacy. Although cancer-specific ROS amplification strategies have been widely explored, most of them suffer from tedious synthesis procedures and complex components, which will bring about undesired side effects and unsatisfactory results. Herein, we design a cancer-specific oxidative stress amplification nanomedicine (CA-Cu-PDA), which is simply fabricated through integrating the glutathione (GSH) responsive/depleting nanocarrier of copper-polydopamine (Cu-PDA) nanoparticles with a ROS-generating drug cinnamaldehyde (CA) via a facile one-pot polymerization route. It is verified that GSH could trigger the breakage of CA-Cu-PDA networks and the subsequent release of both copper ions and CA in cancer cells. The released copper ions efficiently oxidize GSH, thereby weakening the antioxidant system of cancer cells and increasing the ROS levels. On the other hand, extra ROS are generated by the reduced copper ions through a Fenton reaction, so that a synergistic ROS therapy with CA is achieved. Consequently, oxidative stress is specifically increased within cancer cells, leading to efficient cancer cell apoptosis, significant tumor suppression and minimized side effects. Such an ingenious structure realizes the interlocking cooperation and full utilization of each component's function, presenting promising perspectives for nanomedicine design.

A "Valve-Closing" Starvation Strategy for Amplification of Tumor-Specific Chemotherapy.

Starvation-dependent differential stress sensitization effect between normal and tumor cells provides a potentially promising strategy to amplify chemotherapy effects and reduce side effects. However, the conventional starvation approaches such as glucose oxidase (Gox)-induced glucose depletion and nanomedicine-enabled vascular embolism usually suffer from aggravated tumor hypoxia, systemic toxicity, and unpredictable metabolic syndrome. Herein, a novel "valve-closing" starvation strategy is developed to amplify the chemotherapy effects via closing the "valve" of glucose transported into tumor cells, which is accomplished by a glucose transporters 1 (GLUT1, valve of glucose uptake) inhibitor (Genistein, Gen) and chemotherapeutic agent (Curcumin, Cur) coloaded hybrid organosilica-micelles nanomedicine (designated as (Gen + Cur)@FOS) with controllable stability. In vitro and in vivo results demonstrate that (Gen + Cur)@FOS can effectively reduce glucose/adenosine triphosphate levels in tumor cells by inhibiting GLUT1 expression (i.e., "valve-closing") to induce the starvation of tumor cells, thus weakening the resistance of tumor cells to apoptosis caused by chemotherapy, and consequently contributing to the remarkably improved antitumor efficiency and minimized side effects based on the stress sensitization effect mediated by GLUT1 inhibition-induced starvation. This "valve-closing" starvation strategy provides a promising paradigm for the development of novel nanotherapeutics with amplified chemotherapy effect.

Biomimic Binding Affinity Gradients Triggered GSH-Response of Core-Shell Nanoparticles for Cascade Chemo/Chemodynamic Therapy.

In eukaryotes and prokaryotes, some copper transportations driven by gradient copper-binding affinities exhibit typical glutathione (GSH)-responsive features. Inspired by these delicate endogenous processes, a biomimic copper-ion mediated GSH-responsive nanomedicine is designed based on the gradient copper-binding strengths between polydopamine (PDA) species and GSH. The nanomedicine is constructed as core-shell nanoparticles with copper-polydopamine (Cu-PDA) coordinated shell and micellar core encapsulating chemotherapeutic drug of ß-lapachone (ß-lapa). In tumor cells, the excess intracellular GSH will reduce and extract the Cu(II) from the Cu-PDA network, triggered by the binding affinity gradients between Cu-PDA and Cu-GSH, resulting in the breaking of the shell and the releasing of ß-lapa and Fenton agent copper. The additional Fenton reaction of copper ions induces excess oxidative damage of tumor cells assisted by the abundant H2 O2 amplified by ß-lapa, achieving cascade anticancer effects combining chemodynamic therapy with chemotherapy. This multilevel anticancer system exhibits an efficient tumor inhibitory rate and a negligible systematic toxicity for normal organs in vivo, presenting a new bioinspired GSH-responsive strategie to develop stimuli-responsive structures.

Structure Engineering of a Lanthanide-Based Metal-Organic Framework for the Regulation of Dynamic Ranges and Sensitivities for Pheochromocytoma Diagnosis.

Exploring innovative technologies to precisely quantify biomolecules is crucial but remains a great challenge for disease diagnosis. Unfortunately, the humoral concentrations of most biotargets generally vary within rather limited scopes between normal and pathological states, while most literature-reported biosensors can detect large spans of targets concentrations, but are less sensitive to small concentration changes, which consequently make them mostly unsatisfactory or even unreliable in distinguishing positives from negatives. Herein, a novel strategy of precisely quantifying the small concentration changes of a certain biotarget by editing the dynamic ranges and sensitivities of a lanthanide-based metal-organic framework (Eu-ZnMOF) biosensor is reported. By elaborately tailoring the biosensor's structure and surface areas, the tunable Eu-ZnMOF is developed with remarkably enhanced response slope within the "optimized useful detection window," enabling it to serve as a powerful signal amplifier (87.2-fold increase) for discriminating the small concentration variation of urinary vanillylmandelic acid (an early pathological signature of pheochromocytoma) within only three times between healthy and diseased subjects. This study provides a facile approach to edit the biosensors' performances through structure engineering, and exhibits promising perspectives for future clinical application in the non-invasive and accurate diagnosis of severe diseases.

Multivalued Logic Assay of the Disease Marker of α-Ketoglutaric Acid by a Luminescent MOF-Based Biosensor.

α-Ketoglutaric acid (α-KA) is an important endogenous metabolite in the Krebs cycle and considered a critical marker for various diseases. Several approaches for identifying α-KA have been reported. However, most of them are limited to single-signal transduction modes in one assay and working in the suspension state, which easily cause quantification errors and lead to false-positive detection results. Herein, a multivalue-responsive and semi-solid EuMOF-gel (EuMOG) logic biosensor is first designed and fabricated, which can realize the specific, rapid, and easy-to-differentiate naked-eye detection of the disease-associated marker of α-KA in serum through implementing one-to-two logic operation with three multicolor gates. The implementation of one-to-two logic operation can be rationally achieved by assembling 2,6-naphthalenedicarboxylic acid as both the energy donor and blue-colored output 1, photoactive Eu3+ ions as the red-emissive output 2, and α-KA stimuli as an input and energy blocker between the dual spectrum-resolved outputs into one unit. With the specific input of α-KA among various analytes, the binary code of the logic decoder switches from (0,1) to (1,0) with an obvious color change from red to cyan. Moreover, by integrating the output chromaticity into the logical operations, the concentration levels of α-KA could be easily evaluated with the intelligent EuMOG detector, which has three multicolor gates in parallel encoding low (0,1), normal (1,1), and danger (1,0) statuses. Such multivalued logic biosensor provides a facile strategy to improve the analysis reliability of disease-associated biomarkers.

Biodegradable organosilica magnetic micelles for magnetically targeted MRI and GSH-triggered tumor chemotherapy.

Recently, block copolymer micelles have attracted widespread attention due to their controlled biodegradability and excellent loading capability. Unfortunately, the poor in vivo stability and low delivery efficiency of drug-loaded micelles greatly hampered their biomedical applications. Herein, we develop a new kind of biodegradable magnetite/doxorubicin (Fe3O4/DOX) co-loaded PEGylated organosilica micelles (designated as FDPOMs) with both high circulating stability and smart GSH-triggered biodegradability for magnetically targeted magnetic resonance imaging (MRI) and tumor chemotherapy. The FDPOMs are prepared by the self-assembly of biodegradable polycaprolactone-block-poly(glutamic acid) (PCL-b-PGA), a chemotherapeutic DOX drug and Fe3O4 nanoparticles in an oil/water system, subsequent organosilica cross-linking with 3-mercaptopropyltrimethoxysilane (MPTMS) molecules and surface PEGylation. The resultant FDPOMs exhibit excellent dispersity and stability in biological media, remarkable T2-weighted MR imaging capability, unique GSH-responsive release behavior and selective toxicity to tumor cells. The in vivo experiments show that the FDPOMs not only have improved MR tumor imaging capability, but also exhibit high anti-tumor efficacy due to the strong magnetic targeting ability under an external magnetic field. Consequently, the FDPOMs are promising candidates for magnetically targeted MR imaging and imaging-guided tumor chemotherapy.

Facile synthesis of organosilica-capped mesoporous silica nanocarriers with selective redox-triggered drug release properties for safe tumor chemotherapy.

As drug-delivery carriers for cancer chemotherapy, gatekeeper-capped mesoporous silica nanoparticles (MSNs) have been widely studied due to their high drug-loading capability, controlled drug release property and good biocompatibility. However, the currently reported gatekeeper-capped MSNs suffer from complex synthetic procedures, potential toxicity of gatekeepers, unsatisfactory control on drug stimuli-release, etc. In this work, we develop a simple but efficient approach to fabricate PEGylated organosilica-capped mesoporous silica nanoparticles (POMSNs) by employing a disulfide-doped organosilica coating as the gatekeeper formed by the hydrolysis and condensation of a silane coupling agent 3-(mercaptopropyl)trimethoxysilane (MPTMS) to block the mesopores of MSNs. Owing to the glutathione (GSH)-responsive biodegradation behavior of the disulfide-doped organosilica gatekeeper, the DOX-loaded POMSNs exhibit only 20% cell viability towards SMMC-7721 tumor cells, and almost no toxicity towards L-02 cells at a DOX concentration of 50 µg mL-1 was measured, demonstrating their selective cytotoxicity in vitro. More importantly, it is demonstrated that the DOX-loaded POMSNs exhibit a tumor inhibition rate of 71.3% and negligible systematic toxicity. Consequently, the resultant POMSNs show great potential as drug nanocarriers for redox-responsive drug release and passive-targeting tumor chemotherapy.

Extraction-Induced Fabrication of Yolk-Shell-Structured Nanoparticles with Deformable Micellar Cores and Mesoporous Silica Shells for Multidrug Delivery.

Yolk-shell-structured nanoparticles (YSNs) provide useful carriers for applications in biomedicine and catalysis due to the excellent loading capability and versatile functionality of the flexible core and porous shell. Unfortunately, the reported YSNs always require complex multistep synthesis processes and a harsh hard-template etching strategy. Herein, a facile "selective extraction" strategy is developed to synthesize yolk-shell-structured polymer@void@mSiO2 nanoparticles (designated as YSPNs) comprising deformable and soft polystyrene-b-poly(acrylic acid) (PS-b-PAA) micellar cores and mesoporous silica shells. The YSPNs are formed by a morphological change and volume shrinkage of the PS-b-PAA aggregates from large compound vesicles to large compound micelles during the extraction process. As a multidrug vehicle, both hydrophobic curcumin (Cur, 6.4 wt %) and hydrophilic doxorubicin hydrochloride (Dox, 19.4 wt %) can be coloaded onto YSPNs through a successive impregnation method. Moreover, the resulting Cur/Dox@YSPNs possess intelligent pH-responsive capability, time-sequenced release behavior, and high in vivo antitumor efficiency, demonstrating excellent potential as safe and efficient multidrug nanocarriers for tumor chemotherapy. We envision that such a facile "selective extraction" strategy will enable pathways to construct organic-inorganic hybrid nanoparticles with yolk-shell structures for various applications.

Synthesis of a Pillar[5]arene-Based Polyrotaxane for Enhancing the Drug Loading Capacity of PCL-Based Supramolecular Amphiphile as an Excellent Drug Delivery Platform.

A pillar[5]arene-based nonionic polyrotaxane (PR) with star-poly(ε-caprolactone) ( S-PCL) as the axle, pillar[5]arene (DEP5) as the wheel and adamantane as the end-capped group is designed and synthesized. The resulting PR is subsequently assembled with ß-cyclodextrin end-capped pH-stimulated poly(acrylic acid) (CD-PAA) via a host-guest interaction to form the supramolecular pseudoblock polymer PR-PAA. This supramolecular pseudoblock polymer could self-assemble in aqueous solution to produce PR-PAA-based supramolecular vesicular nanoparticles (PR-SVNPs), which present significantly enhanced drug loading capacity (DLC, 45.6%) of DOX, much higher than those of superamphiphiles (PCL-PAA, 17.1%). Such a high DLC of PR-SVNPs can be most probably attributed to the greatly decreased crystallinity of PCL in PR. Moreover, the loaded drugs could be selectively released in an acidic microenvironment-responsive manner. Compared to free DOX, the DOX-loaded PR-SVNPs (DOX@PR-SVNPs) shows much enhanced cellular uptake and cytotoxicity against the SMMC-7721. More importantly, thanks to the enhanced permeability and retention (EPR) effect, DOX@PR-SVNPs exhibits appealing features such as extremely low toxicity, highly efficient intratumoral accumulation and substantial antitumor efficacy in vivo.

Functionalization of Metal-Organic Frameworks for Photoactive Materials.

Metal-organic frameworks (MOFs) are intriguing platforms with multiple functionalities. Additional functionalization of MOFs generates novel materials for various applications. Here, three main topics are examined regarding the functionalization of MOFs for use as photoactive materials. The first is chemical approaches for postsynthetic modification of the metal clusters and organic linkers in MOFs; that is, sites on pore surfaces and chemical trapping of photoactive moieties within the pores, which create materials with chemical functionalities for water splitting and CO2 reduction by light. The second topic focuses on the functionalization of MOFs for photochemical response and the versatile applications of such materials. State-of-the-art research on functionalizing MOFs through photochemical reactions on the pore surface and within the pores as guests is also summarized. The third topic introduces the functionalization of MOFs for photofunctional materials, including photoluminescent tuning and integration, photoluminescent LED devices and barcodes, and photophysical applications for chemical sensing. Finally, conclusions and perspectives on the fields are given.

A Luminescent 3d-4f-4d MOF Nanoprobe as a Diagnosis Platform for Human Occupational Exposure to Vinyl Chloride Carcinogen.

A luminescent nanoprobe based on a lanthanide-transition heterometallic metal-organic framework (MOF) is first designed for specific detection of urinary thiodiglycolic acid (TDGA) which is the biomarker of carcinogenic vinyl chloride monomer (VCM) and represents the internal dose of human exposure to VCM. The nanoprobe demonstrates high selectivity to TDGA with about 27.5-fold luminescence enhancement. It also displays excellent sensitivity with a detection limit as low as 89 ng·mL-1 and fast response to TDGA within 4 min, while refraining from the interference of other coexisting species in urine. Such good sensing performance enables the nanoprobe to practically monitor TDGA levels in human urine. Moreover, a portable urine dipstick based on the sensor is developed to conveniently evaluate individuals' intoxication degree of VCM. This fast, sensitive, and selective nanoprobe has promising potential to be a useful tool for point-of-care diagnosis of disease associated with VCM exposure.

A Double-Stimuli-Responsive Fluorescent Center for Monitoring of Food Spoilage based on Dye Covalently Modified EuMOFs: From Sensory Hydrogels to Logic Devices.

Unsafe food is a huge threat to human health and the economy, and detecting food spoilage early is an ongoing and imperative need. Herein, a simple and effective strategy combining a fluorescence sensor and one-to-two logic operation is designed for monitoring biogenic amines, indicators of food spoilage. Sensors (methyl red@lanthanide metal-organic frameworks (MR@EuMOFs)) are created by covalently modifying MR into NH2 -rich EuMOFs, which have a high quantum yield (48%). A double-stimuli-responsive fluorescence center is produced via energy transfer from the ligands to Eu3+ and MR. Portable sensory hydrogels are obtained by dispersing and solidifying MR@EuMOFs in water-phase sodium salt of carboxy methyl cellulose (CMC-Na). The hydrogels exhibit a color transition upon "smelling" histamine (HI) vapor. This transition and shift in the MR-based emission peak are closely related to the HI concentration. Using the HI concentration as the input signal and the two fluorescence emissions as output signals, an advanced analytical device based on a one-to-two logic gate is constructed. The four output combinations, NOT (0, 1), YES (1, 0), PASS 1 (1, 1), and PASS 0 (0, 0), allow the direct analysis of HI levels, which can be used for real-time food-freshness evaluation. The novel strategy suggested here may be a new application for a molecular logic system in the sensing field.

A dual-emitting 4d-4f nanocrystalline metal-organic framework as a self-calibrating luminescent sensor for indoor formaldehyde pollution.

A dual-emissive 4d-4f Ag(i)-Eu(iii) functionalized MOF nanocomposite was fabricated and utilized as a self-calibrating luminescent nanoprobe for detecting indoor formaldehyde (FA). The implantation of Ag(+) ions can tune the dual-emissive characters of the material. FA can interact with the Ag(+) ions and induce opposite luminescence behaviors of the two emitters in the singular molecular material, thus realizing its recognition. This nanoprobe for FA exhibits many merits, such as excellent selectivity, high sensitivity with a detection limit of 51 ppb, fast response, room-temperature testing ability, easy preparation and low cost. This is the first example of a MOF-implicated self-calibrated sensor for indoor FA detection.

Simultaneous determination of indoor ammonia pollution and its biological metabolite in the human body with a recyclable nanocrystalline lanthanide-functionalized MOF.

A Eu(3+) post-functionalized metal-organic framework of nanosized Ga(OH)bpydc(Eu(3+)@Ga(OH)bpydc, 1a) with intense luminescence is synthesized and characterized. Luminescence measurements reveal that 1a can detect ammonia gas selectively and sensitively among various indoor air pollutants. 1a can simultaneously determine a biological ammonia metabolite (urinary urea) in the human body, which is a rare example of a luminescent sensor that can monitor pollutants in the environment and also detect their biological markers. Furthermore, 1a exhibits appealing features including high selectivity and sensitivity, fast response, simple and quick regeneration, and excellent recyclability.