Integration of Hybridization Chain Reaction and Protein-Binding Amplification for Long-Term Imaging of Intracellular mRNA: Avoiding Signal Fluctuation.

Amplified nanoprobes based on hybridization chain reaction (HCR) have been widely developed for the detection of intracellular low abundance mRNA. However, the formed chain-like assembly decorated with fluorophore would be degraded rapidly by endogenous enzyme, resulting in failure of the long-term fluorescence imaging. To address this issue, herein, a composite signal-amplifying strategy that integrates HCR into protein-binding signal amplification (HPSA) was communicated for the in situ imaging of mRNA by avoiding signal fluctuation. Different from conventional HCR-based nanoprobes (HCR-nanoprobe), the HCR was used as the signal-triggered mode and the amplifying signal generated from in situ fluorophore-protein binding in cells, which can maintain high stability of the signal for a long time. As a proof-of-principle, a nanobeacon based on HPSA (HPSA-nanobeacon) was constructed to detect TK1 mRNA. Taking advantage of the double signal-amplifying mode, the endogenous TK1 mRNA was sensitively detected and the fluorescence signal was maintained for more than 8 h in HepG2 cells. The attempt in this work provides a new option to the current signal-amplifying strategy for sensing nucleic acid targets with high stability, significantly enhancing the acquisition of intracellular molecular information.

Factors associated with immunological non-response after ART initiation: a retrospective observational cohort study.

BACKGROUND: Among people living with HIV (PLHIV) on antiretroviral therapy (ART), the mortality of immunological non-responders (INRs) is higher than that of immunological responders (IRs). However, factors associated with immunological non-response following ART are not well documented. METHODS: We obtained data for HIV patients from the National Free Antiretroviral Treatment Program database in China. Patients were grouped into IRs (CD4 cell count ≥ 350 cells/µl after 24 months' treatment), immunological incomplete responders (ICRs) (200-350 cells/µl) and INRs (< 200 cells/µl). Multivariable logistic regression was used to assess factors associated with immunological non-response. RESULTS: A total of 3900 PLHIV were included, among whom 2309 (59.2%) were IRs, 1206 (30.9%) ICRs and 385 (9.9%) INRs. In multivariable analysis, immunological non-response was associated with being male (2.07, 1.39-3.09), older age [40-49 years (vs. 18-29 years): 2.05, 1.29-3.25; 50-59 years: 4.04, 2.33-7.00; ≥ 60 years: 5.51, 2.84-10.67], HBV co-infection (1.63, 1.14-2.34), HCV co-infection (2.01, 1.01-4.02), lower CD4 + T cell count [50-200 cells/µl (vs. 200-350 cells/µl): 40.20, 16.83-96.01; < 50 cells/µl: 215.67, 85.62-543.26] and lower CD4/CD8 ratio (2.93, 1.98-4.34) at baseline. Compared with patients treated with non-nucleoside reverse transcriptase inhibitors (NNRTIs) based regimens, those receiving protease inhibitors (PIs) based regimens were less likely to be INRs (0.47, 0.26-0.82). CONCLUSIONS: We found a sizable immunological non-response rate among HIV-infected patients. Being male, older age, coinfection with HBV and HCV, lower CD4 + T cell count and lower CD4/CD8 ratio are risk factors of immunological non-response, whereas PIs-based regimens is a protective factor.

Factors associated with antiretroviral treatment adherence among people living with HIV in Guangdong Province, China: a cross sectional analysis.

BACKGROUND: Understanding factors associated with antiretroviral treatment (ART) adherence is crucial for ART success among people living with HIV (PLHIV) in the "test and treat" era. Multiple psychosocial factors tend to coexist and have a syndemic effect on ART adherence. We aimed to explore factors associated with ART adherence and the syndemic effect of multiple psychosocial factors on ART adherence among PLHIV newly starting ART in Guangdong Province, China. METHODS: Newly diagnosed PLHIV from six cities in Guangdong Province were recruited between May 2018 and June 2019, and then followed up from May 2019 to August 2020. Baseline and follow-up data were collected from a questionnaire and the national HIV surveillance system, the follow-up data of which were analyzed in this study. A Center for Adherence Support Evaluation (CASE) index > 10 points was defined as optimal ART adherence, which was measured via participants' self-reported adherence during follow-up survey. Multivariable logistic regression was used to identify factors associated with ART adherence. Exploratory factor analysis (EFA) and multi-order latent variable structural equation modeling (SEM) were performed to explore the syndemic effect of multiple psychosocial factors on ART adherence. RESULTS: A total of 734 (68.53%) follow-up participants were finally included in this study among the 1071 baseline participants, of whom 91.28% (670/734) had self-reported optimal ART adherence. Unemployment (aOR = 1.75, 95%CI: 1.01-3.02), no medication reminder (aOR = 2.28, 95%CI: 1.09-4.74), low medication self-efficacy (aOR = 2.28, 95%CI: 1.27-4.10), low social cohesion (aOR = 1.82, 95%CI: 1.03-3.19), no social participation (aOR = 5.65, 95%CI: 1.71-18.63), and ART side effects (aOR = 0.46, 95%CI: 0.26-0.81) were barriers to optimal ART adherence. The EFA and second-order latent variable SEM showed a linear relationship (standardized coefficient = 0.43, P < 0.001) between ART adherence and the latent psychosocial (syndemic) factor, which consisted of the three latent factors of medication beliefs and self-efficacy (standardized coefficient = 0.65, P < 0.001), supportive environment (standardized coefficient = 0.50, P < 0.001), and negative emotions (standardized coefficient=-0.38, P < 0.01). The latent factors of medication beliefs and self-efficacy, supportive environment, and negative emotions explained 42.3%, 25.3%, and 14.1% of the variance in the latent psychosocial factor, respectively. CONCLUSIONS: About nine out of ten PLHIV on ART in Guangdong Province self-reported optimal ART adherence. However, more efforts should be made to address barriers to optimal ART adherence.

A Reversible Fluorescent Probe for In Situ Monitoring Redox Imbalance during Mitophagy.

Mitophagy is the lysosome-dependent degradation of damaged and dysfunctional mitochondria, which is closely associated with H2O2-related redox imbalance and pathological processes. However, development of fast-responding and highly sensitive reversible fluorescent probes for monitoring of mitochondrial H2O2 dynamics is still lacking. Herein, we report a reversible fluorescent probe (M-HP) that enables real-time imaging of H2O2-related redox imbalance. In vitro studies demonstrated that M-HP had a rapid response and high sensitivity to the H2O2/GSH redox cycle, with a detection limit of 17 nM for H2O2. M-HP was applied to imaging of H2O2 fluctuation in living cells with excellent reversibility and mitochondrial targeting. M-HP reveals an increase in mitochondrial H2O2 under lipopolysaccharide stimulation and a decrease in H2O2 following the combined treatment with rapamycin. This suggests that the level of oxidative stress is significantly suppressed after the enhancement of mitophagy. The rationally designed M-HP offers a powerful tool for understanding redox imbalance during mitophagy.

A Reaction-Based Ratiometric Bioluminescent Platform for Point-of-Care and Quantitative Detection Using a Smartphone.

Fluorescent probes have emerged as powerful tools for the detection of different analytes by virtue of structural tenability. However, the requirement of an excitation source largely hinders their applicability in point-of-care detection, as well as causing autofluorescence interference in complex samples. Herein, based on bioluminescence resonance energy transfer (BRET), we developed a reaction-based ratiometric bioluminescent platform, which allows the excitation-free detection of analytes. The platform has a modular design consisting of a NanoLuc-HaloTag fusion as an energy donor, to which a synthetic fluorescent probe is bioorthogonally labeled as recognition moiety and energy acceptor. Once activated by the target, the fluorescent probe can be excited by NanoLuc to generate a remarkable BRET signal, resulting in obvious color changes of luminescence, which can be easily recorded and quantitatively analyzed by a smartphone. As a proof of concept, a fluorescent probe for HOCl was synthesized to construct the bioluminescent system. Results demonstrated the system showed a constant blue/red emission ratio which is independent to the signal intensity, allowing the quantification of HOCl concentration with high sensitivity (limit of detection (LOD) = 13 nM) and accuracy. Given the universality, this reaction-based bioluminescent platform holds great potential for point-of-care and quantitative detection of reactive species.

Rigidity-Dependent Emission: Inspired Selection of an ATP-Specific Polyvalent Hydrogen Binding-Lighted Fluorophore for Intracellular Amplified Imaging.

ATP, a small molecule with high intracellular concentration (mM level), provides a fuel to power signal amplification, which is meaningful for biosensing. However, traditional ATP-powered amplification is based on ATP/aptamer recognition, which is susceptible to the complex biological microenvironment (e.g., nuclease). In this work, we communicate a signaling manner termed as ATP-specific polyvalent hydrogen binding (APHB), which is mimetic to ATP/aptamer binding but can avoid interference from biomolecules. The key in APHB is a functional fluorophore that can selectively bind with ATP via polyvalent hydrogen, and the fluorescence was lighted with the changes of the molecular structure from flexibility to rigidity. By designing, synthesizing, and screening a series of compounds, we successfully obtained an ATP-specific binding-lighted fluorophore (ABF). Experimental verification and a complex analogue demonstrated that two melamine brackets in the ABF dominate the polyvalent hydrogen binding between the ABF and ATP. Then, to achieve amplification biosensing, fibroblast activation protein (FAP) in activated hepatic stellate cells was taken as a model target, and a nanobeacon consisting of an ABF, a quencher, and an FAP-activated polymer shell was constructed. Benefiting from the ATP-powered amplification, the FAP was sensitively detected and imaged, and the potential relationship between differentiation of hepatocytes and FAP concentration was first revealed, highlighting the great potential of APHB-mediated signaling for intracellular sensing.

2 MeV proton irradiation effect on the performance of InAs/GaSb type-II superlattice long-wave infrared detectors.

In this work, we investigated the effect of 2 MeV proton irradiation on the performance of InAs/GaSb type-II superlattice long-wave infrared detectors by combining ground-based irradiation experiments with Stopping and Range of Ions in Matter (SRIM) computer simulations. We found that irradiation with 2 MeV protons significantly increases the dark current density of the detector by more than two orders of magnitude. At the same time, the quantum efficiency decreases by an order of magnitude. Moreover, proton irradiation degrades the device's performance by raising bulk and surface leakage currents. As the mesa size of the device increases, the proportion of surface leakage current in the total dark current drops. When the mesa size is smaller, the detector irradiation damage is greater. In addition, simulations indicate that the amount of damage produced by 2 MeV proton irradiation rises as irradiation fluences increase. The trends of the irradiation damage produced by the SRIM simulation results and the photocurrent measurements after proton irradiation are consistent, whereas the dark current measurements are identical only at small fluences.

Brain-targeted Near-Infrared Nanobeacon for In Situ Monitoring H2S Fluctuation during Epileptic Seizures.

Epilepsy is a neurological brain disease, and its recurrent seizures are related to the reductive substance-powered antioxidant defense system (ADS). However, until now, there has been no report on the study of in situ antioxidant fluctuation during epilepsy of varying severity. In this work, hydrogen sulfide (H2S) was selected as the model target, a H2S-responsive near-infrared fluorophore was designed and synthesized, and an amphiphilic molecule was synthesized and modified with angiopep-2 peptide at its hydrophilic terminus. A nanobeacon termed as BFPP was prepared by the formation of micelles with the package of the fluorophore. The nanobeacon was sensitive to H2S, with a low detection limit of 17 nM. The H2S fluctuation in cells can be monitored by fluorescence imaging. In addition, angiopep-2 peptide at the surface of BFPP helps it cross the blood-brain barrier, and near-infrared fluorescence improves in vivo imaging. BFPP revealed that H2S was at a moderate level in the normal brain, but its level was obviously elevated during mild epilepsy because of the activation of the ADS while significantly suppressed during severe epilepsy due to neuronal damage. This approach is generally accessible for other targets by altering the responsive fluorophore, with significance for in situ analysis of brain pathology.

Drug resistance and genetic transmission characteristics of HIV-1 CRF59_01B in infected patients in Guangdong Province, China.

OBJECTIVES: To comprehensively analyse the prevalence of drug resistance and the transmission characteristics of CRF59_01B strains in infected patients in Guangdong, China. METHODS: CRF59_01B-infected individuals were recruited, and the HIV-1 pol region was amplified. Drug resistance-associated mutations (DRMs) and antiretroviral susceptibility were examined using the Stanford University HIV Drug Resistance Database to analyse pretreatment drug resistance (PDR) and acquired drug resistance (ADR). Genetic transmission networks were extracted from the maximum likelihood phylogenetic tree with Cluster Picker and visualized with Cytoscape. RESULTS: Two hundred and twenty-five CRF59_01B-infected individuals, comprising 35 ART-experienced and 190 ART-naive individuals, were recruited. No patients harboured PI DRMs, 5.33% (12/225) of the patients harboured NRTI DRMs and 11.11% (25/225) of the patients harboured NNRTI DRMs. The overall prevalence of strains with ADR was 51.43% (18/35), while the prevalence of strains with PDR was 2.63% (5/190). A total of 20 transmission networks, involving 25.78% (58/225) database-derived sequences, were identified. The networks ranged in size from 2 to 10 individuals, of which most (55.00%, 11/20) were made up of two individuals. Among the 225 study subjects, 9.78% (22/225) had 1 link and 16.00% (36/225) had ≥2 links. CONCLUSIONS: The overall prevalence of CRF59_01B strains with ADR among the ART-experienced patients was high. Although the overall prevalence of CRF59_01B strains with PDR among the ART-naive patients was low, it is necessary to remain vigilant regarding some important DRMs.

Large-area SnTe nanofilm: preparation and its broadband photodetector with ultra-low dark current.

Photodetectors are receiving increasing attention because of their widely important applications. Therefore, developing broadband high-performance photodetectors using new materials that can function at room temperature has become increasingly important. As a functional material, tin telluride (SnTe), has been widely studied as a thermoelectric material. Furthermore, because of its narrow bandgap, it can be used as a novel infrared photodetector material. In this study, a large-area SnTe nanofilm with controllable thickness was deposited onto a quartz substrate using magnetron sputtering and was used to fabricate a photodetector. The device exhibited a photoelectric response over a broad spectral range of 400-1050 nm. In the near-infrared band of 940 nm, the detectivity (D*) and responsivity (R) of the photodetector were 3.46×1011 cmHz1/2w-1 and 1.71 A/W, respectively, at an optical power density of 0.2 mWcm-2. As the thickness of the SnTe nanofilm increased, a transition from semiconducting to metallic properties was experimentally observed for the first time. The large-area (2.5cm × 2.5cm) high-performance nanofilms show important potential for application in infrared focal plane array (FPA) detectors.

Transmission networks of hepatitis C virus among HIV/HCV-coinfected patients in Guangdong, China.

BACKGROUND: Coinfection with hepatitis C virus (HCV) is common in human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) patients due to shared routes of transmission. We aimed to investigate the characteristics of HCV subgenotypes among HIV/HCV-coinfected patients in Guangdong and explore the molecular transmission networks and related risk factors for HCV strains. METHODS: Plasma samples were obtained from 356 HIV/HCV-coinfected patients for HCV NS5B region sequencing. A neighbor-joining phylogenetic tree was constructed to affirm HCV subgenotypes. The transmission networks based on maximum likelihood phylogenetic tree were determined by Cluster Picker, and visualized using Cytoscape 3.2.1. RESULTS: A total of 302 HCV NS5B sequences were successfully amplified and sequenced from the 356 plasma samples. A neighbor-joining phylogenetic tree based on the 302 NS5B sequences revealed the profile of HCV subgenotypes circulating among HIV/HCV coinfection patients in Guangdong. Two predominant strains were found to be 6a (58.28%, 176/302) and 1b (18.54%, 56/302), followed by 3a (10.93%, 33/302), 3b (6.95%, 21/302), 1a (3.64%, 11/302), 2a (0.99%, 3/302) and 6n (0.66%, 2/302). A molecular transmission network of five major HCV genotypes was constructed, with a clustering rate of 44.04%. The clustering rates of subgenotypes 1a, 3a, 3b, 1b, and 6a were 18.18% (2/11), 42.42%, 52.38%, 48.21%, and 44.89%, respectively. Multivariate logistic regression analysis showed no significant effects from sex, age, transmission route, geographical region, baseline CD4 + T cell count or subgenotype (P > 0.05), except marital status. Married or cohabiting people (compared with unmarried people) had more difficulty forming transmission networks. CONCLUSIONS: In summary, this study, based on HCV NS5B subgenotypes, revealed the HCV subtype diversity and distribution among HIV/HCV-coinfected patients in Guangdong. Marital status inclined to be the factor influencing HCV transmission networks formation.

MiR-122-5p promotes peritoneal fibrosis in a rat model of peritoneal dialysis by targeting Smad5 to activate Wnt/ß-catenin pathway.

Peritoneal fibrosis (PF) is the main reason leading to declining efficiency and ultrafiltration failure of peritoneum, which restricts the application of peritoneal dialysis (PD). We aimed to investigate the effects and mechanisms of miR-122-5p on the PF. Sprague-Dawley (SD) rats were infused with glucose-based standard PD fluid to establish PF model. HE staining was performed to evaluate the extent of PF. Real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) and fluorescence in situ hybridization (FISH) were performed to measure the expression level of miR-122-5p. Western blot was used to test the expression of transforming growth factor (TGF)-ß1, platelet-derived growth factor (PDGF)-A, Fibronectin 1 (FN1), extracellular matrix protein 1 (ECM1), Smad5, α-smooth muscle actin (SMA), collagen type 1(COL-1), Vimentin, E-Cadherin, Wnt1, ß-catenin, p-ß-catenin, c-Myc, c-Jun, and Cyclin D1. Immunohistochemistry (IHC) staining was used to detect type I collagen alpha 1 (Col1α1), α-SMA, and E-Cadherin expression. We found PF was glucose concentration-dependently enhanced in peritoneum of PD rat. The PD rats showed increased miR-122-5p and decreased Smad5 expression. MiR-122-5p silencing improved PF and epithelial-mesenchymal transition (EMT) process in PD rats. MiR-122-5p silencing attenuated the activity of the Wnt/ß-catenin signaling pathway. Importantly, dual-luciferase reporter assay showed Smad5 was a target gene of miR-122-5p. Smad5 overexpression significantly reversed the increases of PF and EMT progression induced by miR-122-5p overexpression. Moreover, miR-122-5p mimic activated Wnt/ß-catenin activity, which was blocked by Smad5 overexpression. Overall, present results demonstrated that miR-122-5p overexpression showed a deterioration effect on PD-related PF by targeting Smad5 to activate Wnt/ß-catenin pathway.

Long-Lasting Bioluminescence Imaging of the Fibroblast Activation Protein by an Amphiphilic Block Copolymer-Based Probe.

Long-term specific tracing of the fibroblast activation protein (FAP) has been of great importance because it is heavily expressed by stromal fibroblasts of multiple diseases, and several disorders associated with FAP are chronical. Bioluminescence (BL) imaging has its advantages to detect FAP in vivo since no external excitation is required, but the current FAP-responsive BL probe was constructed by covalently masking the firefly luciferase substrate and easily secreted out from the animal, resulting in transient BL imaging of FAP. To circumvent this problem, a peptide-linked amphiphilic block copolymer-based probe (PABC) was developed and applied to the long-lasting BL image of FAP in vivo. For this purpose, an amphiphilic block copolymer containing an FAP-responsive peptide was fabricated to self-assemble into micelles, which act as a depot to load amounts of d-luciferin for constructing the BL probe. Upon reaction with FAP, the micelle would be destroyed to release the internal d-luciferin for BL emission by a luciferase-catalyzed reaction. By virtue of the high loading capability of micelles, the FAP was determined from 0.5 to 10 ng/mL with a detection limit of 0.105 ng/mL, and the high sensitivity makes the PABC capable of distinguishing cancer cells from normal ones. Importantly, compared with free d-luciferin, PABC can be used to persistently image the FAP in living cells and in vivo. This characteristic of long-lasting specific tracing of the FAP makes us envision that this BL probe could be used for screening of FAP inhibitors and diagnosing various FAP-related diseases in future.

Self-Immolative Dye-Doped Polymeric Probe for Precisely Imaging Hydroxyl Radicals by Avoiding Leakage.

For sensing low abundance of biomarkers, utilizing nanocarriers to load dyes is an efficient method to amplify the detected signal. However, the non-specific leak of the internal dyes in this approach is accompanied by false positive signals, resulting in inaccurate signal acquirement. To address this issue, in this work, we reported a novel signal amplification strategy with dye as a scaffold to construct a self-immolative dye-doped polymeric probe (SDPP). In our proposed approach, the dyes were covalently integrated into the main chain of a polymer, which can avoid the non-specific leak of the dye when used in a rigorous biological environment, thus evading the false positive signal. As a prototype of this concept, a SDPP, which responds to hydroxyl radicals (•OH), was rationally fabricated. Upon being activated by •OH, SDPP will liberate the dye through a self-immolative reaction to bind with protein for amplifying the fluorescence signal. Compared with a dye-loaded nanoprobe, SDPP can precisely track intracellular basal •OH levels and visualize the •OH associated with myocarditis in vivo. More importantly, the attempt in this work not only provides an effective molecular tool to investigate the role of •OH in cardiopathy, but also puts forward a new direction to current signal-amplifying strategies for precisely and reliably acquiring the intracellular molecular information.

Transmitted drug resistance and transmission clusters among HIV-1 treatment-naïve patients in Guangdong, China: a cross-sectional study.

BACKGROUND: Transmitted drug resistance (TDR) that affects the effectiveness of the first-line antiretroviral therapy (ART) regimen is becoming prevalent worldwide. However, its prevalence and transmission among HIV-1 treatment-naïve patients in Guangdong, China are rarely reported. We aimed to comprehensively analyze the prevalence of TDR and the transmission clusters of HIV-1 infected persons before ART in Guangdong. METHODS: The HIV-1 treatment-naïve patients were recruited between January 2018 and December 2018. The HIV-1 pol region was amplified by reverse transcriptional PCR and sequenced by sanger sequencing. Genotypes, surveillance drug resistance mutations (SDRMs) and TDR were analyzed. Genetic transmission clusters among patients were identified by pairwise Tamura-Nei 93 genetic distance, with a threshold of 0.015. RESULTS: A total of 2368 (97.17%) HIV-1 pol sequences were successfully amplified and sequenced from the enrolled 2437 patients. CRF07_BC (35.90%, 850/2368), CRF01_AE (35.56%, 842/2368) and CRF55_01B (10.30%, 244/2368) were the main HIV-1 genotypes circulating in Guangdong. Twenty-one SDRMs were identified among fifty-two drug-resistant sequences. The overall prevalence of TDR was 2.20% (52/2368). Among the 2368 patients who underwent sequencing, 8 (0.34%) had TDR to protease inhibitors (PIs), 22 (0.93%) to nucleoside reverse transcriptase inhibitors (NRTIs), and 23 (0.97%) to non-nucleoside reverse transcriptase inhibitors (NNRTIs). Two (0.08%) sequences showed dual-class resistance to both NRTIs and NNRTIs, and no sequences showed triple-class resistance. A total of 1066 (45.02%) sequences were segregated into 194 clusters, ranging from 2 to 414 sequences. In total, 15 (28.85%) of patients with TDR were included in 9 clusters; one cluster contained two TDR sequences with the K103N mutation was observed. CONCLUSIONS: There is high HIV-1 genetic heterogeneity among patients in Guangdong. Although the overall prevalence of TDR is low, it is still necessary to remain vigilant regarding some important SDRMs.

Genetic characteristics of HIV-1 CRF06_cpx and CRF56_cpx strains isolated in Guangzhou, China.

Strains of the HIV-1 circulating recombinant forms (CRFs) 06_cpx and 56_cpx were identified for the first time in Guangzhou, China. The nearly full-length genome (NFLG) sequence was amplified, and the PCR products were sequenced by the Sanger method. The CRF06_cpx and CRF56_cpx strains were identified using the Basic Local Alignment Search Tool (BLAST) and confirmed by neighbour-joining (NJ) phylogenetic analysis. Additionally, these strains were found to contain transmitted drug resistance mutations that have little effect on first-line efavirenz (EFV)-based treatment. Genetic analysis of the detailed sequence data will provide more information on the HIV-1 epidemic in China.

Multicolor Two-Photon Nanosystem for Multiplexed Intracellular Imaging and Targeted Cancer Therapy.

The novel theranostic nanosystems based on two-photon fluorescence can achieve higher spatial resolution of deep tissue imaging for simultaneous diagnosis and therapy of a variety of cancers. Herein, we have designed and prepared FRET-based two-photon mesoporous silica nanoparticles (MTP-MSNs) for single-excitation multiplexed intracellular imaging and targeted cancer therapy for the first time. This nanosystem includes two constituents, containing (1) multicolor two-photon mesoporous silica nanoparticles and (2) cancer cell-targeting aptamers that act as gatekeepers for MTP-MSNs. After incubation with cancer cells, the Dox-loaded and aptamer-capped MTP-MSNs could be internalized into the cells, opening the pores and releasing the drug. Furthermore, using two-photon multicolor fluorescence, MTP-MSNs could serve as good contrast agents for multicolor two-photon intracellular imaging with increased imaging depth and improved spatial localization of tissue. In sum, these multicolor MTP-MSNs provide a promising system for traceable targeted cancer therapy with further applications in multiplex intracellular imaging and the screening of drug.

Near-Infrared Fluorescent Furin Probe for Revealing the Role of Furin in Cellular Carcinogenesis and Specific Cancer Imaging.

Furin, an important member in the family of proprotein convertases, is a participant in the activation of various precursor proteins. The expression level of furin stays in a very low range in most normal cells, but elevates with a big margin in many cancer cells. More importantly, furin is closely related to tumor formation and migration. Herein, a furin-activatable near-infrared (NIR) fluorescent probe (HD-F) was first developed that allowed for specific, sensitive detection and imaging of furin both in vitro and in vivo. HD-F consists of a classical NIR fluorophore (HD), a furin-particular polypeptide sequence RVRR, and a self-eliminating linker. Without the interaction with furin, no noticeable fluorescence enhancement was detected, even over 3 days, demonstrating the excellent stability of HD-F. Upon conversion by furin, there was a distinct signal increase around 708 nm. It has achieved assay and visualization of endogenous furin in various cells, tumor tissues, and tumor-bearing mouse models. Importantly, HD-F is well-suited for monitoring the change of furin expression level in the process of hypoxia-inducible factor-1 stabilized by CoCl2. Moreover, HD-F could visualize the divergence in the expression level of furin between normal and cancer cells, indicating its potential in specific cancer imaging. Thus, this novel probe is able to serve as a potential tackle for better understanding of the intrinsic link between a hypoxic physiological environment and cellular carcinogenesis and predicting cancer in preclinical applications.

A Bioluminescent Probe for Imaging Endogenous Peroxynitrite in Living Cells and Mice.

Peroxynitrite (ONOO-), an extremely reactive nitrogen species (RNS), is implicated in diverse pathophysiological conditions, including cancer, neurodegenerative diseases, and inflammation. Sensing and imaging of ONOO- in living systems remains challenging due to the high autofluorescence and the limited light penetration depth. In this work, we developed a bioluminescent probe BP-PN, based on luciferase-luciferin pairs and the ONOO--responded group α-ketoamide, for highly sensitive detection and imaging of endogenous ONOO- in living cells and mice for the first time. Attributed to the BL without external excitation, the probe BP-PN exhibits a high signal-to-noise ratio with relatively low autofluorescence. Furthermore, we examine the application of the probe BP-PN using the mice model of inflammation, and BP-PN shows high sensitivity for imaging endogenous ONOO- in inflamed mice. This newly developed bioluminescent probe would be a potentially useful tool for in vivo imaging of ONOO- in wider physiological and pathological processes.

In Situ Imaging of Furin Activity with a Highly Stable Probe by Releasing of Precipitating Fluorochrome.

Furin, a kind of trans-Golgi proprotein convertases, plays important role in various physiological processes. It is overexpressed in many cancers and relates to tumor growth and migration. In situ detection and imaging of furin is of great significance for obtaining real-time information about its activity. However, the previously reported fluorescent probes for furin usually failed to realize in situ detection and long-term bioimaging, because these probes are based on water-soluble fluorophores, which tend to diffuse away from the reaction sites after converted by furin. Such a problem can be addressed by designing a probe, which releases a precipitating fluorophore upon furin conversion. Herein, we developed a probe HPQF for in situ detection of endogenous furin activity and long-term bioimaging by integrating a strictly insoluble solid-state fluorophore 6-chloro-2-(2-hydroxyphenyl) quinazolin-4(3H)-one (Cl-HPQ) with a furin specific peptide substrate (RVRR) through a self-immolative linker. The HPQF probe shows high selectivity and sensitivity to furin. Upon converted by furin, HPQF releases free Cl-HPQ, which precipitates near the enzyme active site. The precipitates emit bright solid-state fluorescence for in situ imaging. HPQF could truly visualize the location of intracellular furin, which was further confirmed by colocalization and immunofluorescence experiments. Excitingly, the long-term bioimaging was also achieved benefiting from its outstanding signal-stability and antidiffusion ability. HPQF was further utilized to monitor the level change of furin under stabilizing of hypoxia-inducible factor (HIF) regulated by cobalt chloride (CoCl2) as well as visualization of furin in MDA-MB-468 cell tumor tissues.