Multifunctional Probe Based on "Chemical Antibody-Aptamer" for Noninvasive Detection of PD-L1 Expression in Cancer.

Immune checkpoint inhibitors (ICIs) therapy based on programmed cell death ligand 1 (PD-L1) has shown significant development in treating several carcinomas, but not all patients respond to this therapy due to the heterogeneity of PD-L1 expression. The sensitive and accurate quantitative analysis of in vivo PD-L1 expression is critical for treatment decisions and monitoring therapy. In the present study, an aptamer-based dual-modality positron emission tomography/near-infrared fluorescence (PET/NIRF) imaging probe was developed, and its specificity and sensitivity to PD-L1 were assessed in vitro and in vivo. The probe precursor NOTA-Cy5-R1 was prepared by using automated solid-phase oligonucleotide synthesis. PET/NIRF dual-modality probe [68Ga]Ga-NOTA-Cy5-R1 was successfully synthesized and radiolabeled. The binding specificity of [68Ga]Ga-NOTA-Cy5-R1 to PD-L1 was evaluated by flow cytometry, fluorescence imaging, and cellular uptake in A375-hPD-L1 and A375 cells, and it showed good fluorescence properties and stability in vitro. In vivo PET/NIRF imaging studies illustrated that [68Ga]Ga-NOTA-Cy5-R1 can sensitively and specifically bind to PD-L1 positive tumors. Meanwhile, the rapid clearance of probes from nontarget tissues achieved a high signal-to-noise ratio. In addition, changes of PD-L1 expression in NCI-H1299 xenografts treated with cisplatin (CDDP) were sensitivity monitored by [68Ga]Ga-NOTA-Cy5-R1 PET imaging, and ex vivo autoradiography and western blot analyses correlated well with the change of PD-L1 expression in vivo. Overall, [68Ga]Ga-NOTA-Cy5-R1 showed notable potency as a dual-modality PET/NIRF imaging probe for visualizing tumors and monitoring the dynamic changes of PD-L1 expression, which can help to direct and promote the clinical practice of ICIs therapy.

Development of novel peptide-based radiotracers for detecting PD-L1 expression and guiding cancer immunotherapy.

PURPOSE: Due to tumor heterogeneity, immunohistochemistry (IHC) showed poor accuracy in detecting the expression of programmed cell death ligand-1 (PD-L1) in patients. Positron emission tomography (PET) imaging is considered as a non-invasive technique to detect PD-L1 expression at the molecular level visually, real-timely and quantitatively. This study aimed to develop novel peptide-based radiotracers [68Ga]/[18F]AlF-NOTA-IMB for accurately detecting the PD-L1 expression and guiding the cancer immunotherapy. METHODS: NOTA-IMB was prepared by connecting 2,2'-(7-(2-((2,5-dioxopyrrolidin-1-yl)oxy)- 2-oxoethyl)-1,4,7-triazonane-1,4-diyl) diacetic acid (NOTA-NHS) with PD-L1-targeted peptide IMB, and further radiolabeled with 68Ga or 18F-AlF. In vitro binding assay was conducted to confirm the ability of [68Ga]/[18F]AlF-NOTA-IMB to detect the expression of PD-L1. In vivo PET imaging of [68Ga]NOTA-IMB and [18F]AlF-NOTA-IMB in different tumor-bearing mice was performed, and dynamic changes of PD-L1 expression level induced by immunotherapy were monitored. Radioautography, western blotting, immunofluorescence staining and biodistribution analysis were carried out to further evaluate the specificity of radiotracers and efficacy of PD-L1 antibody immunotherapy. RESULTS: [68Ga]NOTA-IMB and [18F]AlF-NOTA-IMB were both successfully prepared with high radiochemical yield (> 95% and > 60%, n = 5) and radiochemical purity (> 95% and > 98%, n = 5). Both tracers showed high affinity to human and murine PD-L1 with the dissociation constant (Kd) of 1.00 ± 0.16/1.09 ± 0.21 nM (A375-hPD-L1, n = 3) and 1.56 ± 0.58/1.21 ± 0.39 nM (MC38, n = 3), respectively. In vitro cell uptake assay revealed that both tracers can specifically bind to PD-L1 positive cancer cells A375-hPD-L1 and MC38 (5.45 ± 0.33/3.65 ± 0.15%AD and 5.87 ± 0.27/2.78 ± 0.08%AD at 120 min, n = 3). In vivo PET imaging and biodistribution analysis showed that the tracer [68Ga]NOTA-IMB and [18F]AlF-NOTA-IMB had high accumulation in A375-hPD-L1 and MC38 tumors, but low uptake in A375 tumor. Treatment of Atezolizumab induced dynamic changes of PD-L1 expression in MC38 tumor-bearing mice, and the tumor uptake of [68Ga]NOTA-IMB decreased from 3.30 ± 0.29%ID/mL to 1.58 ± 0.29%ID/mL (n = 3, P = 0.026) after five treatments. Similarly, the tumor uptake of [18F]AlF-NOTA-IMB decreased from 3.27 ± 0.63%ID/mL to 0.89 ± 0.18%ID/mL (n = 3, P = 0.0004) after five treatments. However, no significant difference was observed in the tumor uptake before and after PBS treatment. Biodistribution, radioautography, western blotting and immunofluorescence staining analysis further demonstrated that the expression level of PD-L1 in tumor-bearing mice treated with Atezolizumab significantly reduced about 3 times and correlated well with the PET imaging results. CONCLUSION: [68Ga]NOTA-IMB and [18F]AlF-NOTA-IMB were successfully prepared for PET imaging the PD-L1 expression noninvasively and quantitatively. Dynamic changes of PD-L1 expression caused by immunotherapy can be sensitively detected by both tracers. Hence, the peptide-based radiotracers [68Ga]NOTA-IMB and [18F]AlF-NOTA-IMB can be applied for accurately detecting the PD-L1 expression in different tumors and monitoring the efficacy of immunotherapy.

The serum creatinine to cystatin C to waist circumference ratios predicts risk for type 2 diabetes: A Chinese cohort study.

BACKGROUND: There is a lack of research regarding the relationship between creatinine to cystatin C to waist circumference ratio (CCR/WC ratios) and the development of type 2 diabetes mellitus (T2DM). We aimed to evaluate the association between CCR/WC ratios and incident T2DM in Chinese adults. METHODS: This prospective study was from the China Health and Retirement Longitudinal Study (2011, 2013, 2015, and 2018). The participants were divided into three groups by tertiaries of the CCR/WC ratios. Cox proportional-hazards models were used to identify the relationship between CCR/WC and T2DM. RESULTS: Overall, 5938 participants were included for analysis, 766 of whom developed T2DM between 2011 and 2018. Risk of incident T2DM was decreased with tertiaries 2, 3 versus tertiary 1 of the CCR/WC index (adjusted hazard ratio [HR] 0.772 [95% confidence interval 0.647-0.921] and 0.724 [0.596-0.880], p for trend = .001 across tertiaries of the CCR/WC index). The results were consistent excluding participants with T2DM in the first 2 years. CONCLUSIONS: This study demonstrated that CCR/WC was negatively correlated with the risk of T2DM in Chinese adults. Early detection is necessary to control the development of T2DM in Chinese with low CCR/WC levels.

Senolytic Drug Quercetin Rescues Survival from Blue Light Toxicity in Drosophila Model.

With the increasing frequency of human exposure to blue light, the harmfulness of blue light has received wider attention. The damaging effect of blue light is complex and long-lasting. In this study, Drosophila melanogaster was used as a model organism to investigate the protective effect of the senolytic drug quercetin on blue light toxicity. As one of the first senolytic drugs discovered, quercetin not only has antioxidant properties, but also has been used to treat various neurological disorders. Our study shows that quercetin can effectively prolong the survival of flies under blue light irradiation, and it significantly increases the egg production of female flies under blue light. In addition, after flies intaking quercetin under blue light, both the spontaneous activity and nutrient metabolism show significant sex-specificity. The experimental results provide a potentially effective intervention method for organisms to defend against blue light toxicity, and reveal a new function of the senolytic drug quercetin from another perspective.

Development of a radiolabeled site-specific single-domain antibody positron emission tomography probe for monitoring PD-L1 expression in cancer.

Despite advances in immunotherapy for the treatment of cancers, not all patients can benefit from programmed cell death ligand 1 (PD-L1) immune checkpoint blockade therapy. Anti-PD-L1 therapeutic effects reportedly correlate with the PD-L1 expression level; hence, accurate detection of PD-L1 expression can guide immunotherapy to achieve better therapeutic effects. Therefore, based on the high affinity antibody Nb109, a new site-specifically radiolabeled tracer, 68Ga-NODA-cysteine, aspartic acid, and valine (CDV)-Nb109, was designed and synthesized to accurately monitor PD-L1 expression. The tracer 68Ga-NODA-CDV-Nb109 was obtained using a site-specific conjugation strategy with a radiochemical yield of about 95% and radiochemical purity of 97%. It showed high affinity for PD-L1 with a dissociation constant of 12.34 ± 1.65 nM. Both the cell uptake assay and positron emission tomography (PET) imaging revealed higher tracer uptake in PD-L1-positive A375-hPD-L1 and U87 tumor cells than in PD-L1-negative A375 tumor cells. Meanwhile, dynamic PET imaging of a NCI-H1299 xenograft indicated that doxorubicin could upregulate PD-L1 expression, allowing timely interventional immunotherapy. In conclusion, this tracer could sensitively and dynamically monitor changes in PD-L1 expression levels in different cancers and help screen patients who can benefit from anti-PD-L1 immunotherapy.

Alkaline Phosphatase Enabled Fluorogenic Reaction and in situ Coassembly of Near-Infrared and Radioactive Nanoparticles for in vivo Imaging.

Smart near-infrared (NIR) fluorescence (FL) and positron emission tomography (PET) bimodal probes have shown promise for preoperative and intraoperative imaging of tumors. In this paper, we report an enzyme-activatable probe (P-CyFF-68Ga) and its cold probe (P-CyFF-Ga) using an enzyme-induced fluorogenic reaction and in situ coassembly strategy and demonstrate the utility for NIR FL/PET bimodality imaging of enzymatic activity. P-CyFF-68Ga and P-CyFF-Ga can be converted into dephosphorylated CyFF-68Ga and CyFF-Ga in response to alkaline phosphatase (ALP) and subsequently coassemble into fluorescent and radioactive nanoparticles (NP-68Ga). The ALP-triggered in situ formed NP-68Ga is prone to anchoring on the ALP-positive HeLa cell membrane, permitting the concurrent enrichment of NIR FL and radioactivity. The enhancements in NIR FL and radioactivity enables high sensitivity and deep-tissue imaging of ALP activity, consequently facilitating the delineation of HeLa tumor foci from the normal tissues in vivo.

Promising potential of a 18F-labelled small-molecular radiotracer to evaluate PD-L1 expression in tumors by PET imaging.

Programmed death ligand 1 (PD-L1) expression level is a reproducible biomarker for guiding stratification of patients to immunotherapy. However, the most widely used immunohistochemistry method is incompetent to fully understand the PD-L1 expression level in the whole body because of the highly complex PD-L1 expression in the tumor microenvironment. In this work, a novel small-molecular radiotracer [18F]LG-1 based on the biphenyl active structure was developed to evaluate PD-L1 expression in tumors. [18F]LG-1 was obtained by conjugating and radiolabeling with [18F]FDG with high radiochemical purity (>98.0%) and high molar activity (37.2 ± 2.9 MBq/nmol). In vitro experimental results showed that [18F]LG-1 could target PD-L1 in tumor cells and the cellular uptake in A375-hPD-L1 cells (PD-L1 + ) was clearly higher than that in A375 cells (PD-L1-). In vivo dynamic PET images of [18F]LG-1 provided clear visualization of A375-hPD-L1 tumor with high tumor-to-background contrast, and the tumor uptake was determined to be 3.98 ± 0.21 %ID/g at 60 min, which was 2.6-fold higher than that of A375 tumor. These results suggested that [18F]LG-1 had great potential as a promising PD-L1 radiotracer.

Enzyme-Mediated In Situ Self-Assembly Promotes In Vivo Bioorthogonal Reaction for Pretargeted Multimodality Imaging.

Pretargeted imaging has emerged as a promising approach to advance nuclear imaging of malignant tumors. Herein, we combine the enzyme-mediated fluorogenic reaction and in situ self-assembly with the inverse electron demand Diels-Alder (IEDDA) reaction to develop an activatable pretargeted strategy for multimodality imaging. The trans-cyclooctene (TCO) bearing small-molecule probe, P-FFGd-TCO, can be activated by alkaline phosphatase and in situ self-assembles into nanoaggregates (FMNPs-TCO) retained on the membranes, permitting to (1) amplify near-infrared (NIR) fluorescence (FL) and magnetic resonance imaging (MRI) signals, and (2) enrich TCOs to promote IEDDA ligation. The Gallium-68 (68 Ga) labeled tetrazine can readily conjugate the tumor-retained FMNPs-TCO to enhance radioactivity uptake in tumors. Strong NIR FL, MRI, and positron emission tomography (PET) signals are concomitantly achieved, allowing for pretargeted multimodality imaging of ALP activity in HeLa tumor-bearing mice.

Preclinical Evaluation of a Fluorine-18 Labeled Probe for the Detection of the Expression of PSMA Level in Cancer.

Prostate-specific membrane antigen (PSMA) is a prospect biomarker for the treatment of prostate cancer. Meanwhile, positron emission tomography (PET) is being developed as a significant imaging modality in cancer diagnosis. A new PET probe Glu-ureido-Lys-naphthylalanine-tranexamic acid-Gly(AMBF3)-triiodobenzoic acid (18F-GLNTGT) was radiosynthesized by a one-step 18F-labeled method. 18F-GLNTGT was obtained with a radioactivity yield (RCY) of 12.16 ± 6.4% and a good radiochemical purity (RCP > 96%). The cell uptakes of 18F-GLNTGT were determined to be 15.9 ± 0.43% ID and 9.47 ± 1.26% ID at 15 min in LNCaP cells and PC-3 cells, respectively. The cell internalization of 18F-GLNTGT was determined to be 12.89 ± 0.94% ID and 5.34 ± 0.15% ID at 15 min in LNCaP cells and PC-3 cells, respectively. It is suggested that the probe has good specificity targeting PSMA. From the results of 18F-GLNTGT binding affinity with PSMA, it has a higher affinity and a K i value of 0.49 nM (95% confidence interval (CI): 0.35-0.67 nM). In PET imaging, 18F-GLNTGT showed the highest tumor uptake of 3.51 ± 0.15% ID/g at 45 min and the maximum tumor/muscle (T/Mmax) ratio of 3.68 ± 0.29 at 60 min post-injection (p.i.) in LNCaP tumors. The control probe 18F-AlF-NOTA-RGD2 presented the highest tumor uptake of 4.2 ± 0.54% ID/g at 7.5 min and the T/Mmax ratio of 2.72 ± 0.63 at 45 min p.i. in LNCaP tumors. The results showed that the probe has a higher tumor/muscle ratio compared with the control probe 18F-AlF-NOTA-RGD2. Although the probe 18F-GLNTGT has some limitations for CT signal detection both in cells and in vivo, it is still a promising PET probe for targeting PSMA membrane protein.

Structural characterization and statistical properties of jammed soft ellipsoid packing.

The jamming transition and jammed packing structures of hydrogel soft ellipsoids are studied using magnetic resonance imaging techniques. As the packing fraction increases, the fluctuation of local free volume decreases and the fluctuation of particle deformation increases. Effective thermodynamic quantities are obtained by characterizing these fluctuations using k-gamma distributions based on an underlying statistical model for granular materials. Surprisingly, the two granular temperatures measuring the relative fluctuations of both free volume and particle deformation remain basically unchanged as the packing fraction increases. The total configurational entropy is also approximately constant for packing with different packing fractions. The significantly different behaviors of these effective thermodynamic quantities compared with hard sphere systems are further attributed to a statistically affine structural transformation of the packing structures along with particle deformations when the packing fraction changes.

One-step radiosynthesis and initial evaluation of a small molecule PET tracer for PD-L1 imaging.

Programmed cell death protein-ligand 1 (PD-L1) is a crucial biomarker in immunotherapy and its expression level plays a key role in the guidance of anti-PD-L1 therapy. It had been reported that PD-L1 was quantified by noninvasive imaging with more developed radiotracers. In our study, a novel [18F]fluoride labeled small molecule inhibitor, [18F]LN was designed for positron emission tomography (PET) imaging in both PD-L1 transfected (A375-hPD-L1) and non-transfected (A375) melanoma-bearing mice. LN showed the specificity (IC50 = 50.39 ± 2.65 nM) to PD-L1 confirmed by competitive combination and cell flow cytometry (FACS) analysis. The radiotracer [18F]LN was obtained via 18F-19F isotope exchange from precursor LN. After radiosynthesis, [18F]LN was achieved with a high radiochemical purity (RCP) above 95% and got a favorable molar activity of 36.34 ± 5.73 GBq/µmol. [18F]LN displayed the moderate affinity (Kd = 65.27 ± 3.47 nM) to PD-L1 by specific binding assay. And it showed 1.3-fold higher uptake in A375-hPD-L1 cells than that in A375 cells. PET imaging revealed that [18F]LN could enter into PD-L1 expressing tumor site and visualize the outline of tumor. And tumor uptake (1.96 ± 0.27 %ID/g) reached the maximum at 15 min in the positive group, showed 2.2-fold higher than the negative (0.89 ± 0.31 %ID/g) or the blocked (1.07 ± 0.26 %ID/g) groups. Meanwhile, biodistribution could slightly distinguish the positive from the negative. The results indicated [18F]LN would become an efficient tool for evaluating PD-L1 expression with further optimization.

Preparation of metallic monolithic Pt/FeCrAl fiber catalyst by suspension spraying for VOCs combustion.

We report a facile and general strategy for the preparation of metallic monolithic catalysts. Our strategy involved subjecting the surfaces of FeCrAl fibers to thermal treatment and the spraying of Pt nanoparticles suspension liquid. The catalyst exhibited high catalytic activity and good stability in the combustion of volatile organic compounds to CO2 and H2O at mild temperature. The exceptional activity of the catalyst can be attributed to the well-adhered alumina coating that formed on the surfaces of the FeCrAl fibers after thermal treatment and the highly dispersed Pt nanoparticles on the surface of the alumina coating.

Mesoporous MnCeOx solid solutions for low temperature and selective oxidation of hydrocarbons.

The development of noble-metal-free heterogeneous catalysts that can realize the aerobic oxidation of C-H bonds at low temperature is a profound challenge in the catalysis community. Here we report the synthesis of a mesoporous Mn0.5Ce0.5Ox solid solution that is highly active for the selective oxidation of hydrocarbons under mild conditions (100-120 °C). Notably, the catalytic performance achieved in the oxidation of cyclohexane to cyclohexanone/cyclohexanol (100 °C, conversion: 17.7%) is superior to those by the state-of-art commercial catalysts (140-160 °C, conversion: 3-5%). The high activity can be attributed to the formation of a Mn0.5Ce0.5Ox solid solution with an ultrahigh manganese doping concentration in the CeO2 cubic fluorite lattice, leading to maximum active surface oxygens for the activation of C-H bonds and highly reducible Mn(4+) ions for the rapid migration of oxygen vacancies from the bulk to the surface.

Cu-Mn-Ce ternary mixed-oxide catalysts for catalytic combustion of toluene.

Cu-Mn, Cu-Mn-Ce, and Cu-Ce mixed-oxide catalysts were prepared by a citric acid sol-gel method and then characterized by XRD, BET, H2-TPR and XPS analyses. Their catalytic properties were investigated in the toluene combustion reaction. Results showed that the Cu-Mn-Ce ternary mixed-oxide catalyst with 1:2:4 mole ratios had the highest catalytic activity, and 99% toluene conversion was achieved at temperatures below 220°C. In the Cu-Mn-Ce catalyst, a portion of Cu and Mn species entered into the CeO2 fluorite lattice, which led to the formation of a ceria-based solid solution. Excess Cu and Mn oxides existed on the surface of the ceria-based solid solution. The coexistence of Cu-Mn mixed oxides and the ceria-based solid solution resulted in a better synergetic interaction than the Cu-Mn and Cu-Ce catalysts, which promoted catalyst reducibility, increased oxygen mobility, and enhanced the formation of abundant active oxygen species.

Ionic liquid-mediated synthesis of meso-scale porous lanthanum-transition-metal perovskites with high CO oxidation performance.

Lanthanum-transition-metal perovskites with robust meso-scale porous frameworks (meso-LaMO3) are synthesized through the use of ionic liquids. The resultant samples demonstrate a rather high activity for CO oxidation, by taking advantage of unique nanostructure-derived benefits. This synthesis strategy opens up a new opportunity for preparing functional mesoporous complex oxides of various compositions.

Novel hydrophobic PDVB/R-SiO2 for adsorption of volatile organic compounds from highly humid gas stream.

A novel organic-inorganic hydrophobic polydivinylbenzene-silica adsorbent (PDVB/R-SiO2) was successfully prepared by introducing a specific amount of divinylbenzene and solvent (i.e., tetrahydrofuran) to SiO2pores and initiating polymerization under solvothermal conditions. New smaller structures and surface areas were formed in the SiO2 pores. The PDVB/R-SiO2-0.5 samples exhibited a bimodal pore size distribution with both SiO2 micropores/mesopores (0.5-2.0 nm) and mesopores (2.0-5.0 nm). The surface areas increased from 116 m(2)/g (SiO2) to 246 m(2)/g. The breakthrough curves of toluene adsorption indicated that the amount adsorbed on PDVB/R-SiO2-0.5 was 12 times higher than that on SiO2. The highly humid environment exhibited no effect on adsorption because the surface of PDVB was functionalized. The adsorbed toluene was easily desorbed in hot N2 stream at 100 °C. After 10 adsorption-desorption cycles, PDVB/R-SiO2-0.5 continued exhibiting excellent adsorption, indicating superior structural and regeneration abilities.