Enhanced biomimetic catalysis via self-cascade photocatalytic hydrogen peroxide production over modified carbon nitride nanozymes for total antioxidant capacity evaluation.

The peroxidase mimics usually requires the addition of exogenous hydrogen peroxide (H2O2), which greatly hinder their practical applications. Herein, through rational co-modification of multiple elements (potassium (K), chlorine (Cl) and iodine (I)), the modified carbon nitride nanomaterials (KCl/KI-CN) could serve as efficient bifunctional catalysts. The multiple elements doping and the incorporation of cyano groups (CN) are deemed to enhance their photocatalytic and peroxidase-like activity, respectively. Based on the photocatalytic function, H2O2 can be produced continuously and steadily via two-electron oxygen reduction over modified carbon nitride under visible light irradiation. Subsequently, the KCl/KI-CN could catalyze the chromogenic substrate by the in-situ produced H2O2. Taking advantage of the bifunctional properties of modified carbon nitride, we for the first time demonstrate a self-cascade catalytic process and apply successfully for the ascorbic acid (AA) detection and versatile total antioxidant capacity (TAC) evaluation. This paper not only prepares an efficiently bifunctional catalyst but also provides a new self-cascade photocatalytic H2O2 production strategy for the peroxidase-like application.

Single-atom Fe nanozymes with excellent oxidase-like and laccase-like activity for colorimetric detection of ascorbic acid and hydroquinone.

Although traditional Fe-based nanozymes have shown great potential, generally only a small proportion of the Fe atoms on the catalyst's surface are used. Herein, we synthesized single-atom Fe on N-doped graphene nanosheets (Fe-CNG) with high atom utilization efficiency and a unique coordination structure. Active oxygen species including superoxide radicals (O2•-) and singlet oxygen (1O2) were efficiently generated from the interaction of the Fe-CNG with dissolved oxygen in acidic conditions. The Fe-CNG nanozymes were found to display enhanced oxidase-like and laccase-like activity, with Vmax of 2.07 × 10-7 M∙S-1 and 4.54 × 10-8 M∙S-1 and Km of 0.324 mM and 0.082 mM, respectively, which is mainly due to Fe active centers coordinating with O and N atoms simultaneously. The oxidase-like performance of the Fe-CNG can be effectively inhibited by ascorbic acid (AA) or hydroquinone (HQ), which can directly obstruct the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB). Therefore, a direct and sensitive colorimetric method for the detection of AA and HQ activity was established, which exhibited good linear detection and limit of detection (LOD) of 0.048 µM and 0.025 µM, respectively. Moreover, a colorimetric method based on the Fe-CNG catalyst was fabricated for detecting the concentration of AA in vitamin C. Therefore, this work offers a new method for preparing a single-atom catalyst (SAC) nanozyme and a promising strategy for detecting AA and HQ.

Transcriptome analysis revealed differentially expressed genes in rice functionally associated with brown planthopper defense in near isogenic lines pyramiding BPH14 and BPH15.

Although rice has many pests, brown planthopper (BPH) in particular is known to cause substantial damage. The pyramiding application of BPH-resistance genes BPH14 and BPH15 has proven effective in enhancing rice defense against BPH. However, the molecular mechanisms underlying BPH14/BPH15-conferred resistance remain unexplained. In this investigation, we analyzed the transcriptomes of near isogenic lines (NILs) containing either BPH14 (B14), BPH15 (B15), or BPH14/BPH15 (B1415), as well as their recurrent parent (RP) 'Wushansimiao'. In total, we detected 14,492 differentially expressed genes (DEGs) across 12 mRNA profiles of resistant NILs and RP at different feeding stages. In the transcriptomic analysis, 531 DEGs appeared to be common among the resistant NILs compared to RP before and after BPH feeding. These common DEGs were enriched in defense response, phosphorylation, and salt stress response. In addition, 258 DEGs shared only in resistant NILs were obtained among the different feeding stages, which were enriched in oxidative stress response, karrikin response, and chloroplast organization. Considering the expression patterns and relevant research reports associated with these DEGs, 21 were chosen as BPH resistance candidates. In rice protoplasts, the candidate DEG OsPOX8.1 was confirmed to increase reactive oxygen species (ROS) accumulation by chemiluminescence measurement. Our results provide valuable information to further explore the defense mechanism of insect-resistant gene pyramiding lines and develop robust strategies for insect control.

BSA-stabilized silver nanoclusters for efficient photoresponsive colorimetric detection of chromium(VI).

Hexavalent chromium is a highly toxic substance, which will pose a serious threat to human life and health and the entire ecosystem. Therefore, it is crucial to establish a simple and rapid detection method for hexavalent chromium. In this work, we fabricated bovine serum albumin-stabilized silver nanocluster (BSA-Ag13 NC) which exhibited photoresponsive oxidase-like activity, catalyzing the oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) to the blue oxidized state TMB (oxTMB) in a short time. Interestingly, 8-hydroxyquinoline (8-HQ) can significantly inhibit the color reaction of TMB oxidation while Cr(VI) can interact specifically with 8-HQ to restore this chromogenic reaction. Based on the above facts, a colorimetric sensing system for detecting Cr(VI) was developed. The sensing system shows a wide linear range, and good selectivity, with a low detection limit of 2.32 nM. Moreover, this sensing system could be successfully applied to the detection of Cr(VI) in lake water, tap water, and sewage with satisfactory results.

Platinum nanoparticles confined in metal-organic frameworks as excellent peroxidase-like nanozymes for detection of uric acid.

High levels of uric acid (UA) in humans can cause a range of diseases, and traditional assays that rely on uric acid enzymes to break down uric acid are limited by the inherent deficiencies of natural enzymes. Fortunately, the rapid development of nanozymes in recent years is expected to solve the above-mentioned problems. Hence, we used a host-guest strategy to synthesize a platinum nanoparticle confined in a metal-organic framework (Pt NPs@ZIF) that can sensitively detect UA levels in human serum. Unlike previously reported free radical-catalyzed oxidation systems, its unique electron transfer mechanism confers excellent peroxidase-like activity to Pt NPs@ZIF. In addition, UA can selectively inhibit the chromogenic reaction of TMB, thus reducing the absorbance of the system. Therefore, using the peroxidase-like activity of Pt NPs@ZIF and using TMB as a chromogenic substrate, UA can be detected directly without relying on natural enzymes. The results showed a relatively wide detection range (10-1000 µM) and a low detection limit (0.2 µM). Satisfactory results were also obtained for UA in human serum. This study with simple operation and rapid detection offers a promising method for efficiently detecting UA in serum.

Development and Characterization of a Nanobody against Human T-Cell Immunoglobulin and Mucin-3.

Monoclonal antibodies and antibody-derived biologics are essential tools for cancer research and therapy. The development of monoclonal antibody treatments for successful tumor-targeted therapies took several decades. A nanobody constructed by molecular engineering of heavy-chain-only antibody, which is unique in camel or alpaca, is a burgeoning tools of diagnostic and therapeutic in clinic. In this study, we immunized a 4-year-old female alpaca with TIM-3 antigen. Then, a VHH phage was synthesized from the transcriptome of its B cells by nested PCR as an intermediate library; the library selection for Tim-3 antigen is carried out in three rounds of translation. The most reactive colonies were selected by periplasmic extract monoclonal ELISA. The nanobody was immobilized by metal affinity chromatography (IMAC) purification with the use of a Ni-NTA column, SDS-PAGE, and Western blotting. Finally, the affinity of TIM3-specific nanobody was determined by ELISA. As results, specific 15 kD bands representing nanomaterials were observed on the gel and confirmed by Western blotting. The nanobody showed obvious specific immune response to Tim-3 and had high binding affinity. We have successfully prepared a functional anti-human Tim-3 nanobody with high affinity in vitro.

MIIP inhibits clear cell renal cell carcinoma proliferation and angiogenesis via negative modulation of the HIF-2α-CYR61 axis.

OBJECTIVE: In various cancers, migration and invasion inhibitory protein (MIIP) is expressed at low level and is involved in cancer pathogenesis. Herein, we sought to explore the function of MIIP in clear cell renal cell carcinoma (ccRCC). METHODS: CCK-8, colony formation, cell cycle, and endothelial cell tube formation assays were performed to evaluate the roles of MIIP in ccRCC proliferation and angiogenesis. To explore the underlying mechanism, we conducted RNA-sequencing, GSEA, qRT-PCR, Western blot, ELISA, cell transfection, coimmunoprecipitation, and ubiquitination assays in ccRCC cell lines. Furthermore, xenograft tumor growth in nude mice, and Ki-67 and CD31 staining in xenograft tissues were examined. Finally, the association of MIIP expression with clinical pathology and the expression status of HIF-2α and cysteine-rich 61 (CYR61) were further analyzed in human RCC tissues through Western blot and immunohistochemistry. RESULTS: Both in vitro and in vivo functional experiments indicated that forced expression of MIIP inhibited ccRCC proliferation and angiogenesis, whereas silencing MIIP either in normal HK-2 cells or in ccRCC cells had the opposite effect (P < 0.05). Mechanistically, CYR61 was identified as a gene significantly downregulated by MIIP overexpression, and was required for the suppressive role of MIIP in ccRCC. MIIP was found to promote HSP90 acetylation and thus impair its chaperone function toward HIF-2α. Consequently, RACK1 binds HIF-2α and causes its ubiquitination and proteasomal degradation, thus decreasing the transcription of its target, CYR61. Finally, analyses of clinical samples demonstrated that MIIP is significantly downregulated in cancer vs. normal tissues in RCC cases, and its expression is negatively associated with histological grade, metastasis, the prognosis of patients with RCC, and the expression of HIF-2α and CYR61 (P < 0.05). CONCLUSIONS: MIIP is a novel tumor suppressor in ccRCC via negative regulation of HIF-2α-CYR61 axis.

Cistanoside of Cistanche Herba ameliorates hypoxia-induced male reproductive damage via suppression of oxidative stress.

Increasing evidence shows that hypoxia is a cause of male infertility, and hypoxia may be related to oxidative stress (OS). Cistanoside (Cis) is a phenylethanoid glycoside compound that can be extracted from Cistanches Herba and possesses various biological functions. This study aimed to investigate the protective effects of Cis on reproductive damage induced by hypoxia and explore the specific underlying mechanisms. Cell and animal hypoxia experimental models were constructed, and the protective effects of different subtypes of Cis on the male reproductive system were assessed both in vitro and in vivo. The results indicated that hypoxia significantly reduced the viability of GC-1 cells through cell cycle arrest and apoptosis activation, which were associated with increased OS. Moreover, Cis showed strong antioxidative effects both in vitro and in vivo, significantly restoring antioxidant enzyme activities and downregulating reactive oxygen species (ROS) levels while increasing cell viability and decreasing apoptosis. Importantly, the Cis subtypes (Cis-A, Cis-B, Cis-C and Cis-H) studied herein all showed certain antioxidant effects, among which the effects of Cis-B were the most significant. This study demonstrates that Cis markedly attenuates the harmful effects of hypoxia-induced OS by affecting antioxidant enzyme activities in testes and GC-1 cells.

MIIP inhibits EMT and cell invasion in prostate cancer through miR-181a/b-5p-KLF17 axis.

Growing evidence have shown that the migration and invasion inhibitory protein (MIIP, also known as IIp45) functions as a tumor suppressor and its expression is downregulated in several types of cancer, yet the function of MIIP in prostate cancer (PCa) and the underlying mechanism of action remains largely unknown. Here we demonstrated that MIIP acts as a suppressor of PCa by inhibiting epithelial-mesenchymal transition (EMT) and cell invasion. Overexpressing MIIP repressed cellular invasion of PC3 and DU145 in vitro, accompanied by a decrease of EMT-inducing factors, and an increase of E-cadherin and KLF17. Moreover, a stable MIIP knockdown in PCa cells promoted the tumor growth or bone osteolytic lesions, when xenografted subcutaneously or via tibia injection. Mechanistically, MIIP represses two onco-miRNAs, miR-181a-5p and miR-181b-5p, thus removing the inhibitory effect of these two miRNAs on their target KLF17, which functions as a negative regulator of EMT by directly suppressing the transcription of SNAIL1/2 and TWIST. Finally, by examining the expression of MIIP, miR-181a/b-5p, KLF17, and E-cadherin in paired cancer samples v.s. adjacent normal tissues from a cohort of human prostate cancer patients, we demonstrated that downregulation of MIIP was well associated with downregulation of KLF17 and E-cadherin, but upregulation of miR-181a/b-5p. The positive correlation between MIIP and KLF17 was also confirmed via immunohistochemical staining of a PCa tissue microarray. Taken together, our findings reveal a novel function of MIIP as an EMT inhibitor in PCa and illustrate the underlying molecular mechanisms, providing new insights into the tumor-suppressor role of MIIP.