Zirconium-containing nanoscale coordination polymers for positron emission tomography and fluorescence-guided cargo delivery to triple-negative breast tumors.

Nanoscale coordination polymer (NCP) is a class of hybrid materials formed by self-assembly of metal ions and organic ligands through coordination. The applications of NCP in biomedicine are quite extensive due to the diversity choice of metal ions and organic ligands. Here we designed Zr-P1 NCP based on Zr4+ selected as metal ion nodes and tetrakis(4-carboxyphenyl) ethylene as bridging ligands. Zr-P1 NCP was modified with functionalized pyrene derived polyethylene glycol (Py-PAA-PEG-Mal) on the surface and further conjugated with cRGD for active targeting of integrin αvß3 overexpressed in triple-negative breast cancer. Doxorubicin was loaded on Zr-P1 NCP with encapsulation efficiency up to 22 % for the treatment of triple negative breast cancer. 89Zr-P1 NCP can be used for in vivo tumor imaging due to the fluorescence properties resulting from the enhanced aggregation-induced Emission (AIE) behavior of P1 ligands and its positron emission tomography (PET) capability. Cellular evaluation indicated that the functionalized Zr-P1@PEG-RGD presented a good function for tumor cell targeting imaging and doxorubicin could be targeted to triple negative breast cancer when it was loaded onto Zr-P1@PEG-RGD, which corroborated with the in vivo results. In summary, 89Zr-P1@PEG-RGD can serve as a biocompatible nanoplatform for fluorescence and PET image-guided cargo delivery. STATEMENT OF SIGNIFICANCE: Nanoscale coordination polymer (NCP) is a class of hybrid materials formed by self-assembly of metal ions and organic ligands through coordination. The diversity of available metals and ligand structures upon NCP synthesis plays an advantage in establishing multimodal imaging platforms. Here we designed 89Zr-P1@PEG-RGD NCP based on Zr4+ selected as metal ion nodes and tetrakis(4-carboxyphenyl) ethylene as bridging ligands. 89Zr-P1@PEG-RGD nanomaterials have positron emission tomography (PET) capability due to the incorporation of zirconium-89, which can be used for in vivo tumor imaging with high sensitivity. The chemotherapeutic drug DOX was loaded on Zr-P1 NCP for the treatment of triple-negative breast cancer, and dual modality imaging can provide visual guidance for drug delivery.

Metal Nanoparticles@Covalent Organic Framework@Enzymes: A Universal Platform for Fabricating a Metal-Enzyme Integrated Nanocatalyst.

Cascade catalysis that combines chemical catalysis and biocatalysis has received extensive attention in recent years, especially the integration of metal nanoparticles (MNPs) with enzymes. However, the compatibility between MNPs and enzymes, and the stability of the integrated nanocatalyst should be improved to promote the application. Therefore, in this study, we proposed a strategy to space-separately co-immobilize MNPs and enzymes to the pores and surface of a highly stable covalent organic framework (COF), respectively. Typically, Pd NPs that were prepared by in situ reduction with triazinyl as the nucleation site were distributed in COF (Tz-Da), and organophosphorus hydrolase (OPH) was immobilized on the surface of Tz-Da by a covalent method to improve its stability. The obtained integrated nanocatalyst Pd@Tz-Da@OPH showed high catalytic efficiency and reusability in the cascade degradation of organophosphate nerve agents. Furthermore, the versatility of the preparation strategy of COF-based integrated nanocatalyst has been preliminarily expanded: (1) Pd NPs and OPH were immobilized in the triazinyl COF (TTB-DHBD) with different pore sizes for cascade degradation of organophosphate nerve agent and the particle size of MNPs can be regulated. (2) Pt NPs and glucose oxidase were immobilized in COF (Tz-Da) to obtain an integrated nanocatalyst for efficient colorimetric detection of phenol.

Emerging risks of toxic metal(loid)s in soil-vegetables influenced by steel-making activities and isotopic source apportionment.

Industrial activities tend to deteriorate adjacent agricultural lands due to accumulation of potentially toxic elements in soils and crops. However, better understanding of their distinctive source partitions and transfer process remains insufficient in steel-making area. The paper focuses on the pollution levels, health risks, and provenance identification of Tl, As, Pb, Cu, Ni, Co, Sb, Cd, Zn, Be, Cr, Fe, Mn, Mo, Sn, and V in common vegetables from different farmlands near a steel-making plant. The results showed that the Tl, As, Pb, Cd, Cr, Cu and Mn were of high-level contamination in soils and generally above the maximum permissible level (MPL). Calculation using hazard quotients (HQ) exhibited that consumption of the studied vegetables may entail significant health risks to residents, especially for children, resulting from the elevated contents of Tl, As and associated toxic elements. Calculation by binary mixing model using Pb isotopic compositions suggested that steel-making activities contributed to 35-80% of the contamination of Pb and As in vegetables. It is necessary to adopt appropriate remediation measures to mitigate the farmland contamination and ensure the food safety of the agricultural products.

Loss-of-function mutations in Lysyl-tRNA synthetase cause various leukoencephalopathy phenotypes.

OBJECTIVE: To expand the clinical spectrum of lysyl-tRNA synthetase (KARS) gene-related diseases, which so far includes Charcot-Marie-Tooth disease, congenital visual impairment and microcephaly, and nonsyndromic hearing impairment. METHODS: Whole-exome sequencing was performed on index patients from 4 unrelated families with leukoencephalopathy. Candidate pathogenic variants and their cosegregation were confirmed by Sanger sequencing. Effects of mutations on KARS protein function were examined by aminoacylation assays and yeast complementation assays. RESULTS: Common clinical features of the patients in this study included impaired cognitive ability, seizure, hypotonia, ataxia, and abnormal brain imaging, suggesting that the CNS involvement is the main clinical presentation. Six previously unreported and 1 known KARS mutations were identified and cosegregated in these families. Two patients are compound heterozygous for missense mutations, 1 patient is homozygous for a missense mutation, and 1 patient harbored an insertion mutation and a missense mutation. Functional and structural analyses revealed that these mutations impair aminoacylation activity of lysyl-tRNA synthetase, indicating that defective KARS function is responsible for the phenotypes in these individuals. CONCLUSIONS: Our results demonstrate that patients with loss-of-function KARS mutations can manifest CNS disorders, thus broadening the phenotypic spectrum associated with KARS-related disease.

Co-immobilization of glucose oxidase and catalase in silica inverse opals for glucose removal from commercial isomaltooligosaccharide.

In this work, glucose oxidase (GOD) and catalase (CAT) were co-immobilized on novel silica inverse opals (IO-SiO2) through sol-gel process. The immobilized bi-enzyme system named GOD/CAT@IO-SiO2 was successfully fabricated and characterized. Morphology characterization indicated that GOD/CAT@IO-SiO2 had hierarchical porous structure, and the pore diameter of macroporous and mesoporous were 500±50nm and 6.8nm, respectively. The macrospores were connected through windows of 100±30nm. The results of stability tests indicated that both acid (or base) resistance and thermal tolerance of GOD/CAT@IO-SiO2 were improved. When GOD/CAT@IO-SiO2 was used to remove glucose from commercial isomaltooligosaccharide (IMO), the immobilized bi-enzyme system exhibited the good performance. The removal efficiency of glucose reached up to 98.97% under the conditions of GOD/CAT activity ratio of 1:30, the amount of enzyme of 68.8mg, reaction time of 9.39h, reaction temperature of 35.2°C and pH of 7.05. After reused 6 times, 79.19% of removal efficiency could be still retained. The present work demonstrates that the immobilized bi-enzyme (GOD/CAT@IO-SiO2) is not only a very promising system for glucose removal but also has great potential for applications in production of gluconic acid, preparation of biosensors, enzyme bioreactors, etc.

Protein-based inverse opals: A novel support for enzyme immobilization.

In this study, protein-based inverse opals were prepared for the first time by using the colloidal crystal templating method. The preparation process involved three steps including filling the templates with protein molecules, crosslinking, and template removal. The obtained inverse opals were used to immobilize Penicillin G acylase (PGA) because of its intrinsic biocompatible property. The immobilization process was optimized and the properties of the immobilized PGA (PGA@IO) were investigated. PGA@IO exhibited improved thermal and pH stability compared with its free counterpart. After reusing nine times, it retained 70% of the initial activity. Besides, the PGA@IO retained high activity during the hydrolysis reactions in continuous catalysis in packed-bed reactor (PBR) after 15 days.

Immobilization of glucose oxidase on polydopamine-functionalized graphene oxide.

In this study, graphene oxide (GO) was modified with dopamine to create a matrix for enzyme immobilization. Dopamine can self-polymerize to get polydopamine (PDA) and coated on GO surface. At the same time, GO was reduced to get PDA/rGO biocomposite. The PDA/rGO may offer adherent surface for enzyme immobilization. Glucose oxidase (GOD), an oxidoreductase, was chosen as model enzyme and can be easily immobilized on PDA/rGO. Experimental results indicated that the thermal and pH stability as well as the storage stability and resistance toward the denaturing agents of GOD were significantly improved after immobilization. The Michaelis constant (K m) of the immobilized GOD was very close to that of the free GOD. This study offers a versatile approach for deposition of biopolymer on GO and provides a way for enzyme immobilization. Hopefully, the immobilized GOD may be further applied for biosensor and biofuel cell applications.

Improved stability of the carbon nanotubes-enzyme bioconjugates by biomimetic silicification.

Nano-materials have been applied in many fields due to their excellent characteristics, such as the high surface area-to-volume ratio, excellent physicochemical properties and biological compatibility. In this study, multi-walled carbon nanotubes (MWCNTs) were utilized to prepare MWCNTs-papain bioconjugates and then realized the immobilization of papain. MWCNTs functionalized with carboxyl- and amine- groups on their surface were used as immobilization carriers. The immobilization of papain on the functionalized MWCNTs through physical absorption was examined. The conjugates were denoted as MWCNTs-papain bioconjugates. To improve the stability, the bioconjugates were further coated by silica through the biomimetic silicification process that induced by papain (denoted as silica-coated bioconjugates). The as-prepared MWCNTs-papain bioconjugates and the silica-coated bioconjugates were characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The preliminary results showed that the bioconjugates could retain most of the initial activity of papain. Compared to free papain and MWCNTs-papain bioconjugates, the silica-coated bioconjugates exhibited significantly improved thermal, pH and recycling stability. Comparisons of the kinetic parameters between MWCNTs-papain bioconjugates and the silica-coated bioconjugates revealed that the K(m) value of the immobilized papain experienced a slight increase after silica coating, which suggested that the silica coating did not significantly hinder papain's access to substrate or release of product.

Comparison of the properties of lipase immobilized onto mesoporous resins by different methods.

Genipin, a natural cross-linking agent, was used for the immobilization of lipase from Candida sp. 99-125 by cross-linking to two kinds of mesoporous resins. Under optimum conditions, the activity recovery of immobilized lipase on resin NKA-9 could reach up to 96.99% when the genipin concentration was 0.5%, and it could reach up to 86.18% for S-8 with a genipin concentration of 0.25%. Compared with using glutaraldehyde as a cross-linking agent, the immobilized lipase using genipin showed better pH and thermal stability, storage stability, and reusability. The residual activity of immobilized lipase using genipin as cross-linker remained more than 60% of its initial activity after six hydrolytic cycles, whereas only about 35% activity remained by using glutaraldehyde as cross-linker.

Sandwich-structured enzyme membrane reactor for efficient conversion of maltose into isomaltooligosaccharides.

A novel enzyme membrane reactor with sandwich structure has been developed by confining glucosidase between two sheets of ultrafiltration membranes to effectively convert maltose to isomaltooligosaccharides (IMOs). The hydrophilic ultrafiltration membranes, which were prepared by phase inversion method using PES as bulk polymer and Pluronic F127 as both surface modification and pore formation agent, exhibited the desirable enzyme adsorption-resistant property. The scanning electron microscopy (SEM) photographs showed that two sheets of PES/Pluronic F127 membranes were packed tightly and glucosidase was kept in a free state within a nanoscale space. When the weight ratio of Pluronic F127 to PES was 30%, glucosidase could be completely rejected by the membranes. Due to the sandwich structuring of the membrane reactor and the high hydrophilicity of the PES/Pluronic F127 membrane surface, maltose conversion and yield reached 100% and 58% under the optimum experimental conditions (pH 6.0, 50 degrees C), respectively.

Biomimetic fabrication of hydroxyapatite-polysaccharide-formate dehydrogenase composite capsules for efficient CO(2) conversion.

In this study, a novel kind of hydroxyapatite-polysaccharide capsules was prepared through a bio-inspired process in simulated body fluid for efficient encapsulation of formate dehydrogenase. In this process, a thin alginate/chitosan film formed immediately around the capsules coupled with in situ precipitation of hydroxyapatite when alginate HPO(4)(2-)-stock solution droplets were added into chitosan Ca(2+)-stock solution. The biomineralization of hydroxyapatite was mimicked by the counter-diffusion system in which calcium ions and phosphate ions migrated into the alginate/chitosan film from opposite directions. Formation of capsule was confirmed by Zoom Stereo Microscopy, the surface morphology of the capsule was characterized by SEM, the surface element composition of capsules was analyzed by EDX and the pore size distribution of capsule shell was determined by BET. As compared to the free formate dehydrogenase, hydroxyapatite-polysaccharide-formate dehydrogenase composite capsules exhibited significantly higher activity and storage stability in a broader temperature and pH range when converting CO(2) to formic acid.