高效液相色谱-串联质谱法同时测定供港生猪尿液中29种限用兽药残留

建立了高效液相色谱-串联质谱(HPLC-MS/MS)同时测定生猪尿液中喹诺酮类、磺胺类、磺胺增效剂、四环素类、林可胺类、大环内脂共29种限用兽药残留量的检测方法。试样经乙酸铵和EDTA-Na缓冲液提取,HLB固相萃取小柱净化后,HPLC-MS/MS进行测定,其中β-受体激动剂类用内标法定量,其余兽药用外标法定量。在电喷雾电离正离子模式下,以多反应监测(MRM)方式采集数据进行定性与定量分析。29种兽药在猪尿基质中标准曲线的线性系数(r)均大于0.99,3个不同加标水平下的平均回收率为58%~108%,日内相对标准偏差(RSD)为1.9%~18.9%,日间RSD为3.4%~20.9%;定量下限(LOQ,S/N≥10)为1.0~10.0μg/L。该方法经济、高效、可靠,可用于生猪屠宰前兽药多残留的快速检测。     

Transformable Peptide Nanocarriers for Expeditious Drug Release and Effective Cancer Therapy via Cancer‐Associated Fibroblast Activation

A novel cleavable amphiphilic peptide (CAP) was designed to be specifically responsive to fibroblast activation protein‐α (FAP‐α), a protease specifically expressed on the surface of cancer‐associated fibroblasts. The CAP self‐assembled into fiber‐like nanostructures in solution, while the presence of hydrophobic chemotherapeutic drugs readily transformed the assemblies into drug‐loaded spherical nanoparticles. The disassembly of these nanoparticles (CAP‐NPs) upon FAP‐α cleavage resulted in rapid and efficient release of the encapsulated drugs specifically at tumor sites. This Transformers‐like drug delivery strategy could allow them to disrupt the stromal barrier and enhance local drug accumulation. Therapeutic results suggested that drug‐loaded CAP‐NPs hold promising tumor specificity and therapeutic efficacy for various solid tumor models, confirming its potential utility and versatility in antitumor therapy.     

Diamond Quantum Devices in Biology

The currently available techniques for molecular imaging capable of reaching atomic resolution are limited to low temperatures, vacuum conditions, or large amounts of sample. Quantum sensors based on the spin‐dependent photoluminescence of nitrogen‐vacancy (NV) centers in diamond offer great potential to achieve single‐molecule detection with atomic resolution under ambient conditions. Diamond nanoparticles could also be prepared with implanted NV centers, thereby generating unique nanosensors that are able to traffic into living biological systems. Therefore, this technique might provide unprecedented access and insight into the structure and function of individual biomolecules under physiological conditions as well as observation of biological processes down to the quantum level with atomic resolution. The theory of diamond quantum sensors and the current developments from their preparation to sensing techniques have been critically discussed in this Minireview.     

Microporous Polymeric 3D Scaffolds Templated by the Layer‐by‐Layer Self‐Assembly

Polymeric scaffolds serve as valuable supports for biological cells since they offer essential features for guiding cellular organization and tissue development. The main challenges for scaffold fabrication are i) to tune an internal structure and ii) to load bio‐molecules such as growth factors and control their local concentration and distribution. Here, a new approach for the design of hollow polymeric scaffolds using porous CaCO₃ particles (cores) as templates is presented. The cores packed into a microfluidic channel are coated with polymers employing the layer‐by‐layer (LbL) technique. Subsequent core elimination at mild conditions results in formation of the scaffold composed of interconnected hollow polymer microspheres. The size of the cores determines the feature dimensions and, as a consequence, governs cellular adhesion: for 3T3 fibroblasts an optimal microsphere size is 12 μm. By making use of the carrier properties of the porous CaCO₃ cores, the microspheres are loaded with BSA as a model protein. The scaffolds developed here may also be well suited for the localized release of bio‐molecules using external triggers such as IR‐light.

     

Solvent‐Free Fabrication of polyHIPE Microspheres for Controlled Release of Growth Factors

The growth factor bone morphogenetic protein 2 (BMP‐2) is utilized in surgical procedures to improve bone regeneration; however, current treatments deliver BMP‐2 at amounts greater than 100 000 fold of physiological levels, which increases treatment costs and risk of side effects. Drug‐eluting microcarriers developed to improve these therapies have faced significant commercialization challenges including particle size distributions, solvent removal, low encapsulation efficiency, and bioactivity loss. In this study, a solvent‐free method is presented for fabrication of uniform polyHIPE microspheres for controlled growth factor release. Emulsion templating principles and fluid dynamics were used to fabricate uniform particles with tunable particle size (200–800 μm) and pore size (10–30 μm). The ability to independently tune particle and pore size is expected to provide excellent control of release kinetics. Overall, this solvent‐free method for making porous microspheres displays strong promise for the controlled release of BMP‐2 and other growth factors.

     

Multi‐Responsive Polypeptidosome: Characterization,Morphology Transformation,and Triggered Drug Delivery

The biodegradable polymeric nanomedicines that may be integrated with multi‐stimuli‐sensitivity to achieve triggered or on‐demand drug release kinetics are challenging for polymer therapeutics and drug delivery systems. By controlling the structure transformation of one polypeptide‐b‐PEO copolymer, a novel multi‐responsive polypeptide‐based vesicle (polypeptidosome) presents the combined sensitivity of multiple physiological and clinic‐related stimuli, and both morphology and size of the polypeptidosome are changed during the triggered process. The designer polypeptide has unique structures composed of 1) light‐responsive o‐nitrobenzyl groups, 2) oxidizable thioether linkers, 3) photo‐caged redox thiol groups on parent poly(L‐cysteine), and 4) tunable conformation, which enable the polypeptidosome to have a peculiar multi‐response. The anticancer drug doxorubicin can be released in a controlled or on–off manner. The combination stimuli of UV irradiation and H₂O₂ oxidation induces a large effect and a lower IC₅₀ of 3.80 μg doxorubicin (DOX) equiv/mL compared to 5.28 μg DOX equiv/mL of individual H₂O₂ trigger.

     

Tumor‐Acidity Activated Surface Charge‐Conversion of Polymeric Nanocarriers for Enhanced Cell Adhesion and Targeted Drug Release

The development of stimuli‐responsive polymeric nanocarriers could significantly enhance drug bioavailability due to improved pharmacokinetics and biodistribution. However, in the drug delivery process, the poor cell uptake of drug‐loaded carriers has greatly limited the therapeutic efficiency for anti‐cancer applications. Herein, 2,3‐dimethylmaleic anhydride (DMMA) is engineered into the well‐defined biodegradable amphiphilic block copolymer poly(D,L‐lactide)‐block‐poly(2‐aminoethyl methacrylate) (PLA‐b‐PAEMA) to construct a tumor‐acidity activated nanocarrier (PLA‐b‐PAEMA/DMMA) for potential tumor therapy. After the loading of positively charged DOX·HCl into the negatively charged corona structure through electrostatic attraction, this carrier is expected to prolong the blood circulation time and smartly convert surface charge from negative to positive for enhanced tumor cell uptake and targeted drug release. Furthermore, this carrier exhibits additional cytotoxicity for tumor cells after the tumor‐acidity activated surface charge‐conversion from negative to positive. Thus, this smart carrier is a feasible candidate for potential cancer therapy.

     

Metallo‐Supramolecular Nanogels for Intracellular pH‐Responsive Drug Release

A simple process is developed to fabricate metallo‐supramolecular nanogels (MSNs) by the metallo‐supramolecular‐coordinated interaction between histidine and iron‐meso‐tetraphenylporphin. MSNs are composed of histidine‐modified dextran (DH) and iron‐meso‐tetraphenylporphin (Fe–Por) and exhibit excellent biocompatibility and stability. MSNs show pH responsiveness in the intracellular mildly acidic environment, which has great potential for acid‐triggered drug release delivery. In vitro drug release profiles demonstrate that the pH‐dependent disassembly of MSNs to histidine and Por results in a quicker release rate of loaded‐DOX at pH 5.3, while at pH 7.4 MSNs could hinder the release of loaded‐DOX due to the enhanced stability of MSNs.

     

Aromatic interactions impact ligand binding and function at serotonin 5-HT2C G protein-coupled receptors: receptor homology modelling,ligand docking,and molecular dynamics results validated by experimental studies

The serotonin (5-hydroxytryptamine, 5-HT) 5-HT₂ G protein-coupled receptor (GPCR) family consists of types 2A, 2B, and 2C that share ～75% transmembrane (TM) sequence identity. Agonists for 5-HT_2C receptors are under development for psychoses; whereas, at 5-HT_2A receptors, antipsychotic effects are associated with antagonists – in fact, 5-HT_2A agonists can cause hallucinations and 5-HT_2B agonists cause cardiotoxicity. It is known that 5-HT_2A TM6 residues W6.48, F6.51, and F6.52 impact ligand binding and function; however, ligand interactions with these residues at the 5-HT_2C receptor have not been reported. To predict and validate molecular determinants for 5-HT_2C-specific activation, results from receptor homology modelling, ligand docking, and molecular dynamics simulation studies were compared with experimental results for ligand binding and function at wild type and W6.48A, F6.51A, and F6.52A point-mutated 5-HT_2C receptors.     

Protamine‐Capped Mesoporous Silica Nanoparticles for Biologically Triggered Drug Release

The fabrication of a mesoporous silica nanoparticle (MSN)?protamine hybrid system (MSN?PRM) is reported that selectively releases drugs in the presence of specific enzyme triggers present in the proximity of cancer cells. The enzyme trigger involved is a protease called trypsin, which is overexpressed in certain specific pathological conditions, such as inflammation and cancer. Overexpression of trypsin is known to be associated with invasion, metastasis, and growth in several cancers, such as leukemia, colon cancer, and colorectal cancer. The current system (MSN–PRM) consists of an MSN support in which mesopores are capped with an FDA‐approved peptide drug protamine, which effectively blocks the outward diffusion of the drug molecules from the mesopores of the MSNs. On exposure to the enzyme trigger, the protamine cap disintegrates, opening up the molecular gates and releasing the entrapped drug molecules. The system exhibits minimal premature release in the absence of the trigger and selectively releases the encapsulated drugs in the presence of the proteases secreted by colorectal cancer cells. The ability of the MSN–PRM particles to deliver anticancer drugs to colorectal cancer cells has also been demonstrated. The hydrophobic drug is released into cancer cells subsequent to disintegration of the protamine cap, resulting in cell death. Drug‐induced cell death in colorectal cancer cells is significantly enhanced when the hydrophobic drug that is known to degrade in aqueous environments is encapsulated in the MSN–PRM system in comparison to the free drug (P < 0.05). The system, which shows good biocompatibility and selective drug release, is a promising platform for cancer specific drug delivery.