Self-Healable Sandfish Scale-Inspired Scalable Triboelectric Layer for Hybrid Energy Harvesting in Desert Environment.

In deserts, sedimentation from frequent dust activities on solar cells poses a substantial technical challenge, reducing efficiency and necessitating advanced cost-inefficient cleaning mechanisms. Herein, a novel sandfish scale-inspired self-healing fluorinated copolymer-based triboelectric layer is directly incorporated on top of the polysilicon solar cell for sustained hybrid energy harvesting. The transparent biomimetic layer, with distinctive saw-tooth microstructured morphology, exhibits ultra-low sand adhesion and high abrasion-resistant properties, inhibits sedimentation deposition on solar cells, and concurrently harvests kinetic energy from wind-driven sand particles through triboelectric nanogenerator (TENG). The film exhibits a low friction coefficient (0.149), minimal sand adhesion force (27 nN), and a small wear area (327 µm2). In addition, over 2 months, a solar cell with the sandfish scale-inspired structure demonstrates only a 16% decline in maximum power output compared to the bare solar cell, which experiences a 60% decline. Further, the sandfish scale-based TENG device's electrical output is fully restored to its original value after a 6-h self-healing cycle and maintains consistent stable outputs. These results highlight the exceptional advantages of employing biomimetic self-healing materials as robust triboelectric layers, showcasing sustained device stability and durability for prolonged use in harsh desert environments, ultimately contributing to a low cost-of-electricity generation paradigm.

Injectable Self-Oxygenating Cardio-Protective and Tissue Adhesive Silk-Based Hydrogel for Alleviating Ischemia After Mi Injury.

Myocardial infarction (MI) is a significant cardiovascular disease that restricts blood flow, resulting in massive cell death and leading to stiff and noncontractile fibrotic scar tissue formation. Recently, sustained oxygen release in the MI area has shown regeneration ability; however, improving its therapeutic efficiency for regenerative medicine remains challenging. Here, a combinatorial strategy for cardiac repair by developing cardioprotective and oxygenating hybrid hydrogels that locally sustain the release of stromal cell-derived factor-1 alpha (SDF) and oxygen for simultaneous activation of neovascularization at the infarct area is presented. A sustained release of oxygen and SDF from injectable, mechanically robust, and tissue-adhesive silk-based hybrid hydrogels is achieved. Enhanced endothelialization under normoxia and anoxia is observed. Furthermore, there is a marked improvement in vascularization that leads to an increment in cardiomyocyte survival by ≈30% and a reduction of the fibrotic scar formation in an MI animal rodent model. Improved left ventricular systolic and diastolic functions by ≈10% and 20%, respectively, with a ≈25% higher ejection fraction on day 7 are also observed. Therefore, local delivery of therapeutic oxygenating and cardioprotective hydrogels demonstrates beneficial effects on cardiac functional recovery for reparative therapy.

Enhanced management and antifouling performance of a novel NiFe-LDH@MnO2/PVDF hybrid membrane for efficient oily wastewater treatment.

Layered double hydroxides (LDHs) have gained significant recognition for their facile synthesis and super-hydrophilic two-dimensional (2D) structure to fabricate antifouling membranes for oily wastewater separation. However, conventional PVDF membranes, due to their hydrophobic nature and inert matrix, often exhibit insufficient permeance and compatibility. In this study, a novel NiFe-LDH@MnO2/PVDF membrane was synthesized using ultrasonic, redox, and microwave-hydrothermal processes. This innovative approach cultivated grass-like NiFe-LDH@MnO2 nanoparticles within an inert PVDF matrix, promoting the growth of highly hydrophilic composites. The presence of NiFe-LDH@MnO2 resulted in pronounced enhancements in surface morphology, interfacial wettability, and oil rejection for the fabricated membrane. The optimal NiFe-LDH@MnO2/PVDF-2 membrane exhibited an extremely high pure water flux (1364 L m-2•h-1), and increased oil rejection (from 81.2% to 93.5%) without sacrificing water permeation compared to the original PVDF membrane. Additionally, the NiFe-LDH@MnO2/PVDF membrane demonstrated remarkable antifouling properties, evident by an exceptional fouling resistance ratio of 96.8% following slight water rinsing. Mechanistic insights into the enhanced antifouling performance were elucidated through a comparative "semi-immersion" investigation. The facile synthesis method, coupled with the improved membrane performance, highlights the potential application prospects of this hybrid membrane in emulsified oily wastewater treatment and environmental remediation.

Sialic acid-engineered mesoporous polydopamine dual loaded with ferritin gene and SPIO for achieving endogenous and exogenous synergistic T2-weighted magnetic resonance imaging of HCC.

BACKGROUND: Hepatocellular carcinoma (HCC) is a common malignant tumor with poor prognosis. Magnetic resonance imaging (MRI) is one of the most effective imaging methods for the early diagnosis of HCC. However, the current MR contrast agents are still facing challenges in the early diagnosis of HCC due to their relatively low sensitivity and biosafety. Thus, the development of effective MR agents is highly needed for the early diagnosis of HCC. RESULTS: Herein, we fabricated an HCC-targeted nanocomplexes containing SPIO-loaded mesoporous polydopamine (MPDA@SPIO), sialic acid (SA)-modified polyethyleneimine (SA-PEI), and alpha-fetoprotein regulated ferritin gene (AFP-Fth) which was developed for the early diagnosis of HCC. It was found that the prepared nanocomplexes (MPDA@SPIO/SA-PEI/AFP-Fth) has an excellent biocompatibility towards the liver cells. In vivo and in vivo studies revealed that the transfection of AFP-Fth gene in hepatic cells significantly upregulated the expression level of ferritin, thereby resulting in an enhanced contrast on T2-weighted images via the formed endogenous MR contrast. CONCLUSIONS: The results suggested that MPDA@SPIO/SA-PEI/AFP-Fth had a superior ability to enhance the MR contrast of T2-weighted images of tumor region than the other preparations, which was due to its HCC-targeted ability and the combined T2 contrast effect of endogenous ferritin and exogenous SPIO. Our study proved that MPDA@SPIO/SA-PEI/AFP-Fth nanocomplexes could be used as an effective MR contrast agent to detect HCC in the early stage.

pH-sensitive microfiltration membrane prepared from polyethersulfone grafted with poly(itaconic acid) synthesized by simultaneous irradiation in homogeneous phase.

Poly(itaconic acid) (PIA) was grafted onto polyethersulfone (PES) by homogeneously phased γ-ray irradiation. Kinetic polymerization observed was studied by analyzing the effect of irradiation dosages and monomer concentrations. Then, a pH-sensitive microfiltration (MF) membrane was prepared from these PES-g-PIA polymers with different degrees of grafting under phase inversion method. Finally, the contact angles, morphologies, pore sizes, deionized water permeability and filtration performance for aqueous polyethylene glycols solution of the MF membranes were studied. The results show that grafting PIA groups onto PES molecular chains endowed the MF membranes with effective pH-sensitive properties.

[Relation between drug release and the drug status within curcumin-loaded microsphere].

To study the relation between drug release and the drug status within curcumin-loaded microsphere, SPG (shirasu porous glass) membrane emulsification was used to prepare the curcumin-PLGA (polylactic-co-glycolic acid) microspheres with three levels of drug loading respectively, and the in vitro release was studied with high-performance liquid chromatography (HPLC). The morphology of microspheres was observed with scanning electron microscopy (SEM), and the drug status was studied with X-ray diffraction (XRD), differential scanning calorimetry (DSC) and infrared analysis (IR). The drug loading of microspheres was (5.85 ± 0.21)%, (11.71 ± 0.39)%, (15.41 ± 0.40)%, respectively. No chemical connection was found between curcumin and PLGA. According to the results of XRD, curcumin dispersed in PLGA as amorphous form within the microspheres of the lowest drug loading, while (2.12 ± 0.64)% and (5.66 ± 0.07)% curcumin crystals was detected in the other two kinds of microspheres, respectively, indicating that the drug status was different within three kinds of microspheres. In the data analysis, we found that PLGA had a limited capacity of dissolving curcumin. When the drug loading exceeded the limit, the excess curcumin would exist in the form of crystals in microspheres independently. Meanwhile, this factor contributes to the difference in drug release behavior of the three groups of microspheres.

Molecularly imprinted polymer-based electrochemical sensor for rapid detection of masked deoxynivalenol with Mn-doped CeO2 nanozyme as signal amplifier.

Deoxynivalenol-3-glucoside (D3G), the masked form of the important mycotoxin deoxynivalenol (DON), displays potential toxicity but is difficult to control owing to the lack of rapid detection methods. Herein, an innovative molecularly imprinted polymer (MIP)-based electrochemical sensor was developed for the rapid detection of D3G. MIP, an efficient recognition element for D3G, was electropolymerized using o-phenylenediamine based on a surface functional monomer-directing strategy for the first time. CeO2, which contains both Ce3+ and Ce4+ oxidation states, was introduced as a nanozyme to catalyze H2O2 reduction, while Mn doping generated more oxygen vacancies and considerably improved the catalytic activity. Mn-CeO2 also served as a promising substrate material because of its large surface area and excellent conductivity. Under optimal conditions, a good linear relationship was observed for D3G detection over the concentration range of 0.01-50 ng/mL. The proposed sensor could detect D3G down to 0.003 ng/mL with excellent selectivity, even distinguishing its precursor DON in complex samples. The sensor exhibited acceptable stability with high reproducibility and accuracy, and could successfully determine D3G in grain samples. To the best of our knowledge, this is the first electrochemical sensing platform for rapid D3G detection that can easily be expanded to other masked mycotoxins.

Guanidinium-Functionalized Polymer Dielectrics for Triboelectric Bacterial Detection.

Development of rapid detection strategies that target potentially pathogenic bacteria has gained increasing attention due to the increasing awareness for better health and safety. In this study, we evaluate an intrinsically antimicrobial polymer, 2Gdm, which is a poly(norbornene)-based functional polymer featuring guanidinium groups as side chains, for bacterial detection by the means of triboelectric nanogenerators (TENGs) and triboelectric nanosensors (TENSs). Attachment of bacteria to the sensing layer is anticipated to alter the overall triboelectric properties of the underlying polymer layer. The positively charged guanidinium functional groups can interact with the negatively charged phospholipid bilayer of bacteria and lead to bacterial death, which can then be detected by optical microscopy, X-ray photoelectron microscopy, and more advanced self-powered sensing techniques such as TENGs and TENSs. The double bonds present along the poly(norbornene) backbone allow for thermally induced cross-linking to obtain X-2Gdm and thus rendering materials remain stable in water. By monitoring the change in voltage output after immersion in various concentrations of Gram-negative Escherichia coli (E. coli) and Gram-positive Streptococcus pneumoniae (S. pneumoniae), we have demonstrated the utility of X-2Gdm as a new polymer dielectric for autonomous bacterial detection. As the bacterial concentration increases, the amount of adsorbed bacteria also increases, resulting in a decrease in the surface potential of the X-2Gdm thin film; this reduction in surface potential can cause a decrease in the triboelectric output for both TENGs and TENSs, which serves as a key working mechanism for facile bacterial detection. TENG and TENS systems are capable of detecting E. coli and S. pneumoniae within a range of 4 × 105 to 4 × 108 CFU/mL with a limit of detection of 106 CFU/mL. This report highlights the promising prospects of employing TENGs and TENSs as innovative sensing technologies for rapid bacterial detection by leveraging the electrostatic interactions between bacterial cell membranes and cationic groups present on polymer surfaces.

Spatial distribution, source identification, and transportation paths of plutonium in the Beibu Gulf, South China Sea.

To investigate the spatial distribution and source of plutonium isotopes in the Beibu Gulf, surface sediments were collected and analyzed using sector field inductively coupled plasma mass spectrometry (SF-ICP-MS). The activities of 239+240Pu in surface sediments ranged from 0.012 to 0.451 mBq/g (mean: 0.171 ± 0.138 mBq/g, n = 36), indicating a decreasing trend in a counterclockwise direction from the southern bay mouth. The counterclockwise decreasing trend in the south of the bay mouth is similar to the current in the Beibu Gulf. The 240Pu/239Pu atom ratios in surface sediments ranged from 0.156 to 0.283 (mean: 0.236 ± 0.031, n = 36), slightly higher than that of the global fallout value of 0.18. This suggests that the Pu in the Beibu Gulf was a combination of global fallout and Pacific Proving Ground (PPG). The average contribution of the plutonium (Pu) derived from the PPG in the sediment was estimated to be 52 % ± 24 %.

Polystyrene microplastic particles: In vivo and in vitro ocular surface toxicity assessment.

Microplastics (MPs) have become a global concern as a key environmental pollutant. MPs are widely found in oceans, rivers, bottled water, plastic-packaged foods, and toiletries. The ocular surface is the exposed mucosal tissue, which comes in contact with MP particles contained in toiletries, tap water, cosmetics, and air. However, the effects of MPs on ocular surface health are still unclear. In this study, the toxic effects of polystyrene MPs (PS-MPs) on the ocular surface in vivo and in vitro were explored. The results demonstrated that 50 nm or 2 µm PS-MPs, following exposure for 48 h appeared in the cytoplasm of two kinds of eye cells in vitro and caused a concentration dependent reduction in cell viability, further causing oxidative stress and cell apoptosis. In addition, after treatment for 2 or 4 weeks, 50 nm and 2 µm PS-MPs were deposited in the conjunctival sac of mice. After 2 and 4 weeks of PS-MP treatment, the number of goblet cells in the lower eyelid conjunctival sac decreased to 65% and 40% of that in the control group, respectively. Moreover, dry eye like ocular surface damage and inflammation of conjunctiva and lacrimal gland in mice were observed. In conclusion, this study revealed that PS-MPs could cause ocular surface dysfunctions in mice, thus providing a new perspective for the toxic effects of MPs on ocular surface.

Anti-fouling and protein separation of PVDF-g-PMAA@MnO2 filtration membrane with in-situ grown MnO2 nanorods.

MnO2 nanorods with controllable scale were grown in the PVDF-g-PMAA modified membrane to form PVDF-g-PMAA@ MnO2 membrane through the in situ redox reaction of KMnO4 solution, which is confirmed by scanning electron microscopy (SEM) and X-ray energy-dispersion spectroscopy (EDX). The pore size of the membrane decreased with the increase of KMnO4 solution concentration. The thermodynamic stability and the hydrophilicity of the membrane were also enhanced by the MnO2 nanorods. The water flux, bovine serum albumin (BSA)/Lysozyme protein solution flux and rejection, flux recovery, etc. showed effective improvement of the anti-fouling performance of the PVDF-g-PMAA@ MnO2 membrane. More importantly, it can effectively separate BSA from lysozyme, which provided a potential application in the field of biology, food, and other industrial fields for the requirement of separation and purification.

Enzyme-Mediated Alleviation of Peroxide Toxicity in Self-Oxygenating Biomaterials.

Oxygen releasing biomaterials can facilitate the survival of living implants by creating environments with a viable oxygen level. Hydrophobic oxygen generating microparticles (HOGMPs) encapsulated calcium peroxide (CPO) have recently been used in tissue engineering to release physiologically relevant amounts of oxygen for several weeks. However, generating oxygen using CPO is mediated via the generation of toxic levels of hydrogen peroxide (H2 O2 ). The incorporation of antioxidants, such as catalases, can potentially reduce H2 O2 levels. However, the formulation in which catalases can most effectively scavenge H2 O2 within oxygen generating biomaterials has remained unexplored. In this study, three distinct catalase incorporation methods are compared based on their ability to decrease H2 O2 levels. Specifically, catalase is incorporated within HOGMPs, or absorbed onto HOGMPs, or freely laden into the hydrogel entrapping HOGMPs and compared with control without catalase. Supplementation of free catalase in an HOGMP-laden hydrogel significantly decreases H2 O2 levels reflecting a higher cellular viability and metabolic activity of all the groups. An HOGMP/catalase-laden hydrogel precursor solution containing cells is used as an oxygenating bioink allowing improved viability of printed constructs under severe hypoxic conditions. The combination of HOGMPs with a catalase-laden hydrogel has the potential to decrease peroxide toxicity of oxygen generating tissues.

Necrotizing fasciitis of the jaw, neck and mediastinum caused by Klebsiella oxytoca and Streptococcus constellatus: a case report.

Necrotizing fasciitis (NF) is a rare, fulminant, lethal soft-tissue infection result in fascial necrosis, it is rarer in the head and neck area. Infection caused by Klebsiella oxytoca is much less common. Therefore, we reported a case of NF in the maxillofacial region, neck and upper mediastinum caused by Klebsiella oxytoca as the main cause recently treated in our department. The patient is a middle-aged male with a 10-year history of diabetes with unstable insulin control. The main symptoms were pain on left side with dysphagia and fever and the situation was getting worse. The patient had limited ability to have mouth open and had hyperemia, swelling on the left pharynx, maxillofacial area, and upper left neck and skin tenderness, and all symptoms were getting worse quick. The CT mainly found out that left oropharyngeal wall, parotid gland area, bilateral submaxilla, left neck, and superior mediastinum are swelling with gas. The blood test result: leukocytes count 16.64×109/L, neutrophils percentage 85.8%; C-Pr 320 mg/L; urinary routine: urine glucose (+++++), ketone bodies (+++++); fasting glucose metabolism: glucose 21.33 mmol/L, glycosylated albumin 47.67%. Three incisions of facial and neck were performed to drain pus. Result of bacteria culture: Klebsiella oxytoca and Streptococcus constellatus During treatment of DKA and reduce patient glucose level, we also treated patient with neck and trachea incisions to drain pus and cleaned daily wound area and used different antibiotics according to the bacteria culture and CT results. And finally, the patient was cured and discharged from hospital. This case of NF was very rare not only the bacteria in this case but also the pathological changes related (involving the mediastinum). The report of his diagnosis and treatment can provide experience for future treatments.

[Preparation of polyvinyl alcohol film inlaid with silk fibroin peptide nano-scale particles and evaluation of its function to promote cell growth].

Nano-scale particles of silk fibroin peptide (SFP) were prepared from discarded materials of cocoon or filature by dissolving and enzymolysis. Polyvinyl Alcohol films inlaid with silk fibroin peptide nano-scale particles (SFP in PVA) were prepared by blending nano-SFP and PVA in water according to different blending ratios. The films' characteristics and their promoting cell growth functions were investigated. Silk fibroin fiber was dissolved in 60% NaSCN solution, and was decomposed with alpha-Chymotrypsin, Trypsin and Neutral, respectively. The uniformity of size of SFP nano-particles prepared by Neutral was better and appeared about 80-150 nm. (SFP in PVA) films were characterized by infrared spectroscopy (IR) measurement which demonstrated the combination of SFP and PVA. Scanning electron microscopy revealed the PVA films already inlaid with SFP micro-segment. The surface and form stability in water of the (SFP in PVA) films with blending ratios of 10/90, 20/80, 30/70 and 40/60 were observed. And the results showed that SFP/PVA film with the blending ratio of 30/70 has smoother surface and better stability in water. The Chinese hamster ovary (CHO) cells were cultured, and the promoting cell growth function of (SFP in PVA) films was assessed by MTT colorimetric assay. These findings indicate that SFP/PVA (30/70) film has excellent function of promoting cell growth.

Species and sex differences in the blood clearance and immunogenicity of PEGylated uricase: A comparative 26-week toxicity study in rats and monkeys.

Low response rates and high immunogenicity were observed after repeated injections of pegloticase (Krystexxa) into gout patients during clinical trials. However, related research had not been reported in preclinical animal experiments, which has limited the development of this drug. In this study, the toxicity of mPEG-UHC was studied in rats and monkeys over a 26-week period of repeated intravenous dosing. There were no obvious toxic reactions in the tested animals, with the exception of mPEG-UHC blood clearance and immunogenicity. After repeated injections of mPEG-UHC, rapid loss of uricolytic activity (RLA) was not detected in rats, whereas RLA was observed in 44.4% of drug-treated monkeys. In these monkeys, RLA was observed in 11.1% of males and 77.8% of females, and such incidences increased with higher dosing. High titres of anti-uricase IgG antibodies were associated with RLA but did not result in any toxicity. Remission and recurrence of RLA occurred in one female monkey in the high-dose group because of suppressed and altered immune responses in this animal. The predicted incidence of RLA after repeated injections of mPEG-UHC in gout patients may be lower than that of pegloticase. In this study, the no-observed-adverse-effect levels (NOAELs) of mPEG-UHC in rats and monkeys were 32.0 mg/kg and 20.0 mg/kg, respectively. Therefore, the results showed that rats and monkeys could tolerate long-term and high-dose administrations of mPEG-UHC, and mPEG-UHC blood clearance and immunogenicity showed obvious species and sex differences. These findings will provide valuable information to direct the clinical use of mPEG-UHC.

PEGylated lipid bilayer coated mesoporous silica nanoparticles co-delivery of paclitaxel and curcumin leads to increased tumor site drug accumulation and reduced tumor burden.

Homogeneous PEGylated lipid bilayer coated highly ordered MSNs (PLMSNs) which were systematically optimized and characterized to co-encapsulate paclitaxel (Tax) and curcumin (Cur) were verified to manifest prolonged and enhanced cytotoxic effect against canine breast cancer cells in our previous study. In this article, we took further study of the pharmacokinetic property, cellular uptake, subcellular localization, in vivo distribution and tumor accumulation ability, and treatment efficacy of the drug delivery system. The results revealed that the delivery system could significantly increase the AUC of two drugs, and the anti-tumor effect showed that both intravenous and intratumoral administration group better controlled the tumor weight than that of other groups (P < .05), and the anti-tumor rates were 58.4% and 58.3% respectively. Cell uptake and localization study showed that PLMSNs could effectively carry drugs into cancer cells with sustained release characteristics. The subcellular localization of PLMSNs was mainly in lysosomes and mitochondria. In vivo fluorescence tracing results showed that PLMSNs could be effectively accumulated in the tumor site. The results revealed that the delivery system could effectively reduce the clinical dosage of drugs and reduce its toxic side effects, effectively carry drugs into cancer cells, and exhibit good targeting characteristics for breast cancer.

PEGylated Lipid bilayer coated mesoporous silica nanoparticles for co-delivery of paclitaxel and curcumin: Design, characterization and its cytotoxic effect.

Highly ordered mesoporous silica nanoparticles (MSNs) with pore diameter of 2.754nm and particle size of 115±15nm were prepared with etching method. Homogeneous PEGylated lipid bilayer with 10-15nm thickness was coated around the surface of MSNs using film hydration method. Systematic optimization and characterization of co-encapsulation process of paclitaxel (Tax) and curcumin (Cur) into PEGylated lipid bilayer coated mesoporous silica nanoparticles (PLMSNs) were performed carrying out single factor test, associated with Box-Behnken Design. The concentration of encapsulated drugs was measured by reversed phase high performance liquid chromatography (RP-HPLC) method. Optimal factor settings were as follows: 50mg MSNs, ratio of MSNs to lipid (w/w)=1:1.11, and ratio of lipid to CHO (w/w)=3.93:1. The average experimental EETax, EECur and stability score value were (77.48±2.73) %, (30.70±3.56) % and 4 point respectively based on the conditions mentioned above. Morphology determination of Tax-Cur-PLMSNs revealed that the composite nanoparticles were spherical particals with uniform dispersion. In vitro release experiment indicated that PLMSNs improved dissolution of Tax compared to Tax powder suspension and exhibited sustained release property. Tax-Cur-PLMSNs manifested definite and persistently promoted cytotoxic effect against canine breast cancer cells. This prolonged and enhanced activity of Tax-Cur-PLMSNs might contribute to its sustained release effect.

The Application and Distribution of Magnetic Field Modulation in the Detection Apertures of X-band EPR Cavities for In Vivo Tooth Dosimetry.

In vivo electron paramagnetic resonance tooth dosimetry could be a practical and ideal tool for quick mass triage of victims in the rescue following a disaster event involving irradiation radiation. Magnetic field modulation is an important issue to improve the sensitivity of X-band in vivo tooth dosimetry. We designed a couple of trapezoidal modulation coil sets fixed on the magnet poles that could be used to apply sufficient magnet field modulation into the detection aperture of the resonant cavity. Measurements of irradiated teeth with such coil sets demonstrated significant radiation-induced signals. The modulation generation efficiencies and magnetic field distributions in apertures with different cavity geometries were analytically calculated, simulated by a finite element method and evaluated by measurements of a free radical point sample to study the influences caused by the geometries of the apertures and other factors.

Impact of large aggregated uricases and PEG diol on accelerated blood clearance of PEGylated canine uricase.

BACKGROUND: Uricase has proven therapeutic value in treating hyperuricemia but sufficient reduction of its immunogenicity may be the largest obstacle to its chronic use. In this study, canine uricase was modified with 5 kDa mPEG-SPA and the impact of large aggregated uricases and cross-linked conjugates induced by difunctional PEG diol on immunogenicity was investigated. METHODS AND FINDINGS: Recombinant canine uricase was first expressed and purified to homogeneity. Source 15Q anion-exchange chromatography was used to separate tetrameric and aggregated uricase prior to pegylation, while DEAE anion-exchange chromatography was used to remove Di-acid PEG (precursor of PEG diol) from unfractionated 5 kDa mPEG-propionic acid. Tetrameric and aggregated uricases were separately modified with the purified mPEG-SPA. In addition, tetrameric uricases was modified with unfractionated mPEG-SPA, resulting in three types of 5 kDa mPEG-SPA modified uricase. The conjugate size was evaluated by dynamic light scattering and transmission electron microscope. The influence of differently PEGylated uricases on pharmacokinetics and immunogenicity were evaluated in vivo. The accelerated blood clearance (ABC) phenomenon previously identified for PEGylated liposomes occurred in rats injected with PEGylated uricase aggregates. Anti-PEG IgM antibodies, rather than neutralizing antibodies, were found to mediate the ABC. CONCLUSIONS: The size of conjugates is important for triggering such phenomena and we speculate that 40-60 nm is the lower size limit that can trigger ABC. Removal of the uricase aggregates and the PEG diol contaminant and modifying with small PEG reagents enabled ABC to be successfully avoided and sufficient reduction in the immunogenicity of 5 kDa mPEG-modified tetrameric canine uricase.

Characterization, efficacy, pharmacokinetics, and biodistribution of 5kDa mPEG modified tetrameric canine uricase variant.

PEGylated uricase is a promising anti-gout drug, but the only commercially marketed 10kDa mPEG modified porcine-like uricase (Pegloticase) can only be used for intravenous infusion. In this study, tetrameric canine uricase variant was modified by covalent conjugation of all accessible ɛ amino sites of lysine residues with a smaller 5kDa mPEG (mPEG-UHC). The average modification degree and PEGylation homogeneity were evaluated. Approximately 9.4 5 kDa mPEG chains were coupled to each monomeric uricase and the main conjugates contained 7-11 mPEG chains per subunit. mPEG-UHC showed significantly therapeutic or preventive effect on uric acid nephropathy and acute urate arthritis based on three different animal models. The clearance rate from an intravenous injection of mPEG-UHC varied significantly between species, at 2.61 mL/h/kg for rats and 0.21 mL/h/kg for monkeys. The long elimination half-life of mPEG-UHC in non-human primate (191.48 h, intravenous injection) indicated the long-term effects in humans. Moreover, the acceptable bioavailability of mPEG-UHC after subcutaneous administration in monkeys (94.21%) suggested that subcutaneous injection may be regarded as a candidate administration route in clinical trails. Non-specific tissue distribution was observed after administration of (125)I-labeled mPEG-UHC in rats, and elimination by the kidneys into the urine is the primary excretion route.