ACS Biomater Sci Eng. 2019 Nov 11;5(11):5759-5769.  doi: 10.1021/acsbiomaterials.9b00218.  Epub 2019 Apr 24. N-Hydroxysuccinimide Bifunctionalized Triblock Cross-Linker Having Hydrolysis Property for a Biodegradable and Injectable Hydrogel System Abstract The design of biocompatible, degradable, and injectable hydrogel has been attractive for achievement of safe and efficient tissue engineering.  Herein, we designed a N-hydroxysuccinimide (NHS) ester-terminated ABA triblock copolymer composed of poly(ethylene glycol) (PEG) as hydrophilic A segments and poly(dl-lactide) (PLA) as B segment having hydrolysis property (NHS-PEG-b-PLA-b-PEG-NHS) to be a cross-linker of polymer segments having amine groups for facile construction of injectable and degradable hydrogel.  The PLA domain, which is widely accepted hydrolyzable segments, is inherently hydrophobic and simple introduction of the NHS group on the ends of PLA would not have high reactivity in aqueous milieu to construct injectable hydrogel.  Thus, in this design, hydrophilic PEG was introduced as A segments to increase the reactivity of NHS groups at the ends of linkers by increasing the mobility.  To demonstrate the property as a cross-linker for constructing degradable and injectable hydrogel, carboxylmethyl chitosan (CH), which is a polymer segment having amine groups, and NHS-PEG-b-PLA-b-PEG-NHS solutions were mixed to form the hydrogel (CH/PEG-PLA-PEG) under physiological condition.  The formation of CH/PEG-PLA-PEG hydrogel proceeded within minute-order period after mixing the solutions, suggesting NHS-PEG-b-PLA-b-PEG-NHS is applicable to the cross-linker for construction of injectable hydrogel system with time-dependent gelation property.  Degradation of the obtained CH/PEG-PLA-PEG hydrogel was observed, whereas that of CH/PEG, which was prepared from NHS-PEG-NHS and CH, was not observed, appealing the degradation property of the CH/PEG-PLA-PEG hydrogel based on hydrolysis of the PLA domain.  Furthermore, chondrocytes embedded in CH/PEG-PLA-PEG hydrogels promoted collagen synthesis compared to CH/PEG.  These demonstrations indicate the designed NHS-PEG-b-PLA-b-PEG-NHS is a promising cross-linker to construct the injectable and degradable hydrogel and eventually promote hydrogel performance as a tissue regeneration scaffold. Keywords: biodegradable and injectable hydrogel;  chitosan;  poly(dl-lactide);  poly(ethylene glycol);  tissue engineering. For more product information, please contact us at: US Tel: 1-844-782-5734 US Tel: 1-844-QUAL-PEG CHN Tel: 400-918-9898 Email: sales@sinopeg.com

J Biotechnol. 2012 Dec 31;162(2-3):283-8. doi: 10.1016/j.jbiotec.2012.09.008. Epub 2012 Sep 20. Preparation, structural analysis and bioactivity of ribonuclease A-albumin conjugate: tetra-conjugation or PEG as the linker Abstract Ribonuclease A (RNase A) is a therapeutic enzyme with cytotoxic action against tumor cells. Its clinical application is limited by the short half-life and insufficient stability. Conjugation of albumin can overcome the limitation, whereas dramatically decrease the enzymatic activity of RNase A. Here, three strategies were proposed to prepare the RNase A-bovine serum albumin (BSA) conjugates. R-SMCC-B (a conjugate of four RNase A attached with one BSA) and R-PEG-B (a mono-conjugate) were prepared using Sulfo-SMCC (a short bifunctional linker) and mal-PEG-NHS (a bifunctional PEG), respectively. Mal-PEG-NHS and hexadecylamine (HDA) were used to prepare the mono-conjugate, R-HDA-B, where HDA was adopted to bind BSA. The PEG linker can elongate the proximity between RNase A and BSA. In contrast, four RNase A were closely located on BSA in R-SMCC-B. R-SMCC-B showed the lowest K(m) and the highest relative enzymatic activity and k(cat)/K(m) in the three conjugates. Presumably, the tetravalent interaction of RNase A in R-SMCC-B can increase the binding affinity to its substrate. In addition, the slow release of BSA from R-HDA-B may increase the enzymatic activity of R-HDA-B. Our study is expected to provide strategies to develop protein-albumin conjugate with high therapeutic potential. For more product information, please contact us at: US Tel: 1-844-782-5734 US Tel: 1-844-QUAL-PEG CHN Tel: 400-918-9898 Email: sales@sinopeg.com

Biomacromolecules. 2013 Feb 11;14(2):331-41. doi: 10.1021/bm301511w. Epub 2013 Jan 18. Phenyl linker-induced dense PEG conformation improves the efficacy of C-terminally monoPEGylated staphylokinase Abstract PEGylation can improve the protein efficacy by prolonging serum half-life and reducing proteolytic sensitivity and immunogenicity. However, PEGylation may decrease the bioactivity of a protein by interfering with binding of its substrate or receptors. Here, staphylokinase (SAK), a thrombolysis agent for therapy of myocardial infarction, was mono-PEGylated at the C-terminus of SAK far from its bioactive domain. Phenyl, propyl, and amyl moieties were used as linkers between SAK and polyethylene glycol (PEG), respectively. Flexible propyl and amyl linkers lead to loose conformation. In contrast, rigid and hydrophobic phenyl linker induces dense PEG conformation that can extensively shield most domains adjacent to C-terminus (e.g., the antigen epitopes and proteolytic sites) of SAK and inefficiently shield its bioactive domain. As compared with loose PEG conformation, dense PEG conformation is more efficient to maintain the bioactivity, increase the plasma half-life, and decrease the proteolytic sensitivity and immunogenicity of the PEGylated SAK. For more product information, please contact us at: US Tel: 1-844-782-5734 US Tel: 1-844-QUAL-PEG CHN Tel: 400-918-9898 Email: sales@sinopeg.com

Merry Christmas! Happy New Year! As the warmth of Christmas fills our hearts, let us cherish the moments with loved ones and spread joy. May the New Year bring fresh beginnings, hope, and endless possibilities. Wishing you a Merry Christmas and a Happy New Year filled with love and laughter!

Bioconjug Chem. 2021 Jul 21;32(7):1263-1275.  doi: 10.1021/acs.bioconjchem.1c00172.  Epub 2021 May 30. The Influence of a Polyethylene Glycol Linker on the Metabolism and Pharmacokinetics of a 89Zr-Radiolabeled Antibody Abstract Most experimental work in the space of bioconjugation chemistry focuses on using new methods to construct covalent bonds between a cargo molecule and a protein of interest such as a monoclonal antibody (mAb).  Bond formation is important for generating new diagnostic tools, yet when these compounds advance to preclinical in vitro and in vivo studies, and later for translation to the clinic, understanding the fate of potential metabolites that arise from chemical or enzymatic degradation of the construct is important to obtain a full picture of the pharmacokinetic performance of a new compound.  In the context of designing new bioconjugate methods for labeling antibodies with the positron-emitting radionuclide 89Zr, we previously developed a photochemical process for making 89Zr-mAbs.  Experimental studies on [89Zr]ZrDFO-PEG3-azepin-mAb constructs revealed that incorporation of the tris-polyethylene glycol (PEG3) linker improved the aqueous phase solubility and radiochemical conversion.  However, the use of a PEG3 linker also has an impact on the whole-body residence time of the construct, leading to a more rapid excretion of the 89Zr activity when compared with radiotracers that lack the PEG3 chain.  In this work, we investigated the metabolic fate of eight possible metabolites that arise from the logical disconnection of [89Zr]ZrDFO-PEG3-azepin-mAb at bonds which are susceptible to chemical or enzymatic cleavage.  Synthesis combined with 89Zr-radiolabeling, small-animal positron emission tomography imaging at multiple time points from 0 to 20 h, and measurements of the effective half-life for whole-body excretion are reported.  The conclusions are that the use of a PEG3 linker is non-innocent in terms of its impact on enhancing the metabolism of [89Zr]ZrDFO-PEG3-azepin-mAbs.  In most cases, degradation can produce metabolites that are rapidly eliminated from the body, thereby enhancing image contrast by reducing nonspecific accumulation and retention of 89Zr in background organs such as the liver, spleen, kidney, and bone. For more product information, please contact us at: US Tel: 1-844-782-5734 US Tel: 1-844-QUAL-PEG CHN Tel: 400-918-9898 Email: sales@sinopeg.com

J Mater Chem B. 2021 May 5;9(17):3666-3676.  doi: 10.1039/d1tb00362c. PEG-PEI-modified gated N-doped mesoporous carbon nanospheres for pH/NIR light-triggered drug release and cancer phototherapy Abstract A novel hybrid drug carrier has been designed, taking N-doped mesoporous carbon (NMCS) as the core and PEG-PEI as the outer shell.  NMCS was functionalized with a photocleavable nitrobenzyl-based linker following a click reaction.  Gemcitabine was loaded into NMCS prior to the functionalization via π-π stacking interactions.  NIR and the pH-responsive behavior of NMCS-linker-PEG-PEI bestow the multifunctional drug carrier with the controlled release of gemcitabine triggered by dual stimuli.  The NMCS core upconverts NIR light to UV, which is absorbed by a photosensitive molecular gate and results in its cleavage and drug release.  Further, NMCS converts NIR to heat, which deforms the outside polymer shell, thus triggering the drug release process.  The release can be promptly arrested if the NIR source is switched off.  A promising gemcitabine release of 75% has been achieved within 24 h under the dual stimuli of pH and temperature.  NMCS-linker-PEG-PEI produced reactive oxygen species (ROS), which were verified in FaDu cells using flow cytometry.  In vitro experiments showed that the NMCS-linker-PEG-PEI-GEM hybrid particle can induce synergistic therapeutic effects in FADU cells when exposed to the NIR light. For more product information, please contact us at: US Tel: 1-844-782-5734 US Tel: 1-844-QUAL-PEG CHN Tel: 400-918-9898 Email: sales@sinopeg.com

Int J Mol Sci. 2023 Jun 5;24(11):9779.  doi: 10.3390/ijms24119779. A dePEGylated Lipopeptide-Based Pan-Coronavirus Fusion Inhibitor Exhibits Potent and Broad-Spectrum Anti-HIV-1 Activity without Eliciting Anti-PEG Antibodies Abstract We previously identified a lipopeptide, EK1C4, by linking cholesterol to EK1, a pan-CoV fusion inhibitory peptide via a polyethylene glycol (PEG) linker, which showed potent pan-CoV fusion inhibitory activity.  However, PEG can elicit antibodies to PEG in vivo, which will attenuate its antiviral activity.  Therefore, we designed and synthesized a dePEGylated lipopeptide, EKL1C, by replacing the PEG linker in EK1C4 with a short peptide.  Similar to EK1C4, EKL1C displayed potent inhibitory activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and other coronaviruses.  In this study, we found that EKL1C also exhibited broad-spectrum fusion inhibitory activity against human immunodeficiency virus type 1 (HIV-1) infection by interacting with the N-terminal heptad repeat 1 (HR1) of viral gp41 to block six-helix bundle (6-HB) formation.  These results suggest that HR1 is a common target for the development of broad-spectrum viral fusion inhibitors and EKL1C has potential clinical application as a candidate therapeutic or preventive agent against infection by coronavirus, HIV-1, and possibly other class I enveloped viruses. Keywords: HIV-1;  broad-spectrum fusion inhibitor;  coronavirus;  six-helix bundle. For more product information, please contact us at: US Tel: 1-844-782-5734 US Tel: 1-844-QUAL-PEG CHN Tel: 400-918-9898 Email: sales@sinopeg.com

Mol Cancer Ther. 2017 Jan;16(1):116-123.  doi: 10.1158/1535-7163.MCT-16-0343.  Epub 2016 Nov 9. Optimization of a PEGylated Glucuronide-Monomethylauristatin E Linker for Antibody-Drug Conjugates Abstract The emergence of antibody-drug conjugates (ADC), such as brentuximab vedotin and ado-trastuzumab emtansine, has led to increased efforts to identify new payloads and develop improved drug-linker technologies.  Most antibody payloads impart significant hydrophobicity to the ADC, resulting in accelerated plasma clearance and suboptimal in vivo activity, particularly for conjugates with high drug-to-antibody ratios (DAR).  We recently reported on the incorporation of a discrete PEG24 polymer as a side chain in a β-glucuronidase-cleavable monomethylauristatin E (MMAE) linker to provide homogeneous DAR 8 conjugates with decreased plasma clearance and increased antitumor activity in xenograft models relative to a non-PEGylated control.  In this work, we optimized the drug-linker by minimizing the size of the PEG side chain and incorporating a self-stabilizing maleimide to prevent payload de-conjugation in vivo Multiple PEG-glucuronide-MMAE linkers were prepared with PEG size up to 24 ethylene oxide units, and homogeneous DAR 8 ADCs were evaluated.  A clear relationship was observed between PEG length and conjugate pharmacology when tested in vivo Longer PEG chains resulted in slower clearance, with a threshold length of PEG8 beyond which clearance was not impacted.  Conjugates bearing PEG of sufficient length to minimize plasma clearance provided a wider therapeutic window relative to faster clearing conjugates bearing shorter PEGs.  A lead PEGylated glucuronide-MMAE linker was identified incorporating a self-stabilizing maleimide and a PEG12 side chain emerged from these efforts, enabling highly potent, homogeneous DAR 8 conjugates and is under consideration for future ADC programs.  Mol Cancer Ther;  16(1);  116-23.  ©2016 AACR. For more product information, please contact us at: US Tel: 1-844-782-5734 US Tel: 1-844-QUAL-PEG CHN Tel: 400-918-9898 Email: sales@sinopeg.com