Development of histidine-tagged cyclic peptide functionalized monolithic material for the affinity purification of antibodies in biological matrices

Simple surface modification of polypropylene pipette tips for anchoring of organic monolithic-based materials for micro-solid-phase extraction

This paper presents a simple method for the surface modification of polypropylene pipette tips by adsorbing a photo-initiator, 2,2-dimethoxy-2-phenylacetophenone (DMPAP), to create reactive sites for the formation of a layer of ethylene dimethacrylate (EDMA) and subsequent monolith polymerization. The types of monomers and the degree of crosslinking dramatically affected the monolith shrinkage and detachment in unmodified tips. Effective surface modification for anchoring monolithic materials to pipette tips was achieved using 15 wt% DMPAP and 10 wt% EDMA in methanol with UV irradiation at 365 nm. The extraction of 5-hydroxyindoleacetic acid, serotonin, and bisphenol A (BPA) using methacrylate and activated charcoal composite monoliths was investigated in terms of breakthrough capacity. The application of monolithic pipette tip micro-solid-phase extraction followed by HPLC-UV was demonstrated for determining BPA leaching from baby-feeding bottles and canned foods. Wide linearity ranging from 0.1 to 100 ng mL-1 (R2 = 0.9998) with good repeatability (% RSD = 3.9 %) and accuracy (% recovery = 93-106 %) was obtained. The limit of detection and limit of quantification were 0.084 and 0.280 ng mL-1, respectively. By varying the sample loading volume from 0.50 to 10.00 mL with eluting volume of 150 μL, a 2-to-52-fold pre-concentration factor was observed.

Mimotope peptide modified pompon mum-like magnetic microparticles for precise recognition, capture and biotransformation analysis of rituximab in biological fluids

Due to low immobilized ligand density, limited binding capacity, and severe interference from serum proteins, developing ideal peptide-based biomaterials for precise recognition and in vivo analysis of biopharmaceuticals remains a huge challenge. In this study, mimotope peptide modified pompon mum-like biomimetic magnetic microparticles (MMPs, 3.8 μm) that mimic the specific functionalities of CD20 on malignant B cells were developed for the first time. Benefit from the numerous ligand binding sites (Ni2+) on the pompon mum-like MMPs, these novel materials achieved ≥10 times higher peptide ligand densities (>2300 mg/g) and antibody binding capacities (1380 mg/g) compared to previous reported biomaterials. Leveraging the high specificity of the mimotope peptide, rituximab can be precisely recognized and enriched from cell culture media or serum samples. We also established an LC‒MS/MS method using the MMPs for tracking rituximab biotransformation in patient serum. Intriguingly, deamidation of Asn55 and Asn33, as well as oxidation of Met81 and Met34 were observed at the key complementarity determining regions of rituximab, which could potentially influence antibody function and require careful monitoring. Overall, these versatile biomimetic MMPs demonstrate superior recognition and enrichment capabilities for target antibodies, offering interesting possibilities for biotransformation analysis of biopharmaceuticals in patient serum.

Tetrapeptide-based mimotope affinity monolith for the enrichment and analysis of anti-HER2 antibody and antibody-drug conjugate

Selective enrichment and analysis of therapeutic antibodies in biological fluids are crucial for the development of biopharmaceuticals. Recently, peptide-based affinity chromatography has exhibited fascinating prospects for antibody enrichment due to the high affinity and specificity of small peptides. However, the post-modification approach of peptide ligands on the material surface is complicated and time-consuming. In this study, a methacrylate modified tetrapeptide (m-EDPW) was firstly demonstrated as the affinity ligand of trastuzumab (K_d = 1.91 ± 1.81 μM). Next, the m-EDPW based affinity monolith was prepared using a facile one-step polymerization method, which could overcome the drawbacks of traditional post-modification preparation strategies. Based on the monolith as described above, a simple enrichment approach was developed under the optimal washing and elution conditions. Based on the excellent properties, such as high porosity (53.09%), weak electrostatic interaction and suitable affinity (1.00 ± 2.14 μM for anti-HER2 ADC), this novel monolith exhibited good specificity and recovery for antibodies (91.6% for trastuzumab, 98.37% for anti-HER2 ADC), and low nonspecific adsorption for human serum albumin (DBC_10% = 0.5 mg/g polymer). Particularly, this material was successfully applied to enrich trastuzumab and its related antibody-drug conjugate (ADC) from different cell culture medias. The dynamic tracking analysis of ADC in the critical quality attributes (e.g., charge variants, drug to antibody ratio and subunit conjugation ratio) was also achieved by combining the enrichment approach, capillary electrophoresis or reversed phase liquid chromatography. In summary, the exploited peptide-based mimotope affinity materials showed a great potential for the application in biopharmaceutical analysis.