@article{karchilakis2024capturing,

title = {Capturing Enzyme-Loaded Diblock Copolymer Vesicles Using an Aldehyde-Functionalized Hydrophilic Polymer Brush},

author = {Georgios Karchilakis and Spyridon Varlas and Edwin C Johnson and Oleta Norvilaite and Matthew AH Farmer and George Sanderson and Graham J Leggett and Steven P Armes},

url = {https://pubs.acs.org/doi/full/10.1021/acs.langmuir.4c01561},

doi = {https://doi.org/10.1021/acs.langmuir.4c01561},

year  = {2024},

date = {2024-06-27},

urldate = {2024-06-27},

journal = {Langmuir},

publisher = {ACS Publications},

abstract = {Compared to lipids, block copolymer vesicles are potentially robust nanocontainers for enzymes owing to their enhanced chemical stability, particularly in challenging environments. Herein we report that cis-diol-functional diblock copolymer vesicles can be chemically adsorbed onto a hydrophilic aldehyde-functional polymer brush via acetal bond formation under mild conditions (pH 5.5, 20 °C). Quartz crystal microbalance studies indicated an adsorbed amount, Γ, of 158 mg m–2 for vesicle adsorption onto such brushes, whereas negligible adsorption (Γ = 0.1 mg m–2) was observed for a control experiment conducted using a cis-diol-functionalized brush. Scanning electron microscopy and ellipsometry studies indicated a mean surface coverage of around 30% at the brush surface, which suggests reasonably efficient chemical adsorption. Importantly, such vesicles can be conveniently loaded with a model enzyme (horseradish peroxidase, HRP) using an aqueous polymerization-induced self-assembly formulation. Moreover, the immobilized vesicles remained permeable toward small molecules while retaining their enzyme payload. The enzymatic activity of such HRP-loaded vesicles was demonstrated using a well-established colorimetric assay. In principle, this efficient vesicle-on-brush strategy can be applied to a wide range of enzymes and functional proteins for the design of next-generation immobilized nanoreactors for enzyme-mediated catalysis.},

keywords = {Adsorption, openQCM NEXT, peptides, proteins, QCM-D, Quartz Crystal Microbalance, RAFT polymerization, Thickness, Vesicles},

pubstate = {published},

tppubtype = {article}

}

@article{lim2023quartz,

title = {Quartz crystal microbalance-based biosensing of proteins using molecularly imprinted polydopamine sensing films: Interplay between protein characteristics and molecular imprinting effect},

author = {Hui Jean Lim and Tridib Saha and Beng Ti Tey and Sunil Kumar Lal and Chien Wei Ooi},

url = {https://www.sciencedirect.com/science/article/abs/pii/S2468023023002742},

doi = {https://doi.org/10.1016/j.surfin.2023.102904},

year  = {2023},

date = {2023-04-29},

urldate = {2023-04-29},

journal = {Surfaces and Interfaces},

pages = {102904},

publisher = {Elsevier},

abstract = {Biomimetic sensing films based on molecularly imprinted polydopamine (MIPDA) offer a simple, biocompatible, and versatile approach to functionalise quartz crystal microbalance (QCM)-based biosensors for the recognition of target proteins. This study aims to investigate the chemical, morphological, and recognition properties of MIPDA sensing films polymerised on the QCM crystal surface and elucidate the impacts of various parameters on the liquid-phase biosensing behaviour. Pepsin, bovine serum albumin, human serum albumin, and lysozyme were used as model proteins to study the effect of molecular imprinting and the influence of protein characteristics on the recognition behaviour of MIPDA-functionalised QCM crystals. Analysis of the protein adsorption patterns revealed that the MIPDA film contained heterogeneous binding sites with a dissociation constant in the µM range, showing that the binding affinity of the synthetic sensing film for the target protein was comparable to that of commonly used bioreceptors. In a case study using a pepsin-imprinted MIPDA film, the specific conformation and surface chemistry of the recognition cavities were discovered to promote the binding of pepsin (imprinting factor = 5.78) while simultaneously reducing the nonspecific binding of incompatible proteins on the QCM crystal surface. Protein recognition on MIPDA-functionalised QCM crystals was found to be governed by a combination of nonspecific interactions (e.g., electrostatic and polar interactions) between the proteins and the MIPDA sensing film. The findings indicate that increasing the density of selective recognition cavities in the MIPDA film and optimising the sample pH are key strategies to improve the selectivity and sensitivity for protein biosensing.},

keywords = {molecularly imprinting, openQCM Q-1, polydopamine, proteins, QCM, Quartz Crystal Microbalance, sensing films},

pubstate = {published},

tppubtype = {article}

}

@article{brotherton2023hydrophilic,

title = {Hydrophilic Aldehyde-Functional Polymer Brushes: Synthesis, Characterization, and Potential Bioapplications},

author = {Emma E Brotherton and Edwin C Johnson and Mark J Smallridge and Deborah B Hammond and Graham J Leggett and Steven P Armes},

url = {https://pubs.acs.org/doi/full/10.1021/acs.macromol.2c02471},

doi = {https://doi.org/10.1021/acs.macromol.2c02471},

year  = {2023},

date = {2023-02-22},

urldate = {2023-01-01},

journal = {Macromolecules},

publisher = {ACS Publications},

abstract = {Surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) is used to polymerize a cis-diol-functional methacrylic monomer (herein denoted GEO5MA) from planar silicon wafers. Ellipsometry studies indicated dry brush thicknesses ranging from 40 to 120 nm. The hydrophilic PGEO5MA brush is then selectively oxidized using sodium periodate to produce an aldehyde-functional hydrophilic PAGEO5MA brush. This post-polymerization modification strategy provides access to significantly thicker brushes compared to those obtained by surface-initiated ARGET ATRP of the corresponding aldehyde-functional methacrylic monomer (AGEO5MA). The much slower brush growth achieved in the latter case is attributed to the relatively low aqueous solubility of the AGEO5MA monomer. X-ray photoelectron spectroscopy (XPS) analysis confirmed that precursor PGEO5MA brushes were essentially fully oxidized to the corresponding PAGEO5MA brushes within 30 min of exposure to a dilute aqueous solution of sodium periodate at 22 °C. PAGEO5MA brushes were then functionalized via Schiff base chemistry using an amino acid (histidine), followed by reductive amination with sodium cyanoborohydride. Subsequent XPS analysis indicated that the mean degree of histidine functionalization achieved under optimized conditions was approximately 81%. Moreover, an XPS depth profiling experiment confirmed that the histidine groups were uniformly distributed throughout the brush layer. Surface ζ potential measurements indicated a significant change in the electrophoretic behavior of the zwitterionic histidine-functionalized brush relative to that of the non-ionic PGEO5MA precursor brush. The former brush exhibited cationic character at low pH and anionic character at high pH, with an isoelectric point being observed at around pH 7. Finally, quartz crystal microbalance studies indicated minimal adsorption of a model globular protein (BSA) on a PGEO5MA brush-coated substrate, whereas strong protein adsorption via Schiff base chemistry occurred on a PAGEO5MA brush-coated substrate.},

key = {Functionalization,Monomers,Peptides and proteins,Thickness,X-ray photoelectron spectroscopy},

keywords = {Functionalization, Monomers, peptides, proteins, QCM, Thickness, X-ray, X-ray photoelectron spectroscopy},

pubstate = {published},

tppubtype = {article}

}