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Blood compatible materials are required for the development of therapeutic and diagnostic blood contacting devices as blood-material interactions are a key factor dictating device functionality. In this work, we explored biofunctionalization of silk biomaterials with a recombinantly expressed domain V of the human basement membrane proteoglycan perlecan (rDV) towards the development of blood compatible surfaces. Perlecan and rDV are of interest in vascular device development as they uniquely support endothelial cell, while inhibiting smooth muscle cell and platelet interactions. rDV was covalently immobilized on silk biomaterials using plasma immersion ion implantation (PIII), a new method of immobilizing proteins on silk biomaterials that does not rely on modification of specific amino acids in the silk protein chain, and compared to physisorbed and carbodiimide immobilized rDV. Untreated and treated silk biomaterials were examined for interactions with blood components with varying degrees of complexity, including isolated platelets, platelet rich plasma, blood plasma, and whole blood, both under agitated and flow conditions. rDV-biofunctionalized silk biomaterials were shown to be blood compatible in terms of platelet and whole blood interactions and the PIII treatment was shown to be an effective and efficient means of covalently immobilizing rDV in its bioactive form. These biomimetic silk biomaterials are a promising platform toward development of silk-based blood-contacting devices for therapeutic, diagnostic, and research applications. STATEMENT OF SIGNIFICANCE: Blood compatible materials are required for the development of therapeutic and diagnostic blood contacting devices as blood-material interactions are a key factor dictating device functionality. In this work, we explored biofunctionalization of silk biomaterials with a recombinantly expressed domain V (rDV) of the human basement membrane proteoglycan perlecan towards the development of blood compatible surfaces. Perlecan and rDV are of interest in vascular device development as they uniquely support endothelial cell, while inhibiting smooth muscle cell and platelet interactions. rDV was covalently immobilized on silk biomaterials using plasma immersion ion implantation (PIII), a new method of immobilizing proteins on silk biomaterials that does not rely on modification of specific amino acids in the silk protein chain. These biomimetic silk biomaterials are a promising platform toward development of silk-based blood-contacting devices for therapeutic, diagnostic, and research applications., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021. Published by Elsevier Ltd.)

The interactions between biomolecules and solid surfaces play an important role in designing new materials and applications which mimic nature. Recently, solid-binding peptides (SBPs) have emerged as potential molecular building blocks in nanobiotechnology. SBPs exhibit high selectivity and binding affinity towards a wide range of inorganic and organic materials. Although these peptides have been widely used in various applications, there is a need to understand the interaction mechanism between the peptide and its material substrate, which is challenging both experimentally and theoretically. This review describes the main characterisation techniques currently available to study SBP-surface interactions and their contribution to gain a better insight for designing new peptides for tailored binding., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Perlecan, or heparan sulfate proteoglycan 2 (HSPG2), is a ubiquitous heparan sulfate proteoglycan that has major roles in tissue and organ development and wound healing by orchestrating the binding and signaling of mitogens and morphogens to cells in a temporal and dynamic fashion. In this review, its roles in fibrosis are reviewed by drawing upon evidence from tissue and organ systems that undergo fibrosis as a result of an uncontrolled response to either inflammation or traumatic cellular injury leading to an over production of a collagen-rich extracellular matrix. This review focuses on examples of fibrosis that occurs in lung, liver, kidney, skin, kidney, neural tissues and blood vessels and its link to the expression of perlecan in that particular organ system., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Cerium oxide nanoparticles (nanoceria) are widely reported to be cytocompatible and modulate intracellular reactive oxygen species (ROS) in a range of different cell types. In this study, nanoceria (d=7 and 94nm) synthesised by flame spray pyrolysis did not affect the proliferation of SKOV3 human ovarian and WiDr human colon cancer cell lines over a 72h treatment period. The cellular accumulation of nanoceria was uniform and increased up to 24h post-treatment before decreasing. The uptake of nanoceria in both cell lines was energy-dependent and was found to occur via non-specific pathways as well as clathrin-coated vesicles and caveolae. Nanoceria were localised predominantly in the cytoplasm and, to a lesser extent, with clathrin, caveolin-1 and lysosomes. The intracellular trafficking varied with particle size, treatment time and cell type. The larger nanoceria were found to scavenge intracellular ROS to a greater extent than the smaller nanoceria, and ROS scavenging was found to increase with treatment time. Together these data demonstrated that the diameter of the nanoceria and the cell types determined their mechanisms of uptake and intracellular localisation, as well as their ROS scavenging effects., Statement of Significance: Cerium oxide nanoparticles (nanoceria) are a promising biomaterial that can catalytically scavenge reactive oxygen species (ROS). Modulation of ROS may potentially minimise the inflammatory effects of cancer. However, the antioxidant properties of nanoceria are reported to be pH-dependent and, thus, dependent on their mechanisms of endocytosis. This study is the first to examine the effects of particle size on the uptake and intracellular trafficking of flame spray-synthesised nanoceria in human cancer cells. This study demonstrated that the particle diameter, treatment time and cell type determined the mechanisms of uptake and intracellular localisation of nanoceria, as well as their ROS scavenging effects. This study highlighted the importance of testing new nanoparticle systems rather than making assumptions based on previous uptake studies., (Copyright © 2016 Acta Materialia Inc. All rights reserved.)

Modulation of endothelial cell and platelet interactions is an essential feature of vascular materials. Silk biomaterials were functionalized with recombinantly expressed domain V of human perlecan, an essential vascular proteoglycan involved in vasculogenesis, angiogenesis and wound healing, using passive adsorption or covalent cross-linking via carbodiimide chemistry. The orientation of domain V on the surface of silk biomaterials was modulated by the immobilization technique and glycosaminoglycan chains played an essential role in the proteoglycan presentation on the material surface. Covalent immobilization supported improved integrin binding site presentation to endothelial cells compared to passive adsorption in the presence of glycosaminoglycan chains, but removal of glycosaminoglycan chains resulted in reduced integrin site availability and thus cell binding. Silk biomaterials covalently functionalized with domain V supported endothelial cell adhesion, spreading and proliferation and were anti-adhesive for platelets, making them promising surfaces for the development of the next-generation vascular grafts., (Copyright © 2016 Elsevier B.V. All rights reserved.)

In this study polymeric micelles formed from poly(poly(ethylene glycol) methyl ether methacrylate)-block-poly(methyl methacrylate) (P(PEGMEMA75)-b-PMMA80) block copolymer of approximately 25nm in diameter were used to encapsulate the model drug, Nile Red, with a loading efficiency of 0.08wt% and a chemotherapeutic drug, doxorubicin (DOX), with an efficiency of 2.75wt%. The release of DOX from the micelles was sufficient to be cytotoxic to human colon carcinoma cells, WiDr, while Nile Red and the unloaded micelles were found not to be cytotoxic when exposed to the cells at polymer concentrations up to 200μg/mL. Nile Red loaded micelles were used to analyze uptake of the micelles into the cells which were rapidly internalized within minutes of exposure. The three major endocytotic pathways were involved in the internalization of micelles; however other passive mechanisms were also at play as the addition of inhibitors to all three pathways did not completely inhibit the uptake of these nanoparticles. These data demonstrate the potential of the P(PEGMEMA)75-b-PMMA80 block copolymer micelles to be rapidly internalized by carcinoma cells and deliver low doses of drugs intracellularly for controlled drug release., (Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.)

The cartilage growth plate is a specialized developmental tissue containing characteristic zonal arrangements of chondrocytes. The proliferative and differentiative states of chondrocytes are tightly regulated at all stages including the initial limb bud and rudiment cartilage stages of development, the establishment of the primary and secondary ossification centers, development of the growth plates and laying down of bone. A multitude of spatio-temporal signals, including transcription factors, growth factors, morphogens and hormones, control chondrocyte maturation and terminal chondrocyte differentiation/hypertrophy, cell death/differentiation, calcification and vascular invasion of the growth plate and bone formation during morphogenetic transition of the growth plate. This involves hierarchical, integrated signaling from growth and factors, transcription factors, mechanosensory cues and proteases in the extracellular matrix to regulate these developmental processes to facilitate progressive changes in the growth plate culminating in bone formation and endochondral ossification. This review provides an overview of selected components which have particularly important roles in growth plate biology including collagens, proteoglycans, glycosaminoglycans, growth factors, proteases and enzymes., (Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.)

The mammalian HSPG2 gene encodes the proteoglycan protein core perlecan, which has important functions in biology including cell adhesion via integrins, binding to the extracellular matrix via various protein-protein interactions and binding of growth factors via the heparan sulfate chains decorating the N-terminal domain I. Here we show that, in the human mast cell line HMC-1, the transcription of this gene results in a population of mRNA that is processed in such a way to provide a relative increase of transcripts corresponding to domain V or the C-terminus compared to transcripts from either domain III or the N-terminal domain I. This paper also presents evidence of splicing of the HSPG2 gene in HMC-1 cells at exons 2/3 and after comparing this sequence with those published in various databases, a model is postulated to explain what might be happening in these cells with regard to the transcription of the HSPG2 gene. As domain V of perlecan contains the α2β1 integrin binding site that modulates angiogenesis, we hypothesize that the transcriptional control of the HSPG2 gene in mast cells to synthesize these transcripts supports their stimulatory and specific role in wound healing and tissue regeneration., (Copyright © 2013 International Society of Matrix Biology. All rights reserved.)

Smooth muscle cell proliferation can be inhibited by heparan sulfate proteoglycans whereas the removal or digestion of heparan sulfate from perlecan promotes their proliferation. In this study we characterized the glycosaminoglycan side chains of perlecan isolated from either primary human coronary artery smooth muscle or endothelial cells and determined their roles in mediating cell adhesion and proliferation, and in fibroblast growth factor (FGF) binding and signaling. Smooth muscle cell perlecan was decorated with both heparan sulfate and chondroitin sulfate, whereas endothelial perlecan contained exclusively heparan sulfate chains. Smooth muscle cells bound to the protein core of perlecan only when the glycosaminoglycans were removed, and this binding involved a novel site in domain III as well as domain V/endorepellin and the α2β1 integrin. In contrast, endothelial cells adhered to the protein core of perlecan in the presence of glycosaminoglycans. Smooth muscle cell perlecan bound both FGF1 and FGF2 via its heparan sulfate chains and promoted the signaling of FGF2 but not FGF1. Also endothelial cell perlecan bound both FGF1 and FGF2 via its heparan sulfate chains, but in contrast, promoted the signaling of both growth factors. Based on this differential bioactivity, we propose that perlecan synthesized by smooth muscle cells differs from that synthesized by endothelial cells by possessing different signaling capabilities, primarily, but not exclusively, due to a differential glycanation. The end result is a differential modulation of cell adhesion, proliferation and growth factor signaling in these two key cellular constituents of blood vessels., (Copyright © 2014 International Society of Matrix Biology. Published by Elsevier B.V. All rights reserved.)