Publications

Bioprosthetic heart valves made from glutaraldehyde-fixed animal pericardium are widely used for valve replacement but are prone to early degeneration arising from the interplay of thrombosis, inflammation, and calcification. Current chemical treatments passivate the tissue surface but do not address these biological processes. This study introduces a plasma polymerized nanoparticle (PPN) platform that enables rapid, uniform coating of bioprosthetic pericardium and provides binding sites for active drug functionalization. Using PPNs, we immobilized the anticoagulant apixaban, the selective NLRP3-inflammasome inhibitor MCC950, or the anticalcification compound phytic acid directly onto valve tissue. These functionalized coatings reduced thrombosis in vitro and limited fibrosis and calcification in a 28-day rat subcutaneous model, demonstrating the capacity of PPNs to conjugate different small molecules to target multiple mechanisms of valve deterioration. Importantly, PPN coatings did not alter leaflet mechanics or hemodynamic performance when applied to a commercial transcatheter valve. This versatile coating platform represents an important advance in bioprosthetic valve technology with significant implications for their performance.

Small diameter vascular grafts made from expanded polytetrafluoroethylene (ePTFE) dominate clinical practice but are prone to high failure rates due to poor endothelialization, acute thrombosis or mid-term neointimal hyperplasia. The highly hydrophobic surface of ePTFE inhibits endothelial cell attachment and proliferation, making timely recovery of the protective endothelial layer a key challenge. Chemically inert, highly hydrophobic polymers such as ePTFE are amongst the most difficult to improve with biofunctionalization. To address this, a novel surface coating comprising a new class of plasma polymerized nanoparticles (PPN) functionalized with bioactive PF8, a recombinant fibrillin-1 peptide is developed. PPN surface modification significantly reduces ePTFE hydrophobicity, enabling efficient surface coating of PPN-PF8 and promoting endothelial attachment and proliferation in vitro. In a rat abdominal aortic interposition model, PPN-PF8 functionalized ePTFE grafts rapidly re-endothelialized, with extensive coverage of endothelial cells at 3 weeks post-implantation. This leads to increased tissue plasminogen activator (tPA) secretion and reduced fibrin deposition, indicating the formation of a healthy, functional endothelial layer. These findings highlight the potential of plasma-polymerized nanoparticles presenting fibrillin-1 to drive rapid re-endothelialization, offering an accessible and scalable method for improving the performance of small-diameter vascular grafts.

Conventional gas plasma treatments are crucial for functionalizing materials in biomedical applications, but have limitations hindering their broader use. These methods require exposure to reactive media under vacuum conditions, rendering them unsuitable for substrates that demand aqueous environments, such as proteins and hydrogels. In addition, complex geometries are difficult to treat, necessitating extensive customization for each material and shape. To address these constraints, an innovative approach employing plasma polymer nanoparticles (PPN) as a versatile functionalization tool is proposed. PPN share similarities with traditional plasma polymer coatings but offer unique advantages: compatibility with aqueous systems, the ability to modify complex geometries, and availability as off-the-shelf products. Robust immobilization of PPN on various substrates, including synthetic polymers, proteins, and complex hydrogel structures is demonstrated. This results in substantial improvements in surface hydrophilicity. Materials functionalization with RGD-loaded PPN significantly enhances cell attachment, spreading, and substrate coverage on inert scaffolds compared to passive RGD coatings. Improved adhesion to complex geometries and subsequent differentiation following growth factor exposure is also demonstrated. This research introduces a novel substrate functionalization approach that mimics the outcomes of plasma coating technology but vastly expands its applicability, promising advancements in biomedical materials and devices.

Heart failure due to myocardial infarction is a progressive and debilitating condition, affecting millions worldwide. Novel treatment strategies are desperately needed to minimise cardiomyocyte damage after myocardial infarction and to promote repair and regeneration of the injured heart muscle. Plasma polymerized nanoparticles (PPN) are a new class of nanocarriers which allow for a facile, one-step functionalization with molecular cargo. Here, we conjugated platelet-derived growth factor AB (PDGF-AB) to PPN, engineering a stable nano-formulation, and demonstrated safety and bioactivity in vitro and in vivo. We delivered PPN-PDGF-AB to human cardiac cells and directly to the injured rodent heart. We found no evidence of cytotoxicity after delivery of PPN or PPN-PDGFAB to cardiomyocytes in vitro, and no detrimental effect on cardiomyocyte contractility. PDGF-AB remains functional when bound to PPN, with PDGF receptor alpha positive human coronary artery vascular smooth muscle cells and cardiac fibroblasts demonstrating migratory and phenotypic responses to PPN-PDGF-AB. In our rodent model of myocardial infarction, we found a modest improvement in cardiac function in PPN-PDGF-AB treated hearts. These results demonstrate safety and feasibility of the PPN platform for delivery of therapeutics directly to the myocardium.

The rapid growth of nanoparticle-based therapeutics has underpinned significant developments in nanomedicine, which aim to overcome the limitations imposed by conventional therapies. Establishing the safety of new nanoparticle formulations is the first important step on the pathway to clinical translation. We have recently shown that plasma-polymerized nanoparticles (PPNs) are highly efficient nanocarriers and a viable, cost-effective alternative to conventional chemically synthesized nanoparticles. Here, we present the first comprehensive toxicity and biosafety study of PPNs using both established in vitro cell models and in vivo models. Overall, we show that PPNs were extremely well tolerated by all the cell types tested, significantly outperforming commercially available lipid-based nanoparticles (lipofectamine) used at the manufacturer's recommended dosage. Supporting the in vitro data, the systemic toxicity of PPNs was negligible in BALB/c mice following acute and repeated tail-vein intravenous injections. PPNs were remarkably well tolerated in mice without any evidence of behavioral changes, weight loss, significant changes to the hematological profile, or signs of histological damage in tissues. PPNs were tolerated at extremely high doses without animal mortality observed at 6000 mg/kg and 48,000 mg/kg for acute and repeated-injection regimens, respectively. Our findings demonstrate the safety of PPNs in biological systems, adding to their future potential in biomedical applications.

Multifunctional nanocarriers (MNCs) promise to improve therapeutic outcomes by combining multiple classes of molecules into a single nanostructure, enhancing active targeting of therapeutic agents and facilitating new combination therapies. However, nanocarrier platforms currently approved for clinical use can still only carry a single therapeutic agent. The complexity and escalating costs associated with the synthesis of more complex MNCs have been major technological roadblocks in the pathway for clinical translation. Here, we show that plasma polymerized nanoparticles (PPNs), synthesised in reactive gas discharges, can bind and effectively deliver multiple therapeutic cargo in a facile and cost-effective process compatible with up scaled commercial production. Delivery of siRNA against vascular endothelial growth factor (siVEGF) at extremely low concentrations (0.04 nM), significantly reduced VEGF expression in hard-to-transfect cells when compared with commercial platforms carrying higher siRNA doses (6.25 nM). PPNs carrying a combination of siVEGF and standard of care Paclitaxel (PPN-Dual) at reduced doses (< 100 µg/kg) synergistically modulated the microenvironment of orthotopic breast tumors in mice, and significantly reduced tumor growth. We propose PPNs as a new nanomaterial for delivery of therapeutics, which can be easily functionalised in any laboratory setting without the need for additional wet-chemistry and purification steps.

Plasma polymerized nanoparticles (PPN) formed in plasma reactors have been considered undesirable in technological applications. More recently however, PPN were proposed as a new class of multifunctional nanocarriers for drug delivery. Therefore, synthesis of PPN requires cost-effective collection strategies that maximize yield and improve reproducibility. This work shows that the collection of PPN in dusty plasmas is modulated by modifying the geometry of substrates from planar to well-shaped collectors. The electric field profile around the wells acts as an electrostatic lens, concentrating nanoparticles and significantly bolstering process yield. The aggregation of PPN is governed by a balance between plasma expansion throughout the wells, inter-particle repulsion, particle size and density. PPN are readily dispersed in aqueous solution yielding monodisperse populations. The use of a disposable well-shape collector provides a cost-effective nanoparticle collection approach that can be adopted in a wide range of plasma polymerization configurations without the need for reactor re-design.

Multifunctional nanoparticles are increasingly employed to improve biological efficiency in medical imaging, diagnostics, and treatment applications. However, even the most well-established nanoparticle platforms rely on multiple-step wet-chemistry approaches for functionalization often with linkers, substantially increasing complexity and cost, while limiting efficacy. Plasma dust nanoparticles are ubiquitous in space, commonly observed in reactive plasmas, and long regarded as detrimental to many manufacturing processes. As the bulk of research to date has sought to eliminate plasma nanoparticles, their potential in theranostics has been overlooked. Here we show that carbon-activated plasma-polymerized nanoparticles (nanoP3) can be synthesized in dusty plasmas with tailored properties, in a process that is compatible with scale up to high throughput, low-cost commercial production. We demonstrate that nanoP3 have a long active shelf life, containing a reservoir of long-lived radicals embedded during their synthesis that facilitate attachment of molecules upon contact with the nanoparticle surface. Following synthesis, nanoP3 are transferred to the bench, where simple one-step incubation in aqueous solution, without the need for intermediate chemical linkers or purification steps, immobilizes multiple cargo that retain biological activity. Bare nanoP3 readily enter multiple cell types and do not inhibit cell proliferation. Following functionalization with multiple fluorescently labeled cargo, nanoP3 retain their ability to cross the cell membrane. This paper shows the unanticipated potential of carbonaceous plasma dust for theranostics, facilitating simultaneous imaging and cargo delivery on an easily customizable, functionalizable, cost-effective, and scalable nanoparticle platform.