Efficacy of sustained delivery of GC-1 from a Nanofluidic system in a spontaneously obese non-human primate: a case study

Carbon fiber reinforced polymers for implantable medical devices

Carbon fibers reinforced polymers (CFRPs) are prolifically finding applications in the medical field, moving beyond the aerospace and automotive industries. Owing to its high strength-to-weight ratio, lightness and radiolucency, CFRP-based materials are emerging to replace traditional metal-based medical implants. Numerous types of polymers matrices can be incorporated with carbon fiber using various manufacturing methods, creating composites with distinct properties. Thus, prior to biomedical application, comprehensive evaluation of material properties, biocompatibility and safety are of paramount importance. In this study, we systematically evaluated a series of novel CFRPs, aiming at analyzing biocompatibility for future development into medical implants or implantable drug delivery systems. These CFRPs were produced either via Carbon Fiber-Sheet Molding Compound or Fused Deposition Modelling-based additive manufacturing. Unlike conventional methods, both fabrication processes afford high production rates in a time-and cost-effective manner. Importantly, they offer rapid prototyping and customization in view of personalized medical devices. Here, we investigate the physicochemical and surface properties, material mutagenicity or cytotoxicity of 20 CFRPs, inclusive of 2 surface finishes, as well as acute and sub-chronic toxicity in mice and rabbits, respectively. We demonstrate that despite moderate in vitro physicochemical and surface changes over time, most of the CFRPs were non-mutagenic and non-cytotoxic, as well as biocompatible in small animal models. Future work will entail extensive material assessment in the context of orthopedic applications such as evaluating potential for osseointegration, and a chronic toxicity study in a larger animal model, pigs.

Technologies for intrapericardial delivery of therapeutics and cells

The pericardium, which surrounds the heart, provides a unique enclosed volume and a site for the delivery of agents to the heart and coronary arteries. While strategies for targeting the delivery of therapeutics to the heart are lacking, various technologies and nanodelivery approaches are emerging as promising methods for site specific delivery to increase therapeutic myocardial retention, efficacy, and bioactivity, while decreasing undesired systemic effects. Here, we provide a literature review of various approaches for intrapericardial delivery of agents. Emphasis is given to sustained delivery approaches (pumps and catheters) and localized release (patches, drug eluting stents, and support devices and meshes). Further, minimally invasive access techniques, pericardial access devices, pericardial washout and fluid analysis, as well as therapeutic and cell delivery vehicles are presented. Finally, several promising new therapeutic targets to treat heart diseases are highlighted.

2-Hydroxypropyl-β-cyclodextrin-enhanced pharmacokinetics of cabotegravir from a nanofluidic implant for HIV pre-exposure prophylaxis

Preexposure prophylaxis (PrEP) with antiretrovirals (ARV) can prevent human immunodeficiency virus (HIV) transmission, but its efficacy is highly dependent on strict patient adherence to daily dosing regimen. Long-acting (LA) ARV formulations or delivery systems that reduce dosing frequency may increase adherence and thus PrEP efficacy. While cabotegravir (CAB) long-acting injectable (CAB LA), an integrase strand transfer inhibitor (INSTI), reduces dosing frequency to bimonthly injections, variable pharmacokinetics (PK) between patients and various adverse reactions necessitate improvement in delivery methods. Here we developed a subcutaneously implantable nanofluidic device for the sustained delivery of CAB formulated with 2-hydroxypropyl-β-cyclodextrin (βCAB) and examined the pharmacokinetics (PK) in Sprague-Dawley rats for 3 months in comparison to CAB. Our study demonstrated βCAB treatment group maintained clinically-relevant plasma CAB concentrations 2 times above the protein-adjusted concentration that inhibits viral replication by 90% (2 × PA-IC₉₀) and drug penetration into tissues relevant to HIV-1 transmission. Further, we successfully fitted plasma CAB concentrations into a PK model (R² = 0.9999) and determined CAB apparent elimination half-life of 47 days. Overall, our data shows the potential of sustained release of βCAB via a nanofluidic implant for long-term PrEP delivery, warranting further investigation for efficacy against HIV infections.

Gas Flow at the Ultra-nanoscale: Universal Predictive Model and Validation in Nanochannels of Ångstrom-Level Resolution

Gas transport across nanoscale pores is determinant in molecular exchange in living organisms as well as in a broad spectrum of technologies. Here, we report an unprecedented theoretical and experimental analysis of gas transport in a consistent set of confining nanochannels ranging in size from the ultra-nanoscale to the sub-microscale. A generally applicable theoretical approach quantitatively predicting confined gas flow in the Knudsen and transition regime was developed. Unlike current theories, specifically designed for very simple channel geometries, our approach can be applied to virtually all geometries, for which the probability distribution of path lengths for particle-interface collisions can be computed, either analytically or by numerical simulations. To generate a much needed benchmark experimental model, we manufactured extremely reproducible membranes with two-dimensional nanochannels. Channel sizes ranged from 2.5 to 250 nm, and angstrom level of size control and interface tolerances were achieved using leading-edge nanofabrication techniques. We then measured gas flow in the Knudsen number range from 0.2 to 20. Excellent agreement between theoretical predictions and experimental data was found, demonstrating the validity and potential of our approach.