Biomimetic delivery with micro- and nanoparticles

Interfacial interactions between natural RBC membranes and synthetic polymeric nanoparticles

The unique structural features and stealth properties of a recently developed red blood cell membrane-cloaked nanoparticle (RBC-NP) platform raise curiosity over the interfacial interactions between natural cellular membranes and polymeric nanoparticle substrates. Herein, several interfacial aspects of the RBC-NPs are examined, including completeness of membrane coverage, membrane sidedness upon coating, and the effects of polymeric particles' surface charge and surface curvature on the membrane cloaking process. The study shows that RBC membranes completely cover negatively charged polymeric nanoparticles in a right-side-out manner and enhance the particles' colloidal stability. The membrane cloaking process is applicable to particle substrates with a diameter ranging from 65 to 340 nm. Additionally, the study reveals that both surface glycans on RBC membranes and the substrate properties play a significant role in driving and directing the membrane-particle assembly. These findings further the understanding of the dynamics between cellular membranes and nanoscale substrates and provide valuable information toward future development and characterization of cellular membrane-cloaked nanodevices.

Electrically controlled drug delivery from graphene oxide nanocomposite films

On-demand, local delivery of drug molecules to target tissues provides a means for effective drug dosing while reducing the adverse effects of systemic drug delivery. This work explores an electrically controlled drug delivery nanocomposite composed of graphene oxide (GO) deposited inside a conducting polymer scaffold. The nanocomposite is loaded with an anti-inflammatory molecule, dexamethasone, and exhibits favorable electrical properties. In response to voltage stimulation, the nanocomposite releases drug with a linear release profile and a dosage that can be adjusted by altering the magnitude of stimulation. No drug passively diffuses from the composite in the absence of stimulation. In vitro cell culture experiments demonstrate that the released drug retains its bioactivity and that no toxic byproducts leach from the film during electrical stimulation. Decreasing the size and thickness of the GO nanosheets, by means of ultrasonication treatment prior to deposition into the nanocomposite, alters the film morphology, drug load, and release profile, creating an opportunity to fine-tune the properties of the drug delivery system to meet a variety of therapeutic needs. The high level of temporal control and dosage flexibility provided by the electrically controlled GO nanocomposite drug delivery platform make it an exciting candidate for on-demand drug delivery.

Bioactive baculovirus nanohybrids for stent based rapid vascular re-endothelialization

Present study, for the first time, reports the development of a nanohybridized baculovirus based stent that can locally promote vascular re-endothelialization by efficient delivery of pro-angiogenic vascular endothelial growth factor (Vegf) genes. In vitro data demonstrated rapid expression of functionally active Vegf by the bioactive stent-transduced vascular cells. In vivo site-specific transgene expression was observed at the stented regions of balloon-denuded canine femoral artery, which eventually lead to significant endothelial recovery at the injured sites. A significant reduction in neointima formation (2.23 ± 0.56 mm² vs 2.78 ± 0.49 mm² and 3.11 ± 0.23 mm², p < 0.05; n = 8) and percent stenosis was observed in treated stent group compared to negative control and bare metal stent groups. These findings collectively implicate the potential of this newly developed baculovirus based biotherapeutic stent to ameliorate damaged vascular biology and attenuate re-narrowing of stented artery by inhibiting neointima formation.

Particle shape dependence of CD8+ T cell activation by artificial antigen presenting cells

Previous work developing particle-based acellular, artificial antigen presenting cells (aAPCs) has focused exclusively on spherical platforms. To explore the role of shape, we generated ellipsoidal PLGA microparticles with varying aspect ratios (ARs) and synthesized aAPCs from them. The ellipsoidal biomimetic aAPCs with high-AR showed significantly enhanced in vitro and in vivo activity above spherical aAPCs with particle volume and antigen content held constant. Confocal imaging indicates that CD8+ T cells preferentially migrate to and are activated by interaction with the long axis of the aAPC. Importantly, enhanced activity of high-AR aAPCs was seen in a mouse melanoma model, with high-AR aAPCs improving melanoma survival compared to non-cognate aAPCs (p = 0.004) and cognate spherical aAPCs (p = 0.05). These findings indicate that particle geometry is a critical design criterion in the generation of aAPCs, and may offer insight into the essential role of geometry in the interaction between CD8+ T cells and biological APCs.

In silico programming of degradable microparticles to hide and then reveal immunogenic payloads in vivo

Poly(lactic-co-glycolic) acid microparticles, mathematically designed for delayed release in vitro, hide and then reveal ovalbumin-alum in vivo without altering its immunogenicity.

Nanoscale artificial antigen presenting cells for T cell immunotherapy

Artificial antigen presenting cells (aAPC), which deliver stimulatory signals to cytotoxic lymphocytes, are a powerful tool for both adoptive and active immunotherapy. Thus far, aAPC have been synthesized by coupling T cell activating proteins such as CD3 or MHC-peptide to micron-sized beads. Nanoscale platforms have different trafficking and biophysical interaction properties and may allow development of new immunotherapeutic strategies. We therefore manufactured aAPC based on two types of nanoscale particle platforms: biocompatible iron-dextran paramagnetic particles (50-100 nm in diameter) and avidin-coated quantum dot nanocrystals (~30 nm). Nanoscale aAPC induced antigen-specific T cell proliferation from mouse splenocytes and human peripheral blood T cells. When injected in vivo, both iron-dextran particles and quantum dot nanocrystals enhanced tumor rejection in a subcutaneous mouse melanoma model. This is the first description of nanoscale aAPC that induce antigen-specific T cell proliferation in vitro and lead to effective T cell stimulation and inhibition of tumor growth in vivo.

FROM THE CLINICAL EDITOR

Artifical antigen presenting cells could revolutionize the field of cancer-directed immunotherapy. This team of investigators have manufactured two types of nanoscale particle platform-based aAPCs and demonstrates that both iron-dextran particles and quantum dot nanocrystals enhance tumor rejection in a melanoma model, providing the first description of nanoscale aAPCs that lead to effective T cell stimulation and inhibition of tumor growth.

Synthesis of biomimetic oxygen-carrying compartmentalized microparticles using flow lithography

We report a microfluidic approach for lithographically photo-patterning compartmentalized microparticles with any 2D-extruded shape, down to the cellular length scale (~10 microns). The prepolymer solution consists of a UV crosslinkable perfluorodecalin-in-water nanoemulsion stabilized by Pluronic(®) F-68. The nanoemulsions are generated using high-pressure homogenization and are osmotically stabilized by the trapped species method. The presence of PFC droplets increases the solubility and diffusivity of oxygen in the prepolymer solution, thereby enhancing the rate of O2 inhibition during microparticle synthesis. We develop a simple model that successfully predicts the augmented O2 mass transport, which agrees well with experimental data. Informed by our analytical results, cell-sized composite microgels are generated by controlling the oxygen environment around the polydimethylsiloxane (PDMS) microfluidic synthesis device. These nanoemulsion composites are functionally similar to red blood cells as oxygen carriers. Such bio-inspired polymeric particles with controlled physical properties are promising vehicles for drug delivery and clinical diagnostics.

Advanced drug delivery nanosystems (aDDnSs): a mini-review

Significant progress has been made in nanoscale drugs and delivery systems employing diverse chemical formulations to facilitate the rate of drug delivery and to improve its pharmacokinetics. Biocompatible nanomaterials have been used as biological markers, contrast agents for imaging, healthcare products, pharmaceuticals, drug-delivery systems as well as in detection, diagnosis and treatment of various types of diseases. The classification of drug delivery nanosystems (DDnSs) is a crucial issue and fundamental efforts on this subject are missing from the literature. This article deals with the classification of DDnSs with a modulatory controlled release profile (MCR) denoted as modulatory controlled release nanosystems (MCRnSs). Conventional (c) and advanced (a) DDnSs are denoted by the acronyms cDDnSs and aDDnSs, and can be composed of a single or more than one biomaterials, respectively. The classification was based on their characteristics such as: surface functionality (f), the nature of biomaterials used and the kind of interactions between biomaterials. The aDDnSs can be classified as hybridic (Hy-) or chimeric (Chi-) based on the nature - same or different respectively - of biomaterials and inorganic materials used. The nature of the elements used for producing advanced biomaterials is of great importance and medicinal chemistry contributes effectively to the production of aDDnSs.

Merging the best of both worlds: hybrid lipid-enveloped matrix nanocomposites in drug delivery

The advent of nanotechnology has revolutionized drug delivery in terms of improving drug efficacy and safety. Both polymer-based and lipid-based drug-loaded nanocarriers have demonstrated clinical benefit to date. However, to address the multifaceted drug delivery challenges ahead and further expand the spectrum of therapeutic applications, hybrid lipid-polymer nanocomposites have been designed to merge the beneficial features of both polymeric drug delivery systems and liposomes in a single nanocarrier. This review focuses on different classes of nanohybrids characterized by a drug-loaded polymeric matrix core enclosed in a lipid shell. Various nanoengineering approaches to obtain lipid-polymer nanocomposites with a core-shell nanoarchitecture will be discussed as well as their predominant applications in drug delivery.

'Marker-of-self' functionalization of nanoscale particles through a top-down cellular membrane coating approach

We investigate the 'marker-of-self' functionalization of nanoparticles through coating of natural RBC membranes. The membrane translocation approach is shown to be highly efficient and bestows nanoparticles with correctly oriented and functional immunomodulatory proteins such as CD47 at equivalent density to natural RBCs.

Dendritic surface functionalization of nanomaterials: controlling properties and functions for biomedical applications

A wide variety of nanomaterials have demonstrated promise in medical applications such as drug delivery and imaging. In these applications, the surface chemistry of the materials is critical as it plays an important role in determining the toxicity and biodistribution behavior of the material. We review here the functionalization of nanomaterials with dendrons as an efficient method to alter the surface chemistry of the materials, introducing new properties and functions. Described here is the functionalization of superparamagnetic iron oxide nanoparticles (SPIO) with dendritic guanidines to enhance their transport into cells for magnetic resonance imaging applications. The introduction of dendrons bearing peripheral hydroxyls, amines, guanidines, carbohydrates and Gd(III) chelates to polymer vesicles (polymersomes) is also described. These dendritic moieties allow for modulation of toxicity, cell uptake, protein binding, and contrast agent efficiency, while at the same time allowing the stabilities of the polymersomes to be maintained. Thus, this approach holds promise for the development of a wide range of multifunctional materials for pharmaceutical applications.

The effect of monomer order on the hydrolysis of biodegradable poly(lactic-co-glycolic acid) repeating sequence copolymers

The effect of sequence on copolymer properties is rarely studied despite the precedent from Nature that monomer order can create materials of significant diversity. Poly(lactic-co-glycolic acid) (PLGA), one of the most important biodegradable copolymers, is widely used in an unsequenced, random form for both drug delivery microparticles and tissue engineering matrices. Sequenced PLGA copolymers have been synthesized and fabricated into microparticles to study how their hydrolysis rates compare to those of random copolymers. Sequenced PLGA microparticles were found to degrade at slower, and often more constant, rates than random copolymers with the same lactic to glycolic acid ratios as demonstrated by molecular weight decrease, lactic acid release, and thermal property analyses. The impact of copolymer sequence on in vitro release was studied using PLGA microparticles loaded with model agent rhodamine-B. These assays established that copolymer sequence affects the rate of release and that a more gradual burst release can be achieved using sequenced copolymers compared to a random control.