Nano LIFE

There has been a significant amount of research done on liposomes and nanoparticles as drug carriers for protein drugs. Proteins and enzymes have been used both as targeting moieties and for their therapeutic potential. High specificity and rapid reaction rates make proteins and enzymes excellent candidates for therapeutic treatment, but some limitations exist. Many of these limitations can be addressed by a well-studied nanotechnology-based delivery system. Such a system can provide a medium for delivery, stabilization of the drugs, and enable site-specific accumulation of drugs. Nanomedicines such as these have great potential to revolutionize the pharmaceutical industry and improve healthcare worldwide.

Elastin-like polypeptide (ELP) containing materials have spurred significant research interest for biomedical applications exploiting their biocompatible, biodegradable and nonimmunogenic nature while maintaining precise control over their chemical structure and functionality through genetic engineering. Physical, mechanical and biological properties of ELPs could be further manipulated using genetic engineering or through conjugation with a variety of chemical moieties. These chemical and physical modifications also achieve interesting micro- and nanostructured ELP-based materials. Here, we review the recent developments during the past decade in the methods to engineer elastin-like materials, available genetic and chemical modification methods and applications of ELP micro and nanostructures in tissue engineering and drug delivery.

Current chemotherapy treatments are limited by poor drug solubility, rapid drug clearance and systemic side effects. Additionally, drug penetration into solid tumors is limited by physical diffusion barriers [e.g., extracellular matrix (ECM)]. Nanoparticle (NP) blood circulation half-life, biodistribution and ability to cross extracellular and cellular barriers will be dictated by NP composition, size, shape and surface functionality. Here, we investigated the effect of surface charge of poly(lactide)-poly(ethylene glycol) NPs on mediating cellular interaction. Polymeric NPs of equal sizes were used that had two different surface functionalities: negatively charged carboxyl (COOH) and neutral charged methoxy (OCH₃). Cellular uptake studies showed significantly higher uptake in human brain cancer cells compared to noncancerous human brain cells, and negatively charged COOH NPs were uptaken more than neutral OCH₃ NPs in 2D culture. NPs were also able to load and control the release of paclitaxel (PTX) over 19 days. Toxicity studies in U-87 glioblastoma cells showed that PTX-loaded NPs were effective drug delivery vehicles. Effect of surface charge on NP interaction with the ECM was investigated using collagen in a 3D cellular uptake model, as collagen content varies with the type of cancer and the stage of the disease compared to normal tissues. Results demonstrated that NPs can effectively diffuse across an ECM barrier and into cells, but NP mobility is dictated by surface charge. In vivo biodistribution of OCH₃ NPs in intracranial tumor xenografts showed that NPs more easily accumulated in tumors with less collagen. These results indicate that a robust understanding of NP interaction with various tumor environments can lead to more effective patient-tailored therapies.

Nanoparticles, after incubation in biological fluids, adsorb several kinds of biomolecules like lipids, sugars and mainly proteins with high affinities for the nanoparticle surface and with long residence time, forming the so-called hard corona. The biological machinery, such as cellular barriers and membrane receptors can directly engage with the protein corona while the pristine surface may remain inaccessible. Here we isolate nanoparticles associated with strongly bound biomolecules from the unbound and loosely bound ones, by different approaches: centrifugation, size exclusion chromatography and magnetic isolation. The different separation methodologies, despite requiring diverse time and operating mechanisms, gave nanoparticle-hard corona complexes which were found to be remarkably similar in both dispersion properties and protein composition thus proving to be equally valid.

Tumor-associated macrophages (TAMs) play an important role in tumor progression and metastasis. In this study, we developed a TAM-targeting poly lactic-co-glycolic acid (PLGA) nanoparticle (NP) that encapsulates a bisphosphonate drug, clodronate. Clodronate-loaded NPs killed macrophages more efficiently than the drug alone in vitro. The NPs functionalized with a TAM-targeting tissue-penetrating peptide, LyP-1, selectively accumulated in CD11b-positive (macrophage-rich) regions in mouse 4T1 breast tumor xenografts. Furthermore, clodronate-loaded LyP-1-functionalized NPs reduced the number of macrophages selectively in the 4T1 tumors, and modestly inhibited tumor growth. Our results support the idea that LyP-1-functionalized clodronate-loaded PLGA NPs could be a promising anti-tumor agent.

We report a straightforward synthesis of superparamagnetic Janus Polystyrene/Fe₃O₄@Silica ternary nanocomposites via a one-pot miniemulsion approach. The nanocomposites are dual functionalized simultaneously on the same physical carrier, with the carboxyl groups on the polystyrene surface while the silica region is functionalized with silano. With such a unique dual surface structure, it is possible to selectively functionalize multiple surfaces of a single carrier nanoparticle. Multifunctionality can be more readily achieved by this approach for biomedical applications. In this experiment, Doxorubicin is loaded on the silica region, as the model drug, for controlled release via a pH-responsive triggering mechanism. Meanwhile, the polystyrene surface is available for conjugating cancer-specific markers, which is needed for cell targeting. Also discussed are the reaction mechanisms and the key processing parameters in the synthesis of Polystyrene/Fe₃O₄@Silica nanocomposites.

With the demonstration of direct electron transfer between the redox active prosthetic group, flavin adenine dinucleotide (FAD), of glucose oxidase (GOx) and single-walled carbon nanotubes (SWCNT), there has been growing interest in the fabrication of CNT-enzyme supramolecular constructs that control the placement of SWCNTs within the tunneling distance of co-factors for enhanced electron transfer efficiency in generation-3 biosensors and advanced biofuel cells. These conjugate systems raise a series of questions such as: which peptide sequences within the enzymes have high affinity for the SWCNTs? And, are these high affinity sequences likely to be in the vicinity of the redox-active co-factor to allow for direct electron transfer? Phage display has recently been used to identify specific peptide sequences that have high affinity for SWCNTs. Molecular dynamics simulations were performed to study the interactions of five discrete peptides with (16,0) SWCNT in explicit water as well as with graphene. From the progression of the radius of gyration, R_g, the peptides studied were concertedly adsorbed to both the SWCNT and graphene. Peptide properties calculated using individual amino acid values, such as hydrophobicity indices, did not correlate with the observed adsorption behavior as quantified by R_g, indicating that the adsorption behavior of the peptide was not based on the individual amino acid residues. However, the R_g values, reflective of the physicochemical embrace of the surface (SWCNT or graphene) had a strong positive correlation with the solubility parameter, indicating concerted, cooperative interaction of peptide segments with the materials. The end residues appear to dominate the progression of adsorption regardless of character. Sequences identified by phage display share some homology with key enzymes (GOx, lactate oxidase and laccase) used in biosensors and enzyme-based biofuel cells. These analogous sequences appear to be buried deep within the shell of fully folded proteins and as such are expected to be close to the redox-active prosthetic group.

"Label-free" biomolecule sensors are designed and fabricated utilizing polystyrene microparticles and gold nanoparticles as sensing elements for quantification of the ultrasensitive cardiac biomarker troponin-T. A powerful diagnostic tool electrochemical impedance spectroscopy, used to characterize significant changes at biomolecular level, has been employed to detect troponin-T at 10 fg/mL sensitivity in phosphate buffered saline. This paper presents the theory, modeling and experimental study on the behavior of micro and nanoparticles under the influence of applied sinusoidal potential. This paper also demonstrates the advantages of utilizing gold nanoparticles to amplify electrical impedance signals obtained due to particle–biomolecule conjugation for designing electrical immunoassays for detecting troponin-T. The results indicate that electrode design and particle scaling are critical factors that determine the performance for rapid biomolecular analysis. Size-based scaling enhances sensitivity by amplifying the measured signal by an order of 10 when the sizes of the particles were reduced from 5 μm to 5 nm.

Mesenchymal stromal cells (MSC) can promote tissue protection following injury, in part by modulating inflammatory cell responses. The aim of this study was to investigate the potential tissue protective properties of encapsulated MSCs (eMSC) in an organotypic injury model induced by fibronectin culture. MSC were encapsulated in alginate beads containing a network of nanopores, which segregate the cells from the extracapsular milieu, while still permitting diffusion into and out of the capsule. An increase in blood brain barrier permeability during pathological conditions permits the influx of blood plasma constituents that can be quite harmful to surrounding tissues. In particular, increased concentrations of fibronectin have been shown in a number of diseases and CNS traumas, co-localizing in areas of activated microglia. We observed over a 14-day period, a consistent increase in OHC degradation in the presence of fibronectin measured by a significant decrease in slice area, the breakdown in OHC pyramidal layers, and consistent cell death over the culture period. Microglial ionized calcium-binding adapter molecule 1 (IBA-1) expression remained elevated throughout the culture period with the majority found within the pyramidal layers. When eMSC were added to the cultures, a significant decrease in OHC degradation was observed as reflected by a reduction in OHC area shrinkage and in the amount of cell death. In the presence of eMSC, pyramidal layer structure was maintained and axonal extension from the periphery of the OHCs was observed. Therefore, MSC, delivered in a nanoporous alginate matrix, can modulate responses to injury by reversing fibronectin-induced OHC degradation.