Author Correction: Towards an arthritis flare-responsive drug delivery system.

In the original version of this Article, financial support was not fully acknowledged. The PDF and HTML versions of the Article have now been corrected to include support from the National Football League Players Association.

Towards an arthritis flare-responsive drug delivery system.

Local delivery of therapeutics for the treatment of inflammatory arthritis (IA) is limited by short intra-articular half-lives. Since IA severity often fluctuates over time, a local drug delivery method that titrates drug release to arthritis activity would represent an attractive paradigm in IA therapy. Here we report the development of a hydrogel platform that exhibits disassembly and drug release controlled by the concentration of enzymes expressed during arthritis flares. In vitro, hydrogel loaded with triamcinolone acetonide (TA) releases drug on-demand upon exposure to enzymes or synovial fluid from patients with rheumatoid arthritis. In arthritic mice, hydrogel loaded with a fluorescent dye demonstrates flare-dependent disassembly measured as loss of fluorescence. Moreover, a single dose of TA-loaded hydrogel but not the equivalent dose of locally injected free TA reduces arthritis activity in the injected paw. Together, our data suggest flare-responsive hydrogel as a promising next-generation drug delivery approach for the treatment of IA.

Early animal model evaluation of an implantable contrast agent to enhance magnetic resonance imaging of arterial bypass vein grafts.

Background Non-invasive monitoring of autologous vein graft (VG) bypass grafts is largely limited to detecting late luminal narrowing. Although magnetic resonance imaging (MRI) delineates vein graft intima, media, and adventitia, which may detect early failure, the scan time required to achieve sufficient resolution is at present impractical. Purpose To study VG visualization enhancement in vivo and delineate whether a covalently attached MRI contrast agent would enable quicker longitudinal imaging of the VG wall. Material and Methods Sixteen 12-week-old male C57BL/6J mice underwent carotid interposition vein grafting. The inferior vena cava of nine donor mice was treated with a gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA)-based contrast agent, with control VGs labeled with a vehicle. T1-weighted (T1W) MRI was performed serially at postoperative weeks 1, 4, 12, and 20. A portion of animals was sacrificed for histopathology following each imaging time point. Results MRI signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were significantly higher for treated VGs in the first three time points (1.73 × higher SNR, P = 0.0006, and 5.83 × higher CNR at the first time point, P = 0.0006). However, MRI signal enhancement decreased consistently in the study period, to 1.29 × higher SNR and 2.64 × higher CNR, by the final time point. There were no apparent differences in graft morphometric analyses in Masson's trichrome-stained sections. Conclusion A MRI contrast agent that binds covalently to the VG wall provides significant increase in T1W MRI signal with no observed adverse effects in a mouse model. Further optimization of the contrast agent to enhance its durability is required.

Impedance Spectroscopy of Ionic Ligand-Modulated Charge Transport of Gold Nanoparticle Films.

Assembled monolayer-protected nanoparticles (NPs) possess unique electrical properties that are determined by the coupled effects of their nano-sized electroactive inorganic cores that are capable of donating and accepting electrons and the organic shells. Core and ligand engineering for NP conductance modulation has been extensively explored; however, most studies focus on electron transport and not the interplay between the ion and electron transport processes. It is demonstrated here that electronic- and ionic-conducting properties of nanoparticle assemblies can be controlled by engineering the charge and flexibility of the ligand shell. By using impedance spectroscopy, the electronic, mixed ionic and electronic, and responsive conductance of the nanoparticle film and structure-function correlation are systematically investigated, and this correlation is used to provide a prototype volatile gas sensor based on the combined ionic and electronic conductance behavior of ionic ligand-functionalized gold NPs.

Clinical applications of biomedical microdevices for controlled drug delivery.

Miniaturization of devices to micrometer and nanometer scales, combined with the use of biocompatible and functional materials, has created new opportunities for the implementation of drug delivery systems. Advances in biomedical microdevices for controlled drug delivery platforms promise a new generation of capabilities for the treatment of acute conditions and chronic illnesses, which require high adherence to treatment, in which temporal control over the pharmacokinetic profiles is critical. In addition, clinical conditions that require a combination of drugs with specific pharmacodynamic profiles and local delivery will benefit from drug delivery microdevices. This review provides a summary of various clinical applications for state-of-the-art controlled drug delivery microdevices, including cancer, endocrine and ocular disorders, and acute conditions such as hemorrhagic shock. Regulatory considerations for clinical translation of drug delivery microdevices are also discussed. Drug delivery microdevices promise a remarkable gain in clinical outcomes and a substantial social impact. A review of articles covering the field of microdevices for drug delivery was performed between January 1, 1990, and January 1, 2014, using PubMed as a search engine.

A multichannel nanosensor for instantaneous readout of cancer drug mechanisms.

Screening methods that use traditional genomic, transcriptional, proteomic and metabonomic signatures to characterize drug mechanisms are known. However, they are time consuming and require specialized equipment. Here, we present a high-throughput multichannel sensor platform that can profile the mechanisms of various chemotherapeutic drugs in minutes. The sensor consists of a gold nanoparticle complexed with three different fluorescent proteins that can sense drug-induced physicochemical changes on cell surfaces. In the presence of cells, fluorescent proteins are rapidly displaced from the gold nanoparticle surface and fluorescence is restored. Fluorescence 'turn on' of the fluorescent proteins depends on the drug-induced cell surface changes, generating patterns that identify specific mechanisms of cell death induced by drugs. The nanosensor is generalizable to different cell types and does not require processing steps before analysis, offering an effective way to expedite research in drug discovery, toxicology and cell-based sensing.

Engineering cells with intracellular agent-loaded microparticles to control cell phenotype.

Cell therapies enable unprecedented treatment options to replace tissues, destroy tumors and facilitate regeneration. The greatest challenge facing cell therapy is the inability to control the fate and function of cells after transplantation. We have developed an approach to control cell phenotype in vitro and after transplantation by engineering cells with intracellular depots that continuously release phenotype-altering agents for days to weeks. The platform enables control of cells' secretome, viability, proliferation and differentiation, and the platform can be used to deliver drugs or other factors (e.g., dexamethasone, rhodamine and iron oxide) to the cell's microenvironment. The preparation, efficient internalization and intracellular stabilization of ∼1-µm drug-loaded microparticles are critical for establishing sustained control of cell phenotype. Herein we provide a protocol to generate and characterize micrometer-sized agent-doped poly(lactic-co-glycolic) acid (PLGA) particles by using a single-emulsion evaporation technique (7 h), to uniformly engineer cultured cells (15 h), to confirm particle internalization and to troubleshoot commonly experienced obstacles.

The role of ligand coordination on the cytotoxicity of cationic quantum dots in HeLa cells.

The effect of ligand structure on the cytotoxicity of cationic CdSe/ZnS quantum dots (QDs) was systematically investigated using mono- and bidentate ligands. Monothiol-functionalized QDs are more cytotoxic than dithiol-functionalized QDs.

Prodrugs as self-assembled hydrogels: a new paradigm for biomaterials.

Prodrug-based self-assembled hydrogels represent a new class of active biomaterials that can be harnessed for medical applications, in particular the design of stimuli responsive drug delivery devices. In this approach, a promoiety is chemically conjugated to a known-drug to generate an amphiphilic prodrug that is capable of forming self-assembled hydrogels. Prodrug-based self-assembled hydrogels are advantageous as they alter the solubility of the drug, enhance drug loading, and eliminate the use of harmful excipients. In addition, self-assembled prodrug hydrogels can be designed to undergo controlled drug release or tailored degradation in response to biological cues. Herein we review the development of prodrug-based self-assembled hydrogels as an emerging class of biomaterials that overcome several common limitations encountered in conventional drug delivery.

Surface functionality of nanoparticles determines cellular uptake mechanisms in mammalian cells.

Nanoparticles (NPs) are versatile scaffolds for numerous biomedical applications including drug delivery and bioimaging. The surface functionality of NPs essentially dictates intracellular NP uptake and controls their therapeutic action. Using several pharmacological inhibitors, it is demonstrated that the cellular uptake mechanisms of cationic gold NPs in both cancer (HeLa) and normal cells (MCF10A) strongly depend on the NP surface monolayer, and mostly involve caveolae and dynamin-dependent pathways as well as specific cell surface receptors (scavenger receptors). Moreover, these NPs show different uptake mechanisms in cancer and normal cells, providing an opportunity to develop NPs with improved selectivity for delivery applications.

Effect of surface charge on the uptake and distribution of gold nanoparticles in four plant species.

Small (6-10 nm) functionalized gold nanoparticles (AuNPs) featuring different, well-defined surface charges were used to probe the uptake and distribution of nanomaterials in terrestrial plants, including rice, radish, pumpkin, and perennial ryegrass. Exposure of the AuNPs to plant seedlings under hydroponic conditions for a 5-day period was investigated. Results from these studies indicate that AuNP uptake and distribution depend on both nanoparticle surface charge and plant species. The experiments show that positively charged AuNPs are most readily taken up by plant roots, while negatively charged AuNPs are most efficiently translocated into plant shoots (including stems and leaves) from the roots. Radish and ryegrass roots generally accumulated higher amounts of the AuNPs (14-900 ng/mg) than rice and pumpkin roots (7-59 ng/mg). Each of the AuNPs used in this study were found to accumulate to statistically significant extents in rice shoots (1.1-2.9 ng/mg), while none of the AuNPs accumulated in the shoots of radishes and pumpkins.

Direct patterning of engineered ionic gold nanoparticles via nanoimprint lithography.

Gold nanoparticles are engineered for direct imprinting of stable structures. This imprinting strategy provides access to new device architectures, as demonstrated through the fabrication of a prototype photoswitchable device.

Array-based sensing of metastatic cells and tissues using nanoparticle-fluorescent protein conjugates.

Rapid and sensitive methods of discriminating between healthy tissue and metastases are critical for predicting disease course and designing therapeutic strategies. We report here the use of an array of gold nanoparticle-green fluorescent protein elements to rapidly detect metastatic cancer cells (in minutes), as well as to discriminate between organ-specific metastases and their corresponding normal tissues through their overall intracellular proteome signatures. Metastases established in a new preclinical non-small-cell lung cancer metastasis model in athymic mice were used to provide a challenging and realistic testbed for clinical cancer diagnosis. Full differentiation between the analyte cell/tissue was achieved with as little as 200 ng of intracellular protein (~1000 cells) for each nanoparticle, indicating high sensitivity of this sensor array. Notably, the sensor created a distinct fingerprint pattern for the normal and metastatic tumor tissues. Moreover, this array-based approach is unbiased, precluding the requirement of a priori knowledge of the disease biomarkers. Taken together, these studies demonstrate the utility of this sensor for creating fingerprints of cells and tissues in different states and present a generalizable platform for rapid screening amenable to microbiopsy samples.

Aggregation and interaction of cationic nanoparticles on bacterial surfaces.

Cationic monolayer-protected gold nanoparticles (AuNPs) with sizes of 6 or 2 nm interact with the cell membranes of Escherichia coli (Gram-) and Bacillus subtilis (Gram+), resulting in the formation of strikingly distinct AuNP surface aggregation patterns or lysis depending upon the size of the AuNPs. The aggregation phenomena were investigated by transmission electron microscopy and UV-vis spectroscopy. Upon proteolytic treatment of the bacteria, the distinct aggregation patterns disappeared.

Determination of the intracellular stability of gold nanoparticle monolayers using mass spectrometry.

Monolayer stability of core-shell nanoparticles is a key determinant of their utility in biological studies such as imaging and drug delivery. Intracellular thiols (e.g., cysteine, cysteamine, and glutathione) can trigger the release of thiolate-bound monolayers from nanoparticles, a favorable outcome for controllable drug release applications but an unfavorable outcome for imaging agents. Here, we describe a method to quantify the monolayer release of gold nanoparticles (AuNPs) in living cells using parallel measurements by laser desorption/ionization (LDI) and inductively coupled plasma (ICP) mass spectrometry. This combination of methods is tested using AuNPs with structural features known to influence monolayer stability and on cells types with varying concentrations of glutathione. On the basis of our results, we predict that this approach should help efforts to engineer nanoparticle surface monolayers with tunable stability, providing stable platforms for imaging agents and controlled release of therapeutic monolayer payloads.

Identifying new therapeutic targets via modulation of protein corona formation by engineered nanoparticles.

BACKGROUND: We introduce a promising methodology to identify new therapeutic targets in cancer. Proteins bind to nanoparticles to form a protein corona. We modulate this corona by using surface-engineered nanoparticles, and identify protein composition to provide insight into disease development. METHODS/PRINCIPAL FINDINGS: Using a family of structurally homologous nanoparticles we have investigated the changes in the protein corona around surface-functionalized gold nanoparticles (AuNPs) from normal and malignant ovarian cell lysates. Proteomics analysis using mass spectrometry identified hepatoma-derived growth factor (HDGF) that is found exclusively on positively charged AuNPs ((+)AuNPs) after incubation with the lysates. We confirmed expression of HDGF in various ovarian cancer cells and validated binding selectivity to (+)AuNPs by Western blot analysis. Silencing of HDGF by siRNA resulted s inhibition in proliferation of ovarian cancer cells. CONCLUSION: We investigated the modulation of protein corona around surface-functionalized gold nanoparticles as a promising approach to identify new therapeutic targets. The potential of our method for identifying therapeutic targets was demonstrated through silencing of HDGF by siRNA, which inhibited proliferation of ovarian cancer cells. This integrated proteomics, bioinformatics, and nanotechnology strategy demonstrates that protein corona identification can be used to discover novel therapeutic targets in cancer.

Nanoparticle hydrophobicity dictates immune response.

Understanding the interactions of nanomaterials with the immune system is essential for the engineering of new macromolecular systems for in vivo applications. Systematic study of immune activation is challenging due to the complex structure of most macromolecular probes. We present here the use of engineered gold nanoparticles to determine the sole effect of hydrophobicity on the immune response of splenocytes. The gene expression profile of a range of cytokines (immunological reporters) was analyzed against the calculated log P of the nanoparticle headgroups, with an essentially linear increase in immune activity with the increase in hydrophobicity observed in vitro. Consistent behavior was observed with in vivo mouse models, demonstrating the importance of hydrophobicity in immune system activation.

Control of surface tension at liquid-liquid interfaces using nanoparticles and nanoparticle-protein complexes.

Subtle changes in the monolayer structure of nanoparticles (NPs) influence the interfacial behavior of both NPs and NP-protein conjugates. In this study, we use a series of monolayer-protected gold NPs to explore the role of particle hydrophobicity on their dynamic behavior at the toluene-water interface. Using dynamic surface tension measurements, we observed a linear decrease in the meso-equilibrium surface tension (γ) and faster dynamics as the hydrophobicity of the ligands increases. Further modulation of γ is observed for the corresponding NP-protein complexes at the charge-neutralization point.

Modulating pharmacokinetics, tumor uptake and biodistribution by engineered nanoparticles.

BACKGROUND: Inorganic nanoparticles provide promising tools for biomedical applications including detection, diagnosis and therapy. While surface properties such as charge are expected to play an important role in their in vivo behavior, very little is known how the surface chemistry of nanoparticles influences their pharmacokinetics, tumor uptake, and biodistribution. METHOD/PRINCIPAL FINDINGS: Using a family of structurally homologous nanoparticles we have investigated how pharmacological properties including tumor uptake and biodistribution are influenced by surface charge using neutral (TEGOH), zwitterionic (Tzwit), negative (TCOOH) and positive (TTMA) nanoparticles. Nanoparticles were injected into mice (normal and athymic) either in the tail vein or into the peritoneum. CONCLUSION: Neutral and zwitterionic nanoparticles demonstrated longer circulation time via both i.p. and i.v. administration, whereas negatively and positively charged nanoparticles possessed relatively short half-lives. These pharmacological characteristics were reflected on the tumor uptake and biodistribution of the respective nanoparticles, with enhanced tumor uptake by neutral and zwitterionic nanoparticles via passive targeting.

Colorimetric bacteria sensing using a supramolecular enzyme-nanoparticle biosensor.

Rapid and sensitive detection of pathogens is a key requirement for both environmental and clinical settings. We report here a colorimetric enzyme-nanoparticle conjugate system for detection of microbial contamination. In this approach, cationic gold nanoparticles (NPs) featuring quaternary amine headgroups are electrostatically bound to an enzyme [ß-galactosidase (ß-Gal)], inhibiting enzyme activity. Analyte bacteria bind to the NP, which releases the ß-Gal and restores its activity, providing an enzyme-amplified colorimetric readout of the binding event. Using this strategy, we have been able to quantify bacteria at concentrations of 1 × 10(2) bacteria/mL in solution and 1 × 10(4) bacteria/mL in a field-friendly test strip format.