Synthesis of nanodiamond-daunorubicin conjugates to overcome multidrug chemoresistance in leukemia.

Nanodiamonds (NDs) are promising candidates in nanomedicine, demonstrating significant potential as gene/drug delivery platforms for cancer therapy. We have synthesized ND vectors capable of chemotherapeutic loading and delivery with applications towards chemoresistant leukemia. The loading of Daunorubicin (DNR) onto NDs was optimized by adjusting reaction parameters such as acidity and concentration. The resulting conjugate, a novel therapeutic payload for NDs, was characterized extensively for size, surface charge, and loading efficiency. A K562 human myelogenous leukemia cell line, with multidrug resistance conferred by incremental DNR exposure, was used to demonstrate the efficacy enhancement resulting from ND-based delivery. While resistant K562 cells were able to overcome treatment from DNR alone, as compared with non-resistant K562 cells, NDs were able to improve DNR delivery into resistant K562 cells. By overcoming efflux mechanisms present in this resistant leukemia line, ND-enabled therapeutics have demonstrated the potential to improve cancer treatment efficacy, especially towards resistant strains. FROM THE CLINICAL EDITOR: The authors of this study demonstrate superior treatment properties of resistant leukemia cell lines by utilizing nanodiamond vectors loaded with daunorubicin, paving the way to clinical studies in the hopefully not too distant future.

Convection-enhanced delivery of nanodiamond drug delivery platforms for intracranial tumor treatment.

This study examined a novel drug delivery system for treatment of malignant brain gliomas: DOX complexed with nanodiamonds (ND-Dox), and administered via convection-enhanced delivery (CED). Drug retention and toxicity were examined in glioma cell lines, and distribution, retention and toxicity were examined in normal rat parenchyma. Efficacy was assessed in a bioluminescence rodent tumor model. NDs markedly enhanced DOX uptake and retention in glioma cells. ND-Dox delivered via CED extended DOX retention and localized DOX toxicity in normal rodent parenchyma, and was significantly more efficient at killing tumor cells than uncomplexed DOX. Outcomes from this work suggest that CED of ND-Dox is a promising approach for brain tumor treatment. FROM THE CLINICAL EDITOR: In this paper, nanodiamonds were utilized to enhance delivery of DOX in a preclinical glioma model using a convection-enhanced delivery method, demonstrating remarkably enhanced efficacy.

Ultrananocrystalline diamond thin films functionalized with therapeutically active collagen networks.

The fabrication of biologically amenable interfaces in medicine bridges translational technologies with their surrounding biological environment. Functionalized nanomaterials catalyze this coalescence through the creation of biomimetic and active substrates upon which a spectrum of therapeutic elements can be delivered to adherent cells to address biomolecular processes in cancer, inflammation, etc. Here, we demonstrate the robust functionalization of ultrananocrystalline diamond (UNCD) with type I collagen and dexamethasone (Dex), an anti-inflammatory drug, to fabricate a hybrid therapeutically active substrate for localized drug delivery. UNCD oxidation coupled with a pH-mediated collagen adsorption process generated a comprehensive interface between the two materials, and subsequent Dex integration, activity, and elution were confirmed through inflammatory gene expression assays. These studies confer a translational relevance to the biofunctionalized UNCD in its role as an active therapeutic network for potent regulation of cellular activity toward applications in nanomedicine.

Localized therapeutic release via an amine-functionalized poly-p-xylene microfilm device.

Developing biocompatible polymeric platforms for drug delivery with enhanced localized activity represents a key facet of advanced interventional therapy. In this work, the drug-eluting potential of an amine-functionalized poly- p-xylene commonly known as Parylene A (4-amino(2,2)paracyclophane) was conducted with the microfilm device consisting of a primary base layer, drug film, and a secondary eluting layer presenting exposed amine groups which enhance the range of modifications that can be incorporated into the film. The murine macrophage cell line RAW 264.7 served as a cellular response to dexamethasone, a synthetic anti-inflammatory glucocorticoid and doxorubicin, an anticancer therapeutic. Decreased expression of NFkappa-B-mediated cytokines Interleukin-6 (IL-6) and Tumor Necrosis Factor-alpha (TNFalpha), resultant DNA fragmentation, and spectroscopic analysis revealed the efficient and localized drug-eluting properties of the Parylene A polymeric bilayer.

Combinatorial release of dexamethasone and amiodarone from a nano-structured parylene-C film to reduce perioperative inflammation and atrial fibrillation.

Suppressing perioperative inflammation and post-operative atrial fibrillation requires effective drug delivery platforms (DDP). Localized anti-inflammatory and anti-arrhythmic agent release may be more effective than intravenous treatment to improve patient outcomes. This study utilized a dexamethasone (DEX) and amiodarone (AMIO)-loaded Parylene-C (PPX) nano-structured film to inhibit inflammation and atrial fibrillation. The PPX film was tested in an established pericardial adhesion rabbit model. Following sternotomy, the anterior pericardium was resected and the epicardium was abraded. Rabbits were randomly assigned to five treatment groups: control, oxidized PPX (PPX-Oxd), PPX-Oxd infused with DEX (PPX-Oxd[DEX]), native PPX (PPX), and PPX infused with DEX and AMIO (PPX[AMIO, DEX]). 4 weeks post-sternotomy, pericardial adhesions were evaluated for gross adhesions using a 4-point grading system and histological evaluation for epicardial neotissue fibrosis (NTF). Atrial fibrillation duration and time per induction were measured. The PPX[AMIO, DEX] group had a significant reduction in mean adhesion score compared with the control group (control 2.75 ± 0.42 vs. PPX[AMIO, DEX] 0.25 ± 0.42, P < 0.001). The PPX[AMIO, DEX] group was similar to native PPX (PPX 0.38 ± 0.48 vs. PPX[AMIO, DEX] 0.25 ± 0.42, P=NS). PPX-Oxd group adhesions were indistinguishable from controls (PPX-Oxd 2.83 ± 0.41 vs. control 2.75 ± 0.42, P=NS). NTF was reduced in the PPX[AMIO, DEX] group (0.80 ± 0.10 mm) compared to control (1.78 ± 0.13 mm, P < 0.001). Total duration of atrial fibrillation was decreased in rabbits with PPX[AMIO, DEX] films compared to control (9.5 ± 6.8 s vs. 187.6 ± 174.7 s, p = 0.003). Time of atrial fibrillation per successful induction decreased among PPX[AMIO, DEX] films compared to control (2.8 ± 1.2 s vs. 103.2 ± 178 s, p = 0.004). DEX/AMIO-loaded PPX films are associated with reduced perioperative inflammation and a diminished atrial fibrillation duration. Epicardial application of AMIO, DEX films is a promising strategy to prevent post-operative cardiac complications.

Triggered release of therapeutic antibodies from nanodiamond complexes.

Recent reports have revealed that detonation nanodiamonds (NDs) can serve as efficient, biocompatible, and versatile drug delivery platforms. Consequently, further investigations exploring additional therapeutic applications are warranted. Current limitations associated with the non-specific nature of intravenous drugs limit the potential of certain pharmacological agents. One such treatment that could benefit from a stable delivery platform is antibody (Ab) therapy. Determination of Ab adsorption and desorption to a ND surface was subsequently examined using the transforming growth factor ß (TGF-ß) antibody as a model therapeutic. ND-Ab complexes were found to be stable in water through enzyme-linked immunosorbent assays (ELISAs), UV-vis spectroscopy and TEM, with no Ab released after ten days. Released Abs were detected in extreme pH solutions (3.5), DMEM (+) serum with pH levels ranging from 4 to 10.5, and inorganic saline solutions. Preserved activity of Abs released in DMEM (+) serum was confirmed using an ELISA. These results suggest ND-Ab complexes are synthesized and stabilized in water and are triggered to release active Abs upon exposure to physiological conditions.

Nanodiamond therapeutic delivery agents mediate enhanced chemoresistant tumor treatment.

Enhancing chemotherapeutic efficiency through improved drug delivery would facilitate treatment of chemoresistant cancers, such as recurrent mammary tumors and liver cancer. One way to improve drug delivery is through the use of nanodiamond (ND) therapies, which are both scalable and biocompatible. Here, we examined the efficacy of an ND-conjugated chemotherapeutic in mouse models of liver and mammary cancer. A complex (NDX) of ND and doxorubicin (Dox) overcame drug efflux and significantly increased apoptosis and tumor growth inhibition beyond conventional Dox treatment in both murine liver tumor and mammary carcinoma models. Unmodified Dox treatment represents the clinical standard for most cancer treatment regimens, and NDX had significantly decreased toxicity in vivo compared to standard Dox treatment. Thus, ND-conjugated chemotherapy represents a promising, biocompatible strategy for overcoming chemoresistance and enhancing chemotherapy efficacy and safety.

Parylene-encapsulated copolymeric membranes as localized and sustained drug delivery platforms.

Parylene is a biologically inert material capable of being deposited in conformal nanoscale layers on virtually any surface, making it a viable structural material for the fabrication of drug delivery devices, as well as implant coatings, sensors, and other biomedical technologies. Here we explore its novel drug delivery applications by using parylene to package the polymethyloxazoline-polydimethylsiloxane-polymethyloxazoline (PMOXA-PDMS-PMOXA) block copolymer membrane of a nanoscale thickness (approximately 4 nm/layer) mixed with a therapeutic element, creating an active parylene-encapsulated copolymeric (APC) membrane for slow release drug delivery of dexamethasone (Dex), a potent anti-inflammatory and immunosuppressant synthetic glucocorticoid. Given current needs for localized therapeutic release for conditions such as cancer, post-surgical inflammation, wound healing, regenerative medicine, to name a few, this stand-alone and minimally invasive implantable technology may impact a broad range of medical scenarios. To evaluate the applicability of the APC membrane as a biocompatible drug delivery system, real-time polymerase chain reaction (RT-PCR) was performed to investigate the expression of cytokines that regulate cellular stress and inflammation as a result of in vitro RAW264.7 macrophage cell growth on the APC membrane. Significant decreases in relative mRNA levels of IL-6, TNF-alpha, and iNOS were observed. Dex functionalized APC membranes were further found to effectively slow-elute the drug via confocal microscopy, with a confirmed extended elution capability over a period of several days, undergoing phosphate buffered saline washes between time points. In addition, we examined the membrane surface through atomic force microscopy (AFM) to examine Dex/copolymer deposition, and to characterize the surface of the APC membrane. Furthermore, we evaluated the effects of incubation with the APC membrane in solution on macrophage growth behavior and cellular adhesion, including the physical properties of parylene and the copolymer to elucidate the anti-adhesive responses we observed. The results of this study will provide insight into ultra-thin and flexible devices of parylene-encapsulated copolymer membranes as platform drug delivery technologies capable of localized and precision therapeutic drug elution.

Nanodiamond-insulin complexes as pH-dependent protein delivery vehicles.

Enhanced specificity in drug delivery aims to improve upon systemic elution methods by locally concentrating therapeutic agents and reducing negative side effects. Due to their robust physical properties, biocompatibility and drug loading capabilities, nanodiamonds serve as drug delivery platforms that can be applied towards the elution of a broad range of therapeutically-active compounds. In this work, bovine insulin was non-covalently bound to detonated nanodiamonds via physical adsorption in an aqueous solution and demonstrated pH-dependent desorption in alkaline environments of sodium hydroxide. Insulin adsorption to NDs was confirmed by FT-IR spectroscopy and zeta potential measurements, while both adsorption and desorption were visualized with TEM imaging, quantified using protein detection assays and protein function demonstrated by MTT and RT-PCR. NDs combined with insulin at a 4:1 ratio showed 79.8+/-4.3% adsorption and 31.3+/-1.6% desorption in pH-neutral and alkaline solutions, respectively. Additionally, a 5-day desorption assay in NaOH (pH 10.5) and neutral solution resulted in 45.8+/-3.8% and 2.2+/-1.2% desorption, respectively. MTT viability assays and quantitative RT-PCR (expression of Ins1 and Csf3/G-csf genes) reveal bound insulin remains inactive until alkaline-mediated desorption. For applications in sustained drug delivery and therapy we have developed a therapeutic protein-ND complex with demonstrated tunable release and preserved activity.

Dynamic Cellular Adhesion Mediated by Copolymeric Nanofilm Substrates.

Amphiphilic block copolymers are finding increased potential in biological and medical research due to their innate alternating hydrophilic and hydrophilic blocks/segments which can be used to package therapeutics, or coat a broad array of biological interfaces. Some studies are already directed towards utilizing these copolymers' ability to form micelles or vesicles to develop novel methods of drug delivery to prevent inflammation or pro-cancer activity. Our study, however, aims to investigate the more fundamental cell-block copolymer interaction for use in protective nanofilms to prevent bio-fouling of non-tissue based implantable devices. Block copolymers could potentially fill the demand for biologically inert, highly functionalizable biomaterials desirable for this type of application. Two such polymers used in our study include PMOXA-PDMS-PMOXA triblock copolymer and PEO/PMMA diblock copolymer. Each block copolymer possesses hydrophilic and hydrophobic blocks that enable it to mimic the cell lipid membrane. So far we have shown that triblock copolymer is capable of inhibiting the accumulation of murine macrophages onto glass substrates. Preliminary evidence has suggested that the triblock copolymer has anti-adsorptive as well as non-inflammatory capabilities during short incubation periods (7 days) in vitro. While the diblock copolymer displays minimal anti-adsorptive activities, nanofilms comprised of a mixture of the two copolymers were able to significantly reduce macrophage accumulation onto glass substrates. The disparate behavior seen by macrophages on the different materials may be due to specific inherent properties such as preference for hydrophobic vs. hydrophilic surfaces and/or rough vs. smooth nano-textures. Furthermore, the specific end groups of the two polymers may exhibit varying capacities to resisting non-specific protein adsorption. Continued investigation outlining the physical and chemical properties desirable for an anti-adsorptive nano-film coating will serve as a basis upon which to design durable implant-tissue interfaces that can react to various external stimuli.