An aptamer-doxorubicin physical conjugate as a novel targeted drug-delivery platform.
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Antineoplastic Agents↗
Biomedical subjects
Sangyong Jon
Publications and source records attributed to Sangyong Jon.
Antibiofouling polymer-coated superparamagnetic iron oxide nanoparticles as potential magnetic resonance contrast agents for in vivo cancer imaging.
We report the fabrication and characterization of antifouling polymer-coated magnetic nanoparticles as nanoprobes for magnetic resonance (MR) contrast agents. Magnetite superparamagnetic iron oxide nanoparticles (SPION) were coated with the protein- or cell-resistant polymer, poly(TMSMA-r-PEGMA), to generate stable, protein-resistant MR probes. Coated magnetic nanoparticles synthesized using two different preparation methods (in situ and stepwise, respectively) were both well dispersed in PBS buffer at a variety of pH conditions (pH 1-10). In addition, dynamic light scattering data revealed that their sizes were not altered even after 24 h of incubation in 10% serum containing cell culture medium, indicative of a lack of protein adsorption on their surfaces. When the antibiofouling polymer-coated SPION were incubated with macrophage cells, uptake was significantly lower in comparison to that of the popular contrast agent, Feridex I.V., suggesting that the polymer-coated SPION can be long-circulated in plasma by escaping from uptake by the reticular endothelial system (RES) such as macrophages. Indeed, when the coated SPION were administered to tumor xenograft mice by intravenous injection, the tumor could be detected in T2-weighted MR images within 1 h as a result of the accumulation of the nanomagnets within the tumor site. Although the poly(TMSMA-r-PEGMA)-coated SPION do not have any targeting ligands on their surface, they are potentially useful for cancer diagnosis in vivo.
Animals↗
Targeted nanoparticle-aptamer bioconjugates for cancer chemotherapy in vivo.
Targeted uptake of therapeutic nanoparticles in a cell-, tissue-, or disease-specific manner represents a potentially powerful technology. Using prostate cancer as a model, we report docetaxel (Dtxl)-encapsulated nanoparticles formulated with biocompatible and biodegradable poly(D,L-lactic-co-glycolic acid)-block-poly(ethylene glycol) (PLGA-b-PEG) copolymer and surface functionalized with the A10 2'-fluoropyrimidine RNA aptamers that recognize the extracellular domain of the prostate-specific membrane antigen (PSMA), a well characterized antigen expressed on the surface of prostate cancer cells. These Dtxl-encapsulated nanoparticle-aptamer bioconjugates (Dtxl-NP-Apt) bind to the PSMA protein expressed on the surface of LNCaP prostate epithelial cells and get taken up by these cells resulting in significantly enhanced in vitro cellular toxicity as compared with nontargeted nanoparticles that lack the PSMA aptamer (Dtxl-NP) (P < 0.0004). The Dtxl-NP-Apt bioconjugates also exhibit remarkable efficacy and reduced toxicity as measured by mean body weight loss (BWL) in vivo [body weight loss of 7.7 +/- 4% vs. 18 +/- 5% for Dtxl-NP-Apt vs. Dtxl-NP at nadir, respectively (mean +/- SD); n = 7]. After a single intratumoral injection of Dtxl-NP-Apt bioconjugates, complete tumor reduction was observed in five of seven LNCaP xenograft nude mice (initial tumor volume of approximately 300 mm3), and 100% of these animals survived our 109-day study. In contrast, two of seven mice in the Dtxl-NP group had complete tumor reduction with 109-day survivability of only 57%. Dtxl alone had a survivability of only 14%. Saline and nanoparticles without drug were similarly nonefficacious. This report demonstrates the potential utility of nanoparticle-aptamer bioconjugates for a therapeutic application.
Animals↗
Magnetically responsive polymeric microparticles for oral delivery of protein drugs.
PURPOSE: Protein drugs cannot be delivered efficiently through oral routes. To address this challenge, we evaluated the effect of prolonged gastrointestinal transit on the bioavailability of insulin carried by magnetically responsive microparticles in the presence of an external magnetic field. METHODS: Magnetite nanocrystals and insulin were coencapsulated into poly(lactide-co-glycolide) (PLGA) microparticles and their effects on hypoglycemia were evaluated in mice in the presence of a circumferentially applied external magnetic field. RESULTS: A single administration of 100 U/kg of insulin-magnetite-PLGA microparticles to fasted mice resulted in a reduction of blood glucose levels of up to 43.8% in the presence of an external magnetic field for 20 h (bioavailability = 2.77 +/- 0.46 and 0.87 +/- 0.29% based on glucose and ELISA assay, respectively), significantly higher than similarly dosed mice without a magnetic field (bioavailability = 0.66 +/- 0.56 and 0.30 +/- 0.06%, based on glucose and ELISA assay, respectively). CONCLUSIONS: A substantially improved hypoglycemic effect was observed in mice that were orally administered with insulin-magnetite-PLGA microparticles in the presence of an external magnetic field, suggesting that magnetic force can be used to improve the efficiency of orally delivered protein therapeutics.
Administration, Oral↗
Direct confinement of individual viruses within polyethylene glycol (PEG) nanowells.
Individual M13 viruses were spatially confined within wells fabricated from nanomolding of a PEG-based random copolymer. The viruses were selectively adhered to the region pretreated with an antibody against the virus, resulting in individual virus arrays. The polymer surface was found to be highly resistant to the attachment of the virus (approximately 0.02 microm-2), approximately 2 orders of magnitude lower than that on a bare silicon surface. The physical height of the template provided an additional barrier to the attachment of the virus due to entropic penalty in bending of a semi-flexible M13 virus. The effects of pattern size and barrier height were investigated, revealing that a certain critical height is needed to ensure successful confinement within the template for a given pattern size.
Bacteriophage M13↗
Anion-directed self-organization of thermotropic liquid crystalline materials containing a guanidinium moiety.
New wedge-shaped thermotropic liquid crystalline materials containing a guanidinium moiety at the apex organize into various supramolecular structures such as hexagonal columnar, rectangular columnar and Pm3n cubic mesophases depending on anions illustrating guest-directed self-organization in mesophases.
Journal Article↗
Microfluidic system for studying the interaction of nanoparticles and microparticles with cells.
Nanoparticles and microparticles have many potential biomedical applications ranging from imaging to drug delivery. Therefore, in vitro systems that can analyze and optimize the interaction of such particles with cells may be beneficial. Here, we report a microfluidic system that can be used to study these interactions. As a model system, we evaluated the interaction of polymeric nanoparticles and microparticles and similar particles conjugated to aptamers that recognize the transmembrane prostate specific membrane antigen (PSMA), with cells seeded in microchannels. The binding of particles to cells that expressed or did not express the PSMA (LNCaP or PC3, respectively) were evaluated with respect to changes in fluid shear stress, PSMA expression on target cells, and particle size. Nanoparticle-aptamer bioconjugates selectively adhered to LNCaP but not PC3 cells at static and low shear (<1 dyn/cm2) but not higher shear (approximately 4.5 dyn/cm2) conditions. Control nanoparticles and microparticles lacking aptamers and microparticle-aptamer bioconjugates did not adhere to LNCaP cells, even under very low shear conditions (approximately 0.28 dyn/cm2). These results demonstrate that the interaction of particles with cells can be studied under controlled conditions, which may aid in the engineering of desired particle characteristics. The scalability, low cost, reproducibility, and high-throughput capability of this technology is potentially beneficial to examining and optimizing a wide array of cell-particle systems prior to in vivo experiments.
Biosensing Techniques↗
Control over wettability of polyethylene glycol surfaces using capillary lithography.
We demonstrate that wettability of poly(ethylene glycol) (PEG) surfaces can be controlled using nanostructures with various geometrical features. Capillary lithography was used to fabricate PEG nanostructures using a new ultraviolet (UV) curable mold consisting of functionalized polyurethane with acrylate group (MINS101m, Minuta Tech.). Two distinct wetting states were observed depending of the height of nanostructures. At relatively lower heights (< 300 nm for 150 nm pillars with 500 nm spacing), the initial contact angle of water was less than 80 degrees and the water droplet easily invaded into the surface grooves, leading to a reduced contact angle at equilibrium (Wenzel state). At relatively higher heights (> 400 nm for 150 nm pillars with 500 nm spacing), on the other hand, the nanostructured PEG surface showed hydrophobic nature and no significant change in contact angle was observed with time (Cassie state). The presence of two wetting states was also confirmed by dynamic wetting properties and contact-angle hysteresis. The wetting transition from hydrophilic (bare PEG surface) to hydrophobic (PEG nanostructures) was described by the Cassie-Baxter equation assuming that enhanced hydrophobicity is due to the heterogeneous wetting mediated by an air pocket on the surface. The measured contact angles in the Cassie state were increased with increasing air fraction, in agreement with the theoretical prediction.
Journal Article↗
Artificial ion channel formed by cucurbit[n]uril derivatives with a carbonyl group fringed portal reminiscent of the selectivity filter of K+ channels.
Novel artificial ion channels (1 and 2) based on CB[n] (n = 6 and 5, respectively) synthetic receptors with carbonyl-fringed portals (diameter 3.9 and 2.4 A, respectively) can transport proton and alkali metal ions across a lipid membrane with ion selectivity. Fluorometric experiments using large unilamellar vesicles showed that 1 mediates proton transport across the membranes, which can be blocked by a neurotransmitter, acetylcholine, reminiscent of the blocking of the K+ channels by polyamines. The alkali metal ion transport activity of 1 follows the order of Li+ > Cs+ approximately Rb+ > K+ > Na+, which is opposite to the binding affinity of CB[6] toward alkali metal ions. On the other hand, the transport activity of 2 follows the order of Li+ > Na+, which is also opposite to the binding affinity of 2 toward these metal ions, but virtually no transport was observed for K+, Rb+, and Cs+. It is presumably because the carbonyl-fringed portal size of 2 (diameter 2.4 A) is smaller than the diameters of these alkali metal ions. To determine the transport mechanism, voltage-clamp experiments on planar bilayer lipid membranes were carried out. The experiments showed that a single-channel current of 1 for Cs+ transport is approximately 5 pA, which corresponds to an ion flux of approximately 3 x 107 ions/s. These results are consistent with an ion channel mechanism. Not only the structural resemblance to the selectivity filter of K+ channels but also the remarkable ion selectivity makes this model system unique.
Biomimetic Materials↗
Protein patterning based on electrochemical activation of bioinactive surfaces with hydroquinone-caged biotin.
We report a protein attachment and patterning method based on a hydroquinone-caged biotin surface that generates bioactive biotin by mild electrochemical perturbation. The electrochemical activation proceeds under the buffered aqueous environment at neutral pH. It also allows site-selective generation of bioactive biotin for the immobilization of target protein by using prepatterned electrode arrays.
Bacterial Proteins↗
Nanoparticle-aptamer bioconjugates: a new approach for targeting prostate cancer cells.
Nucleic acid ligands (aptamers) are potentially well suited for the therapeutic targeting of drug encapsulated controlled release polymer particles in a cell- or tissue-specific manner. We synthesized a bioconjugate composed of controlled release polymer nanoparticles and aptamers and examined its efficacy for targeted delivery to prostate cancer cells. Specifically, we synthesized poly(lactic acid)-block-polyethylene glycol (PEG) copolymer with a terminal carboxylic acid functional group (PLA-PEG-COOH), and encapsulated rhodamine-labeled dextran (as a model drug) within PLA-PEG-COOH nanoparticles. These nanoparticles have the following desirable characteristics: (a) negative surface charge (-50 +/- 3 mV, mean +/- SD, n = 3), which may minimize nonspecific interaction with the negatively charged nucleic acid aptamers; (b) carboxylic acid groups on the particle surface for potential modification and covalent conjugation to amine-modified aptamers; and (c) presence of PEG on particle surface, which enhances circulating half-life while contributing to decreased uptake in nontargeted cells. Next, we generated nanoparticle-aptamer bioconjugates with RNA aptamers that bind to the prostate-specific membrane antigen, a well-known prostate cancer tumor marker that is overexpressed on prostate acinar epithelial cells. We demonstrated that these bioconjugates can efficiently target and get taken up by the prostate LNCaP epithelial cells, which express the prostate-specific membrane antigen protein (77-fold increase in binding versus control, n = 150 cells per group). In contrast to LNCaP cells, the uptake of these particles is not enhanced in cells that do not express the prostate-specific membrane antigen protein. To our knowledge, this represents the first report of targeted drug delivery with nanoparticle-aptamer bioconjugates.
Antigens, Surface↗
Molded polyethylene glycol microstructures for capturing cells within microfluidic channels.
The ability to control the deposition and location of adherent and non-adherent cells within microfluidic devices is beneficial for the development of micro-scale bioanalytical tools and high-throughput screening systems. Here, we introduce a simple technique to fabricate poly(ethylene glycol)(PEG) microstructures within microfluidic channels that can be used to dock cells within pre-defined locations. Microstructures of various shapes were used to capture and shear-protect cells despite medium flow in the channel. Using this approach, PEG microwells were fabricated either with exposed or non-exposed substrates. Proteins and cells adhered within microwells with exposed substrates, while non-exposed substrates prevented protein and cell adhesion (although the cells were captured inside the features). Furthermore, immobilized cells remained viable and were stained for cell surface receptors by sequential flow of antibodies and secondary fluorescent probes. With its unique strengths in utility and control, this approach is potentially beneficial for the development of cell-based analytical devices and microreactors that enable the capture and real-time analysis of cells within microchannels, irrespective of cell anchorage properties.
Animals↗
A soft lithographic approach to fabricate patterned microfluidic channels.
The control of surface properties and spatial presentation of functional molecules within a microfluidic channel is important for the development of diagnostic assays and microreactors and for performing fundamental studies of cell biology and fluid mechanics. Here, we present a simple technique, applicable to many soft lithographic methods, to fabricate robust microchannels with precise control over the spatial properties of the substrate. In this approach, the patterned regions were protected from oxygen plasma by controlling the dimensions of the poly(dimethylsiloxane) (PDMS) stamp and by leaving the stamp in place during the plasma treatment process. The PDMS stamp was then removed, and the microfluidic mold was irreversibly bonded to the substrate. The approach was used to pattern a nonbiofouling poly(ethylene glycol)-based copolymer or the polysaccharide hyaluronic acid within microfluidic channels. These nonbiofouling patterns were then used to fabricate arrays of fibronectin and bovine serum albumin as well as mammalian cells. In addition, further control over the deposition of multiple proteins onto multiple or individual patterns was achieved using laminar flow. Also, cells that were patterned within channels remained viable and capable of performing intracellular reactions and could be potentially lysed for analysis.
Animals↗
Degradable poly(amino alcohol esters) as potential DNA vectors with low cytotoxicity.
The synthesis of a new degradable polymer system, poly(amino alcohol esters) and the resulting polymers' potential for use in gene transfection vectors are reported. The polymerization proceeded in a one step reaction from commercially available bis(secondary amines) monomers (N,N'-dimethyl-1,3-propanediamine and N,N'-dimethyl-1,6-hexanediamine, respectively) through nucleophilic addition to the diglycidyl ester of dicarboxylic acid (diglycidyl adipate). Poly(amino alcohol ester) 1 and 2 were synthesized with a yield of 89% and 91% with Mn = 24,800 and Mn = 36,400, respectively. Poly(amino alcohol ester) 1 degraded hydrolytically in phosphate buffer at pH 7.4 with a half-life of approximately 5 days. Both polymers readily self-assembled with plasmid DNA into nanometer-sized DNA/polymer complexes less than 180 nm diameter and are significantly less cytotoxic than the commonly used DNA delivery polymer, poly(ethylene imine) (PEI).
3T3 Cells↗