ABSTRACT: Bioluminescence, due to its high sensitivity, has been exploited in various analytical and imaging applications. In this work, we report a highly stable, cell-transductable, and wavelength-tunable bioluminescence system achieved with an elegant and simple design. Using aqueous in situ polymerization on a bioluminescent enzyme anchored with polymerizable vinyl groups, we obtained nanosized core-shell nanocapsules with the enzyme as the core and a cross-linked thin polymer net as the shell. These nanocapsules possess greatly enhanced stability, retained bioactivity, and a readily engineered surface. In particular, by incorporating polymerizable amines in the polymerization, we endowed the nanocapsules with efficient cell-transduction and sufficient conjugation sites for follow-up modification. Following in situ polymerization, decorating the polymer shell with fluorescent quantum dots allowed us to access a continuous tunable wavelength, which extends the application of such bioluminescent nanocapsules, especially in deep tissue. In addition, the unique core-shell structure and adequate conjugation sites on surface enabled us to maximize the BRET efficiency by adjusting the QD/enzyme conjugation ratio.
Project description:Droplet microfluidics has enabled the synthesis of polymeric particles with controlled sizes, shell thickness, and morphologies. Here, we report the Janus to core-shell structural evolution of biphasic droplets formed in a microfluidic flow-focusing device (MFFD) for the synthesis of polymer microcapsules with oil core/thickness-tunable shell via off-chip photo- and thermally induced polymerization. First, nanoliter-sized biphasic Janus droplets comprising an acrylate monomer and silicone oil were generated in a co-flowing aqueous polyvinyl alcohol (PVA) solution in an MFFD on a glass chip. Immediately following their break-off, the produced Janus droplets started to change their geometry from Janus to core-shell structure comprising a single silicone-oil core and an acrylate-monomer shell by the minimization of interfacial energy. Thus, we could produce monodisperse core-shell drops with average diameters of 105-325 ?m, coefficient of variation (CV) values of 1.0-4.5%, and shell thickness of 1-67 ?m. Subsequently, these drops were synthesized to fabricate polymeric microcapsules with tunable shell thickness via photo- and thermally induced polymerization. By increasing the concentration of the photo- and thermal initiator, we successfully produced thinner and ultra-thin shell (800?nm thickness) microcapsules. The surface structure of resulting particles was smooth in photopolymerization and porous in thermal polymerization.
Project description:We report a facile strategy for engineering diverse particles based on the supramolecular assembly of natural polyphenols and a self-polymerizable aromatic dithiol. In aqueous conditions, uniform and size-tunable supramolecular particles are assembled through ?-? interactions as mediated by polyphenols. Owing to the high binding affinity of phenolic motifs present at the surface, these particles allow for the subsequent deposition of various materials (i.e., organic, inorganic, and hybrid components), producing a variety of monodisperse functional particles. Moreover, the solvent-dependent disassembly of the supramolecular networks enables their removal, generating a wide range of corresponding hollow structures including capsules and yolk-shell structures. The versatility of these supramolecular networks, combined with their negligible cytotoxicity provides a pathway for the rational design of a range of particle systems (including core-shell, hollow, and yolk-shell) with potential in biomedical and environmental applications.
Project description:We report the plasmonic enhancement of the photocatalytic properties of Pt/n-Si/Ag photodiode photocatalysts using Au/Ag core/shell nanorods. We show that Au/Ag core/shell nanorods can be synthesized with tunable plasmon resonance frequencies and then conjugated onto Pt/n-Si/Ag photodiodes using well-defined chemistry. Photocatalytic studies showed that the conjugation with Au/Ag core/shell nanorods can significantly enhance the photocatalytic activity by more than a factor of 3. Spectral dependence studies further revealed that the photocatalytic enhancement is strongly correlated with the plasmonic absorption spectra of the Au/Ag core/shell nanorods, unambiguously demonstrating the plasmonic enhancement effect.
Project description:We report the synthesis of high-performance organic-inorganic hybrid fluorescent nanocapsules comprising a polymer shell armored with an inorganic layer and a liquid core containing a fluorophore. The polymeric capsules are synthesized by free radical miniemulsion polymerization and contain covalently bound carboxylate surface functionalities that allow for the binding of metal ions through electrostatic interaction. A cerium(IV) oxide nanoparticle layer, formed in situ at the surface of the hybrid nanocapsules, acts as oxygen scavenger and keeps external reactive molecular oxygen from entering into the capsules, eventually resulting in a reduction of the photooxidation of encapsulated fluorescent molecules. This approach shows an increase in the fluorescence of the model organic fluorophore terrylene diimide by avoiding the ground-state molecular oxygen to react with electronically excited states of the fluorescent hydrocarbon molecule.
Project description:Bioorthogonal conjugation eliminates the shortcomings of classical conjugation methods. The conjugation of antibodies to reporter proteins, such as bioluminescent protein, can be controlled with orthogonal conjugation methods. Here we report a bioluminescent immunoassay for the sensitive detection of interferon-? (IFN-?) that utilizes orthogonal conjugation of bioluminescent protein, Gaussia luciferase to anti-IFN-? antibody. The IFN-? is produced by the immune system and the detection of the IFN-? is pivotal for the detection of persistent viral and bacterial infections. A bioorthogonal conjugation approach is used to conjugate an anti-IFN-? antibody with a GLuc mutant containing the N-terminal tyrosine using formylbenzene diazonium hexafluorophosphate reagent (FBDP) in hydrophilic mild pH environment yielding high conjugation efficiency (60%). This reagent is shown to be specific for tyrosine (Tyr) residues. Therefore, conjugation through Tyr was orthogonal and not detrimental to the bioluminescence activity of GLuc. The immunoassay described in this paper is a sandwich type assay and involves a capture and a detection antibody. The assay was validated for its robustness, precision, accuracy, limit of detection, and recovery.
Project description:The dual-mode emission and multicolor outputs in the time domain from core-shell microcrystals are presented. The core-shell microcrystals, with NaYF?:Yb/Er as the core and NaYF?:Ce/Tb/Eu as the shell, were successfully fabricated by employing the hydrothermal method, which confines the activator ions into a separate region and minimizes the effect of surface quenching. The material is capable of both upconversion and downshifting emission, and their multicolor outputs in response to 980 nm near-infrared (NIR) excitation laser and 252 nm, and 395 nm ultraviolet (UV) excitation light have been investigated. Furthermore, the tunable color emissions by controlling the Tb3+- Eu3+ ratio in shells and the energy transfer of Ce3+?Tb3+? Eu3+ were discussed in details. In addition, color tuning of core-shell-structured microrods from green to red region in the time domain could be obtained by setting suitable delay time. Due to downshifting multicolor outputs (time-resolved and pump-wavelength-induced downshifting) coupled with the upconversion mode, the core-shell microrods can be potentially applied to displays and high-level security.
Project description:Hollow nanoparticles represent an emerging area of development for the encapsulation of active ingredients. Expanding the capabilities of these nanomaterials will require continued efforts to infill properties such as size control, biodegradability, and environmental responsiveness. Acid-labile poly(N-vinylformamide) (PNVF) nanocapsules were synthesized by free radical polymerization of N-vinylformamide on the surface of silica nanoparticles. Polymerization in the presence of a novel crosslinker that contains an acid-labile ketal facilitated stable etching of silica nanoparticle templates using sodium hydroxide and recovery of degradable PNVF nanocapsules. The formamido side group of PNVF was then hydrolyzed by extended exposure to sodium hydroxide to produce polyvinylamine (PVAm) micro- and nanocapsules. Both capsule types demonstrated an increasing dissolution rate as pH decreased. In addition, PVAm nanocapsules exhibited swelling in proportion to the relative charge density of the PVAm network (a function of the degree of formamide hydrolysis and pH), presumably due to the repulsion of positively charged amino groups within the elastic shell network. The synthetic approaches reported provide methods to endow nanocapsules with key attributes such as size control, pH sensitive degradation, swelling in response to pH, and amine functionality.
Project description:We present a proof of concept for tunable plasmon resonance frequencies in a core shell nano-architectured hybrid metal-semiconductor multilayer structure, with Ag as the active shell and ITO as the dielectric modulation media. Our method relies on the collective change in the dielectric function within the metal semiconductor interface to control the surface. Here we report fabrication and optical spectroscopy studies of large-area, nanostructured, hybrid silver and indium tin oxide (ITO) structures, with feature sizes below 100 nm and a controlled surface architecture. The optical and electrical properties of these core shell electrodes, including the surface plasmon frequency, can be tuned by suitably changing the order and thickness of the dielectric layers. By varying the dimensions of the nanopillars, the surface plasmon wavelength of the nanopillar Ag can be tuned from 650 to 690 nm. Adding layers of ITO to the structure further shifts the resonance wavelength toward the IR region and, depending on the sequence and thickness of the layers within the structure, we show that such structures can be applied in sensing devices including enhancing silicon as a photodetection material.
Project description:We report the synthesis and properties of temperature- and pH-responsive p([NIPAm-co-PEGMA] (core)/[NIPAm-co-AAc] (shell)) nanogels with narrow size distributions, tunable sizes and increased drug loading efficiencies. The core-shell nanogels were synthesized using an optimized two-stage seeded polymerization methodology. The core-shell nanogels show a narrow size distribution and controllable physico-chemical properties. The hydrodynamic sizes, charge distributions, temperature-induced volume phase transition behaviors, pH-responsive behaviors and drug loading capabilities of the core-shell nanogels were investigated using transmission electron microscopy, zeta potential measurements, dynamic light scattering and UV-Vis spectroscopy. The size of the core-shell nanogels was controlled by polymerizing NIPAm with crosslinker poly(ethylene glycol) dimethacrylate (PEGDMA) of different molecular weights (Mn-200, 400, 550 and 750 g/mol) during the core synthesis. It was found that the swelling/deswelling kinetics of the nanogels was sharp and reversible; with its volume phase transition temperature in the range of 40⁻42 °C. Furthermore, the nanogels loaded with l-3,4-dihydroxyphenylalanine (L-DOPA), using a modified breathing-in mechanism, showed high loading and encapsulation efficiencies, providing potential possibilities of such nanogels for biomedical applications.
Project description:Polymerizable lipids have been used in research and medical applications such as membrane models, imaging platforms, drug delivery systems, vaccine carriers, biosensors, and coating materials. The polymerization of these lipid molecules forms a covalent bond between lipid moieties, which improves the noncovalent interactions that maintain the lipid lamellar phase architecture and increases the stability of the polymerized system. Because such lipid molecules form nanoassemblies with modifiable structures that acquire the stability of polymers following covalent bond formation, these lipids are of considerable interest in the emerging field of theranostics. In this Account, we summarize the biomedical applications of polymerizable lipids (primarily phospholipids) in the context of various nanoplatforms. We discuss stable nanoplatforms, which have been used in a variety of theranostics applications. In addition, we describe methods for assembling triggerable theranostics by combining appropriate nonpolymerizable lipids with polymerizable lipids. Polymeric lipids hold promise as nanotools in the field of medical imaging, targeting, and on-demand drug delivery. Because of their similarity to biological lipids, long-term toxicity issues from polymerizable lipid nanoplatforms are predicted to be minimal. Although the field of polymeric nanocapsules is still in development, intensive efforts are underway to produce systems which could be applied to disease diagnosis and treatment. We envision that nanoimaging platforms coupled with localized drug delivery technology will have a significant impact on cancer therapy and other related diseases. The existing wealth of clinical knowledge both in the photochemistry of imaging agents and/or drugs and modifications of these agents using light will prove valuable in the further development of polymeric theranostic lipid-based nanoparticles.