Quantum-Dot-Decorated Robust Transductable Bioluminescent Nanocapsules

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 bioluminescent enzyme anchored with polymerizable vinyl groups, we obtained nano-sized core-shell nanocapsules with enzyme as the core and crosslinked thin polymer net as the shell. These nanocapusles possess greatly enhanced stability, retained bioactivity, and 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 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. Bioluminescence1, the light emission resulted from enzymatic reactions within living organisms, is commonly used for various applications2 -3, such as whole-cell biosensors, immunoassays, nucleic-acid hybridization assays and in-vivo imaging. Many of these applications, however, require transfection of bioluminescent reporter genes, accompanied with many other limitations, such as safety. Moreover, the wavelengths of bioluminescence are still limited to blue/green light, which hinders its use in deep-tissue applications 4 -5.Herein, we report a novel class of bioluminescent nanocapsules (BNs) that are robust, cellpermeable, and tunable in wavelength. Scheme 1 illustrates our synthesis strategy. Starting with a bioluminescent protein, mild chemical modification attaches the protein with polymerizable vinyl groups; subsequent polymerization in an aqueous solution containing acrylamide (AAm) and N-(3-aminopropyl)methacrylamide (APMAAm) wraps the protein * mingyan@ucla.edu; chenwei0226@yahoo.com.cn; luucla@ucla.edu . Supporting Information Available:Full experimental details for preparation of bioluminescent nanocapsules; TEM images; fluorescence and bioluminescence spectra; cell internalization protocols. This material is available free of charge via the Internet at http://pubs.acs.org. NIH Public AccessAuthor Manuscript J Am Chem Soc. Author manuscript; available in PMC 2011 September 22. This unique architecture endows the BNs with many advantages: 1) the thin polymer layer stabilizes the protein and enables rapid transport of the substrate to the encased protein, ensuring bioactivity and stability of the BNs7; 2) fluorophores can be attached to the protein conjugates with controlled density, ensuring an efficient BRET. Particularly, quantum dots (QD), a class of fluorophores with high photo-stability and quantum efficien...

Design and development of high bioluminescent resonance energy transfer efficiency hybrid-imaging constructs

“…This can be achieved by developing methodologies in which individual reagent-components are modified in such a way as to support self-assembly [18] of the desired light emitting constructs. These light emitting constructs often utilize fluorescent resonance energy transfer (FRET) [3, 19] or bioluminescent resonance energy transfer (BRET) [4, 20-23] mechanisms.…”

“…Many commercially available organic dyes fulfill some of these requirements, however, they can be either sensitive to photobleaching, unstable under different pHs, exhibit small Stokes shifts, have narrow excitation and broad emission peaks, or have small molar extinction coefficients. Recent developments in the synthesis of colloidal semiconducting nanoparticles have expanded their use in various optically-demanding applications such as FRET, BRET, and chemiluminescent resonance energy transfer (CRET) [20]. These luminescent “quantum dots” (QDs) have good photostability and high fluorescence quantum yield.…”

“…While the broad UV-Vis absorption band of QDs makes them suitable as energy donors, their application as energy acceptors remained relatively limited until recently [4, 27] and is mainly limited to sensing applications [28, 29]. Du et al [20] reported the design of QD-decorated chemiluminescent (CL) nanocapsules employing vinyl-encapsulated horseradish peroxidase conjugated to QDs. CL was generated using hydrogen peroxide and p -iodophenol as substrates.…”

Superoxide Dismutase, A Potential Theranostics Against Oxidative Stress Caused by Nanomaterials

“…Different from Physical adsorbed encapsulation, in situ polymerization-based encapsulation occurs on the surface of core materials, similar to interfacial polymerization. Du et al utilized the "single protein nanocapsule" concept to encapsulate HRP and decorate the polymeric shell of nanocapsules with quantum dots (QDs) for a bioluminescence study [31]. The bioluminescence generated from HRP-mediated oxidation of luminol can well-overlap with the absorbance wavelengths of QDs, which enables their effective bioluminescence resonance energy transfer (BRET).…”

Fabrication of porous scaffolds with protein nanogels

“…Both the protein species and polymer constitutes could be pre-designed and adjusted, so that scaffolds with different degradation cycles, surface properties, porous morphologies, and cell interactions would be obtained. Specifically, we used the bovine serum albumin (BSA) as a model protein to prepare BSA nanogels based on a two-step procedure including aqueous surface acryloylation and in situ polymerization as reported [17][18][19]. Through a solvent evaporating method, the resulting homogeneous nanogels self-assembled into the porous scaffolds driven by hydrogen bonding interactions.…”