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Manipulation and Deposition of Complex, Functional Block Copolymer Nanostructures using Optical Tweezers
摘要： Block copolymer self-assembly has enabled the creation of a range of solution-phase nanostructures with applications from optoelectronics and biomedicine to catalysis. However, to incorporate such materials into devices a method that facilitates their precise manipulation and deposition is desirable. Herein we describe how optical tweezers can be used to trap, manipulate, and pattern individual cylindrical micelles and larger hybrid micellar materials. Through the combination of TIRF imaging and optical trapping we can precisely control the three-dimensional motion of individual cylindrical block copolymer micelles in solution, enabling the creation of customizable arrays. We also demonstrate that dynamic holographic assembly enables the creation of ordered customizable arrays of complex hybrid block copolymer structures. By creating a program which automatically identifies, traps and then deposits multiple assemblies simultaneously we have been able to dramatically speed up this normally slow process, enabling the fabrication of arrays of hybrid structures containing hundreds of assemblies in minutes rather than hours.
关键词： optical trapping,directed assembly,block copolymers,self-assembly,nanofibers
更新于2025-11-21 11:24:58
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Self-Assembled Nanostructures of Red Fluorescent Amphiphilic Block Copolymers as Both Imaging Probes and Drug Carriers
摘要： We report a red-?uorescent drug delivery system formed by biodegradable and biocompatible amphiphilic A-B-A block copolymers. Each polymer consists of a red ?uorescent dye covalently bonded in the middle of hydrophobic block (B) of polylactone, tethered at both ends with poly[(oligo ethylene glycol) methyl ether methacrylate] (POEGMA) as the hydrophilic block. Two types of polylactones, i.e., semicrystalline poly(ε-caprolactone) (PCL) and amorphous poly(δ-decalactone) (PDL), respectively, were incorporated as the hydrophobic segment in the block copolymers. Using transmission electron microscopy, we characterized the self-assembled nanostructures formed by these amphiphilic block copolymers in mixtures of water/tetrahydrofuran or water/dimethylformamide. All of these polymers remained highly ?uorescent in water, although some extent of aggregation-induced ?uorescence quenching was still observed. Among the three types of polymers presented here, the polymer (RPO-3) containing an amorphous block of PDL showed the highest drug-loading capacity and the largest extent of drug release in acidic media. RPO-3 micelles loaded with doxorubicin as a model of anticancer drug showed sustainable intracellular release and cytotoxicity against HeLa cells.
关键词： self-assembly,drug delivery,polymer,?uorescence,bioimaging
更新于2025-11-21 11:08:12
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From colloidal CdSe quantum dots to microscale optically anisotropic supercrystals through bottom-up self-assembly
摘要： The development of fabrication techniques for novel nanostructured materials is one of the key tasks of modern materials science. One pathway to successfully complete this task is the bottom-up assembly of colloidal nanoparticles into ordered superstructures, possessing both the properties of individual nanoparticles and further novel properties resulting from their interactions. However, nanoparticle self-assembly depends on a variety of parameters, which makes the precise control of this process a complicated problem. Here, the time course of quantum dot (QD) self-assembly into ordered superstructures has been analyzed, along with the evolution of their morphological and optical properties. QD self-assembly occurs through two distinct stages (homo- and hetero-geneous), leading to the formation of supercrystals with a layered morphology. Analysis of the optical properties throughout the superstructures’ growth has shown that the absorption and photoluminescence (PL) bands are blue shifted, retaining almost the same PL lifetimes as in the initial QD solution. The supercrystals formed possess a further unique optical property caused by their layered morphology; namely, a four-fold symmetry characterized by strong birefringence. Such supercrystals may be used for the fabrication of microscale optical paths with high extinction coefficients and specific polarization properties for novel optoelectronic devices.
关键词： optical anisotropy,nanostructured materials,birefringence,self-assembly,quantum dots,supercrystals
更新于2025-11-21 11:08:12
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A Fluorescent Supramolecular Biosensor for Bacterial Detection via Binding-Induced Changes in Coiled-Coil Molecular Assembly
摘要： The essential elements required for any sensors are a receptor, a signal converter, and a detector. Here, we report the construction of bacterial biosensors in which all of the required biosensor elements are furnished in one supramolecular assembly. The supramolecular biosensor is based on a double-layered octa-helical coiled-coil peptide assembly that contains tetravalent bioreceptors on the outer surface and environment-sensitive fluorophores in the core. The signal conversion takes advantage of the noncovalent and reversible nature of the self-assembled system, i.e., the multivalent binding of bacteria induces conformational changes in the supramolecular state, which is translated into differential fluorescence emissions. We show that fluorescent supramolecular biosensors (fSBs) can selectively detect E. coli over other bacteria. Because the fSBs were resistant to heat-induced denaturation, they retained their bacterial-sensing capability even at an elevated temperature (50 ℃). Biosensors based on responsive supramolecular assemblies can be further developed to detect various large and flat biological objects and biomacromolecules.
关键词： Escherichia coli,Supramolecule,Biosensor,Bacteria,Self-assembly,Peptide-based probe
更新于2025-11-21 11:08:12
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Dopamine-Mediated Assembly of Citrate-Capped Plasmonic Nanoparticles into Stable Core-Shell Nanoworms for Intracellular Applications
摘要： Plasmonic nanochains, derived from the one-dimensional assembly of individual plasmonic nanoparticles (NPs), remain infrequently explored in biological investigations due to their limited colloidal stability, ineffective cellular uptake, and susceptibility to intracellular disassembly. We report the synthesis of polydopamine (PDA)-coated plasmonic “nanoworms” (NWs) by sonicating citrate-capped gold (Cit-Au) NPs in a concentrated dopamine (DA) solution under alkaline conditions. DA mediates the assembly of Cit-Au NPs into Au NWs within 1 min, and subsequent self-polymerization of DA for 60 min enables the growth of an outer conformal PDA shell that imparts stability to the inner Au NW structure in solution, yielding “core–shell” Au@PDA NWs with predominantly 4–5 Au cores per worm. Our method supports the preparation of monometallic Au@PDA NWs with different core sizes and bimetallic PDA-coated NWs with Au and silver cores. The protonated primary amine and catechol groups of DA, with their ability to interact with Cit anions via hydrogen bonding and electrostatic attraction, are critical to assembly. When compared to unassembled PDA-coated Au NPs, our Au@PDA NWs scatter visible light and absorb near-infrared light more intensely, and enter HeLa cancer cells more abundantly. Au@PDA NWs cross the cell membrane as intact entities primarily via macropinocytosis, mostly retain their inner NW structure and outer PDA shell inside the cell for 24 h, and do not induce noticeable cytotoxicity. We showcase three intracellular applications of Au@PDA NWs, including label-free dark-field scattering cell imaging, delivery of water-insoluble cargos without pronounced localization in acidic compartments, and photothermal killing of cancer cells.
关键词： 1D assembly,citrate-capped nanoparticles,polydopamine coating,photothermal killing,intracellular delivery,plasmonic nanoworms,dark-field scattering imaging
更新于2025-11-19 16:56:42
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Control of Excited-State Supramolecular Assembly Leading to Halide Photorelease
摘要： Ground- and excited-state control of halide supramolecular assembly was achieved through the preparation of a series of ester- and amide-functionalized ruthenium polypyridyl complexes in CH2Cl2. Hydrogen-bonding amide and alcohol groups on the receptor ligand were found to direct interactions with halide, while halide association with the ethyl ester groups was not observed. The various functional groups on the receptor ligands tuned the ground-state equilibrium constants over 2 orders of magnitude (1 × 10^5 to 1 × 10^7 M^?1), and the fractional contribution of each hydrogen-bond donor to the total equilibrium constant was determined. Pulsed-laser excitation of the complexes resulted in excited-state localization on the ester- or amide-functionalized ligands. In the case where the excited state was oriented toward an associated halide ion (the amide complexes), an 80 ± 10 meV Coulombic repulsion was induced that lowered the excited-state equilibrium constant (K*_eq) and resulted in halide photorelease. The rate constants for excited-state halide release (k*_21) were determined, and the values varied based on the functional groups present in the receptor ligand. Complexes with more hydrogen-bonding donors had smaller rate constants for halide photorelease. In a complex without a specific receptor ligand, the excited-state dipole was not oriented toward the associated halide, and the excited state was therefore found to have a larger equilibrium constant for halide association than the ground state.
关键词： halide supramolecular assembly,excited-state equilibrium,photorelease,hydrogen-bonding,ruthenium polypyridyl complexes
更新于2025-11-19 16:56:35
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Assembly structure and free energy change of a chromonic liquid crystal formed by a perylene dye
摘要： The nematic (chromonic N) and isotropic phases formed by aqueous solutions of a perylene dye are investigated by x-ray diffraction and visible light absorption spectroscopy. X-ray diffraction shows that the molecules assemble into columns one molecule wide. The change in the visible absorption spectrum with concentration indicates that the molecules stack in a more or less isodesmic manner and that the free energy change associated with the addition or removal of a single molecule from a stack is 16–20 kBT. This range is appreciably higher than those of any previously-measured simple chromonic systems, i.e. those with single molecule-wide columns. It is suggested that the large free energy change promotes the formation of extremely long columns of molecules, and in turn leads to the low concentration at which mesophase formation takes place.
关键词： chromonic,isodesmic,scission energy,perylene dye,assembly structure,lyotropic chromonic,Liquid crystals
更新于2025-11-19 16:56:35
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Constructing electrostatic self-assembled 2D/2D ultra-thin ZnIn2S4/protonated g-C3N4 heterojunctions for excellent photocatalytic performance under visible light
摘要： 2D/2D ultra-thin ZnIn2S4/protonated g-C3N4 nanocomposites (ZnIn2S4/pCN) are fabricated by electrostatic self-assembly strategy between negatively charged 2D ultra-thin ZnIn2S4 nanosheets and 2D protonated g-C3N4 nanosheets. The optimized ZnIn2S4/pCN (5:3) shows excellent photocatalytic activity toward H2 production (~8601.16 μmol·g?1·h?1) under visible light. In addition, ZnIn2S4/pCN also exhibits superior visible-light-driven photocatalytic tetracycline degradation efficiency, about ~4.13 and ~2.28 times higher than protonated g-C3N4 and ultra-thin ZnIn2S4, respectively. The optimal ZnIn2S4/pCN (5:3) also has good photostability. The excellent photocatalytic activity of ZnIn2S4/pCN can be attributed to the unique 2D/2D heterojunctions, which are obtained by electrostatic self-assembly. The intimate interfacial contact and larger contact areas promote the separation and migration of photogenerated carriers, which contribute to the improvement of photocatalytic activity and photostability. Our research on the 2D/2D nanocomposites provides a scalable solution for the research of efficient and active photocatalysts.
关键词： protonated g-C3N4,ultra-thin ZnIn2S4 nanosheets,electrostatic self-assembly,2D/2D
更新于2025-11-19 16:46:39
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Enzyme-free fluorometric assay for chloramphenicol based on double stirring bar-assisted dual signal amplification
摘要： An enzyme-free fluorometric assay is described that accomplishes dual signal amplification by making use of a two stirring bars. Two Y-shaped DNA probes were designed and placed on the bars. When the target (with chloramphenicol as model analyte) is added, it triggers target recycling and simultaneously catalyzes hairpin assembly (CHA). A large fraction of DNA primers is released by the analyte from the bar to the supernatant and open hairpins with G-quadruplex DNA sequence. The G-quadruplex can specifically bind thioflavin T (ThT) to emit fluorescence (with excitation/emission maxima at 445 and 485 nm) for quantification of chloramphenicol. An enzyme is not needed. ThT is added to the system as a fluorescent DNA probe. All this strongly reduces the cost for sensor construction and usage. The dual signal amplification steps occur simultaneously which reduces the detection time. The assay was successfully employed to the determination of CAP in spiked milk and fish samples within 60 min and with a 16 pM limit of detection (at S/N = 3).
关键词： Food safety,Antibiotics detection,Thioflavin T,Catalyzed hairpin assembly,Target recycling
更新于2025-11-19 16:46:39
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Self-assembling Non-conjugated Poly(amide-imide) into Thermoresponsive Nanovesicles with Unexpected Red fluorescence for Bioimaging
摘要： Non-conjugated red fluorescent polymers have been increasingly studied to improve the biocompatibility and penetration depth over conventional fluorescent materials. However, the accessibility of such polymers remains challenging due to the scarcity of non-conjugated fluorophores and lacking relevant mechanism of red-shifted fluorescence. Herein, we discovered that the combination of hydrogen bonding and π-π stacking interactions provides non-conjugated poly(amide-imide) with a large bathochromic shift (> 100 nm) from blue-green fluorescence to red emission. The amphiphilic PEGylated poly(amide-imide) derived from in-situ PEGylation self-assembled into nanovesicles in water, which isolated the aminosuccinimide fluorophore from the solvents and suppressed the hydrogen bonds formation between aminosuccinimide fluorophores and water. Therefore, the fluorescence of PEGylated poly(amide-imide) in water was soundly retained. Furthermore, the strong hydrogen bonding and hydrophobic interactions with water provided PEGylated poly(amide-imide) with a reversible thermoresponsiveness and presented a concentration-dependent behavior. Finally, accompanied with the excellent biostability and photostability, PEGylated poly(amide-imide) exhibited as a good candidate for cell imaging.
关键词： poly(amide-imide),red-shifted fluorescence,self-assembly,bioimaging,nanovesicles
更新于2025-11-14 17:04:02