Free‐standing nanoparticle films are of great importance for developing future nano‐electronic devices. We introduce a protein‐based fabrication strategy of free‐standing nanoparticle monolayer films. α‐Synuclein, an amyloidogenic protein, was utilized to yield a tightly packed gold‐nanoparticle monolayer film interconnected by protein β‐sheet interactions. Owing to the stable protein–protein interaction, the film was successfully expanded to a 4‐inch diameter sheet, which has not been achieved with any other free‐standing nanoparticle monolayers. The film was flexible in solution, so it formed a conformal contact, surrounding even microspheres. Additionally, the monolayer film was readily patterned at micrometer‐scale and thus unprecedented double‐component nanoparticle films were fabricated. Therefore, the free‐floating gold‐nanoparticle monolayer sheets with these properties could make the film useful for the development of bio‐integrated nano‐devices and high‐performance sensors. 相似文献
l ‐Asparaginase (l ‐Asnase) can suppress the growth of malignant cells by rapid depletion of two essential amino acids, l ‐glutamine (l ‐Gln) and l ‐asparagine (l ‐Asn). To study the cytotoxic effect and the secondary complications of l ‐Asnase in the treatment of acute lymphoblastic leukemia, the development of a novel enzyme reactor of l ‐Asnase for the hydrolysis of l ‐Gln, employing the enzyme‐gold nanoparticle conjugates in capillary, was reported in this work. First, a microchip CE (MCE)‐LIF was established for the separation of l ‐amino acids (l ‐Gln and l ‐glutamic acid) and studying the hydrolysis of l ‐Gln by using l ‐Asnase enzyme reactor. Then, using l ‐Gln as target analyte, the enzyme kinetics of l ‐Asnase in free solution, enzyme‐gold nanoparticle conjugates (E‐GNP), and the enzyme‐gold nanoparticle conjugates immobilized in capillary (E‐GNP‐C) were investigated in detail with the proposed MCE‐LIF method. Moreover, for optimizing the enzymatic reaction efficiency, three important parameters, including the length of capillary, the enzyme concentration reacted with gold nanoparticle and the amount of l ‐Asnase immobilized on the gold nanoparticle, have been studied. Owing to the high specific activity, the E‐GNP‐C enzyme reactor exhibited the best performance for the hydrolysis of l ‐Gln. 相似文献
Surface chemical composition and roughness caused by micro/nano‐topographical structures are two predominant factors in determining cellular response. A series of gold nanoparticle layers (GNPLs) with increasing surface roughness are prepared by depositing gold nanoparticles onto planar gold films. Glycine‐arginine‐glycine‐aspartic acid‐tyrosine (GRGDY) peptide is then conjugated to the surface through poly[oligo(ethylene glycol) methacrylate] polymer brushes as spacers. The pristine micro/nano‐roughness structures significantly inhibit L929 cell growth. After modification with POEGMA‐GRGDY, however, the micro/nano‐structures greatly enhance L929 cell‐specific interactions while maintaining superior low‐fouling ability compared to planar gold.
Nano‐Zn‐[2‐boromophenyl‐salicylaldimine‐methylpyranopyrazole]Cl2 (nano‐[Zn‐2BSMP]Cl2) as a nanoparticle Schiff base complex and a catalyst was introduced for the solvent‐free synthesis of 4‐((2‐hydroxynaphthalen‐1‐yl)(aryl)methyl)‐5‐methyl‐2‐phenyl‐1H‐pyrazol‐3(2H)‐ones by the multicomponent condensation reaction of various aromatic aldehydes, β‐naphthol, ethyl acetoacetate, and phenyl hydrazine at room temperature. 相似文献
In the present work, a newly functional nanoparticle has been prepared to immobilize the protein for the detection of α‐1‐fetoprotein (AFP). Prussian blue (PB) nanoparticle was initially synthesized under ultrasonic condition, then bovine serum albumin (BSA) was used to coat the PB nanoparticle to improve the stability of the PB nanoparticle as well as functionalize the surface of PB nanoparticle, and then gold colloids were loaded on the BSA‐coated PB nanoparticle to construct a core‐shell‐shell nanostructure via the conjunction of thiolate linkages or alkylamines of the BSA. Finally, a convenient, effective and sensitivity amperometric immunosensor for the detection of α‐1‐fetoprotein (AFP) was constructed by the employment of these functional core‐shell‐shell microspheres. The preparation of the nanoparticle (Au‐BSA‐PB NPs) was characterized by transmission electron microscopy (TEM), and the assembly of the biosensor was characterized with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The dynamic range of the resulted immunosensor for the detection of AFP is from 0.02 ng/mL to 200.0 ng/mL with a detection limit of 0.006 ng/mL (S/N=3). Moreover, this biosensor displays good selectivity, stability and reproducibility. 相似文献
Gold nanoparticles with carbohydrate ligands attached on their surface have been synthesized and characterized with various techniques. The new nanoparticle conjugates have shown great potentials as a contrast agent for opto‐acoustic imaging. Hemocompatibility measurements of human blood for the carbohydrate‐gold nanoparticles have shown that the conjugates are feasible for in vivo testing. Preliminary quantitative flow measurements using the conjugates were also studied in this work based on the indicator‐dilution theory. In vitro phantom experiments were designed and conducted, and results were discussed. 相似文献
The use of a thiol‐functionalized nonionic surfactant to stabilize spherical gold nanoparticles in water induces the spontaneous formation of polyrotaxanes at the nanoparticle surface in the presence of the macrocycle α‐cyclodextrin. Whereas using an excess of surfactant an amorphous gold nanocomposite is obtained, under controlled drying conditions the self‐assembly between the surface supramolecules provides large and homogenous supercrystals with hexagonal close packing of nanoparticles. Once formed, the self‐assembled supercrystals can be fully redispersed in water. The reversibility of the crystallization process may offer an excellent reusable material to prepare gold nanoparticle inks and optical sensors with the potential to be recovered after use. 相似文献
An ultrasensitive surface‐enhanced Raman spectroscopy (SERS) sensor based on rolling‐circle amplification (RCA)‐increased “hot‐spot” was developed for the detection of thrombin. The sensor contains a SERS gold nanoparticle@Raman label@SiO2 core‐shell nanoparticle probe in which the Raman reporter molecules are sandwiched between a gold nanoparticle core and a thin silica shell by a layer‐by‐layer method. Thrombin aptamer sequences were immobilized onto the magnetic beads (MBs) through hybridization with their complementary strand. In the presence of thrombin, the aptamer sequence was released; this allowed the remaining single‐stranded DNA (ssDNA) to act as primer and initiate in situ RCA reaction to produce long ssDNAs. Then, a large number of SERS probes were attached on the long ssDNA templates, causing thousands of SERS probes to be involved in each biomolecular recognition event. This SERS method achieved the detection of thrombin in the range from 1.0×10?12 to 1.0×10?8 M and a detection limit of 4.2×10?13 M , and showed good performance in real serum samples. 相似文献
The multiparametric nature of nanoparticle self‐assembly makes it challenging to circumvent the instabilities that lead to aggregation and achieve crystallization under extreme conditions. By using non‐base‐pairing DNA as a model ligand instead of the typical base‐pairing design for programmability, long‐range 2D DNA–gold nanoparticle crystals can be obtained at extremely high salt concentrations and in a divalent salt environment. The interparticle spacings in these 2D nanoparticle crystals can be engineered and further tuned based on an empirical model incorporating the parameters of ligand length and ionic strength. 相似文献
A signal‐enhanced label‐free electrochemical immunosensor was constructed by the employment of Prussian blue doped silica dioxide (PB‐SiO2) nanocomposite. At first, PB‐SiO2 nanocomposite which was produced by using a microemulsion method was used to obtain a nanostructural monolayer on a glassy carbon electrode (GCE) surface. Next amino‐functionalized interface were prepared by self‐assembling 3‐aminopropyltriethoxy silane (APTES) on the PB‐SiO2 nanoparticle surface. Then chitosan stabled gold nanoparticle (CS‐nanoAu) was subsequently attached, while the entire surface was finally loaded with neuron‐specific enolase antibody (anti‐NSE) via the adsorption of gold nanoparticle. The sensitivity of the proposed immunosensor has greatly improved as the PB‐SiO2 nanostructural sensing film provides plenty of active sites which might catalyze the reduction of H2O2. The immunosensor exhibited good linear behavior in the concentration range from 0.25–5.0 and 5.0–75 ng/mL for the quantitative analysis of neuron‐specific enolase (NSE), a putative serum marker of small‐cell lung carcinoma (SCLC), with a limit of detection of 0.08 ng/mL. The resulting NSE immunosensor showed high sensitivity and long‐term lifetime which can be attributed to the extremely high catalytic activity and biocompatibility of CS‐nanoAu/APTES/PB‐SiO2 nanostructural multilayers. 相似文献
Insufficient or excess drug doses, due to unknown actual drug concentrations at the focus, are one of the main causes of chemotherapy failure for cancers. In this regard, the real‐time monitoring of the release of anticancer drugs from nanoparticle drug delivery systems is of crucial importance, but it remains a critical and unsolved challenge. Herein, we report the proposal and development of a novel concept of real‐time monitoring of NIR‐triggered drug release in vitro and in vivo by using simultaneous upconverted luminescence (UCL) and magnetic resonance (MR) imaging. Such a monitoring strategy features the high sensitivity of UCL and the high‐resolution, noninvasiveness, and tissue‐depth‐independence of MR imaging. The dual‐mode real‐time and quantitative monitoring of drug release can be applied to determine online the drug concentrations in vivo in the tissue regions of interest and, therefore, to avoid insufficient or excess drug dosings. 相似文献
Yolk‐shell nanoreactors with metal nanoparticle core and ultrathin porous polymer shells are effective catalysts for heterogeneous reactions. Polymer shells provide size‐selectivity and improved reusability of catalyst. Nanocapsules with single‐nanometer porous shells are prepared by vesicle‐templated directed assembly. Metal nanoparticles are formed either by selective initiation in pre‐fabricated nanocapsules or simultaneously with the creation of a crosslinked polymer shell. In this study, we investigated the oxidation of benzyl alcohol and benzaldehyde catalyzed by gold nanoparticles and hydrogenation of cyclohexene catalyzed by platinum nanoparticles. Comparison of newly created nanoreactors with commercially available nanoparticles revealed superior reusability and size selectivity in nanoreactors while showing no negative effect on reaction kinetics. 相似文献
The binding and detachment of carboxyl‐modified gold nanoparticles from liposomes is used for controlled drug delivery. This study reveals that the binding and detachment of nanoparticles from liposomes depends on the degree of hydration of the liposomes. Liposomes with a lower hydration level undergo stronger electrostatic interactions with negatively charged gold nanoparticles, thus leading to a slower detachment of the carboxyl‐modified gold nanoparticles under gastric conditions. Therefore, under gastric conditions, gold‐nanoparticle‐decorated dipalmitoylphosphatidylcholine (DPPC) liposomes exhibit an at least ten‐times‐slower drug release compared to gold‐nanoparticle‐decorated 1,2‐dimyristoyl‐sn‐glycero‐3‐phosphocholine (DMPC) liposomes, although both liposomes in the bare state fail to pursue controlled release. Our study also reveals that one can modulate the drug‐release rate by simply varying the concentration of nanoparticles. This study highlights a novel strategy for the controlled release of drug molecules from liposomes. 相似文献
Induced‐charge electroosmosis (ICEO) has attracted tremendous popularity for driving fluid motion from the microfluidic community since the last decade, while less attention has been paid to ICEO‐based nanoparticle manipulation. We propose herein a unique concept of hybrid electroosmotic kinetics (HEK) in terms of bi‐phase ICEO (BICEO) actuated in a four‐terminal spiral electrode array, for effective electrokinetic enrichment of fluorescent polystyrene nanoparticles on ideally polarizable metal strips. First, by alternating the applied AC voltage waves between consecutive discrete terminals, the flow stagnation lines where the sample nanoparticles aggregate can be switched in time between two different distribution modes. Second, we innovatively introduce the idea of AC field‐effect flow control on BICEO; by altering the combination of gating voltage sequence, not only the number of circulative particle trapping lines is doubled, but the collecting locations can be flexibly reconfigured as well. Third, hydrodynamic streaming of DC‐biased BICEO is tested in our device design, wherein the global linear electroosmosis dominates BICEO contributed from both AC and DC components, resulting in a reduction of particle enrichment area, while with a sharp increase in sample transport speed inside the bulk phase. The flow field associated with HEK is predicted using a linear asymptotic analysis under Debye–Huckel limit, with the simulation results in qualitative agreement with in‐lab observations of nanoparticle trapping by exploiting a series of improved ICEO techniques. This work provides an affordable and field‐deployable platform for real‐time nanoparticle trapping in the context of dilute electrolyte. 相似文献