Photoswitchable carbon-dot liposomes mediate catalytic cascade reactions for amplified dynamic treatment of tumor cells.

Most biochemical reactions that occur in living organisms are catalyzed by a series of enzymes and proceed in a tightly controlled manner. The development of artificial enzyme cascades that resemble multienzyme complexes in nature is of current interest due to their potential in various applications. In this study, a nanozyme based on photoswitchable carbon-dot liposomes (CDsomes) was developed for use in programmable catalytic cascade reactions.

Copper Sulfide Nanoassemblies for Catalytic and Photoresponsive Eradication of Bacteria from Infected Wounds.

Bovine serum albumin (BSA)-encapsulated copper sulfide nanocrystals (CuS NCs) were prepared by heating an alkaline solution containing copper ions and BSA without an additional sulfur source. At a high BSA concentration (0.8 mM), nanoassembly of the as-formed CuS NCs occurs to form BSA-CuS NCs as a result of the formation of BSA gel-like structures.

Carbon dots as artificial peroxidases for analytical applications.

Nanozymes have become attractive in analytical and biomedical fields, mainly because of their low cost, long shelf life, and less environmental sensitivity. Particularly, nanozymes formed from nanomaterials having high surface area and rich active sites are interesting since their activities can be tuned through carefully controlling their size, morphology, and surface properties. This review article focuses on preparation of carbon dots (C dots) possessing peroxidase-like activity and their analytical applications.

The analytical and biomedical applications of carbon dots and their future theranostic potential: A review.

In recent years, carbon dots (C-dots) have gained appreciable interest owing to their unique optical properties, including tunable fluorescence, stability against photobleaching and photoblinking, and strong fluorescence. Simple and low-cost hydrothermal and electrochemical approaches have been widely used in the preparation of biocompatible and high-quality C-dots. Various C-dots have been used for the quantitation of small analytes, mostly based on analyte induced fluorescence quenching.

Fluorescent Carbon Dots for Selective Labeling of Subcellular Organelles.

With the recent advancement in understanding and control of the structure and optical properties of fluorescent carbon dots (CDs), they have been shown to be valuable in biolabeling of bacteria, tumor cells, tissues, and organelles. Their extremely small size and tunable functional properties coupled with ultrastable fluorescence enable CDs to be used for easy and effective labeling of various organelles. In addition, CDs with advantages of easy preparation and functionalization with recognition elements and/or drugs have emerged as nanocarriers for organelle-targeted drug delivery.

Capping 1,3-propanedithiol to boost the antibacterial activity of protein-templated copper nanoclusters.

We have prepared copper nanoclusters (Cu NCs) in the presence of bovine serum albumin (BSA) and 1,3-propanedithiol (PDT). The PDT/BSA-Cu NCs possess great activities against different types of bacteria, including non-multidrug-resistant bacteria (Escherichia coli, Salmonella Enteritidis, Pseudomonas aeruginosa, and Staphylococcus aureus) and multidrug-resistant bacteria (methicillin-resistant S. aureus).

Dual-functional gold nanoparticles with antimicrobial and proangiogenic activities improve the healing of multidrug-resistant bacteria-infected wounds in diabetic mice.

Gold nanoparticles (Au NPs) are conjugated with the vascular endothelial growth factor-A (VEGF-A) and (11-mercaptoundecyl)-N,N,N-trimethylammonium (11-MTA) cation to form dual-functional gold nanoparticles (11-MTA/VEGF-Au NPs) that possess antimicrobial and proangiogenic activities for wound healing in diabetic (db/db) mice. VEGF-A is a popular proangiogenic growth factor that stimulates multiple components in the wound-healing cascade. On the other hand, 11-MTA possesses antibacterial activity and can be bound to Au NPs easily through Au-S bonding.

Synergistically dual-functional nano eye-drops for simultaneous anti-inflammatory and anti-oxidative treatment of dry eye disease.

We have developed a rapid and straightforward topical treatment method for dry eye disease (DED) using poly(catechin) capped-gold nanoparticles (Au@Poly-CH NPs) carrying amfenac [AF; a nonsteroidal anti-inflammatory drug (NSAID)] through effective attenuation of ocular surface tissue damage in dry eyes. A dual-targeted strategy based on ocular therapeutics was adopted to simultaneously block the cyclooxygenase enzymes-induced inflammation and reactive oxygen species (ROS)-induced oxidative stress, the primary two causes of DED. The self-assembled core-shell Au@Poly-CH NPs synthesized via a simple reaction between tetrachloroaurate(iii) and catechin possess a poly(catechin) shell (∼20 nm) on the surface of each Au NP (∼60 nm).

Mesoporous manganese oxide/manganese ferrite nanopopcorns with dual enzyme mimic activities: A cascade reaction for selective detection of ketoses.

Nanomaterials possessing enzyme-like activity have been extensively studied owing to their high stability and tunable catalytic properties. In this work, a simple method has been developed for the synthesis of porous manganese oxide/manganese ferrite (MnO/MnFeO) nanopopcorns (MFNPs) in neutral media. The MFNPs exhibit dual enzymatic activities towards selective oxidation of ketoses followed by HO-induced decline of its catalytic activity.

Graphene oxide and carbon dots as broad-spectrum antimicrobial agents - a minireview.

Due to the increasing global population, growing contamination of water and air, and wide spread of infectious diseases, antibiotics are extensively used as a major antibacterial drug. However, many microbes have developed resistance to antibiotics through mutation over time. As an alternative to antibiotics, antimicrobial nanomaterials have attracted great attention due to their advantageous properties and unique mechanisms of action toward microbes.

Ultrafast Excited-State Dynamics of Hydrogen-Bonded Cytosine Microsolvated Clusters with Protic and Aprotic Polar Solvents.

Microsolvation effects on the ultrafast excited-state deactivation dynamics of cytosine (Cy) were studied in hydrogen-bonded Cy clusters with protic and aprotic solvents using mass-resolved femtosecond pump-probe ionization spectroscopy. Two protic solvents, water (HO) and methanol (MeOH), and one aprotic solvent, tetrahydrofuran (THF), were investigated, and transients of Cy·(HO), Cy·(MeOH), and Cy·THF microsolvated clusters produced in supersonic expansions were measured. With the aid of electronic structure calculations, we assigned the observed dynamics to the low-energy isomers of various Cy clusters and discussed the microsolvation effect on the excited-state deactivation dynamics.

Green synthesis of catalytic gold/bismuth oxyiodide nanocomposites with oxygen vacancies for treatment of bacterial infections.

We have developed a simple and green solution for the synthesis of catalytic gold-doped bismuth oxyiodide (Au/BiOI) nanocomposites at room temperature from an aqueous mixture of gold ions, bismuth ions, and iodide ions. Au nanoparticles (NPs) were formed in situ and doped into BiOI nanosheets. The oxygen vacancies generated in BiOI give rise to its oxidase-like activity, and Au doping facilitated the reaction leading to a 4-fold higher oxidase-like activity of the Au/BiOI nanocomposite.

Self-Assembled Chiral Gold Supramolecules with Efficient Laser Absorption for Enantiospecific Recognition of Carnitine.

Stereospecific recognition of chiral molecules is ubiquitous in chemical and biological systems, thus leading to strong demand for the development of enantiomeric drugs, enantioselective sensors, and asymmetric catalysts. In this study, we demonstrate the ratio of d-Cys and l-Cys playing an important role in determining the optical properties and the structures of self-assembled Cys-Au(I) supramolecules prepared through a simple reaction of tetrachloroaurate(III) with chiral cysteine (Cys). The irregularly shaped -[d-Cys-Au(I)] - or - [l-Cys-Au(I)] - supramolecules with a size larger than 500 nm possessing strong absorption in the near-UV region and chiroptical characteristics were only obtained from the reaction of Au(III) with d-Cys or l-Cys.

Graphene oxide membrane as an efficient extraction and ionization substrate for spray-mass spectrometric analysis of malachite green and its metabolite in fish samples.

A graphene oxide (GO) nanosheet-modified N-nylon membrane (GOM) has been prepared and used as an extraction and spray-ionization substrate for robust mass spectrometric detection of malachite green (MG), a highly toxic disinfectant in liquid samples and fish meat. The GOM is prepared by self-deposition of GO thin film onto an N-nylon membrane, which has been used for efficient extraction of MG in aquaculture water samples or homogenized fish meat samples. Having a dissociation constant of 2.

DNA Modulates the Interaction of Genetically Engineered DNA-Binding Proteins and Gold Nanoparticles: Diagnosis of High-Risk HPV Infection.

Gene detection has an important role in diagnosing several serious diseases and genetic defects in modern clinical medicine. Herein, we report a fast and convenient gene detection method based on the modulation of the interaction between a heat-resistant double-stranded DNA (dsDNA)-binding protein (Sso7d) and gold nanoparticles (Au NPs). We prepared a recombinant Cys-Sso7d, which is Sso7d with an extra cysteine (Cys) residue in the N-terminus, through protein engineering to control the interaction between Sso7d and Au NPs.

Ultrastrong trapping of VEGF by graphene oxide: Anti-angiogenesis application.

Angiogenesis is the process of formation of new blood vessels, which is essential to human biology, and also plays a crucial role in several pathologies such as tumor growth and metastasis, exudative age-related macular degeneration, and ischemia. Vascular endothelial growth factor (VEGF), in particular, VEGF-A is the most important pro-angiogenic factor for angiogenesis. Thus, blocking the interaction between VEGFs and their receptors is considered an effective anti-angiogenic strategy.

Using Pyridinium Styryl Dyes as the Standards of Time-Resolved Instrument Response.

In this paper, two pyridinium styryl dyes, [2-(4-dimethylamino-phenyl)-vinyl]-1-methylpyridinium iodide (DASPMI), were synthesized and characterized by steady state fluorescence spectroscopy as well as picosecond and femtosecond time-resolved fluorescence spectroscopies. Both dyes exhibit large Stokes shifts and fluorescence decays equivalent to the instrument response function (IRF) standards employed in time-correlated single-photon counting. Due to their styryl and pyridinium moieties, DASPMIs have higher peak fluorescence intensity and shorter excited-state lifetimes than iodide ion-quenched fluorophores.

Gold nanoparticles modified with self-assembled hybrid monolayer of triblock aptamers as a photoreversible anticoagulant.

We demonstrated that thrombin-binding aptamer-conjugated gold nanoparticles (TBA-Au NPs), prepared from a self-assembled hybrid monolayer (SAHM) of triblock aptamers on Au NPs (13 nm), can effectively inhibit thrombin activity toward fibrinogen. The first block poly(adenine) at the end of the triblock TBA was used for the self-assembly on Au NP surface. The second block, in the middle of TBA, was composed of oligonucleotides that could hybridize with each other.

Nitrite ion-induced fluorescence quenching of luminescent BSA-Au(25) nanoclusters: mechanism and application.

Fluorescence quenching is an interesting phenomenon which is highly useful in developing fluorescence based sensors. A thorough understanding of the fluorescence quenching mechanism is essential to develop efficient sensors. In this work, we investigate different aspects governing the nitrite ion-induced fluorescence quenching of luminescent bovine serum albumin stabilized gold nanoclusters (BSA-Au NCs) and their application for detection of nitrite in urine.

Selective detection of iodide and cyanide anions using gold-nanoparticle-based fluorescent probes.

We developed two simple, rapid, and cost-effective fluorescent nanosensors, both featuring bovine serum albumin labeled with fluorescein isothiocyanate (FITC))-capped gold nanoparticles (FITC-BSA-Au NPs), for the selective sensing of cyanide (CN(-)) and iodine (I(-)) ions in high-salinity solutions and edible salt samples. During the preparation of FITC-BSA-Au NP probes, when AuNPs were introduced to the mixture containing FITC and BSA, the unconjugated FITC and FITC-labeled BSA (FITC-BSA) adsorbed to the particles' surfaces. These probes operated on a basic principle that I(-) and CN(-) deposited on the surfaces of the Au NPs or the etching of Au NPs induced the release of FITC molecules or FITC-BSA into the solution, and thus restored the florescence of FITC.

Excited-state intramolecular proton transfer molecules bearing o-hydroxy analogues of green fluorescent protein chromophore.

o-Hydroxy analogues, 1a-g, of the green fluorescent protein chromophore have been synthesized. Their structures and electronic properties were investigated by X-ray single-crystal analyses, electrochemistry, and luminescence properties. In solid and nonpolar solvents 1a-g exist mainly as Z conformers that possess a seven-membered-ring hydrogen bond and undergo excited-state intramolecular proton transfer (ESIPT) reactions, resulting in a proton-transfer tautomer emission.

Highly efficient control of thrombin activity by multivalent nanoparticles.

We have demonstrated that the incorporation of sulfated galactose acid (sulf-Gal) into thrombin-binding-aptamer (TBA)-conjugated gold nanoparticles (TBA-AuNPs) enables highly effective inhibition of thrombin activity toward fibrinogen. AuNP bioconjugates (TBA(15)/TBA(29)/sulf-Gal-AuNPs) were prepared from 13 nm AuNPs, 15-mer thrombin-binding aptamer (TBA(15)), 29-mer thrombin-binding aptamer (TBA(29)), and sulf-Gal. The numbers of TBA and sulf-Gal molecules per AuNP proved to have a strong impact on inhibitory potency.

Octanuclear gold(I) alkynyl-diphosphine clusters showing thermochromic luminescence.

The unprecedented, purely gold(I) alkynyl-diphosphine clusters 1-3 demonstrate intense room-temperature phosphorescence with maximum quantum efficiency of 92% in solution (3) and 86% in solid (2) and thermally dependent emission in the crystalline form, attributed to the crystal lattice arrangement.

Comprehensive studies on an overall proton transfer cycle of the ortho-green fluorescent protein chromophore.

Initiated by excited-state intramolecular proton transfer (ESIPT) reaction, an overall reaction cycle of 4-(2-hydroxybenzylidene)-1,2-dimethyl-1H-imidazol-5(4H)-one (o-HBDI), an analogue of the core chromophore of the green fluorescent protein (GFP), has been investigated. In contrast to the native GFP core, 4-(4-hydroxybenzylidene)-1,2-dimethyl-1H-imidazol-5(4H)-one (p-HBDI), which requires hydrogen-bonding relay to accomplish proton transfer in vivo, o-HBDI possesses a seven-membered-ring intramolecular hydrogen bond and thus provides an ideal system for mimicking an intrinsic proton-transfer reaction. Upon excitation, ESIPT takes place in o-HBDI, resulting in a ∼600 nm proton-transfer tautomer emission.