Baodui Wang

Dumbbell-Like Au-Fe3O4 Nanoparticles for Target-Specific Platin Delivery

Dumbbell-like Au-Fe(3)O(4) nanoparticles (NPs) were made and coupled with Herceptin and a platin complex. The platin-Au-Fe(3)O(4)-Herceptin NPs act as a target-specific nanocarriers for delivery of platin into Her2-positive breast cancer cells (Sk-Br3) with strong therapeutic effects. The conjugate has a half-maximal inhibitory concentration (IC(50)) toward Sk-Br3 cells of 1.76 microg of Pt/mL, which is lower than that needed for cisplatin (3.5 microg/mL). The work demonstrates that the dumbbell-like Au-Fe(3)O(4) NPs are promising nanocarriers for highly sensitive diagnostic and therapeutic applications.

Selective Detection of Iron(III) by Rhodamine-Modified Fe3O4 Nanoparticles†

The highly selective and sensitive detection of metal ions in aqueous solution is of great importance in tracking and studying the physiological functions of these ions in living organisms. Fe is a biologically important metal ion and plays an essential role in oxygen uptake, oxygen metabolism, and electron transfer. However, the presence of Fe in biological systems has to be efficiently moderated as both its deficiency and overloading can induce various biological disorders. Currently, the detection of Fe relies on small organic molecules, but these organic molecules are poorly soluble in water and cannot provide the necessary selectivity and sensitivity for Fe detection in biological environments. Recently, we reported that magnetic Fe3O4 nanoparticles (NPs) that were modified with polyethylene glycol (PEG) derivatives were highly soluble and stable in physiological solutions. These properties indicate that the problems related to the low solubility of small organic molecules in biological solutions can be resolved by coupling these molecules to PEG-Fe3O4 NPs. The increased solubility should thus greatly improve the detection sensitivity. The presence of magnetic Fe3O4 NPs in the sensor-PEG-Fe3O4 NP conjugate should also facilitate the magnetic separation of the Fe-sensor-PEG-Fe3O4 from biological solutions, leading to the selective detection of Fe at ultralow concentrations. Herein, we report that a rhodamine 6G derivative, N(rhodamine-6G)lactam-ethylenediamine (Rh6G-LEDA) (1a), can be coupled to the PEG-Fe3O4 NPs (1b) and act as an Fe-selective fluorescent sensor (1c ; Scheme 1). Rhodamine-based sensors have received ever-increasing interest in sensing Pb, Cu, Hg, Fe, Cr, NO, and OCl ions. Their detection is based on the on/off switch of the spirocyclic moiety, mediated by the metal ion. For example, the spirocyclic form of Rh6G-LEDA (1a) is nearly nonfluorescent and colorless. But once bound to a metal ion, it is converted into the open-cyclic form with much better intramolecular conjugation. As a result, the complex is strongly fluorescent. Unfortunately, most of the reported rhodamine-based sensors that were intended for the detection of metal ions suffer from poor water solubility, thus preventing them from having practical applications in biological systems. We demonstrate that in the presence of various metal ions in water, 1b can selectively bind to Fe (1c), thereby leading to the sensitive detection of Fe with the detection limit reaching below 2 ppb. Such a sensitive Fe probe could also be applied to intracellular Fe detection using the enhanced fluorescence from 1 c. Fe3O4 NPs were synthesized from the thermal decomposition of [Fe(acac)3] (acac = acetylacetonate) in benzyl ether in the presence of oleylamine. The oleylamine-coated 12 nm Fe3O4 NPs, as shown by transmission electron microscopy (TEM; see the Supporting Information, Figure S1 A), were functionalized by replacing oleylamine with dopaminePEG, which had been synthesized from the acylation of PEG (MW = 2000) with bromoacetyl chloride, followed by a nucleophilic substitution reaction in which a bromo substituent was displaced by the dopamine NH2. The bromo-PEGFe3O4 reacted with 1a by a nucleophilic substitution reaction between the bromide and amine groups to give 1b (see the Supporting Information, Scheme S1). 1b was readily dispersed in water, with its solubility reaching 1.23 mgmL , and it stayed in the dispersion state for at least half a month. TEM Scheme 1. Structural illustration of Rh6G-LEDA (1a), its coupling with PEG-Fe3O4 NP (1b), and its complex with Fe III (1c) along with the structural change that enhances its fluorescence property.

pH Controlled Release of Chromone from Chromone-Fe3O4 Nanoparticles

We report a new strategy for coupling chromone to Fe3O4 nanoparticles. The chromone-Fe3O4 NP conjugate shows a dramatic increase in chromone solubility in cell culture medium from less than 2.5 to 633 microg/ml, leading to the enhanced chromone uptake by HeLa cells. Chromone can be released at low pH and as a result, the chromone-Fe3O4 conjugate is much more efficient in inhibiting the HeLa cell proliferation. Such chromone-Fe3O4 NPs are promising as a powerful multifunctional delivery system for both chromone-based diagnostic and therapeutic applications.

Crystal structures, DNA-binding and cytotoxic activities studies of Cu(II) complexes with 2-oxo-quinoline-3-carbaldehyde Schiff-bases

Three novel 2-oxo-quinoline-3-carbaldehyde Schiff-bases and their Cu(II) complexes were synthesized. The molecular structures of Cu(II) complexes were determined by X-ray crystal diffraction. The DNA-binding modes of the complexes were also investigated by UV-vis absorption spectrum, fluorescence spectrum, viscosity measurement and EB-DNA displacement experiment. The experimental evidences indicated that the ligands and Cu(II) complexes could interact with CT-DNA (calf-thymus DNA) through intercalation, respectively. Comparative cytotoxic activities of ligands and Cu(II) complexes were also determined by MTT [3-(4,5-dimethyl-2-thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide] and SRB (sulforhodamine B) methods. The results showed that the three Cu(II) complexes exhibited more effective cytotoxic activity against HL60 cells and HeLa cells than corresponding ligands. Also, CuL(3) showed higher cytotoxic activity than CuL(1) and CuL(2).

A one-step method to produce graphene–Fe3O4 composites and their excellent catalytic activities for three-component coupling of aldehyde, alkyne and amine

The construction of reduced graphene oxide or graphene oxide (GO) with magnetic nanoparticles has gained more and more attention due to its promising and wide applications in catalysis, photoelectric materials, biomedical fields and so on. The synthesis of reduced graphene oxide (RGO) or graphene magnetic nanoparticle nanocomposites with well-dispersed decorated particles is still a challenge. Herein, we first report a simple method to prepare graphene–Fe3O4 with uniform Fe3O4 NPs based on decomposition of Fe(CO)5 on the surface of graphene oxide. The main novelty of this work is that the decomposition products of Fe(CO)5 reacted with GO leading to the formation of graphene–Fe3O4. The resulting sample can be easily manipulated by an external magnetic field and exhibits excellent catalytic activity in the A3-coupling reaction. A diverse range of propargylamines were obtained in a moderate to high yield under mild conditions. The separation and reuse of graphene–Fe3O4 were very simple, effective and economical.

An effective Cu(II) quenching fluorescence sensor in aqueous solution and 1D chain coordination polymer framework

In the article, a novel fluorescent probe for the copper cation based on fluorescence quenching mechanism was designed. It exhibited high selectivity for Cu(II) over other common metal ions in aqueous media. Furthermore the coordination between Cu(II) and the organic molecule sensor fabricated an interesting 1D chain coordination polymer framework.

Coupling of Luminescent Terbium Complexes to Fe3O4 Nanoparticles for Imaging Applications

Coupling optically active components to magnetic nanoparticles (NPs) is an attractive way to develop multifunctional probes for highly sensitive biological imaging and recognition. While iron oxide NPs have been explored as robust magnetic contrast and therapeutic agents, semiconducting quantum dots, fluorescent organic dyes, and metal complexes are now commonly sought after for sensitive optical imaging applications. Among all molecular optical probes studied thus far, lanthanide-based complexes have attracted particular interest due to their unique long luminescence lifetimes (microto milliseconds), sharp emission bands, and insensitivity to photobleaching. Despite numerous efforts researching magnetic NPs and lanthanide-based complexes for biomedical applications, conjugates containing both magnetic NPs and lanthanide complexes have not been synthesized and studied. Such conjugates with both magnetic and optical imaging capabilities should serve as new bifunctional probes for highly sensitive biorecognition applications. We have now designed and prepared a luminescent lanthanide nanoparticle label based on sensitization of an organic chromophore. The particle is made up of Fe3O4 NPs coated with a lanthanide complex (Scheme 1). Ligand 1b is comprised of a quinolone-based dye acting as light-absorption antenna and a polyethylene glycol 3,4-dihydroxybenzylamine (DBI-PEG-NH2) moiety, which enables binding to the surface of Fe3O4 NPs to give water-soluble NPs. These Fe3O4 NPs are strongly luminescent in aqueous solution and have a long fluorescence lifetime. Folic acid (FA) is a high-affinity ligand for folate receptor (FR), and has been widely used for targeted delivery of FAconjugated molecular probes or nanoparticles to FR-overexpressing cancer cell lines (e.g., HeLa and KB cell lines). Since salicylic acid has excellent coordination ability with rare-earth metal ions and can sensitize their luminescence, we used folate-(salicylic acidyl)-amine as cell-targeting agent for further application in bioimaging based on Tb:1b. Synthesis of the luminescent Fe3O4 NPs is presented in Scheme S1 (Supporting Information). The PEG amine 1a was prepared from 1,w-diaminopolyoxyethylene (M = 4000) and 3,4-dihydroxybenzaldehyde. 7-Amino-4-methyl-2(1H)-quinolinone (cs124) was covalently coupled with diethylenetriaminepentaacetic acid (DTPA) by means of its dianhydride, and the product was then treated with 1a to obtain 1b. Complex Tb:1b was formed by stirring 1b with TbCl3 overnight in DMF, and then treated with folate-(salicylic acidyl)-amine in DMF to give Tb:1b-FA. Monodisperse Fe3O4 NPs coated with oleylamine with a size of 12 nm were synthesized by a previously published procedure. Exchange of oleic acid and oleylamine on the surface of Fe3O4 NPs with Tb:1b or Tb:1b-FA was easily achieved by mixing Tb:1b or Tb:1b-FA and Fe3O4 NPs monodispersed in water (Figure S1, Supporting Information); the NPs showed little change in core size after surface modification. According to the Tb/Fe weight percentage (105%), about 2312 Tb units are bound to each Fe3O4 NP, corresponding to about 2312 ligands per Fe3O4 NP. Magnetization of as-synthesized Fe3O4 NPs and Tb:1 bFA-NPs was measured as a function of applied magnetic field (Figure S2, Supporting Information). Little change in magnetic properties was observed between the as-synthesized Fe3O4 NPs and Tb:1b-FA-NPs. None of the samples showed hysteresis, that is, the nanoparticles retain superparamagetism. The saturated magnetization (Ms) of as-synthesized Fe3O4 NPs and Tb:1b-NPs are 54.8 and 17.8 Am 2 kg , respectively. The dispersibility of Tb:1b-FA-NPs was tested by measuring the change of their hydrodynamic size during incubation under different conditions. Figure S3 (Supporting Information) shows that Tb:1b-FA-NPs are stable to dispersion in phosphate buffered saline (PBS) and show no change in the statistical hydrodynamic size over the incubation time, and little change in the size of Tb:1b-FA-NPs occurs with varying temperature. The measured size increase from about 129 to about 219 nm in the presence of fetal bovine serum (FBS) is attributed to adsorption of FBS onto the NP surface, as reported previously. On the other hand, at lower pH 6 (Figure S4, Supporting Information), the particles can be stabilized for only 2 h before serious aggregation occurs. After 8 h, the size of the clustered nanoparticles reaches 190 nm, due to chemical bond cleavage between iron oxide and the catechol unit of 3,4-dihydroxybenzaldehyde under low-pH incubation conditions, which destabilizes the nanoparticle dispersion. [*] B. Wang Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province and State Key Laboratory of Applied Organic Chemistry, Lanzhou University (P.R. China)

Palladium nanoparticles bonded to two-dimensional iron oxide graphene nanosheets: a synergistic and highly reusable catalyst for the Tsuji-Trost reaction in water and air.

Low cost, high activity and selectivity, convenient separation, and increased reusability are the main requirements for noble-metal-nanocatalyst-catalyzed reactions. Despite tremendous efforts, developing noble-metal nanocatalysts to meet the above requirements remains a significant challenge. Here we present a general strategy for the preparation of strongly coupled Fe(3)O(4) and palladium nanoparticles (PdNPs) to graphene sheets by employing polyethyleneimine as the coupling linker. Transmission electron microscopic images show that Pd and Fe(3)O(4) nanoparticles are highly dispersed on the graphene surface, and the mean particle size of Pd is around 3 nm. This nanocatalyst exhibits synergistic catalysis by Pd nanoparticles supported on reduced graphene oxide (rGO) and a tertiary amine of polyethyleneimine (Pd/Fe(3)O(4)/PEI/rGO) for the Tsuji-Trost reaction in water and air. For example, the reaction of ethyl acetoacetate with allyl ethyl carbonate afforded the allylated product in more than 99 % isolated yield, and the turnover frequency reached 2200 h(-1). The yield of allylated products was 66 % for Pd/rGO without polyethyleneimine. The catalyst could be readily recycled by a magnet and reused more than 30 times without appreciable loss of activity. In addition, only about 7.5 % of Pd species leached off after 20 cycles, thus rendering this catalyst safer for the environment.

A multifunctional nanoprobe based on Au–Fe3O4 nanoparticles for multimodal and ultrasensitive detection of cancer cells

A multifunctional nanoprobe, which can be used for dual modal imaging and the detection of cancer cells, has been reported.

Design and synthesis of a chemosensor for the detection of Al3+ based on ESIPT

In this study, a simple fluorescent sensor 2-hydroxybenzcarbaldehyde-(2-methylquinoline-4-formyl) hydrazone (HL) has been designed, synthesized and characterized by 1H-NMR, IR, ESI-MS. Upon addition of Al3+, HL shows a large fluorescence enhancement (220-fold) at 484 nm. The reasons for this phenomenon are attributed to formation of a 1:1 complex (Ka = 5.6 × 104), which inhibits the excited-state intramolecular proton transfer (ESIPT) process and photo-induced electron transfer (PET) process. Other metal ions including Ba2+, Ca2+, Cd2+, Co2+, Cr3+, Hg2+, K+, Mg2+, Mn2+, Na+, Ni2+, Pb2+ and Zn2+, have almost no influence on the fluorescence. The lowest detection limit for Al3+ is calculated to be 7.2 × 10−7 M in ethanol.