Qiwei Li

In vivo self-bio-imaging of tumors through in situ biosynthesized fluorescent gold nanoclusters

Fluorescence imaging in vivo allows non-invasive tumor diagnostic thus permitting a direct monitoring of cancer therapies progresses. It is established herein that fluorescent gold nanoclusters are spontaneously biosynthesized by cancerous cell (i.e., HepG2, human hepatocarcinoma cell line; K562, leukemia cell line) incubated with micromolar chloroauric acid solutions, a biocompatible molecular Au(III) species. Gold nanoparticles form by Au(III) reduction inside cells cytoplasms and ultimately concentrate around their nucleoli, thus affording precise cell imaging. Importantly, this does not occur in non-cancerous cells, as evidenced with human embryo liver cells (L02) used as controls. This dichotomy is exploited for a new strategy for in vivo self-bio-imaging of tumors. Subcutaneous injections of millimolar chloroauric acid solution near xenograft tumors of the nude mouse model of hepatocellular carcinoma or chronic myeloid leukemia led to efficient biosynthesis of fluorescent gold nanoclusters without significant dissemination to the surrounding normal tissues, hence allowing specific fluorescent self-bio-marking of the tumors.

Near-infrared fluorescence imaging of cancer cells and tumors through specific biosynthesis of silver nanoclusters

Human life toll by cancer, one of the highest among most dreaded diseases in advanced societies, could be reduced by implementing evidence-based strategies for its prevention, early diagnosis and assessment of the progress and suitability of therapies by fast and non-invasive methods. In this contribution, a novel strategy is reported for highly sensitive recognition and in vivo imaging of cancer cells taking advantage of their spontaneous ability to generate silver nanoclusters (NCs) with high near-infrared fluorescence emission by intracellular reduction of innocuous silver salts. Both ex vivo experiments comparing cancer cell models to normal cells and in vivo imaging of subcutaneous xenografted tumor (cervical carcinoma model) in nude mice established the validity of this strategy for precise and selective imaging of cells and tumors. Furthermore, it was observed that the spontaneous self-generation of Ag NCs by tumors in their inside led to drastic reduction of their sizes and often to complete remission, thus providing important hope for new therapy strategies based on cheap and readily available agents.

Layer-by-layer assembly of graphene, Au and poly(toluidine blue O) films sensor for evaluation of oxidative stress of tumor cells elicited by hydrogen peroxide

High level of oxidative stress is involved in formation of incipient tumor and carcinomatous cells. Here in this contribution we have explored a facile strategy to assess the oxidative stress elicited by hydrogen peroxide (H(2)O(2)) in cells with amperometric current-time technique in vitro. An electrochemical biosensor exhibiting high sensitivity and selectivity to H(2)O(2) is fabricated by integration of graphene with gold nanoparticles and poly(toluidine blue O) films. The efflux of H(2)O(2) from several representative tumor cells and normal cells on exposure to ascorbic acid could be detected by using the graphene-based nanocomposite films. The results indicate that tumor cells release much more H(2)O(2) than do the normal cells. The novel sensor raises the possibility for clinical diagnostic application to evaluate the higher level of intracellular oxidative stress of tumor cells in comparison with normal cells.

In Situ Biosynthesis of Fluorescent Platinum Nanoclusters: Toward Self-Bioimaging-Guided Cancer Theranostics

Among the noble-metal clusters, very few reports about platinum clusters were used as bioimaging probes of tumors except as a reducing catalyst. It is first established herein that the biocompatible platinum nanoclusters are spontaneously biosynthesized by cancerous cells (i.e., HepG2 (human hepatocarcinoma), A549 (lung cancer), and others) rather than noncancerous cells (i.e., L02 (human embryo liver cells)) when incubated with micromolar chloroplatinic acid solutions. These in situ biosynthesized platinum nanoclusters could be readily realized in a biological environment and emit a bright fluorescence at 460 nm, which could be further utilized to facilitate an excellent cancer-cell-killing efficiency when combined with porphyrin derivatives for photothermal treatment. This raises the possibility of providing a promising and precise bioimaging strategy for specific fluorescent self-biomarking of tumor locations and realizing fluorescence imaging-guided photothermal therapy of tumors.

Cytidine-Directed Rapid Synthesis of Water-Soluble and Highly Yellow Fluorescent Bimetallic AuAg Nanoclusters

Fluorescent gold/silver nanoclusters templated by DNA or oligonucleotides have been widely reported since DNA or oligonucleotides could be designed to position a few metal ions at close proximity prior to their reduction, but nucleoside-templated synthesis is more challenging. In this work, a novel type of strategy taking cytidine (C) as template to rapid synthesis of fluorescent, water-soluble gold and silver nanoclusters (C-AuAg NCs) has been developed. The as-prepared C-AuAg NCs have been characterized by UV-vis absorption spectroscopy, fluorescence, transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and inductively coupled plasma mass spectroscopy (ICP-MS). The characterizations demonstrate that C-AuAg NCs with a diameter of 1.50 ± 0.31 nm, a quantum yield ∼9%, and an average lifetime ∼6.07 μs possess prominent fluorescence properties, good dispersibility, and easy water solubility, indicating the promising application in bioanalysis and biomedical diagnosis. Furthermore, this strategy by rapid producing of highly fluorescent nanoclusters could be explored for the possible recognition of some disease-related changes in blood serum. This raises the possibility of their promising application in bioanalysis and biomedical diagnosis.

Rapid and ultrasensitive electrochemical detection of multidrug-resistant bacteria based on nanostructured gold coated ITO electrode.

Rapid and ultrasensitive detection of pathogenic bacteria and their relevant multidrug resistance is particularly important in clinical diagnosis, disease control, and environmental monitoring. In this contribution, we have explored the possibility to rapidly detect some important disease related bacteria based on a nanostructured Au modified indium tin oxide electrode through the antibiotic agents such as doxorubicin. The rapid and real-time electrochemical detection of multidrug resistant bacteria like Escherichia coli and Staphylococcus aureus could be readily realized through the nanostructured Au based biosensor with high sensitivity. The observations of surface-enhanced Raman spectroscopy and laser confocal fluorescence microscopy also demonstrate the effectiveness of the relevant new strategy for the rapid and ultrasensitive electrochemical detection of some disease related bacteria.

Green and facile synthesis of highly biocompatible carbon nanospheres and their pH-responsive delivery of doxorubicin to cancer cells

Developing an efficient nanoparticulate drug-delivery system with a sub-100 nm diameter plays a crucial role in delivering antitumor drugs into cancer cells and improving their therapeutic efficacy. Carbon spheres, due to their large surface areas, unique surface properties and ease of functionalization, can generally deliver a large quantity of therapeutic agents to the target disease sites. In this study, spherical carbon nanoparticles with uniform size (71 nm) and regular shape were synthesized by hydrothermal reaction of bacterial cellulose nanofibers (30–50 nm), which had been achieved by a microorganism synthesis. Then using a simple acidification treatment, we could obtain carbon nanospheres with high drug loading capacity (the drug encapsulation efficiency was found to be about 93.4% and the drug loading efficiency (DL) reached about 52.3%). Meanwhile, the carbon nanospheres also exhibited good pH sensitivity in drug delivery. The results of in vitro experiments demonstrate that the carbon nanospheres prepared played an important part in the increase of the intracellular drug concentration and delayed-efficacy of the drug effect, which make them a promising platform for the delivery of other therapeutic agents beyond DOX.

One-step facile synthesis of fluorescent gold nanoclusters for rapid bio-imaging of cancer cells and small animals

Fluorescent bio-imaging has become a major topic of the modern biomedical research field. Fluorescent metal nanoclusters have been proposed as sensitive optical imaging probes aiming for early cancer diagnosis. We have developed a new strategy for the facile synthesis of Au-BSA nanoclusters (NCs) which have stable and bright fluorescence and could be used as a fluorescent probe for bioimaging rapidly and effectively. In this contribution, we have synthesized Au-BSA NCs at 80 °C for 10 minutes with the pH value of 11.5. At the concentration range of 0.1–10 mg mL−1, Au-BSA NCs have no obvious cell cytotoxicity effect on MCF-7, HeLa, L02, U87, and A549 cells. Then the as-prepared Au-BSA NCs were characterized by using TEM and XPS and applied for rapid tumor imaging. The biocompatible BSA stabilized fluorescent gold nanoclusters (NCs) synthesized through one-step hydrothermal reaction possess strong and bright fluorescence that can be readily utilized as a highly sensitive fluorescence probe for tumor-targeted bio-imaging in vitro and in vivo.

One-step rapid synthesis of fluorescent platinum nanoclusters for cellular imaging and photothermal treatment

Fluorescent platinum nanoclusters constructed through one-step synthesis from chloroplatinic acid cross swiftly across carcinoma cell membranes for bio-imaging and photothermal treatment.

Size-controlled porous superparamagnetic Zn1/3Fe8/3O4 nanospheres: synthesis, properties and application for drug delivery

Magnetic nanospheres have recently attracted much attention in the biomedical areas due to their good biocompatibility and unique magnetic features. Herein we report the synthesis and characterization of different sized porous superparamagnetic iron oxide nanospheres (SPIONs) (Zn1/3Fe8/3O4) which are based on a new rational method of elevated-temperature hydrolysis of chelate iron alkoxide complexes in solutions of the corresponding alcohol, diethyleneglycol (DEG) and diethanolamine (DEA). The size of the SPIONs is controlled by changing the ratio of the reaction media. It is noted that the highly water dispersible porous SPIONs with narrow size distribution can be tuned from 6.5 to 200 nm, each of which is composed of many single magnetite crystallites of approximately 5.5 nm in size. The SPIONs show superparamagnetic properties at room temperature. The superparamagnetic behavior, high magnetization, and high water dispersibility make these nanospheres ideal candidates for various important applications for drug delivery.