Zhiai Xu

Treatment of metastatic breast cancer by combination of chemotherapy and photothermal ablation using doxorubicin-loaded DNA wrapped gold nanorods

Despite the exciting advances in cancer therapy over past decades, tumor metastasis remains the dominate reason for cancer-related mortality. In present work, DNA-wrapped gold nanorods with doxorubicin (DOX)-loading (GNR@DOX) were developed for treatment of metastatic breast cancer via a combination of chemotherapy and photothermal ablation. The GNR@DOX nanoparticles induced significant temperature elevation and DOX release upon irradiation with near infrared (NIR) light as shown in the test tube studies. It was found that GNR@DOX nanoparticles in combination with laser irradiation caused higher cytotoxicity than free DOX in 4T1 breast cancer cells. Animal experiment with an orthotropic 4T1 mammary tumor model demonstrated that GNR@DOX nanoplatform significantly reduced the growth of primary tumors and suppressed their lung metastasis. The Hematoxylin and Eosin (H&E) and immunohistochemistry (IHC) staining assays confirmed that the tumor growth inhibition and metastasis prevention of GNR@DOX nanoparticles were attributed to their abilities to induce cellular apoptosis/necrosis and ablate intratumoral blood vessels. All these results suggested a considerable potential of GNR@DOX nanoplatform for treatment of metastatic breast cancer.

Reversal of Lung Cancer Multidrug Resistance by pH‐Responsive Micelleplexes Mediating Co‐Delivery of siRNA and Paclitaxel

The recent advances in RNA interference (RNAi) technology provided novel and promising solutions for human cancer treatment. In this study, the application of dual pH-responsive cationic micellar nanoparticles for small interfering RNA (siRNA) and paclitaxel (PTX) co-delivery to overcome cancer multidrug resistance (MDR) is reported. The in vitro siRNA transfection shows that siRNA-luciferase (Luc) loaded micelleplexes efficiently silences Luc expression in various carcinoma cell lines. The Luc knockdown ability of the micelleplexes can be enhanced by choloquine (CQ) co-incubation. However, is abolished by bafilomycin-A1 (Baf-A1) treatment. The micelleplexes are further exploited for co-delivery of siRNA-Bcl-2 and PTX to Bcl-2 overexpressing A549 lung cancer cells (A549-Bcl-2). The experimental results show that the micelleplexes could sensitize A549-Bcl-2 cells to PTX via down-regulation of anti-apoptosis gene of Bcl-2, suggesting that PDMA-b-PDPA micelleplexes are promising nanovectors for siRNA and anti-cancer drug co-delivery to overcome cancer MDR.

Intracellular pH-activated PEG-b-PDPA wormlike micelles for hydrophobic drug delivery

Wormlike micelles with intracellular pH-activating properties were developed. The micelles remained in a “silent” state at physiological pH conditions (i.e. pH 7.4), but were activated in the acidic microenvironment of endocytic vesicles. The wormlike micelles could be employed as nanovectors for the intracellular delivery of hydrophobic drugs for cancer therapy.

Visible-light-activated photoelectrochemical biosensor for the study of acetylcholinesterase inhibition induced by endogenous neurotoxins

In this report, a novel visible-light-activated photoelectrochemical biosensor was fabricated to study the inhibition of acetylcholinesterase (AChE) activity induced by two endogenous neurotoxins, 1(R)-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline [(R)-Sal] and 1(R),2(N)-dimethyl-6,7-dihydroxy-1,2,3,4-tetra-hydroisoquinoline [(R)-NMSal], which have drawn much attention in the study of the pathogenesis of neurodegenerative diseases such as Parkinsons disease. The photoelectrode was prepared by three steps, as follows. At first, nitrogen and fluorine co-doped TiO2 nanotubes (TNs) were obtained by anodic oxidation of a Ti sheet. Secondly, silver nanoparticles (AgNPs) were deposited onto the TNs through a microwave-assisted heating polyol (MAHP) process. At last, AChE was immobilized on the obtained photoelectrode and the biosensor was marked as AChE/Ag/NFTNs. Due to the nitrogen and fluorine co-doping, the photoelectrochemical biosensors can produce high photocurrent under visible light irradiation. Moreover, the presence of AgNPs greatly increased the photocurrent response of the biosensor. AChE/Ag/NFTNs hybrid system was used to study AChE inhibition induced by (R)-Sal and (R)-NMSal. The result proved that both (R)-Sal and (R)-NMSal exhibited mixed and reversible inhibition against AChE. This strategy is of great significance for the development of novel photoelectrochemical biosensors in the future.

Cooperative Treatment of Metastatic Breast Cancer Using Host-Guest Nanoplatform Coloaded with Docetaxel and siRNA.

Conventional chemotherapy shows moderate efficiency against metastatic cancer since it targets only part of the mechanisms regulating tumor growth and metastasis. Here, gold nanorod (GNR)-based host-guest nanoplatforms loaded with docetaxel (DTX) and small interfering RNA (siRNA)-p65 (referred to as DTX-loaded GNR (GDTX)/p65) for chemo-, RNA interference (RNAi), and photothermal ablation (PTA) cooperative treatment of metastatic breast cancer are reported. To prepare the nanoplatform, GNRs are first coated with cyclodextrin (CD)-grafted polyethylenimine (PEI) and then loaded with DTX and siRNA through host-guest interaction with CD and electrostatic interaction with PEI, respectively. Upon near-infrared laser irradiation, GNRs generate a significant hyperthermia effect to trigger siRNA and DTX release. DTX reduces tumor growth by inhibiting mitosis of cancer cells. Meanwhile, siRNA-p65 suppresses lung metastasis and proliferation of cancer cells by blocking the nuclear factor kappa B (NF-κB) pathway and downregulating the downstream genes matrix metalloproteinase-9 (MMP-9) and B cell lymphoma-2 (Bcl-2). It is demonstrated that GDTX/p65 in combination with laser irradiation significantly inhibits the growth and lung metastasis of 4T1 breast tumors. The antitumor results suggest promising potential of the host-guest nanoplatform for combinational treatment of metastatic cancer by using RNAi, chemotherapy, and PTA.

Selective amyloid β oligomer assay based on abasic site-containing molecular beacon and enzyme-free amplification

Amyloid-beta (Aβ) oligomers are highly toxic species in the process of Aβ aggregation and are regarded as potent therapeutic targets and diagnostic markers for Alzheimers disease (AD). Herein, a label-free molecular beacon (MB) system integrated with enzyme-free amplification strategy was developed for simple and highly selective assay of Aβ oligomers. The MB system was constructed with abasic site (AP site)-containing stem-loop DNA and a fluorescent ligand 2-amino-5,6,7-trimethyl-1,8-naphyridine (ATMND), of which the fluorescence was quenched upon binding to the AP site in DNA stem. Enzyme-free amplification was realized by target-triggered continuous opening of two delicately designed MBs (MB1 and MB2). Target DNA hybridization with MB1 and then MB2 resulted in the release of two ATMND molecules in one binding event. Subsequent target recycling could greatly amplify the detection sensitivity due to the greatly enhanced turn-on emission of ATMND fluorescence. Combining with Aβ oligomers aptamers, the strategy was applied to analyze Aβ oligomers and the results showed that it could quantify Aβ oligomers with high selectivity and monitor the Aβ aggregation process. This novel method may be conducive to improve the diagnosis and pathogenic study of Alzheimers disease.

Hydrophobic-carbon-dot-based dual-emission micelle for ratiometric fluorescence biosensing and imaging of Cu2+ in liver cells

Copper is closely related to liver damage, therefore, it is essential to develop a simple and sensitive strategy to detect copper ions (Cu2+) in liver cells. A hydrophobic carbon dots (HCDs)-based dual-emission fluorescent probe for Cu2+ was prepared by encapsulating HCDs in micelles formed by self-assembly of amphiphilic polymer DSPE-PEG and tetrakis (4-carboxyphenyl) porphyrin (TCPP)-modified DSPE-PEG. The obtained probe showed characteristic fluorescence emissions of HCDs and TCPP with large emission shift of 170nm with single-wavelength excitation. In the presence of Cu2+, the fluorescence of TCPP was quenched and that of HCDs remained unchanged, displaying ratiometric fluorescence response to Cu2+. The developed probe exhibited high sensitivity (detection limit down to 36nM) and selectivity to Cu2+ over other substances, and the probe was used to image the changes of Cu2+ level in liver cells successfully.

Polydopamine‐Functionalized Graphene Oxide Loaded with Gold Nanostars and Doxorubicin for Combined Photothermal and Chemotherapy of Metastatic Breast Cancer

Breast cancer is the leading cancer type diagnosed in the female population, and cancer metastasis is the main reason for cancer-caused mortality. A novel nanoplatform is herein presented integrating polydopamine-functionalized nanosized reduced graphene oxide (NRGO), gold nanostars (GNS), and doxorubicin (DOX) (denoted as NRGO-GNS@DOX) for combinational treatment of metastatic breast cancer. Upon localized near infrared (NIR) laser irradiation, the NRGO-GNS@DOX nanocomposites induce significant cytotoxicity in 4T1 breast cancer cells due to a cumulative therapy effect of NRGO-GNS-elicited hyperthermia and DOX-induced cytotoxicity. Antitumor studies in orthotopic 4T1 breast tumor-bearing nude mice demonstrate that NRGO-GNS@DOX in combination with NIR laser irradiation inhibit the tumor growth and suppress the lung metastasis. Contribution of DOX-caused apoptosis of the cancer cells and hyperthermia-induced deconstruction of the tumor-associated blood vessels may account for the superior antitumor performance of the NRGO-GNS@DOX nanocomposites. These results imply a good potential of NRGO-GNS@DOX for combined photothermal and chemotherapy of the metastatic cancer.

Three-dimensional ordered macroporous (3DOM) composite for electrochemical study on acetylcholinesterase inhibition induced by endogenous neurotoxin.

In this paper, an electrochemical acetylcholinesterase (AChE) inhibition assay based on three-dimensional ordered macroporous (3DOM) composite was conducted. The 3DOM composite was first fabricated on the glassy carbon electrode by electropolymerization of aniline in the presence of ionic liquid (IL) on a sacrificial silica nanospheres template. After the silica nanospheres were etched, an IL-doped polyaniline (IL-PANI) film with 3DOM morphology was formed. Then, gold nanoparticles (AuNPs) were decorated on the IL-PANI film by electrodeposition. The immobilized AChE on the 3DOM composite displayed favorable affinity to substrate acetylthiocholine chloride (ATCh), and the 3DOM composite showed excellent electrocatalytic effect on thiocholine, the hydrolysis product of ATCh. The presence of IL and AuNPs could improve the sensitivity by accelerating the electron transfer. The designed AChE biosensor was successfully applied to evaluate the AChE inhibition induced by endogenous neurotoxin 1(R),2N-dimethyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline [(R)-NMSal]. The results demonstrate that (R)-NMSal exerts a considerable effect on AChE activity, and the inhibition is reversible. The developed method offers a new approach for AChE inhibition assay, which is of great benefit in understanding the mechanism behind neurotoxin-induced neurodegenerative disorders.

Gold nanomaterials for treatment of metastatic cancer

Nanomedicine has shown good potentials for cancer diagnosis and treatment since the last decades. Among the various nanoparticles exploited for cancer management so far, gold nanomaterials (e.g., spherical gold nanoparticles and gold nanorods) were extensively investigated due to their unique chemo-physical properties. We herein summarize the emerging application and discuss the challenges of using gold nanomaterials for therapy of metastatic cancer.