Xuehua Ma

Inorganic photosensitizer coupled Gd-based upconversion luminescent nanocomposites for in vivo magnetic resonance imaging and near-infrared-responsive photodynamic therapy in cancers.

Inorganic photosensitizer coupled Gd-based upconversion luminescent (UCL) nanocomposites have potential application for both magnetic resonance imaging (MRI) and photodynamic therapy (PDT) of cancers using the light stability and biocompatibility of TiO2 inorganic photosensitizer. However, TiO2 inorganic photosensitizer could only be excited by ultraviolet (UV) light, which was harmful and weakly penetrable in tissues. In this work, folic acid (FA)-targeted NaGdF4:Yb/Tm@SiO2@TiO2 nanocomposites (FA-Gd-Si-Ti NPs) were constructed and synthesized for both in vivo MRI and near infrared (NIR)-responsive inorganic PDT, in which TiO2 component could be excited by NIR light due to the UCL performance of NaGdF4:Yb/Tm component converting NIR to UV light. The results showed the as-prepared FA-Gd-Si-Ti NPs had good biocompatibility in vitro and in vivo. Moreover, MR study indicated that FA-Gd-Si-Ti NPs were good T1-weighted MRI contrast agents with high longitudinal relaxivity (r1) of 4.53 mm(-1) s(-1), also in vivo MRI of nude mice showed bright signal in MCF-7 tumor. Under the irradiation of 980 nm laser at the power density of 0.6 W/cm(2) for 20 min, the viability of HeLa and MCF-7 cells incubated with FA-Gd-Si-Ti NPs could decrease from about 90 % to 35 % and 31%, respectively. Furthermore, in vivo PDT of MCF-7 tumor-bearing nude mice model showed that the inhibition ratio of tumors injected with FA-Gd-Si-Ti NPs reached up to 88.6% after 2-week treatment, compared with that of nude mice in control group. Based on the deep penetration of NIR light and the good biocompatibility of TiO2 inorganic photosensitizer, the as-prepared FA-Gd-Si-Ti NPs could have potential applications in both MRI and NIR-responsive PDT of cancers in deep tissues.

Improved SERS Nanoparticles for Direct Detection of Circulating Tumor Cells in the Blood

The detection of circulating tumor cells (CTCs) in the blood of cancer patients is crucial for early cancer diagnosis, cancer prognosis, evaluation of the treatment effect of chemotherapy drugs, and choice of cancer treatment options. In this study, we propose new surface-enhanced Raman scattering (SERS) nanoparticles for the direct detection of CTCs in the blood. Under the optimized experimental conditions, our SERS nanoparticles exhibit satisfying performances for the direct detection of cancer cells in the rabbit blood. A good linear relationship is obtained between the SERS intensity and the concentration of cancer cells in the range of 5-500 cells/mL (R(2) = 0.9935), which demonstrates that the SERS nanoparticles can be used for the quantitative analysis of cancer cells in the blood and the limit of detection is 5 cells/mL, which is lowest compared with the reported values. The SERS nanoparticles also have an excellent specificity for the detection of cancer cells in the rabbit blood. The above results reinforce that our SERS nanoparticles can be used for the direct detection of CTCs in the blood with excellent specificity and high sensitivity.

Exploring a new SPION-based MRI contrast agent with excellent water-dispersibility, high specificity to cancer cells and strong MR imaging efficacy

Advances in contrast agents have greatly enhanced the sensitivity of magnetic resonance imaging (MRI) technique for early diagnosis of cancer. However, the commercial superparamagnetic iron oxide nanoparticles (SPION)-based contrast agents synthesized by co-precipitation method are not monodisperse with irregular morphologies and ununiform sizes. Other reported SPION-based contrast agents synthesized by solvothermal method or thermal decomposition method are limited by the bad water-dispersibility and low specificity to cancer cells. Herein, we propose a new strategy for exploring SPION-based MRI contrast agents with excellent water-dispersibility and high specificity to cancer cells. The SPION was synthesized by a polyol method and then entrapped into albumin nanospheres (AN). After that, a ligand folic acid (FA) was conjugated onto the surface of the AN to construct a SPION-AN-FA composite. The transmission electron microscope (TEM) and dynamic light scattering (DLS) results indicate that the SPION-AN-FA has a spherical shape, a uniform size and an excellent water-dispersibility (polydispersity index (PDI) <0.05). The results of laser scanning confocal microscope (LSCM) and flow cytometry demonstrate that the SPION-AN-FA nanoparticles are highly specific to MCF-7 and SPC-A-1 cells due to the recognition of ligand FA and folate receptor α (FRα). The r2/r1 value of SPION-AN-FA is around 40, which is much higher than that of Resovist(®) indicating that our SPION-AN-FA has a stronger T2 shortening effect. The T2-weighted images of MCF-7 cells incubated with SPION-AN-FA are significantly darker than those of MCF-7 cells incubated with AN, indicating that our SPION-AN-FA has a strong MR imaging efficacy. In view of the excellent water-dispersibility, the high specificity to cancer cells and the strong MR imaging efficacy, our SPION-AN-FA can be used as a negative MR contrast agent.

Brushing, a simple way to fabricate SERS active paper substrates

A simple and facile method has been demonstrated to fabricate low-cost surface enhanced Raman scattering (SERS) active microfluidic paper chips using a painting brush. This strategy solves the problem of mass production of highly reproducible SERS substrates without complicated or bulky micro- or nanofabrication instruments. Rhodamine 6G (R6G) was chosen as a probe molecule to evaluate the performance of the SERS active chip. To further demonstrate the possibility of this methods potential application in environmental monitoring, trace malachite green (MG) was successfully analyzed on this chip. The performance of our chips was desirable. The paper substrates with silver nanoparticles deposited by brush were found to be cost-efficient and highly sensitive (LOD for R6G and MG are 1 nM and 10 nM, respectively), and have good reproducibility (∼15% relative standard deviation).

Silica-coated super-paramagnetic iron oxide nanoparticles (SPIONPs): a new type contrast agent of T1 magnetic resonance imaging (MRI)

Magnetic resonance imaging (MRI), a sophisticated promising three-dimensional tomographic noninvasive diagnostic technique, has an intrinsic advantage in safety compared with radiotracer and optical imaging modalities; however, MRI contrast agents are less sensitive than complexes used in other imaging techniques. Usually the clinically used Gd-based complexes MRI-T1 contrast agents are toxic; therefore, the demand for nontoxic novel T1-weighted MRI candidates with ultrasensitive imaging and advanced functionality is very high. In this research, silica-coated ultra-small monodispersed super-paramagnetic iron oxide nanoparticles were synthesized via a thermal decomposition method, which demonstrated themselves as a high performance T1-weighted MRI contrast agent for heart, liver, kidney and bladder based on in vivo imaging analyses. Transmission electron microscopy (TEM) results illustrated that the diameter of the SPIONPs was in the range of 4 nm and the average size of Fe3O4@SiO2 was about 30-40 nm. X-ray diffraction (XRD) and Raman spectroscopy analyses revealed the phase purity of the prepared SPIONPs. These magnetite nanoparticles exhibited a weak magnetic moment at room temperature because of the spin-canting effect, which promoted a high positive signal enhancement ability. MTT assays and histological analysis demonstrated good biocompatibility of the SPIONPs in vitro and in vivo. In addition, the silica-coated ultra-small (4 nm sized) magnetite nanoparticles exhibited a good r1 relaxivity of 1.2 mM-1 s-1 and a low r2/r1 ratio of 6.5 mM-1 s-1. In vivo T1-weighted MR imaging of heart, liver, kidney and bladder in mice after intravenous injection of nanoparticles further verified the high sensitivity and biocompatibility of the as-synthesized magnetite nanoparticles. These results reveal silica-coated SPIONPs as a promising candidate for a T1 contrast agent with extraordinary capability to enhance MR images.

Biocompatible composite nanoparticles with large longitudinal relaxivity for targeted imaging and early diagnosis of cancer

Early diagnosis of cancer greatly increases the chances of successful treatment by radical resection. The sensitivity of magnetic resonance imaging (MRI) techniques for detecting early stage tumors can be increased with the assistance of a positive MRI contrast agent. However, the traditional positive MRI contrast agents, such as Gd-chelates and Gd-based inorganic nanoparticles, are often limited by their cytotoxicity and low specificity. Here, we propose a new design of MRI contrast agent based on gadolinium oxide nanocrystals (GON) for targeted imaging and cancer early diagnosis with good biocompatibility. The GON were prepared using a polyol method and then encapsulated into albumin nanoparticles (AN), which were cross-linked with glutaraldehyde and found to exhibit bright and stable autofluorescence without conjugation to any fluorescent agent. After that, a target molecule, folic acid (FA), was conjugated onto the surface of the GON-loaded AN (GON-AN) to construct a GON-AN-FA composite. The as-prepared nanoparticles are biocompatible and stable in serum. The results of MRI relaxation studies show that the longitudinal relaxivities (r1) of GON-AN (11.6 mM-1 s-1) and GON-AN-FA (10.8 mM-1 s-1) are much larger than those of traditional positive MRI contrast agents, such as Magnevist (3.8 mM-1 s-1). The results of cell viability assays indicate that GON-AN and GON-AN-FA are almost non-cytotoxic. Furthermore, the specificities of GON-AN and GON-AN-FA were evaluated with two kinds of cancer cells which overexpress folate receptor alpha (FRα). The results reinforce that the autofluorescent GON-AN-FA is able to target cancer cells via recognition of the ligand FA and the receptor FRα. Therefore, our autofluorescent GON-AN-FA possessing a large longitudinal relaxivity and good biocompatibility represents a significant advance for the targeted imaging and early diagnosis of cancer.

A novel Trojan-horse targeting strategy to reduce the non-specific uptake of nanocarriers by non-cancerous cells

One big challenge with active targeting of nanocarriers is non-specific binding between targeting molecules and non-target moieties expressed on non-cancerous cells, which leads to non-specific uptake of nanocarriers by non-cancerous cells. Here, we propose a novel Trojan-horse targeting strategy to hide or expose the targeting molecules of nanocarriers on-demand. The non-specific uptake by non-cancerous cells can be reduced because the targeting molecules are hidden in hydrophilic polymers. The nanocarriers are still actively targetable to cancer cells because the targeting molecules can be exposed on-demand at tumor regions. Typically, Fe3O4 nanocrystals (FN) as magnetic resonance imaging (MRI) contrast agents were encapsulated into albumin nanoparticles (AN), and then folic acid (FA) and pH-sensitive polymers (PP) were grafted onto the surface of AN-FN to construct PP-FA-AN-FN nanoparticles. Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), transmission electron microscope (TEM) and gel permeation chromatography (GPC) results confirm successful construction of PP-FA-AN-FN. According to difference of nanoparticle-cellular uptake between pH 7.4 and 5.5, the weight ratio of conjugated PP to nanoparticle FA-AN-FN (i.e. graft density) and the molecular weight of PP (i.e. graft length) are optimized to be 1.32 and 5.7xa0kDa, respectively. Inxa0vitro studies confirm that the PP can hide ligand FA to prevent it from binding to cells with FRα at pH 7.4 and shrink to expose FA at pH 5.5. Inxa0vivo studies demonstrate that our Trojan-horse targeting strategy can reduce the non-specific uptake of the PP-FA-AN-FN by non-cancerous cells. Therefore, our PP-FA-AN-FN might be used as an accurately targeted MRI contrast agent.

Multifunctional Theranostic Nanoparticles Based on Exceedingly Small Magnetic Iron Oxide Nanoparticles for T1-Weighted Magnetic Resonance Imaging and Chemotherapy

The recently emerged exceedingly small magnetic iron oxide nanoparticles (ES-MIONs) (<5 nm) are promising T1-weighted contrast agents for magnetic resonance imaging (MRI) due to their good biocompatibility compared with Gd-chelates. However, the best particle size of ES-MIONs for T1 imaging is still unknown because the synthesis of ES-MIONs with precise size control to clarify the relationship between the r1 (or r2/r1) and the particle size remains a challenge. In this study, we synthesized ES-MIONs with seven different sizes below 5 nm and found that 3.6 nm is the best particle size for ES-MIONs to be utilized as T1-weighted MR contrast agent. To enhance tumor targetability of theranostic nanoparticles and reduce the nonspecific uptake of nanoparticles by normal healthy cells, we constructed a drug delivery system based on the 3.6 nm ES-MIONs for T1-weighted tumor imaging and chemotherapy. The laser scanning confocal microscopy (LSCM) and flow cytometry analysis results demonstrate that our strategy of precise targeting via exposure or hiding of the targeting ligand RGD2 on demand is feasible. The MR imaging and chemotherapy results on the cancer cells and tumor-bearing mice reinforce that our DOX@ES-MION3@RGD2@mPEG3 nanoparticles are promising for high-resolution T1-weighted MR imaging and precise chemotherapy of tumors.

Neuropeptide Y Y1 receptors meditate targeted delivery of anticancer drug with encapsulated nanoparticles to breast cancer cells with high selectivity and its potential for breast cancer therapy.

By enabling nanoparticle-based drug delivery system to actively target cancer cells with high selectivity, active targeted molecules have attracted great attention in the application of nanoparticles for anticancer drug delivery. However, the clinical application of most active targeted molecules in breast cancer therapy is limited, due to the low expression of their receptors in breast tumors or coexpression in the normal and tumor breast tissues. Here, a neuropeptide Y Y1 receptors ligand PNBL-NPY, as a novel targeted molecule, is conjugated with anticancer drug doxorubicin encapsulating albumin nanoparticles to investigate the effect of Y1 receptors on the delivery of drug-loaded nanoparticles to breast cancer cells and its potential for breast cancer therapy. The PNBL-NPY can actively recognize and bind to the Y1 receptors that are significantly overexpressed on the surface of the breast cancer cells, and the drug-loaded nanoparticles are delivered directly into the cancer cells through internalization. This system is highly selective and able to distinguish the breast cancer cells from the normal cells, due to normal breast cells that express Y2 receptors only. It is anticipated that this study may provide a guidance in the development of Y1 receptor-based nanoparticulate drug delivery system for a safer and more efficient breast cancer therapy.

Improved double emulsion technology for fabricating autofluorescent microcapsules as novel ultrasonic/fluorescent dual-modality contrast agents

The aim of this study is to explore an improved double emulsion technology with in situ reaction of lysine (Lys) and glutaraldehyde (GA) for fabricating autofluorescent Lys-poly(lactic-co-glycolic acid)-GA (Lys-PLGA-GA) microcapsules as novel ultrasonic/fluorescent dual-modality contrast agents. Scanning electron microscope (SEM) and static light scattering (SLS) results show that 80% of the Lys-PLGA-GA microcapsules are larger than 1.0 μm and 90% of them are smaller than 8.9 μm. SEM and laser confocal scanning microscope (LCSM) data demonstrate that the structure of our Lys-PLGA-GA microcapsules is hollow. Compared with the FT-IR spectrum of PLGA microcapsules, a new peak at 1,644 cm(-1) in that of Lys-PLGA-GA microcapsules confirms the formed Schiff base in Lys-PLGA-GA microcapsules. LCSM images and fluorescence spectra show that our Lys-PLGA-GA microcapsules exhibit bright and stable autofluorescence without conjugation to any fluorescent agent, which can be ascribed to the n-π transitions of the CN bonds in the formed Schiff base. Our autofluorescent Lys-PLGA-GA microcapsules might have more wide applications than traditional fluorescent dyes because their excitation and emission spectra are both broad. The fluorescence intensity can also be tuned by the feeding amount of Lys and GA. The MTT assays reveal that the autofluorescent microcapsules are biocompatible. The results of fluorescent imaging in cells and in vitro ultrasonic imaging demonstrate the feasibility of our autofluorescent Lys-PLGA-GA microcapsules as ultrasonic/fluorescent dual-modality contrast agents. This novel ultrasonic/fluorescent dual-modality contrast agent might have potential for a variety of biological and medical applications.