Porous Prussian Blue Nanocubes as Photothermal Ablation Agents for Efficient Cancer Therapy.

Nanomaterial-based photothermal agents have attracted great attention as near-infrared laser driven ablation agents for tumor therapy. In this work, Prussian blue nanocubes with porous interior were synthesized via controlled chemical etching method and successfully applied for efficient photothermal ablation of tumor cells in vitro. Monodispersed porous Prussian blue nanocubes (115.4±4.7 nm) were produced through a controlled self-etching reaction in the presence of polyvinylpyrrolidone (PVP). Owing to the strong absorbance in near infrared (NIR) region, the resulted porous Prussian blue nanocubes could lead to more than 80% death of Hela cells after being treated with nanocubes of concentration as low as 100 µg mL−1. Compared to the traditional solid Prussian blue nanoparticles, these porous nanocubes can provide extra space for encapsulating anti-cancer drugs in their porous interior. It is anticipated that these porous Prussian blue nanocubes can be applied as an enabling platform to develop the next generation of multifunctional drug carrier for cancer treatments.

A concentration gradient generator on a paper-based microfluidic chip coupled with cell culture microarray for high-throughput drug screening.

Inspired by the paper platforms for 3-D cell culture, a paper-based microfluidic device containing drug concentration gradient was designed and constructed for investigating cell response to drugs based on high throughput analysis. This drug gradient generator was applied to generate concentration gradients of doxorubicin (DOX) as the model drug. HeLa cells encapsulated in collagen hydrogel were incubated in the device reservoirs to evaluate the cell viability based on the controlled release of DOX spatially. It was demonstrated that drug diffusion through the paper fibers created a gradient of drug concentration, which influenced cell viability. This drug screening platform has a great opportunity to be applied for drug discovery and diagnostic studies with simultaneous and parallel tests of drugs under various gradient concentrations.

Protein covalently conjugated SU-8 surface for the enhancement of mesenchymal stem cell adhesion and proliferation.

Cell growing behavior is significantly dependent on the surface chemistry of materials. SU-8 as an epoxy-based negative photoresist is commonly used for fabricating patterned layers in lab-on-a-chip devices. As a hydrophobic material, SU-8 substrate is not favorable for cell culture, and cell attachment on native SU-8 is limited attributed to poor surface biocompatibility. Although physical adsorption of proteins could enhance the cell adhesion, the effect is not durable. In this work, SU-8 surface chemistry is modified by immobilizing fibronectin (FN) and collagen type I (COL I) covalently using (3-aminopropyl)triethoxysilane (APTES) and cross-linker glutaraldehyde (GA) to increase surface biofunctionality. The effectiveness of this surface treatment to improve the adhesion and viability of mesenchymal stem cells (MSCs) is investigated. It is found that the wettability of SU-8 surface can be significantly increased by this chemical modification. In addition, the spreading area of MSCs increases on the SU-8 surfaces with covalently conjugated matrix proteins, as compared to other unmodified SU-8 surface or those coated with proteins simply by physical adsorption. Furthermore, cell proliferation is dramatically enhanced on the SU-8 surfaces modified under the proposed scheme. Therefore, SU-8 surface modification with covalently bound matrix proteins assisted by APTES+GA provides a highly biocompatible interface for the enhanced adhesion, spreading, and proliferation of MSCs.

Combined effects of multi-scale topographical cues on stable cell sheet formation and differentiation of mesenchymal stem cells.

To decipher specific cell responses to diverse and complex in vivo signals, it is essential to emulate specific surface chemicals, extra cellular matrix (ECM) components and topographical signals through reliable and easily reproducible in vitro systems. However, the effect of multiple cues such as micro-hole/pillar architectures under a common and easily tunable platform remains unexplored. Recently we have demonstrated the positive influence of surface chemical modification of polydimethylsiloxane (PDMS) surfaces on directing long-term adhesion, viability and potency of hMSCs. In this study, we include biophysical signals from diverse surface topographical elements along with biochemical influences to develop a holistic understanding of hMSC responses in complex tissue-like niches. We report the influence of chemically modified PDMS structures encompassing hole-, pillar- and groove-based multi-scale architectures on hMSC morphology, adhesion, proliferation and differentiation. The inclusion of hole and pillar features resulted in enhanced adhesion and proliferation of hMSCs. These effects were more pronounced with the inclusion of grooves, which resulted in the highest osteogenic differentiation among other substrates. Our study provides an additional basis for the chemical/physical regulation of hMSC behavior within controlled biomimetic architectures with an aim to foster efficient tissue regeneration strategies.

Functional magnetic Prussian blue nanoparticles for enhanced gene transfection and photothermal ablation of tumor cells.

Gene therapy has been developed as an innovative therapeutic modality in the past few decades for treatment of various fatal diseases such as cancer. However, the lack of gene carriers with reliable biosafety and loading capacity is still impeding the practical applications of gene therapy. Moreover, it has become a trend to combine multiple treatment strategies with gene therapy to achieve an enhanced curative effect. Herein, this study proposes the design of a multifunctional nanoplatform for gene delivery and photothermal therapy enhanced by magnetic targeting using functionalized magnetic Prussian blue nanoparticles. Surface modification of magnetic Prussian blue nanoparticles with chitosan and pDNA has been demonstrated to provide excellent colloidal stability and capacity for the magnetic targeting of HeLa cells. These nanocomposites exhibit superparamagnetism, which is remarkable and could potentiality lead to an improvement in their therapeutic effect under a localized magnetic field. The obtained nanoagent is able to generate a significant photothermal effect due to the strong optical absorbance in the near infrared region. Furthermore, superior gene transfection efficiency is achieved under magnetic guidance. In vitro experiments also reveal that this nanoagent has excellent biocompatibility for safe medical applications. This study can provide critical experimental evidence and encourage further investigation of combining photothermal therapy with gene therapy for treatment of various medical conditions.

Enhanced In Vitro Biocompatibility of Chemically Modified Poly(dimethylsiloxane) Surfaces for Stable Adhesion and Long-term Investigation of Brain Cerebral Cortex Cells.

Studies on the mammalian brain cerebral cortex have gained increasing importance due to the relevance of the region in controlling critical higher brain functions. Interactions between the cortical cells and surface extracellular matrix (ECM) proteins play a pivotal role in promoting stable cell adhesion, growth, and function. Poly(dimethylsiloxane) (PDMS) based platforms have been increasingly used for on-chip in vitro cellular system analysis. However, the inherent hydrophobicity of the PDMS surface has been unfavorable for any long-term cell system investigations due to transitory physical adsorption of ECM proteins on PDMS surfaces followed by eventual cell dislodgement due to poor anchorage and viability. To address this critical issue, we employed the (3-aminopropyl)triethoxysilane (APTES) based cross-linking strategy to stabilize ECM protein immobilization on PDMS. The efficiency of surface modification in supporting adhesion and long-term viability of neuronal and glial cells was analyzed. The chemically modified surfaces showed a relatively higher cell survival with an increased neurite length and neurite branching. These changes were understood in terms of an increase in surface hydrophilicity, protein stability, and cell-ECM protein interactions. The modification strategy could be successfully applied for stable cortical cell culture on the PDMS microchip for up to 3 weeks in vitro.

Synergistic effects of a novel free-standing reduced graphene oxide film and surface coating fibronectin on morphology, adhesion and proliferation of mesenchymal stem cells.

Graphene films have broad use in engineering, energy and biomedical applications. The cost-effective, eco-friendly and easy to scale-up fabrication methods of graphene films are always highly desired. In this work, we develop a novel fabrication method of free-standing reduced graphene oxide (RGO) films by vacuum filtration of graphene oxide aqueous solution through a nanofiber membrane in combination with chemical reduction. Instead of the smooth surface, the generated RGO films have nanoscale patterns transferred from the nanofiber membrane and controlled in a large range by varying the parameters of the electrospinning process. The cellular culture results of the human marrow mesenchymal stem cells (hMSCs) show that the fibronectin modified RGO films could exhibit excellent biocompatibility, which could be attributed to the synergistic effects of the RGO films including both surface morphology and fibronectin modification. The novel fabrication method greatly enhances the fabrication capability and the potential of graphene films for application in cell culture, tissue engineering as well as in other engineering and biomedical applications.

A multiplex RT-PCR assay for detection and differentiation of avian H3, H5, and H9 subtype influenza viruses and Newcastle disease viruses.

Avian influenza viruses (AIVs) and Newcastle disease viruses (NDVs) co-circulate in the poultry population in China. These viruses cause repeated disease outbreaks that exhibit similar clinical symptoms and epidemiological patterns. H5 and H9 influenza viruses are the major pathogens infecting poultry stocks. Recently, H3 AIV (one of the main subtypes in waterfowl) has become endemic in chickens. A multiplex reverse-transcriptase polymerase chain reaction (mRT-PCR) assay was designed for simultaneous detection and differentiation of avian H3, H5, H9 subtype AIVs and NDVs. Four primer sets were evaluated, three of which specifically targeted the hemagglutinin genes of H3, H5 and H9 AIVs, while the other targeted the NDV fusion gene. The sensitivity and specificity of the mRT-PCR assay was determined. The assay detected the major clades or genotypes of all of the reference AIVs and NDVs currently circulating in China. In addition, the mRT-PCR results obtained from screening 380 clinical swabs and 12 experimental tracheal samples were consistent with those obtained using conventional virus isolation methods. The mRT-PCR assay was established successfully for the detection and differentiation of avian H3, H5, and H9 subtype AIVs and NDVs. The method should, therefore, provide a valuable diagnostic tool for these infections.