Flexible superhydrophobic gold film for magnetical manipulation of droplets

Herein, we present a simple, efficient, and economical approach for the preparation of superhydrophobic gold film embedded on polydimethylsiloxane (PDMS) sheets without the requirement of surface pretreatment. The reduction reaction between chloroauric acid (HAuCl₄) and sodium formate (HCOONa) at room temperature was performed to generate the aggregated gold microstructures on a PDMS sheet without chemical residuals. Superhydrophobic property was achieved when deposition time was reached to 2 h with water contact angle >160° and low contact angle hysteresis (H = 1.93°). Systematic investigations of the size, morphology, and mechanism of the generated gold films are presented. The generated gold film contains two different layers involving uniform spherical gold particles attached to the PDMS surface with the complex hierarchical structures on top. The complex structures play an important role in the superhydrophobic property, as they strongly promote the roughness to the PDMS surface. The durability of the fabricated gold film was elucidated by dropping ~7,200 waterdrops and external physical forces (e.g. stretch, bend, and twist). The main structures and their superhydrophobic properties have not disoriented after the tests. Moreover, the surface of the gold film demonstrated the potential applications as magnetical manipulation of droplets and a robust Surface enhanced Raman spectroscopy (SERS substrate).     

Facile synthesis of magnetic silica-mannan nanocomposites for enhancement in internalization and immune response of dendritic cells

Superparamagnetic iron oxide nanoparticles (SPIONs) have been extensively exploited in biomedicine, especially as contrasting agents. In this work, SPIONs are of our interest as directing agents to the targeted dendritic cells (DCs). Mannan extracted from Saccharomyces cerevisiae was used as DCs targeting moieties. Herein, nanocomposites of silica magnetic nanoparticle-mannan (S-SPION-MN) were successfully synthesized as a magnetically assisted delivery system. The materials before Silica magnetic nanoparticles (S-SPION) and after mannan modification were characterized using a vibrating sample magnetometer to confirm their superparamagnetic character. The change in zeta potential from highly negative charge to slightly negative charge of the composites suggested the successful attachment of mannan on their surface. Chemical analysis using x-ray photoelectron spectroscopy revealed the attachment of mannan through chemical bonding, corresponding to the observation of high stability of the particles over a two-week period. The synthesized materials were investigated for cytotoxicity, DC maturation, cytokine production, and cellular uptake. Moderate cell viability was observed after stimulating cells with the particulate mannan, S-SPION-MN, due to high activation of DCs. Under a magnetic induction, S-SPION-MN showed significant enhancement of DCs targeting within 15 min. Owing to the incorporation of mannan and SPIONs, the S-SPION-MN greatly enhanced cellular uptake and accordingly resulted in high DC activation and maturation. The resulted nanocomposites can be beneficial as a potential candidate in antigen delivery to targeted immune cells for further in vivo study.     

Effective gene delivery into primary dendritic cells using synthesized PDMAEMA-iron oxide nanocubes

Dendritic cells (DCs) have been a target of vaccine delivery, gene therapy, and cancer immunotherapy. However, gene delivery to primary DCs using traditional non-viral molecules has been a difficult challenge. Herein we have developed a gene delivery system to primary DCs using magnetic iron oxide nanocubes (MCs) coated with cationic polymer under the induction of a magnetic field. The MCs were coated with positively charged polymer, poly(2-dimethylamino) ethyl methacrylate (MCs-PD) before the plasmid gene (pMAX-GFP) was adsorbed on their surfaces. Three different sizes (15, 40 and 90 nm) of MCs were synthesized, and subsequently, PDMAEMA was assembled onto the MC surfaces (MCs-PD). MCs-PD exhibited zeta potentials of +23 to +26 mV, and the obtained particles showed superparamagnetic character with saturation magnetization of 17–66 emu/g. The MCs-PD of 10–100 μg/mL showed low toxicity on bone marrow-derived dendritic cells (BMDCs) in MTT assay, and they were well taken up by BMDCs under a magnetic field. Moreover, the particles with small size exhibited the enhanced plasmid transfection efficiency without the activation of BMDCs. The MCs-PD could be a promising non-viral gene delivery system that helps to manipulate primary DCs in vitro, which will be beneficial for cell-based immunotherapy.