Metallosomes: artificial cell membranes with ultrathin metallic surfaces derived from cationic cerasomes through electroless plating

Abstract

Novel liposomal membranes having a metallic surface, so-called metallosomes, were prepared by electroless plating of cationic cerasomes, recently developed as organic-inorganic vesicular nanohybrids. The electroless plating of cerasomes was performed by firstly binding PdCl [2][3][4] ions onto the cationic membrane surface through electrostatic interactions, then subsequently reducing this precursor catalyst to Pd(0), and finally, depositing a layer of metal onto the cerasome surface using an appropriate plating bath. While metallosomes coated with an ultrathin Ni layer could be prepared by electroless Ni plating of cationic cerasomes, it was not possible to derive the corresponding Ni-coated vesicles from the liposomal membranes formed with cationic peptide lipids under similar plating conditions, thus reflecting the difference in the morphological stability of these vesicles. The characterization of the Ni-metallosomes was performed using various physical measurements such as scanning and transmission electron microscopies, energy-dispersive X-ray spectroscopy, electron energy-loss spectroscopy, and electron tomography. The Ni layer thickness was controllable on the nanometer scale by changing the plating time. The gel to liquid-crystalline phase transition behavior of the Ni-metallosomes was observed by differential scanning calorimetry, indicating that the metallosomes maintain their lipid bilayer membranes. Ni-metallosomes with various sizes were prepared from the corresponding cerasomes in a diameter range of 50-5000 nm. Metallosomes with an Au layer were also successfully obtained by electroless Ni/Au substitution plating of Ni-metallosomes.

Selective Electroless Metallization of Patterned Polymeric Films for Lithography Applications

“…We have adapted the TSI process for fabrication of patterned EL metal films useful as plasma-etch-resistant masks or electrical interconnects by using organosiloxane SAMs as ultrathin imaging layers for pattern definition (42,44,45). In our initial work, we have demonstrated the feasibility of the approach using simple nonligand phenylsiloxane SAMs patterned with deep-UV light at 193 expulsion of benzene as the sole photoproduct from the SAM during irradiation and the concomitant generation of silanol groups on the surface, respectively, consistent with a simple Si-C bond photocleavage mechanism (45,47). The exposure dose required to sufficiently clear the organofunctional group from the surface to permit selective Pd-Sn binding and EL plating is a critical process variable because it determines the efficiency and throughput of the entire manufacturing process.…”

“…Meanwhile, Bittner and co-workers have utilized PD1 for selective EL Co plating of μCP-patterned PAMAM amine dendrimer ligands on bare Si wafers and developed PD1 analogues capable of selectively plating the interior of a tobacco mosaic virus template, affording continuous EL Co or Ni nanowires having diameters as small as ∼3 nm , . The use of other colloidal PD1 derivatives, prepared via hydrolysis of palladium(II) salts in pH ∼2.5−7.0 aqueous solutions containing various amounts of added chloride ion, has also been reported for EL metallization of ZnO , lipid cerasome membrane , , chitosan − , aminosiloxane SAM−diamond , and aminosiloxane-modified or amine plasma-modified polyimide films.…”

Cerasomes: A New Family of Artificial Cell Membranes with Ceramic Surface

“…Novel liposomal membranes having a metallic surface, so called metallosomes, are prepared by electroless plating of cerasomes (Gu et al, 2008). The electroless plating of a cerasome formed with lipid (5) was performed by first binding palladium tetrachloride ions (PdCl 4 2-) onto the cationic membrane surface through electrostatic interactions, then subsequently reducing this precursor catalyst to Pd(0) and finally depositing a layer of metal onto the cerasome surface using an appropriate plating bath.…”