ABSTRACT
The conformal nature of in situ polymerization of adhesive dopamine molecules permits the strong underwater adhesion between polydopamine (PDA) nanomembranes and the target substrates. However, the adhesive interaction between the postdeposit PDA nanomembranes and other macrobodies is strongly influenced by the texture of PDA nanomembranes. Here we report the texture-dependent adhesion of PDA nanomembranes both in air and aqueous environments. Despite the nanometer-scale roughness of PDA nanomembranes, interfacial adhesion between PDA nanomembranes and elastomeric bodies are the strong function of the root-mean-square roughness of PDA nanomembranes, root-mean-square gradient of PDA nanomembranes, and the elasticity of the bulk materials. Reduced adhesion due to increased texture is intensified in hydrated conditions, possibly hinting that the conventional explanation of the negative effect of water to adhesion from a molecular level needs to be revisited. These findings can inform the role of adhesive interaction in conformal coatings and provide an explanation for the differential adhesion observed in freestanding PDA nanomembranes.
Subject(s)
Indoles/chemistry , Polymers/chemistry , Adhesives , Nanostructures , PolymerizationABSTRACT
Polydopamine is a versatile and organic material that can be deposited as a conformal film with nanometer thickness on virtually any substrate. Much of the initial foundational work regarding polydopamine synthesis and processing was reported during the 2000s. Latter years have witnessed increasing interest and widespread adoption of polydopamine as a material for many applications including medicine. Conformal polydopamine coatings confer unique chemical and physical properties to many substrate materials including metals, ceramics, polymers, and beyond. Polydopamine-modified surfaces permit facile bioconjugation of many biomedical materials for potential use as bioadhesives, contrast agents, drug delivery systems, and protein-adsorption resistant interfaces. Polydopamine-based materials and interfaces may improve the performance of biomedical devices used in neurotechnology, diagnostics, and cardiovascular applications. This highlight article reviews recent advances in polydopamine processing capabilities. The use of polydopamine as a material in various biomedical applications is also discussed. Finally, challenges and opportunites in translating polydopamine for future biomedical technologies are summarized.
ABSTRACT
The properties of redox active polydopamine melanin (PDM) films as a coating material for neural electrodes were evaluated. PDM films with nanometer-scale thicknesses exhibit dc bias dependent charge injection capacities (CIC) with maximum values of 110 ± 23 µC cm-2 at 0.2V (vs Ag/AgCl) and reduce the interfacial impedance compared to inorganic conducting films. PDM films exhibited an asymmetric impedance response to positive and negative dc biases with minimum interfacial impedance at 0.2V (vs Ag/AgCl). An explanation for the observed bias-dependent electrochemical behavior is presented.
ABSTRACT
PURPOSE: The precise role of laparoscopic liver resection in liver malignancies remains controversial despite an increasing number of publications that have used the laparoscopic resection of benign liver tumors. This study was performed to assess the feasibility, safety, and outcome of laparoscopic liver resection for malignant liver tumors. METHODS: This study is a retrospective review of the profiles, pathology, surgery and outcome performed on 61 patients who had undergone laparoscopic liver resection for liver malignancies between January 2004 and March 2011. RESULTS: Among the 61 patients, 34 patients had hepatocellular carcinoma (HCC), 24 patients had liver metastasis. The mean tumor size was 2.8 ± 2.0 cm (mean ± standard deviation). Tumors located at Couinaud segment number 2 to 8. The resection included 36 anatomical resections, 25 wedge resections. The mean surgical time was 209.7 ± 108.9 minutes. There was one operation that resulted in death. Postoperative complications occurred in 9 patients (14%). There were 2 conversions to laparotomy (3%). The mean postoperative hospital stay was 9.0 ± 4.4 days. Blood transfusion was needed in 11 patients (18%). The mean surgical margin was 1.3 ± 1.2 cm. The mean follow-up period was 18.1 ± 11.1 months. The three-year overall survival rate was 87% for patients with HCC and 95% for patients having liver metastases from colorectal cancer. CONCLUSION: Even though laparoscopic liver resection requires a learning curve, it produced acceptable outcomes even in patients who had a malignant liver tumor. This study provides evidence to support further investigation and the establishment of laparoscopic liver resection for malignant liver tumors.
