Macrophages play a crucial role in initiating immune responses with various functions ranging from wound healing to antimicrobial actions. The type of biomaterial is suggested to influence macrophage phenotype. Here, we show that exposing M1- and M2-activated macrophages to polystyrene latex beads bearing different functional groups can alter secretion profiles, providing a possible method for altering the course of the host response. Macrophages were stimulated with either lipopolysaccharide or interleukin (IL) 4 and cultured for 24 h with 10 different latex beads. Proinflammatory cytokines (tumor necrosis factor α, monocyte chemotactic protein 1) and nitrite served as markers for the M1 phenotype and proangiogenic cytokine (IL-10) and arginase activity for M2 cells. The ability of the macrophages to phagocytize Escherichia coli particles and water contact angles of the polymers were also assessed. Different patterns of cytokine expression and phagocytosis activity were induced by the various particles. Particles did not polarize the cells toward one specific phenotype versus another, but rather induced changes in both pro- and anti-inflammatory markers. Our results suggest a dependence of pro- and anti-inflammatory cytokines and phagocytic activities on material type and cytokine stimuli. These data also illustrate how biomaterials can be exploited to alter host responses for drug delivery and tissue engineering applications.
Langmuir-Blodgett films of polyvinylidene fluoride trifluoroethylene - P(VDF-TrFE)-copolymers possess substantially improved electrocaloric and pyroelectric properties, when compared with conventionally spin-cast films. In order to rationalize this, we prepared single-layered films of P(VDF-TrFE) (70 : 30) using both deposition techniques. Grazing incidence wide-angle X-ray scattering (GIWAXS), reveals that Langmuir-Blodgett deposited films have a higher concentration of the ferroelectric β-phase crystals, and that these films are highly oriented with respect to the substrate. Based on these observations, we suggest alternative means of deposition, which may substantially enhance the electrocaloric effect in P(VDF-TrFE) films. This development has significant implications for the potential use of P(VDF-TrFE) in solid-state refrigeration.
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