A facile self-assembly method is described to prepare PEGylated silica nanocarriers using hydrophobic mesoporous silica nanoparticles and a pluronic F127 polymer. Pluronic capped nanocarriers revealed excellent dispersibility in biological media with cyto-and blood compatibilities.The high surface area and pore volume, good chemical stability and ease of surface functionalization of mesoporous silica nanoparticles (MSNs) make them promising materials for biological applications as drug carriers and theranostic agents.1,2 In addition silica based materials are generally accepted as biocompatible materials by the U.S. Food and Drug Administration (FDA). However, recent studies demonstrated their potential in vitro and in vivo toxicity, especially when their size is reduced to the nano scale. 3,4 Although the toxicity of silica based nanomaterials depends on several factors including particle size, shape, surface chemistry and porosity, [5][6][7] there is a general consensus that chemical structure of the surface is the predominant factor which determines the interactions with biological systems. 8 The surface of bare silica is covered with negatively charged silanol groups, which can electrostatically interact with positively charged tetraalkylammonium moieties of the cell membrane and can lead to cytotoxicity by membranolysis or inhibition of cellular respiration. 8,9 Also, rapid aggregation of silica based nanoparticles in biological media can result in mechanical obstruction in the capillary vessels of several vital organs, leading to organ failure and even death. 10,11 Therefore, replacing the surface silanol groups with biocompatible molecules is essential to improve the biocompatibility of MSNs. Among numerous polymeric or organosilane surface modification ligands, polyethylene glycol (PEG) is the mostly used one due to its well established biocompatibility, hydrophilicity, and antifouling properties.12 However, the PEGylation process has some limitations;(i) it mostly requires tedious organic synthesis and surface modification 13 and (ii) pores of MSNs may be closed by the long PEG polymer chains, which can hinder the drug loading process. To overcome these limitations, here we report a facile self-assembly method using octyl modified hydrophobic MSNs and an amphiphilic block copolymer (F127). F127, a FDA approved biocompatible pluronic polymer, contains two hydrophilic PEG blocks and a hydrophobic polypropylene oxide (PPO) between the two PEG blocks. 14 When the powder of hydrophobic MSNs is added into the F127 solution they are easily transferred into water by selfassembly of F127 molecules onto the MSN surface through the hydrophobic interaction between the PPO block of F127 and surface octyl groups of the MSNs (Scheme 1). In addition, cargo loaded and PEGylated MSNs can be simply prepared by loading the hydrophobic MSNs before the F127 capping process. The F127 capped particles are dispersible in both water and phosphate buffered saline (PBS), whereas uncapped MSNs are easily aggregated and precipitated...
Toncelli, C. (2019). Mussel-inspired injectable hydrogel adhesive formed under mild conditions features near-native tissue properties. ACS Applied Materials and Interfaces.
3D human skin models provide a platform for toxicity testing, biomaterials evaluation, and investigation of fundamental biological processes. However, the majority of current in vitro models lack an inflammatory system, vasculature, and other characteristics of native skin, indicating scope for more physiologically complex models. Looking at the immune system, there are a variety of cells that could be integrated to create novel skin models, but to do this effectively it is also necessary to understand the interface between skin biology and tissue engineering as well as the different roles the immune system plays in specific health and disease states. Here, a progress report on skin immunity and current immunocompetent skin models with a focus on construction methods is presented; scaffold and cell choice as well as the requirements of physiologically relevant models are elaborated. The wide range of technological and fundamental challenges that need to be addressed to successfully generate immunocompetent skin models and the steps currently being made globally by researchers as they develop new models are explored. Induced pluripotent stem cells, microfluidic platforms to control the model environment, and new real-time monitoring techniques capable of probing biochemical processes within the models are discussed.
The rational design of alternative antimicrobial materials with reduced toxicity toward mammalian cells is highly desired due to the growing occurrence of bacteria resistant to conventional antibiotics. A promising approach is the design of lipid-based antimicrobial nanocarriers. However, most of the commonly used polymer-stabilized nanocarriers are cytotoxic. Herein, the design of a novel, stabilizer-free nanocarrier for the human cathelicidin derived antimicrobial peptide LL-37 that is cytocompatible and promotes cell proliferation for improved wound healing is reported. The nanocarrier is formed through the spontaneous integration of LL-37 into novel, stabilizer-free glycerol monooleate (GMO)-based cubosomes. Transformations in the internal structure of the cubosomes from Pn3m to Im3m-type and eventually their transition into small vesicles and spherical micelles are demonstrated upon the encapsulation of LL-37 into their internal bicontinuous cubic structure using small angle X-ray scattering, cryogenic transmission electron microscopy, and light scattering techniques. Additional in vitro biological assays show the antimicrobial activity of the stabilizer-free nano-objects on a variety of bacteria strains, their cytocompatibility, and cell-proliferation enhancing effect. The results outline a promising strategy for the comprehensive design of antimicrobial, cytocompatible lipid nanocarriers for the protection and delivery of bioactive molecules with potential for application as advanced wound healing materials.
Biofouling on silicone implants causes serious complications such as fibrotic encapsulation, bacterial infection, and implant failure. Here we report the development of antifouling, antibacterial silicones through covalent grafting with a cell-membrane-inspired zwitterionic gel layer composed of 2-methacryolyl phosphorylcholine (MPC). To investigate how substrate properties influence cell adhesion, we cultured human-blood-derived macrophages and Escherichia coli on poly(dimethylsiloxane) (PDMS) and MPC gel surfaces with a range of 0.5-50 kPa in stiffness. Cells attach to glass, tissue culture polystyrene, and PDMS surfaces, but they fail to form stable adhesions on MPC gel surfaces due to their superhydrophilicity and resistance to biofouling. Cytokine secretion assays confirm that MPC gels have a much lower potential to trigger proinflammatory macrophage activation than PDMS. Finally, modification of the PDMS surface with a long-term stable hydrogel layer was achieved by the surface-initiated atom-transfer radical polymerization (SI-ATRP) of MPC and confirmed by the decrease in contact angle from 110 to 20° and the >70% decrease in the attachment of macrophages and bacteria. This study provides new insights into the design of antifouling and antibacterial interfaces to improve the long-term biocompatibility of medical implants.
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