This study reports the structural transition of electrospun poly(ε‐caprolactone) (PCL)/poly[(propylmethacryl‐heptaisobutyl‐polyhedral oligomeric silsesquioxane)‐co‐(methyl methacrylate)] (POSS‐MMA) blends, from PCL‐rich fibers, to bicontinuous PCL core/POSS‐MMA shell fibers, to POSS‐MMA‐rich fibers with a discontinuous PCL inner phase. A ternary phase diagram depicting the electrospinnability of PCL/POSS‐MMA solutions is constructed by evaluating the morphological features of fibers electrospun from solutions with various concentrations and PCL/POSS‐MMA blend ratios. X‐ray diffraction, Raman spectroscopy, and differential scanning calorimetry are further used to characterize the electrospun PCL/POSS‐MMA hybrid fibers. These physicochemical characterization results are thoroughly discussed to understand the internal structures of the hybrid fibers, which are directly correlated to the phase separation behavior of the electrospun solutions. The current study provides further insight into the complex phase behavior of POSS‐copolymer‐based systems, which hold great potential for a broad spectrum of biomedical applications.
The aim of this study is to design a polymeric nanogel system with tailorable degradation behavior. To this end, hydroxyethyl methacrylate‐oligoglycolates‐derivatized poly(hydroxypropyl methacrylamide) (pHPMAm‐Gly‐HEMA) and hydroxyethyl methacrylamide‐oligoglycolates‐derivatized poly(hydroxyethyl methacrylamide) (pHEMAm‐Gly‐HEMAm) are synthesized and characterized. pHEMAm‐Gly‐HEMAm shows faster hydrolysis rates of both carbonate and glycolate esters than the same ester groups of pHPMAm‐Gly‐HEMA. pHEMAm‐Gly‐HEMAm nanogels have tailorable degradation kinetics from 24 h to more than 4 d by varying their crosslink densities. It is shown that the release of a loaded macromolecular model drug is controlled by degradation of nanogels. The nanogels show similar cytocompatibility as PLGA nanoparticles and are therefore considered to be attractive systems for drug delivery.
The actinomycetes, Gram‐positive filamentous bacteria, are the most prolific source of natural occurring antibiotics. At an industrial level, antibiotics from actinomycete strains are produced by means of submerged fermentations, where one of the major factors negatively affecting bioproductivity is the pellet‐shaped biomass growth. The immobilization of microorganisms on properly chosen supports prevents cell–cell aggregation resulting in improving the biosynthetic capability. Thus, novel porous biopolymer‐based devices are developed by combining melt mixing and particulate leaching. In particular, polycaprolactone (PCL), polyethylene glycol (PEG), and sodium chloride (NaCl) with different grain sizes are used to prepare PCL/PEG/NaCl blends in the melt. These blends are then leached to obtain PCL‐based porous membranes that are used as solid support for the growth of Streptomyces coelicolor, a model streptomycete used to produce various antibiotics including the blue colored actinorhodin (ACT). Thereafter, the effect of the devices' characteristics on the bacterial growth and on the production ACT is evaluated. The results showed that ACT production is strongly dependent on the pore size distribution of the device. Moreover, membranes with pores ranging from 90 to 110 μm are able to offer a potential improvement in volumetric productivity of ACT if compared to conventional submerged liquid culture.
Complementary nucleobase‐functionalized polymeric micelles, a combination of adenine‐thymine (A‐U) base pairs and a blend of hydrophilic–hydrophobic polymer pairs, can be used to construct 3D supramolecular polymer networks; these micelles exhibit excellent self‐assembly ability in aqueous solution, rapid pH‐responsiveness, high drug loading capacity, and triggerable drug release. In this study, a multi‐uracil functionalized poly(ε‐caprolactone) (U‐PCL) and adenine end‐capped difunctional oligomeric poly(ethylene glycol) (BA‐PEG) are successfully developed and show high affinity and specific recognition in solution owing to dynamically reversible A‐U‐induced formation of physical cross‐links. The U‐PCL/BA‐PEG blend system produces supramolecular micelles that can be readily adjusted to provide the desired critical micellization concentration, particle size, and stability. Importantly, in vitro release studies show that doxorubicin (DOX)‐loaded micelles exhibit excellent DOX‐encapsulated stability under physiological conditions. When the pH value of the solution is reduced from 7.4 to 5.0, DOX‐loaded micelles can be rapidly triggered to release encapsulated DOX, suggesting these polymeric micelles represent promising candidate pH‐responsive nanocarriers for controlled‐release drug delivery and pharmaceutical applications.
In this study, a three layered poly (ε‐caprolactone) (PCL) graft (tPCL) was fabricated by electrospinning PCL and electrospraying poly (ethylene oxide) (PEO), which has a thin dense inner layer, a loose middle layer, and a dense outer layer. Regular PCL grafts (rPCL) with only a dense layer were used as control. In vivo evaluation was performed in rabbit carotid artery. Enhanced cell infiltration, rapid regeneration of endothelium and smooth muscle layers, and increased elastin deposition were observed within the tPCL graft wall. After 3 months, tPCL grafts showed faster PCL degradation than the rPCL grafts. Infiltrated macrophages in the tPCL grafts secreted higher level of monocyte chemoattractant protein‐1 (MCP‐1) and vascular endothelial growth factor (VEGF) which enhanced vascular regeneration. In conclusion, the tPCL graft may be a useful vascular prosthesis and worth for further investigation.
Cell‐free approaches to in situ tissue engineering require materials that are mechanically stable and are able to control cell‐adhesive behavior upon implantation. Here, the development of mechanically stable grafts with non‐cell adhesive properties via a mix‐and‐match approach using ureido‐pyrimidinone (UPy)‐modified supramolecular polymers is reported. Cell adhesion is prevented in vitro through mixing of end‐functionalized or chain‐extended UPy‐polycaprolactone (UPy‐PCL or CE‐UPy‐PCL, respectively) with end‐functionalized UPy‐poly(ethylene glycol) (UPy‐PEG) at a ratio of 90:10. Further characterization reveals intimate mixing behavior of UPy‐PCL with UPy‐PEG, but poor mechanical properties, whereas CE‐UPy‐PCL scaffolds are mechanically stable. As a proof‐of‐concept for the use of non‐cell adhesive supramolecular materials in vivo, electrospun vascular scaffolds are applied in an aortic interposition rat model, showing reduced cell infiltration in the presence of only 10% of UPy‐PEG. Together, these results provide the first steps toward advanced supramolecular biomaterials for in situ vascular tissue engineering with control over selective cell capturing.
A visible light and pH responsive anticancer drug delivery system based on polymer‐coated mesoporous silica nanoparticles (MSNs) has been developed. Perylene‐functionalized poly(dimethylaminoethyl methacrylates) sensitive to visible light and pH are electrostatically attached on the surface of MSNs to seal the nanopores. Stimulation of visible light and acid can unseal the nanopores to induce controlled drug release from the MSNs. More interestingly, the release can be enhanced under the combined stimulation of the dual‐stimuli. The synergistic effect of visible light and acid stimulation on the efficient release of anticancer drugs from the nanohybrids endows the system with great potential for cancer therapy.
Biosensing is an important and rapidly developing field, with numerous potential applications in health care, food processing, and environmental control. Polymer–graphene nanocomposites aim to leverage the unique, attractive properties of graphene by combining them with those of a polymer matrix. Molecular imprinted polymers, in particular, offer the promise of artificial biorecognition elements. A variety of polymers, including intrinsically conducting polymers (polyaniline, polypyrrole), bio‐based polymers (chitosan, polycatechols), and polycationic polymers (poly(diallyldimethylammonium chloride), polyethyleneimine), have been utilized as matrices for graphene‐based nanofillers, yielding sensitive biosensors for various biomolecules, such as proteins, nucleic acids, and small molecules.
Reactive oxygen species (ROS) play important roles in cell signaling pathways, while increased production of ROS may disrupt cellular homeostasis, giving rise to oxidative stress and a series of diseases. Utilizing these cell‐generated species as triggers for selective tuning polymer structures and properties represents a promising methodology for disease diagnosis and treatment. Recently, significant progress has been made in fabricating biomaterials including nanoparticles and macroscopic networks to interact with this dynamic physiological condition. These ROS‐responsive platforms have shown potential in a range of biomedical applications, such as cancer targeted drug delivery systems, cell therapy platforms for inflammation related disease, and so on.
Although biodegradable amphiphilic block copolymer micelles have been widely applied in the clinical applications as drug delivery nanocarriers, low‐efficiency cellular internalization frequently reduces therapeutic efficacy of the loaded drugs. Here, photothermal effect‐promoted cellular internalization of finely tuned thermo‐responsive amphiphilic biodegradable block copolymer nanocarriers via noninvasive stimuli of near‐infrared (NIR) light irradiation is demonstrated. Amphiphilic block copolymers, poly(ε‐caprolactone)‐block‐poly(N‐isopropylacrylamide‐co‐N,N‐dimethylacrylamide) (PCL‐b‐P(NIPAM‐co‐DMA)), are prepared with finely tuned compositions of P(NIPAM‐co‐DMA) for desirable lower critical solution temperature of the block copolymer micelles in aqueous solution. The block copolymers are then used to co‐encapsulate doxorubicin and indocyanine green, which show high encapsulation efficiency and significant photothermal effect upon exposure to NIR light irradiation. The photothermal effect‐induced collapse and hydrophilic‐to‐hydrophobic transition of P(NIPAM‐co‐DMA) shells significantly enhance the interactions between drug‐loaded micelles and cell membranes, which dramatically promote the cellular internalization of the micelles and therapeutic efficacy of loaded anticancer drugs.
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