Polymer- and Hybrid-Based Biomaterials for Interstitial, Connective, Vascular, Nerve, Visceral and Musculoskeletal Tissue Engineering

In this review, materials based on polymers and hybrids possessing both organic and inorganic contents for repairing or facilitating cell growth in tissue engineering are discussed. Pure polymer based biomaterials are predominantly used to target soft tissues. Stipulated by possibilities of tuning the composition and concentration of their inorganic content, hybrid materials allow to mimic properties of various types of harder tissues. That leads to the concept of “one-matches-all” referring to materials possessing the same polymeric base, but different inorganic content to enable tissue growth and repair, proliferation of cells, and the formation of the ECM (extra cellular matrix). Furthermore, adding drug delivery carriers to coatings and scaffolds designed with such materials brings additional functionality by encapsulating active molecules, antibacterial agents, and growth factors. We discuss here materials and methods of their assembly from a general perspective together with their applications in various tissue engineering sub-areas: interstitial, connective, vascular, nervous, visceral and musculoskeletal tissues. The overall aims of this review are two-fold: (a) to describe the needs and opportunities in the field of bio-medicine, which should be useful for material scientists, and (b) to present capabilities and resources available in the area of materials, which should be of interest for biologists and medical doctors.</jats:p

Colloids-at-surfaces : physicochemical approaches for facilitating cell adhesion on hybrid hydrogels

Implementation of an effective focal cell adhesion represents a significant challenge because it requires to develop appropriate materials and processes together with assuring that cells would interact with it effectively. Various coatings are under development in the area of biomaterials including hydrogels and polymeric surfaces. Here, we analyse modification of the coatings by colloidal nano- and micro-particles, which effectively modify the surface of soft hydrogel materials, enhance and allow for adjustment of mechanical properties, and enable molecule release capabilities. A classification of such hybrid coatings is presented, where natural and synthetic polymeric coatings are overviewed. These organic coatings are modified by inorganic micro- and nano- particles. Various approaches to the design of such hybrid coatings are overviewed, while additional functionalities such as release of encapsulated biomolecules and enhancement of mechanical properties are highlighted. The developments in this area target effective cell growth, which is shown to be enhanced by the addition of colloidal particles

Polycaprolactone-based, porous CaCO3 and Ag nanoparticle modified scaffolds as a SERS platform with molecule-specific adsorption

Surface-enhanced Raman scattering (SERS) is a high-performance technique allowing detection of extremely low concentrations of analytes. For such applications, fibrous polymeric matrices decorated with plasmonic metal nanostructures can be used as flexible SERS substrates for analysis of analytes in many application. In this study, a three-dimensional SERS substrate consisting of a CaCO3-mineralized electrospun (ES) polycaprolactone (PCL) fibrous matrix decorated with silver (Ag) nanoparticles is developed. Such modification of the fibrous substrate allows achieving a significant increase of the SERS signal amplification. Functionalization of fibers by porous CaCO3 (vaterite) and Ag nanoparticles provides an effective approach of selective adsorption of biomolecules and their precise detection by SERS. This new SERS substrate represents a promising biosensor platform with selectivity to low and high molecular weight molecules

Classification of analytics, sensorics, and bioanalytics with polyelectrolyte multilayer capsules

Polyelectrolyte multilayer (PEM) capsules, constructed by LbL (layer-by-layer)-adsorbing polymers on sacrificial templates, have become important carriers due to multifunctionality of materials adsorbed on their surface or encapsulated into their interior. They have been also been used broadly used as analytical tools. Chronologically and traditionally, chemical analytics has been developed first, which has long been synonymous with all analytics. But it is not the only development. To the best of our knowledge, a summary of all advances including their classification is not available to date. Here, we classify analytics, sensorics, and biosensorics functionalities implemented with polyelectrolyte multilayer capsules and coated particles according to the respective stimuli and application areas. In this classification, three distinct categories are identified: (I) chemical analytics (pH; K+, Na+, and Pb2+ ion; oxygen; and hydrogen peroxide sensors and chemical sensing with surface-enhanced Raman scattering (SERS)); (II) physical sensorics (temperature, mechanical properties and forces, and osmotic pressure); and (III) biosensorics and bioanalytics (fluorescence, glucose, urea, and protease biosensing and theranostics). In addition to this classification, we discuss also principles of detection using the above-mentioned stimuli. These application areas are expected to grow further, but the classification provided here should help (a) to realize the wealth of already available analytical and bioanalytical tools developed with capsules using inputs of chemical, physical, and biological stimuli and (b) to position future developments in their respective fields according to employed stimuli and application areas

Dependence of sub-micron vaterite container release properties on pH and ionic strength of the surrounding solution

We report on the synthesis and characterization of porous monodisperse vaterite containers with controllable average sizes from 400 nm to 10 mu m. Possible release strategies of enclosed substances via recrystallization or by pH-change are presented. As a model experiment, a fluorescent marker was encapsulated and imaged by two-photon microscopy to monitor the dye release. The release process was found to be controllable via the immersion medium's properties. Release times can be further tuned by covering the containers with additional polymer layers, creating a flexible system with promising perspectives for pharmaceutical applications

Polypyrrole Microcontainers: Electrochemical Synthesis and Characterization

We present electrochemically controlled synthesis of polypyrrole microcontainers on electrogenerated hydrogen gas bubbles acting as a template. We performed structural characterization of the obtained microcontainers to gain insight into the growth kinetics of the polypyrrole shell. Experimental results showed that surfactant-mediated polymerization of pyrrole at the hydrogen microbubble surface under controlled electrochemical biasing led to the synthesis of various micro/nanostructures. Dependent upon the electrochemical conditions, such as the number of redox cycles and scan rate, the containers with spherical globules and bowl-like structures, which become lantern-like with increasing the number of cycles, are formed, as revealed by scanning electron microscopy. Their diameter can range between 40 and 200 mu m, and wall thickness can be varied from 2 to 70 mu m, depending upon the electropolymerization conditions

Identification and analysis of key parameters for the ossification on particle functionalized composites hydrogel materials

Developing materials for tissue engineering and studying the mechanisms of cell adhesion is a complex and multifactor process that needs analysis using physical chemistry and biology. The major challenge is the labor-intensive data mining as well as requirements of the number of advanced techniques. For example, hydrogel-based biomaterials with cell-binding sites, tunable mechanical properties and complex architectures have emerged as a powerful tool to control cell adhesion and proliferation for tissue engineering. Composite hydrogels could be used for bone tissue regeneration, but they exhibit poor ossification properties. In current work, we have designed new osteoinductive gellan gum hydrogels by a thermal annealing approach and consequently functionalized them with Ca/Mg carbonates submicron particles. Determination of key parameters, which influence a successful hydroxyapatite generation, were done via the principal component analysis of 18 parameters (Young’s modulus of the hydrogel and particles, particles size and mass) and cell behaviour at various time points (like viability, numbers of the cells, rate of alkaline phosphatase production and cells area) obtained by characterizing such composite hydrogel. It is determined that the particles size and concentration of calcium ions have a dominant effect on the hydroxyapatite formation, because of providing local areas with a high Young’s modulus in a hydrogel – a desirable property for cell adhesion. The presented here detailed analysis allows identifying hydrogels for cell growth applications, while on the other hand, material properties can be predicted, and their overall number can be minimized leading to efficient optimization of bone reconstruction and other cell growth applications

Magnetic and silver nanoparticle functionalized calcium carbonate particles : dual functionality of versatile, movable delivery carriers which can surface-enhance Raman signals

Multifunctional probes play an increasing role even beyond applications in biomedicine. Multifunctionality introduced by the dual types of complementary probes is always attractive because, in this case, functionalized objects inherit the function of both materials. Porous calcium carbonate microparticles are becoming popular carriers of biomolecules and biosensors, as well as imaging enhancers. We demonstrate here a dual function of these carriers by incorporating both magnetic and silver nanoparticles. Magnetic nanoparticles enable movements and displacements by a magnetic field, while silver nanoparticles provide surface-enhanced Raman signal amplification necessary for the detection of biomolecules. Application of such dual-functional carriers is foreseen beyond the applications of biomedicine and theranostics

Polymeric and lipid membranes : from spheres to flat membranes and vice versa

Membranes are important components in a number of systems, where separation and control of the flow of molecules is desirable. Controllable membranes represent an even more coveted and desirable entity and their development is considered to be the next step of development. Typically, membranes are considered on flat surfaces, but spherical capsules possess a perfect infinite or fully suspended membranes. Similarities and transitions between spherical and flat membranes are discussed, while applications of membranes are also emphasized

Biocompatible chitosan nanofibers functionalized with silver nanoparticles for SERS based detection

Electrospun chitosan nanofibrous substrates are functionalized with silver nanoparticles by reduction of silver from Tollens reagent using glucose. Filling factor is estimated through developed protocol by using analysis of scanning electron microscopy images. Obtained nanocomposite silver-chitosan plasmonic films display reliable surface enhanced Raman scattering signal of rhodamine B with the concentration 10(-5) M adsorbed onto the surface of functionalized substrates