•New type of 3D printed polymeric scaffolds having macro- and microscale porosity.•Different blood clots attributable to interactions with the microscale pores and surface roughness.•Blood ...infiltration and clot stabilization a plausible mechanism of strong bone formation.
Blood clotting on implanted porous scaffolds has been suggested to be key to tissue regeneration. We recently reported a new type of 3D printed macroscale porous scaffolds with intra-strut microscale pores, that supported strong bone regeneration in vivo. Yet it remains unclear the effects of this microscale porosity on blood clots. Here, we studied the morphology of the blood clots at the interface with the scaffolds in vitro and analysed the scaffold-tissue interface in vivo. We then suggested a novel role of the scaffold’s microscale pores and surface roughness in supporting bone formation via their effects on blood infiltration and clotting.
Preventing bacterial colonization on scaffolds while supporting tissue formation is highly desirable in tissue engineering as bacterial infection remains a clinically significant risk to any ...implanted biomaterials. Elemental selenium (Se0) nanoparticles have emerged as a promising antimicrobial biomaterial without tissue cell toxicity, yet it remains unknown if their biological properties are from soluble Se ions or from direct cell–nanoparticle interactions. To answer this question, in this study, we developed a layered coating consisting of a Se nanoparticle layer underneath a micrometer-thick, biomimetic calcium phosphate (CaP) layer. We showed, for the first time, that the release of soluble HSe– ions from the Se nanoparticles strongly inhibited planktonic growth and biofilm formation of key bacteria, Staphylococcus aureus. The Se-CaP coating was found to support higher bone formation than the CaP-only coating in critical-size calvarial defects in rats; this finding could be directly attributed to the released soluble Se ions as the CaP layers in both groups had no detectable differences in the porous morphology, chemistry, and release of Ca or P. The Se-CaP coating was highly versatile and applicable to various surface chemistries as it formed through simple precipitation from aqueous solutions at room temperature and therefore could be promising in bone regeneration scaffolds or orthopedic implant applications.
Carbon nanotubes and carbon nanofibers have long been investigated for applications in composite structural materials, semiconductor devices, and sensors. With the recent well-documented ability to ...chemically modify nanofibrous carbon materials to improve their solubility and biocompatibility properties: a whole new class of bioactive carbon nanostructures has been created for biological applications. This review focuses on the latest applications of carbon nanofibers and carbon nanotubes in regenerative medicine.
Hydroxyapatite, the main inorganic material in natural bone, has been used widely for orthopaedic applications. Due to size effects and surface phenomena at the nanoscale, nanophase hydroxyapatite ...possesses unique properties compared to its bulk‐phase counterpart. The high surface‐to‐volume ratio, reactivities, and biomimetic morphologies make nano‐hydroxyapatite more favourable in applications such as orthopaedic implant coating or bone substitute filler. Recently, more efforts have been focused on the possibility of combining hydroxyapatite with other drugs and materials for multipurpose applications, such as antimicrobial treatments, osteoporosis treatments and magnetic manipulation. To build more effective nano‐hydroxyapatite and composite systems, the particle synthesis processes, chemistry, and toxicity have to be thoroughly investigated. In this Minireview, we report the recent advances in research regarding nano‐hydroxyapatite. Synthesis routes and a wide range of applications of hydroxyapatite nanoparticles will be discussed. The Minireview also addresses several challenges concerning the biosafety of the nanoparticles.
Biocompatible nanomaterials: Nano‐hydroxyapatite materials combine the benefits of nanosized particles with the main organic phase of bone, hydroxyapatite. The advantages of nano‐hydroxyapatite are biocompatibility, controlled delivery and capacity to couple with hydrophobic materials. This Minireview discusses the syntheses of nano‐hydroxyapatite materials and their applications in the fields of hard tissue repair, drug delivery, antibacterial treatments, magnetic delivery and gene therapy.
Bacterial biofilms are indicated in most medical device-associated infections. Treating these biofilms is challenging yet critically important for applications such as in device-retention surgeries, ...which can have reinfection rates of up to 80%. This in vitro study centered around our new method of treating biofilm and preventing reinfection. Ionic silver (Ag, in the form of silver nitrate) combined with dopamine and a biofilm-lysing enzyme (α-amylase) were applied to model 4-day-old Staphylococcus aureus biofilms on titanium substrates to degrade the extracellular matrix of the biofilm and kill the biofilm bacteria. In this process, the oxidative self-polymerization of dopamine converted Ag ions into Ag nanoparticles that, together with the resultant self-adhering polydopamine (PDA), formed coatings that strongly bound to the treated substrates. Surprisingly, although these Ag/PDA coatings significantly reduced S. aureus growth in standard bacterial monoculture, they showed much lower antimicrobial activity in coculture of the bacteria and osteoblastic MC3T3-E1 cells in which the bacteria were also found attached to the osteoblasts. This S. aureus– osteoblast interaction was also linked to bacterial survival against gentamicin treatment observed in coculture. Our study thus provided clear evidence suggesting that bacteria's interactions with tissue cells surrounding implants may significantly contribute to their resistance to antimicrobial treatment.
•A model surface repelled S. aureus and supported MC3T3-E1 osteoblastic cell adhesion.•S. aureus adhered to MC3T3-E1 when cocultured on this surface.•S. aureus in coculture were more resistant to ...gentamicin than in monoculture.•Antibacterial surface thus should actively kill bacteria.
There is significant interest in anti-infective biomaterials that have dual properties of promoting tissue integration and inhibiting bacterial adhesion to prevent device associated infection. However, it is also known that bacteria such as S. aureus have abundant surface pathogen-associated molecular patterns can readily interact with mammalian cells such as osteoblasts. Using tissue culture plastic, we found that S. aureus were electrostatically repelled from this surface and that when they were inoculated onto this surface pre-seeded with MC3T3-E1, they formed aggregates that adhered strongly to these osteoblastic cells. Importantly, the bacteria in the aggregates were more resistant to gentamicin compared to those in bacterial monoculture. This finding thus suggested that the bacteria repelled from such a surface might end up establishing biofilm-like community on adjacent mammalian cells or tissue and that anti-infective biomaterials should actively kill bacteria.
Janus particles, which are named after the two-faced Roman god Janus, have two distinct sides with different surface features, structures, and compositions. This asymmetric structure enables the ...combination of different or even incompatible physical, chemical, and mechanical properties within a single particle. Much effort has been focused on the preparation of Janus particles with high homogeneity, tunable size and shape, combined functionalities, and scalability. With their unique features, Janus particles have attracted attention in a wide range of applications such as in optics, catalysis, and biomedicine. As a biomedical device, Janus particles offer opportunities to incorporate therapeutics, imaging, or sensing modalities in independent compartments of a single particle in a spatially controlled manner. This may result in synergistic actions of combined therapies and multi-level targeting not possible in isotropic systems. In this review, we summarize the latest advances in employing Janus particles as therapeutic delivery carriers, in vivo imaging probes, and biosensors. Challenges and future opportunities for these particles will also be discussed.
Bacterial infections remain one of the biggest concerns to our society. Conventional antibiotic treatments showed little effect on the increasing number of antibiotic‐resistant bacteria. Advances in ...synthetic chemistry and nanotechnology have resulted in a new class of nanometer‐scale materials with distinguished properties and great potential to be an alternative for antibiotics. In this Minireview, we address the current situation of medical‐device‐associated infections and the emerging opportunities for antibacterial nanomaterials in preventing these complications. Several important antimicrobial nanomaterials emergent from advances in synthesis chemistry are introduced and their bactericidal mechanisms are analyzed. In addition, concerns regarding the biocompatibility of such materials are also addressed.
Nanomaterials to the rescue: Medical‐device‐associated bacterial infections remain challenges to modern medicine. Several nanomaterials have proven to be effective antibacterial agents (see graphic). The increasing number of antibiotic‐resistant bacteria makes such materials valuable tools for fighting infection.
Wavelength‐Selective Softening of Hydrogel Networks Pelloth, Jessica L.; Tran, Phong A.; Walther, Andreas ...
Advanced materials (Weinheim),
October 1, 2021, 2021-Oct, 2021-10-00, 20211001, Letnik:
33, Številka:
39
Journal Article
Recenzirano
Photoresponsive hydrogels hold key potential in advanced biomedical applications including tissue engineering, regenerative medicine, and drug delivery, as well as intricately engineered functions ...such as biosensing, soft robotics, and bioelectronics. Herein, the wavelength‐dependent degradation of bio‐orthogonal poly(ethylene glycol) hydrogels is reported, using three selective activation levels. Specifically, three chromophores are exploited, that is, ortho‐nitrobenzene, dimethyl aminobenzene, and bimane, each absorbing light at different wavelengths. By examining their photochemical action plots, the wavelength‐dependent reactivity of the photocleavable moieties is determined. The wavelength‐selective addressability of individual photoreactive units is subsequently translated into hydrogel design, enabling wavelength‐dependent cleavage of the hydrogel networks on‐demand. Critically, this platform technology allows for the fabrication of various hydrogels, whose mechanical properties can be fine‐tuned using different colors of light to reach a predefined value, according to the chromophore ratios used. The softening is shown to influence the spreading of pre‐osteoblastic cells adhering to the gels as a demonstration of their potential utility. Furthermore, the materials and photodegradation processes are non‐toxic to cells, making this platform attractive for biomaterials engineering.
The highly selective photochemical behavior of three chromophores with distinct degradation wavelengths is exploited for the construction of selectively degradable hydrogels. Specifically, hydrogel softening can be achieved in a stepwise fashion according to the chromophores’ activation wavelength, enabling fine control over the hydrogel's mechanical properties.
Bacteria colonization on medical devices remains one of the most serious complications following implantation. Traditional antibiotic treatment has proven ineffective, creating an increasingly high ...number of drug-resistant bacteria. Polymeric medical devices represent a significant portion of the total medical devices used today due to their excellent mechanical properties (such as durability, flexibility, etc). However, many polymers (such as polyvinyl chloride (PVC), polyurethane (PU) and silicone) become readily colonized and infected by bacteria immediately after use. Therefore, in this study, a novel antimicrobial coating was developed to inhibit bacterial growth on PVC, PU and silicone. Specifically, here, the aforementioned polymeric substrates were coated with selenium (Se) nanoparticles in situ. The Se-coated substrates were characterized using scanning electron microscopy, energy dispersive x-ray spectroscopy and bacteria assays. Most importantly, bacterial growth was significantly inhibited on the Se-coated substrates compared to their uncoated counterparts. The reduction of bacteria growth directly correlated with the density of Se nanoparticles on the coated substrate surfaces. In summary, these results demonstrate that Se should be further studied as a novel anti-bacterial polymeric coating material which can decrease bacteria functions without the use of antibiotics.
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