Surface morphology and adsorbed proteins affect phagocyte responses to nano-porous alumina

Real-Time Monitoring of Doxorubicin Release from Hybrid Nanoporous Anodic Alumina Structures

This work demonstrates an advanced approach to fabricate Hybrid nanoporous anodic alumina gradient-index filters (Hy-NAA-GIFs) through a heterogeneous anodization process combining sinusoidal current-density anodization and constant potential anodization. As a result, the hybrid structure obtained reveals a single photonic stopband (PSB), which falls within the absorption region of the drug molecule and the intensity of the spectrum that are far from such absorption range. The prepared structures were loaded with the doxorubicin (DOX) drug through the drop-casting method, which allows for evaluating the maximum reflectance of the relative height of the PSB with the average reflectance of the spectrum intensity. Thereafter, this property has been applied in a flow cell setup connected to a reflectance spectrophotometer where different drug-loaded samples were placed to study the behavior and kinetics of the drug release in real-time by varying two parameters, i.e., different pore length and flow rates. As such, obtained results were analyzed with a model that includes a sum of two inverted exponential decay functions with two different characteristic time releases. Overall, this study opens up several possibilities for the Hy-NAA-GIFs to study the drug kinetics from nanoporous structures.

Grooved hydroxyapatite scaffold modulates mitochondria homeostasis and thus promotes osteogenesis in bone mesenchymal stromal cells

Hydroxyapatite scaffolds (HASs) are widely studied as suitable materials for bone replacement scaffolds due to their chemical similarities to organic materials. In our previous study, a novel HAS with a 25–30-µm groove structure (HAS-G) exhibited enhanced osteogenesis of bone mesenchymal stromal cells (BMSCs) compared with HAS, potentially by modulating the macrophage-induced immune microenvironment. However, the exact effects of different surface patterns on the physiological processes of attached cells is not known. The present study aimed to determine the effects of HAS-G on the osteogenesis and physiological processes in BMSCs. Cell counting kit-8 assays and propidium iodide staining followed by flow cytometry were performed, and the results demonstrated that both in normal medium and differentiating medium, HAS-G promoted cell proliferation by decreasing the proportion of G1/G0 cells and decreased reactive oxygen species (ROS) accumulation in BMSCs compared with HAS. Detection markers of osteogenesis revealed that compared with HAS, HAS-G increased runt-related transcription factor 2, osteocalcin and osteopontin protein levels and promoted osteogenesis, which was further confirmed by Alizarin Red S staining. Following JC-1 staining, it was observed that HAS-G maintained the mitochondrial membrane potential, similar to that achieved by N-acetylcysteine pretreatment. In addition, compared with those of HAS, HAS-G decreased mitochondrial ROS levels, which potentially contributed to the promotion of osteogenesis. The results also demonstrated that HAS-G inhibited mitophagy induced by ROS accumulation and ATP synthesis compared with HAS. In conclusion, HAS-G decreased ROS accumulation and mitophagy and thus promoted osteogenesis of BMSCs, indicating that ROS modulation of HAS-G may serve a key role in osteogenesis.

The effects of nanomaterials on blood coagulation in hemostasis and thrombosis

The blood coagulation balance in the organism is achieved by the interaction of the blood platelets (PLTs) with the plasma coagulation system (PCS) and the vascular endothelial cells. In healthy organism, these systems prevent thrombosis and, in events of vascular damage, enable blood clotting to stop bleeding. The dysregulation of hemostasis may cause serious thrombotic and/or hemorrhagic pathologies. Numerous engineered nanomaterials are being investigated for biomedical purposes and are unavoidably exposed to the blood. Also, nanomaterials may access vascular system after occupational, environmental, or other types of exposure. Thus, it is essential to evaluate the effects of engineered nanomaterials on hemostasis. This review focuses on investigations of nanomaterial interactions with the blood components involved in blood coagulation: the PCS and PLTs. Particular emphases include the pathophysiology of effects of nanomaterials on the PCS, including the kallikrein-kinin system, and on PLTs. Methods for investigating these interactions are briefly described, and a review of the most important studies on the interactions of nanomaterials with plasma coagulation and platelets is provided. WIREs Nanomed Nanobiotechnol 2017, 9:e1448. doi: 10.1002/wnan.1448 For further resources related to this article, please visit the WIREs website.

Nanomaterials, inflammation, and tissue engineering

Nanomaterials exhibit unique properties that are absent in the bulk material because decreasing material size leads to an exponential increase in surface area, surface area to volume ratio, and effective stiffness, resulting in altered physiochemical properties. Diverse categories of nanomaterials such as nanoparticles, nanoporous scaffolds, nanopatterned surfaces, nanofibers, and carbon nanotubes can be generated using advanced fabrication and processing techniques. These materials are being increasingly incorporated in tissue engineering scaffolds to facilitate the development of biomimetic substitutes to replace damaged tissues and organs. Long-term success of nanomaterials in tissue engineering is contingent upon the inflammatory responses they elicit in vivo. This review seeks to summarize the recent developments in our understanding of biochemical and biophysical attributes of nanomaterials and the inflammatory responses they elicit, with a focus on strategies for nanomaterial design in tissue engineering applications.

Understanding improved osteoblast behavior on select nanoporous anodic alumina

The aim of this study was to prepare different sized porous anodic alumina (PAA) and examine preosteoblast (MC3T3-E1) attachment and proliferation on such nanoporous surfaces. In this study, PAA with tunable pore sizes (25 nm, 50 nm, and 75 nm) were fabricated by a two-step anodizing procedure in oxalic acid. The surface morphology and elemental composition of PAA were characterized by field emission scanning electron microscopy and X-ray photoelectron spectroscopy analysis. The nanopore arrays on all of the PAA samples were highly regular. X-ray photoelectron spectroscopy analysis suggested that the chemistry of PAA and flat aluminum surfaces were similar. However, contact angles were significantly greater on all of the PAA compared to flat aluminum substrates, which consequently altered protein adsorption profiles. The attachment and proliferation of preosteoblasts were determined for up to 7 days in culture using field emission scanning electron microscopy and a Cell Counting Kit-8. Results showed that nanoporous surfaces did not enhance initial preosteoblast attachment, whereas preosteoblast proliferation dramatically increased when the PAA pore size was either 50 nm or 75 nm compared to all other samples (P<0.05). Thus, this study showed that one can alter surface energy of aluminum by modifying surface nano-roughness alone (and not changing chemistry) through an anodization process to improve osteoblast density, and, thus, should be further studied as a bioactive interface for orthopedic applications.

In vivo fluorescence imaging of biomaterial-associated inflammation and infection in a minimally invasive manner

Implant-associated inflammation and bacterial infection severely limit the functional performance of medical devices and are a major cause of implant failure. Therefore, it is crucial to develop methodologies to monitor/image implant-associated aseptic inflammation and bacterial infection in a minimally invasive manner. Here, we exploited near-infrared fluorescence (NIRF) molecular probes injected locally at the implant site to perform minimally invasive, simultaneous imaging of inflammation, and infection associated with implanted polymer disks. The hydro-sulfo-Cy5 (H-s-Cy5) probe detected reactive oxygen species associated with inflammatory responses to both aseptic and biofilm-containing implants, whereas diaminocyanine sulfonate selectively detected nitric oxide associated with a biofilm on the biomaterial at acute time points (<4 days). This imaging modality also allows longitudinal monitoring because of high specificity and fast clearance rate of the fluorescent probes. Taken together, these NIRF molecular probes represent a useful tool to directly image inflammatory responses and infections associated with implanted devices for the diagnosis of device-associated inflammation and infection as well as the development of effective therapies.

Functionalized ceramics for biomedical, biotechnological and environmental applications

Surface functionalization has become of paramount importance and is considered a fundamental tool for the development and design of countless devices and engineered systems for key technological areas in biomedical, biotechnological and environmental applications. In this review, surface functionalization strategies for alumina, zirconia, titania, silica, iron oxide and calcium phosphate are presented and discussed. These materials have become particularly important concerning the aforementioned applications, being not only of great academic, but also of steadily increasing human and commercial, interest. In this review, special emphasis is given to their use as biomaterials, biosensors, biological targets, drug delivery systems, implants, chromatographic supports for biomolecule purification and analysis, and adsorbents for toxic substances and pollutants. The objective of this review is to provide a broad picture of the enormous possibilities offered by surface functionalization and to identify particular challenges regarding surface analysis and characterization.