Influence of sonication on the physicochemical and biological characteristics of selenium-substituted hydroxyapatites

Although the material hydroxyapatite (HAP) has excellent porous, biocompatible, and biodegradable properties, its mechanical strength and microbial inhibition rate are not adequate for its direct use in bone tissue engineering or in constructing artificial teeth. To overcome some of its limitations, in the present study, we have formed an organic-inorganic composite with an altered internal structureviadoping selenium (Se) cations into the lattice of HAP. We have synthesized Se-substituted HAP (Se-HAP) composites with different Se/P ratios (0.01, 0.05, and 0.1 M)viaa wet chemical route in which two different sets of samples were collected (1) after only precipitation (referred to as the precipitation method) and (2) after precipitation followed by sonication (referred to as the sonochemical method). FTIR and Raman spectroscopic analyses confirmed the successful doping of Se into the HAP matrices, while powder XRD studies indicated their highly crystalline nature, which was significantly influenced by Se doping. The XRD data also showed that the Se-HAP particles formed by the precipitation method have a size of 56 nm and those formed by the sonochemical method have a size of 29 nm. Morphological analysis by means of SEM and TEM indicated that the sonochemical method produces well-defined rod-shaped particles, while the precipitation method produces particles with agglomerated structures. Hemolytic studies confirmed that the Se-HAP particles are biocompatible, and that the hemolytic ratio increases with the Se content. In addition, antibacterial studies indicated that Se-HAP responds quite well against a Gram-positive strain (S. aureus), on a par with the response to a Gram-negative strain (P. aeruginosa). Finally,in vitrocell viability and proliferation studies indicated an increase in the proliferation capacity of non-cancer cells (NIH-3T3 fibroblasts) and a considerable reduction in the viability of cancer cells (MG-63 osteosarcoma). Based on the overall analysis, the Se-HAP samples formed by the sonochemical approach could have potential for biomedical applications in bone cell repair, growth, and regeneration

Retraction Note: Fabrication of a microfluidic device for studying the in situ drug-loading/release behavior of graphene oxide-encapsulated hydrogel beads

This article [1] has been retracted by the authors due to lack of permission to use and publish the data reported. All authors agree to this retraction

Retraction Note: Fabrication of a microfluidic device for studying the in situ drug-loading/release behavior of graphene oxide-encapsulated hydrogel beads

This article [1] has been retracted by the authors due to lack of permission to use and publish the data reported. All authors agree to this retraction

RETRACTED ARTICLE: Fabrication of a microfluidic device for studying the in situ drug-loading/release behavior of graphene oxide-encapsulated hydrogel beads

Abstract Background Controlled drug delivery system is highly important for not only prolonged the efficacy of drug but also cellular development for tissue engineering. A number of biopolymer composites and nanostructured carriers behave been used for the controlled drug delivery of therapeutics. Recently, in vitro microfluidic devices that mimic the human body have been developed for drug-delivery applications. Methods A microfluidic channel was fabricated via a two-step process: (i) polydimethyl siloxane (PDMS) and curing agent were poured with a 10:2 mass ratio onto an acrylic mold with two steel pipes, and (ii) calcium alginate beads were synthesized using sodium alginate and calcium chloride solutions. Different amounts (10, 25, 50 μg) of graphene oxide (GO) were then added by Hummers method, and studies on the encapsulation and release of the model drug, risedronate (Ris), were performed using control hydrogel beads (pH 6.3), GO-containing beads (10GO, 25GO and 50GO), and different pH conditions. MC3T3 osteoblastic cells were cultured in a microchannel with Ris-loaded GO-hydrogel beads, and their proliferation, viability, attachment and spreading were assessed for a week. Results The spongy and textured morphology of pristine hydrogel beads was converted to flowery and rod-shaped structures in drug-loaded hydrogel beads at reduced pH (6.3) and at a lower concentration (10 μg) of GO. These latter 10GO drug-loaded beads rapidly released their cargo owing to the calcium phosphate deposited on the surface. Notably, beads containing a higher amount of GO (50GO) exhibited an extended drug-release profile. We further found that MC3T3 cells proliferated continuously in vitro in the microfluidic channel containing the GO-hydrogel system. MTT and live/dead assays showed similar proliferative potential of MC3T3 cells. Therefore, a microfluidic device with microchannels containing hydrogel beads formulated with different amounts of GO and tested under various pH conditions could be a promising system for controlled drug release. Conclusions The GO and drug (risedronate, Rig) were directed loaded into a hydrogel placed in a microchannel. Through interactions such as hydrogen bonding between Go and the Rig-loaded GO-hydrogel beads, the bead-loaded microfluidic device supported MC3T3 proliferation and development as osteoblast without additional osteogenic differentiation supplements

Optical Diagnostics of Osteoblast Cells and Osteogenic Drug Screening

Microfluidic device based diagnostics involving optical fibre path, in situ imaging and spectroscopy are gaining importance due to recent advances in diagnostics instrumentation and methods, besides other factors such as low amount of reagent required for analysis, short investigation times, and potential possibilities to replace animal model based study in near future. It is possible to grow and monitor tissues in vitro in microfluidic lab-on-chip. It may become a transformative way of studying how cells interact with drugs, pathogens and biomaterials in physiologically relevant microenvironments. To a large extent, progress in developing clinically viable solutions has been constrained because of (i) contradiction between in vitro and in vivo results and (ii) animal model based and clinical studies which is very expensive. Our study here aims to evaluate the usefulness of microfluidic device based 3D tissue growth and monitoring approach to better emulate physiologically and clinically relevant microenvironments in comparison to conventional in vitro 2D culture. Moreover, the microfluidic methodology permits precise high-throughput investigations through real-time imaging while using very small amounts of reagents and cells. In the present study, we report on the details of an osteoblast cell based 3D microfluidic platform which we employ for osteogenic drug screening. The drug formulation is functionalized with fluorescence and other biomarkers for imaging and spectroscopy, respectively. Optical fibre coupled paths are used to obtain insight regarding the role of stress/flow pressure fluctuation and nanoparticle-drug concentration on the osteoblast growth and osteogenic properties of bone

Magnetic nanoparticles for thermal lysis and application in cancer treatment

Chemotherapy and radiation-therapy are conventional treatment procedure of cancer. Though radiation therapy is very common practice for cancer treatment, it has limitations including incomplete and non specific destruction. Heating characteristics of magnetic nanoparticle (MNP) is modelled using molecular dynamics simulation setup. This model would give an understanding for the treatment of cancer cell through MNP associated radiation-therapy. In this paper, alternating magnetic field driven heat generation of MNP is studied using classical molecular dynamics Temperature is measured as an ensemble average of velocity of the atoms. Temperature stabilization is achieved. Under this simulation setting with certain parameters, 45 degrees C temperature was obtained in our simulations. Simulation data would be helpful for experimental analysis to treat cancerous cell in presence of MNP under exposure to radiofrequency. The in vitro thermal characteristics of magnetite nanoparticles using magnetic coil of various frequencies (5, 7.5, 10 and 15 kHz), the saturation temperature was found at 0.5 mg/mL concentration. At frequency 50 kHz the live/dead and MTT assay was performed on magnetite nanoparticles using MC3T3 cells for 10 min duration. Low radio frequency (RF) radiation induced localized heat into the metallic nanoparticles which is clearly understood using the molecular dynamics simulation setup. Heating of nanoparticle trigger the killing of the tumor cells, acts as a local therapy, as it generates less side effects in comparison to other treatments like chemotherapy and radiation therapy

Graphene OxideA Tool for the Preparation of Chemically Crosslinking Free Alginate–Chitosan–Collagen Scaffolds for Bone Tissue Engineering

Developing a biodegradable scaffold remains a major challenge in bone tissue engineering. This study was aimed at developing novel alginate–chitosan–collagen (SA–CS–Col)-based composite scaffolds consisting of graphene oxide (GO) to enrich porous structures, elicited by the freeze-drying technique. To characterize porosity, water absorption, and compressive modulus, GO scaffolds (SA–CS–Col–GO) were prepared with and without Ca²⁺-mediated crosslinking (chemical crosslinking) and analyzed using Raman, Fourier transform infrared (FTIR), X-ray diffraction (XRD), and scanning electron microscopy techniques. The incorporation of GO into the SA–CS–Col matrix increased both crosslinking density as indicated by the reduction of crystalline peaks in the XRD patterns and polyelectrolyte ion complex as confirmed by FTIR. GO scaffolds showed increased mechanical properties which were further increased for chemically crosslinked scaffolds. All scaffolds exhibited interconnected pores of 10–250 μm range. By increasing the crosslinking density with Ca²⁺, a decrease in the porosity/swelling ratio was observed. Moreover, the SA–CS–Col–GO scaffold with or without chemical crosslinking was more stable as compared to SA–CS or SA–CS–Col scaffolds when placed in aqueous solution. To perform in vitro biochemical studies, mouse osteoblast cells were grown on various scaffolds and evaluated for cell proliferation by using MTT assay and mineralization and differentiation by alizarin red S staining. These measurements showed a significant increase for cells attached to the SA–CS–Col–GO scaffold compared to SA–CS or SA–CS–Col composites. However, chemical crosslinking of SA–CS–Col–GO showed no effect on the osteogenic ability of osteoblasts. These studies indicate the potential use of GO to prepare free SA–CS–Col scaffolds with preserved porous structure with elongated Col fibrils and that these composites, which are biocompatible and stable in a biological medium, could be used for application in engineering bone tissues