The Effect of Electrode Topography on the Magnetic Properties and MRI Application of Electrochemically-Deposited, Synthesized, Cobalt-Substituted Hydroxyapatite

Delivery of mGluR5 siRNAs by Iron Oxide Nanocages by Alternating Magnetic Fields for Blocking Proliferation of Metastatic Osteosarcoma Cells

Although osteosarcoma is the most common primary malignant bone tumor, chemotherapeutic drugs and treatment have failed to increase the five-year survival rate over the last three decades. We previously demonstrated that type 5 metabotropic glutamate receptor, mGluR5, is required to proliferate metastatic osteosarcoma cells. In this work, we delivered mGluR5 siRNAs in vitro using superparamagnetic iron oxide nanocages (IO-nanocages) as delivery vehicles and applied alternating magnetic fields (AMFs) to improve mGluR5 siRNAs release. We observed functional outcomes when mGluR5 expression is silenced in human and mouse osteosarcoma cell lines. The results elucidated that the mGluR5 siRNAs were successfully delivered by IO-nanocages and their release was enhanced by AMFs, leading to mGluR5 silencing. Moreover, we observed that the proliferation of both human and mouse osteosarcoma cells decreased significantly when mGluR5 expression was silenced in the cells. This novel magnetic siRNA delivery methodology was capable of silencing mGluR5 expression significantly in osteosarcoma cell lines under the AMFs, and our data suggested that this method can be further used in future clinical applications in cancer therapy.

Fluorescence conjugated nanostructured cobalt-doped hydroxyapatite platform for imaging-guided drug delivery application

Multifunctional nanomaterials developed from hydroxyapatite (HAp) with enhanced biological characteristics have recently attracted attention in the biomedical field. The goal of this study is to investigate the potential applications of cobalt-doped HAp (Co-HAp) in the biomedical imaging and therapeutic applications. The co-precipitation approach was used to substitute different molar concentrations of Ca²⁺ ions with cobalt (Co²⁺) in HAp structure. The synthesized Co-HAp nanoparticles were studied using various sophisticated techniques to verify the success rate of the doping method. The specific crystal structure, functional groups, size, morphology, photoluminescence property, and thermal stability of the Co-HAp nanoparticles were analyzed based on the characterization results. The computational modelling of doped and undoped HAp reveals the difference in crystal structure parameters. The cytotoxicity study (MTT assay and AO/PI/Hoechst fluorescence staining) reveals the non-toxic characteristics of Co-HAp nanoparticles on MDA-MB-231 breast cancer cell lines. The DOX was loaded onto Co-HAp, showing the maximum drug loading capacity for 2.0 mol% Co-HAp. Drug release was estimated in five different pH environments with various time intervals over 72 h. Furthermore, 2.0 mol% Co-HAp shows excellent fluorescence sensitivity with FITC-conjugated MDA-MB-231 cell lines. These results suggest that cobalt improved the fluorescence intensity of FITC-labeled HAp nanoparticles. This work highlights the promising application of Co-HAp nanoparticles with significant enhanced fluorescence activity for imaging-guided drug delivery system.

The construction of multifunctional nanoparticles system for dual-modal imaging and arteriosclerosis targeted therapy

Atherosclerosis is a major risk factor for the development of cardiovascular disease. Unfortunately, due to relatively low sensitivities and poor resolution, the results of surgical resection are often largely unsatisfactory. Moreover, many chemotherapeutic agents, such as curcumin (Cur), are restricted by the low blood-brain barrier (BBB) permeability. Recently, nanotechnology proposes new opportunities to overcome these treatment barriers. In this study, superparamagnetic iron oxide nanoparticles (SPIO) was prepared by the high-temperature solid-state method, and then loaded into amphiphilic polymer DSPE-PEG to form SDP nanoparticles by hydrogen bonding in oil phase. The curcumin was encapsulated in SDP nanoparticles by self-assembly. Finally, vascular cell adhesion molecule-1 (VCAM-1) and Cy5.5 were conjugated on into SDP/Cur nanoparticles by amidation reaction. The average particle size of the prepared multifunctional SDP-VCAM-1/Cur/Cy5.5 nanoparticles is 124.4 nm, which can provide the sustained release of Cur. Moreover, the nanoparticles are proved to have superparamagnetic properties and fluorescence properties. In vitro cell experiments show that nanoparticles have excellent biocompatibility, blood compatibility and macrophage targeting. These results show that SDP-VCAM-1/Cur/Cy5.5 nanoparticles can be used not only as dual imaging probe for magnetic resonance (MR) and fluorescence imaging, but also as carriers to deliver chemotherapeutic drugs to inflammatory tissue, thus providing a promising opportunity for the treatment, molecular imaging and targeted therapy in atherosclerosis due to their established specificity and safety.

Evaluation of Polyvinyl Alcohol/Cobalt Substituted Hydroxyapatite Nanocomposite as a Potential Wound Dressing for Diabetic Foot Ulcers

Diabetic foot ulcers (DFUs) caused by diabetes are prone to serious and persistent infections. If not treated properly, it will cause tissue necrosis or septicemia due to peripheral blood vessel embolism. Therefore, it is an urgent challenge to accelerate wound healing and reduce the risk of bacterial infection in patients. In clinical practice, DFUs mostly use hydrogel dressing to cover the surface of the affected area as an auxiliary treatment. Polyvinyl alcohol (PVA) is a hydrophilic hydrogel polymer widely used in dressings, drug delivery, and medical applications. However, due to its weak bioactivity and antibacterial ability, leads to limited application. Filler adding is a useful way to enhance the biocompatibility of PVA. In our study, cobalt-substituted hydroxyapatite (CoHA) powder was prepared by the electrochemically-deposited method. PVA and PVA-CoHA nanocomposite were prepared by the solvent casting method. The bioactivity of the PVA and composite was evaluated by immersed in simulated body fluid for 7 days. In addition, L929 cells and E. coli were used to evaluate the cytotoxicity and antibacterial tests of PVA and PVA-CoHA nanocomposite. The results show that the addition of CoHA increases the mechanical properties and biological activity of PVA. Biocompatibility evaluation showed no significant cytotoxicity of PVA-CoHA composite. In addition, a small amount of cobalt ion was released to the culture medium from the nanocomposite in the cell culture period and enhanced cell growth. The addition of CoHA also confirmed that it could inhibit the growth of E. coli. PVA-CoHA composite may have potential applications in diabetic trauma healing and wound dressing.

Exploring the Interaction of Cobalt Oxide Nanoparticles with Albumin, Leukemia Cancer Cells and Pathogenic Bacteria by Multispectroscopic, Docking, Cellular and Antibacterial Approaches

Aim

The interaction of NPs with biological systems may reveal useful details about their pharmacodynamic, anticancer and antibacterial effects.

Methods

Herein, the interaction of as-synthesized Co₃O₄ NPs with HSA was explored by different kinds of fluorescence and CD spectroscopic methods, as well as molecular docking studies. Also, the anticancer effect of Co₃O₄ NPs against leukemia K562 cells was investigated by MTT, LDH, caspase, real-time PCR, ROS, cell cycle, and apoptosis assays. Afterwards, the antibacterial effects of Co₃O₄ NPs against three pathogenic bacteria were disclosed by antibacterial assays.

Results

Different characterization methods such as TEM, DLS, zeta potential and XRD studies proved that fabricated Co₃O₄ NPs by sol-gel method have a diameter of around 50 nm, hydrodynamic radius of 177 nm with a charge distribution of −33.04 mV and a well-defined crystalline phase. Intrinsic, extrinsic, and synchronous fluorescence as well as CD studies, respectively, showed that the HSA undergoes some fluorescence quenching, minor conformational changes, microenvironmental changes as well as no structural changes in the secondary structure, after interaction with Co₃O₄ NPs. Molecular docking results also verified that the spherical clusters with a dimension of 1.5 nm exhibit the most binding energy with HSA molecules. Anticancer assays demonstrated that Co₃O₄ NPs can selectively lead to the reduction of K562 cell viability through the cell membrane damage, activation of caspase-9, -8 and -3, elevation of Bax/Bcl-2 mRNA ratio, ROS production, cell cycle arrest, and apoptosis. Finally, antibacterial assays disclosed that Co₃O₄ NPs can stimulate a promising antibacterial effect against pathogenic bacteria.

Conclusion

In general, these observations can provide useful information for the early stages of nanomaterial applications in therapeutic platforms.

Effect of Cobalt Precursors on Cobalt-Hydroxyapatite Used in Bone Regeneration and MRI

In clinical dentistry practice, supplemental bone surgery or jawbone defect after tooth extraction must be assisted by a bone-filling material. Cobalt-substituted hydroxyapatite (COHA) effectively promotes bone cell growth, reduces the inflammatory response, and is an antibacterial agent. COHA can therefore be used as an alveolar bone-filling material or guided bone regeneration membrane. Meanwhile, COHA can be used in magnetic resonance imaging (MRI) with negative contrast agents and targeting materials without causing metal interference with the image. Hence, COHA has received increasing amounts of attention in recent years. However, the influence of different cobalt precursors on the synthesized COHA is still unknown. Therefore, COHA synthesized from 3 cobalt precursors (cobalt chloride, cobalt nitrate, and cobalt sulfate) was compared in this study. The results show that COHA synthesized by the precursor with the smallest anion radius, cobalt chloride, has a larger particle size (239 nm) and a higher cobalt ion substitution rate (15.6%). When the cobalt ion substitution rate increases, the MRI has a stronger contrast. Bioactivity data indicate that COHAC is more susceptible to degradation and therefore releases more cobalt ions to contribute to the differentiation of bone cells. Based on these studies, COHAC prepared with the cobalt chloride precursor has a higher cobalt ion substitution rate, faster degradation rate, better image contrast, and better bioactivity. It is therefore the preferred choice of bone-filling material for alveolar bone regeneration.