Urease-Powered Black TiO2 Micromotors for Photothermal Therapy of Bladder Cancer.

Urease-powered nano/micromotors can move at physiological urea concentrations, making them useful for biomedical applications, such as treating bladder cancer. However, their movement in biological environments is still challenging. Herein, Janus micromotors based on black TiO2 with urease asymmetric catalytic coating were designed to take benefit of the optical properties of black TiO2 under near-infrared light and the movement capability in simulated bladder environments (urea). The black TiO2 microspheres were half-coated with a thin layer of Au, and l-Cysteine was utilized to attach the urease enzyme to the Au surface using its thiol group. Biocatalytic hydrolysis of urea through urease at biologically relevant concentrations provided the driving force for micromotors. A variety of parameters, such as urea fuel concentration, viscosity, and ionic character of the environment, were used to investigate how micromotors moved in different concentrations of urea in water, PBS, NaCl, and urine. The results indicate that micromotors are propelled through ionic self-diffusiophoresis caused by urea enzymatic catalysis. Due to their low toxicity and in vitro anticancer effect, micromotors are effective agents for photothermal therapy, which can help kill bladder cancer cells. These promising results suggest that biocompatible micromotors hold great potential for improving cancer treatment and facilitating diagnosis.

PLGA/TiO2 nanocomposite scaffolds for biomedical applications: fabrication, photocatalytic, and antibacterial properties.

Introduction: Porous 3D scaffolds synthesized using biocompatible and biodegradable materials could provide suitable microenvironment and mechanical support for optimal cell growth and function. The effect of the scaffold porosity on the mechanical properties, as well as the TiO2 nanoparticles addition on the bioactivity, antimicrobial, photocatalytic, and cytotoxicity properties of scaffolds were investigated. Methods: In the present study, porous scaffolds consisting poly (lactide-co-glycolide) (PLGA) containing TiO2 nanoparticles were fabricated via air-liquid foaming technique, which is a novel method and has more advantages due to not using additives for nucleation compared to former ways. Results: Adjustment of the foaming process parameters was demonstrated to allow for textural control of the resulting scaffolds and their pore size tuning in the range of 200-600 µm. Mechanical properties of the scaffolds, in particular, their compressive strength, revealed an inverse relationship with the pore size, and varied in the range of 0.97-0.75 MPa. The scaffold with the pore size 270 µm, compressive strength 0.97 MPa, and porosity level 90%, was chosen as the optimum case for the bone tissue engineering (BTE) application. Furthermore, 99% antibacterial effect of the PLGA/10 wt.% TiO2 nanocomposite scaffolds against the strain was achieved using Escherichia coli. Besides, no negative effect of the new method was observed on the bioactivity behavior and apatite forming ability of scaffolds in the simulated body fluid (SBF). This nanocomposite also displayed a good cytocompatibility when assayed with MG 63 cells. Lastly, the nanocomposite scaffolds revealed the capability to degrade methylene blue (MB) dye by nearly 90% under the UV irradiation for 3 hours. Conclusion: Based on the results, nanocomposite new scaffolds are proposed as a promising candidate for the BTE applications as a replacement for the previous ones.

A facile, two-step synthesis and characterization of Fe 3 O 4 -L Cysteine -graphene quantum dots as a multifunctional nanocomposite.

In this research, a facile, two-step synthesis of Fe3O4-LCysteine-graphene quantum dots (GQDs) nanocomposite is reported. This synthesis method comprises the preparation of GQDs via hydrothermal route, which should be conjugated to the LCysteine functionalized core-shell magnetic structure with the core of about 7.5-nm iron oxide nanoparticle and 3.5-nm LCysteine shell. LCysteine, as a biocompatible natural amino acid, was used to link magnetite nanoparticles (MNPs) with GQDs. X-ray powder diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray were used to investigate the presence and formation of MNPs, L Cysteine functionalized MNPs, and final hybrid nanostructure. Morphology and size distribution of nanoparticles were demonstrated by scanning electron microscopy and transmission electron microscopy. Finally, the magnetic and optical properties of the prepared nanocomposite were measured by vibrating sample magnetometer, ultraviolet-visible, and photoluminescence spectroscopy. The results show that Fe3O4-LCysteine-GQDs nanocomposite exhibits a superparamagnetic behavior at room temperature with high saturation magnetization and low magnetic coercivity, which are 28.99 emu/g and 0.09 Oe, respectively. This nanocomposite also shows strong and stable emission at 460 nm and 530 nm when it is excited with the 235 nm wavelength. The magnetic GQDs structure also reveals the absorption wavelength at 270 nm. Therefore, Fe3O4-LCysteine-GQDs nanocomposite can be considered as a potential multifunctional hybrid structure with magnetic and optical properties simultaneously. This nanocomposite can be used for a wide range of biomedical applications like magnetic resonance imaging (MRI) contrast agents, biosensors, photothermal therapy, and hyperthermia.

Mixed oxide nanotubes in nanomedicine: A dead-end or a bridge to the future?

Nanomedicine has seen a significant rise in the development of new research tools and clinically functional devices. In this regard, significant advances and new commercial applications are expected in the pharmaceutical and orthopedic industries. For advanced orthopedic implant technologies, appropriate nanoscale surface modifications are highly effective strategies and are widely studied in the literature for improving implant performance. It is well-established that implants with nanotubular surfaces show a drastic improvement in new bone creation and gene expression compared to implants without nanotopography. Nevertheless, the scientific and clinical understanding of mixed oxide nanotubes (MONs) and their potential applications, especially in biomedical applications are still in the early stages of development. This review aims to establish a credible platform for the current and future roles of MONs in nanomedicine, particularly in advanced orthopedic implants. We first introduce the concept of MONs and then discuss the preparation strategies. This is followed by a review of the recent advancement of MONs in biomedical applications, including mineralization abilities, biocompatibility, antibacterial activity, cell culture, and animal testing, as well as clinical possibilities. To conclude, we propose that the combination of nanotubular surface modification with incorporating sensor allows clinicians to precisely record patient data as a critical contributor to evidence-based medicine.

Polyethylene glycol-coated porous magnetic nanoparticles for targeted delivery of chemotherapeutics under magnetic hyperthermia condition.

PURPOSE: Although magnetite nanoparticles (MNPs) are promising agents for hyperthermia therapy, insufficient drug encapsulation efficacies inhibit their application as nanocarriers in the targeted drug delivery systems. In this study, porous magnetite nanoparticles (PMNPs) were synthesized and coated with a thermosensitive polymeric shell to obtain a synergistic effect of hyperthermia and chemotherapy. MATERIALS AND METHODS: PMNPs were produced using cetyltrimethyl ammonium bromide template and then coated by a polyethylene glycol layer with molecular weight of 1500 Da (PEG1500) and phase transition temperature of 48 ± 2 °C to endow a thermosensitive behavior. The profile of drug release from the nanostructure was studied at various hyperthermia conditions generated by waterbath, magnetic resonance-guided focused ultrasound (MRgFUS), and alternating magnetic field (AMF). The in vitro cytotoxicity and hyperthermia efficacy of the doxorubicin-loaded nanoparticles (DOX-PEG1500-PMNPs) were assessed using human lung adenocarcinoma (A549) cells. RESULTS: Heat treatment of DOX-PEG1500-PMNPs containing 235 ± 26 mg·g-1 DOX at 48 °C by waterbath, MRgFUS, and AMF, respectively led to 71 ± 4%, 48 ± 3%, and 74 ± 5% drug release. Hyperthermia treatment of the A549 cells using DOX-PEG1500-PMNPs led to 77% decrease in the cell viability due to the synergistic effects of magnetic hyperthermia and chemotherapy. CONCLUSION: The large pores generated in the PMNPs structure could provide a sufficient space for encapsulation of the chemotherapeutics as well as fast drug encapsulation and release kinetics, which together with thermosensitive characteristics of the PEG1500 shell, make DOX-PEG1500-PMNPs promising adjuvants to the magnetic hyperthermia modality.

Novel fluoridated silk fibroin/ TiO2 nanocomposite scaffolds for bone tissue engineering.

It is known that Fluoride ions strongly affect bone mineralization and formation. In the present study, the engineered bone tissue scaffolds are fabricated using silk fibroin (SF) and flouridated TiO2 nanoparticles. TiO2 nanoparticles are modified by fluoride ions, and different levels (0, 5, 10, 15 and 20wt%) of the fluoridated TiO2 nanoparticles (TiO2-F) were subsequently added to the SF matrix through phase separation method to prepare silk fibroin/flouridated TiO2 nanocomposite scaffolds (SF/TiO2-F). Phase structure, functional groups, morphology and mechanical properties of the obtained scaffolds were evaluated by X-ray diffraction method (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and compressive testing, respectively. In vitro degradation studies of scaffolds were performed by incubating the samples in phosphate buffered saline (PBS) at 37°C and pH7.4 for 30days. Additionally, the bioactivity of scaffolds was estimated in a simulated body fluid (SBF) buffered at 37°C and pH7.4 for 28days. Moreover, MTT assay was used to confirm the biocompatibility of the scaffolds using human like SaOS-2 osteoblast cell line for 1, 3 and 5days. The obtained results indicated that the mechanical properties of scaffolds have been improved by increasing the TiO2-F amount up to 15wt%. However, a detrimental effect was observed by a further increase in the TiO2-F content. The bioactivity of SF/TiO2-F nanocomposite scaffolds was promoted by flouridation of TiO2. Furthermore, cell cytotoxicity results demonstrated that the SF/TiO2-F nanocomposite scaffolds are nontoxic to osteoblasts. The cell fixation results after 3days of incubation revealed that the cell attachment and spreading on SF/TiO2-F nanocomposite scaffolds are improved with respect to SF/TiO2 nanocomposite scaffolds control sample.

Physicomechanical properties of spark plasma sintered carbon nanotube-containing ceramic matrix nanocomposites.

Recently, a wide variety of research works have focused on carbon nanotube (CNT)-ceramic matrix nanocomposites. In many cases, these novel materials are produced through conventional powder metallurgy methods including hot pressing, conventional sintering, and hot isostatic pressing. However, spark plasma sintering (SPS) as a novel and efficient consolidation technique is exploited for the full densification of high-temperature ceramic systems. In these binary nanocomposites, CNTs are added to ceramic matrices to noticeably modify their inferior properties and SPS is employed to produce fully dense compacts. In this review, a broad overview of these systems is provided and the potential influences of CNTs on their functional and structural properties are addressed. The technical challenges are then mentioned and the ongoing debates over overcoming these drawbacks are fully highlighted. The structural classification used is material-oriented. It helps the readers to easily find the material systems of interest. The SPSed CNT-containing ceramic matrix nanocomposites are generally categorized into four main classes: CNT-oxide systems; CNT-nitride systems, CNT-carbide systems, and CNT-boride systems. A large number of original curves and bubble maps are provided to fully summarize the experimental results reported in the literature. They pave the way for obviously selecting the ceramic systems required for each industrial application. The properties in consideration include the relative density, hardness, yield strength, fracture toughness, electrical and thermal conductivities, modulus, and flexural strength. These unique graphs facilitate the comparison between reported results and help the reader to easily distinguish the best method for producing the ceramic systems of interest and the optimal conditions under which the superior properties can be reached. The authors have concentrated on the microstructure evolution-physicomechanical property relationship and tried to relate each property to pertinent microstructural phenomena and address why the properties are degraded or enhanced with the variation of SPS conditions or material parameters.

The effect of superparamagnetic iron oxide nanoparticles surface engineering on relaxivity of magnetoliposome.

The purpose of this work is evaluating the effect of ultra small superparamagnetic iron oxide nanoparticles (USPIONs) coatings on encapsulation efficiency in liposomes and cellular cytotoxicity assay. Moreover, we assessed the effects of surface engineering on the relaxivity of magnetoliposome nanoparticles in order to create a targeted reagent for the intelligent diagnosis of cancers by MRI. For estimating the effect of nanoparticle coatings on encapsulation, several kinds of USPIONs coated by dextran, PEG5000 and citrate were used. All kinds of samples are monodispersed and below 100 ± 10 nm and the coatings of USPIONs have no significant effect on magnetoliposome diameter. The coating of USPIONs could have effect on percentage of encapsulation. The dextran coated USPIONs have more stability and quality accordingly the encapsulation increased up to 92%, then the magnetoliposome nano particles have been targeted by Herceptin and anti-HER2 VHH, separately. Over storage period of four weeks the resulting particles were stable and physico-chemical properties such as size and zetapotential did not show any significant changes. The relaxivity of contrast agents was measured using a 1.5 T MRI. The r2/r1 ratio was more than two for all samples which demonstrate the negative contrast enhancing of all SPION embedded specimens. The high ratio of r2/r1 as well as high r2 is the best combination of a negative contrast agent as it is obtained for pure magnetite. The value of r2/r1 for all other samples including Herceptin targeted magnetoliposome, anti-HER2 VHH targeted magnetoliposome and non-targeted magnetoliposome were between ~21 to ~28, which show the magnetite embedded samples have enough negative contrast to be detectable by MRI. Therefore the HER2 targeted magnetoliposomes are a good and stable candidate as contrast agents in clinical radiology and biomedical research with minimal cytotoxicity and biocompatibility effects. Copyright © 2016 John Wiley & Sons, Ltd.

The effect of poly(ethylene glycol) coating on colloidal stability of superparamagnetic iron oxide nanoparticles as potential MRI contrast agent.

Superparamganetic iron oxide-based contrast agents in magnetic resonance imaging (MRI) have offered new possibility for early detection of lymph nodes and their metastases. According to important role of nanoparticle size in biodistribution, magnetite nanoparticles coated with different polyethylene glycol (PEG) concentrations up to 10/1 PEG/iron oxide weight ratio in an ex situ manner. To predict the PEG-coated nanoparticle behavior in biological media, such as blood stream or tissue, colloidal stability evaluation was performed to estimate the coating endurance in different conditions. Accordingly, optical absorbance measurements were conducted in solutions with different values of pH and NaCl concentrations. The results indicated that at neutral pH condition, nanoparticles treated by 3/1 ratio possessed better stability parameters. Investigating at high pH of 10 resulted in superior stability for bare magnetite nanoparticles due to its higher electrophoretic mobility. Coating material was attacked at acidic solutions which cause samples with higher PEG weight ratio to be settled slower. In various ionic strengths of 10(-5) to 0.1 M, 3/1 ratio samples offered greater resistivity to sedimentation. The nanoparticles were further investigated by exposure to L929 cell and following up the iron uptake within cells. Finally, detection sensitivities in lymph nodes were evaluated. Particle uptake and the most signal reduction for in vivo MRI studies were also obtained by nanoparticles acquiring lower PEG contents that showed better colloidal stability.