Mahboobeh Mahmoodi

Effect of Nd:Yttrium-aluminum-garnet laser radiation on Ti6Al4V alloy properties for biomedical applications

The effect of Nd:yttrium-aluminum-garnet laser on the microtopography and physicochemical properties of Ti6Al4V alloy are investigated in the view of biomedical applications. The surface roughness and hardness for laser treated samples (LTS) at 140 J cm−2 were measured 7±0.02 and 825 vickers hardness number, respectively. This superior microhardness value is attributed to grain refinement associated with laser melting and rapid solidification. The electrochemical property, mainly pitting corrosion resistance, has been carried out in Hanks salt balanced physiological solution using standard potentiodynamic polarization testing. A higher corrosion potential of −0.21 V was achieved for LTS. At the optimium treating value of laser fluence (140 J cm−2), the energy dispersive x-ray analysis showed about a 30% decrease of vanadium. The contact angle measurements also indicated an improved surface wettability (i.e., hydrophilicity) characteristic at 35°. Finally, the cell culture studies provided a useful tool to investigate the morphology and cell cytotoxicity.The effect of Nd:yttrium-aluminum-garnet laser on the microtopography and physicochemical properties of Ti6Al4V alloy are investigated in the view of biomedical applications. The surface roughness and hardness for laser treated samples (LTS) at 140 J cm−2 were measured 7±0.02 and 825 vickers hardness number, respectively. This superior microhardness value is attributed to grain refinement associated with laser melting and rapid solidification. The electrochemical property, mainly pitting corrosion resistance, has been carried out in Hanks salt balanced physiological solution using standard potentiodynamic polarization testing. A higher corrosion potential of −0.21 V was achieved for LTS. At the optimium treating value of laser fluence (140 J cm−2), the energy dispersive x-ray analysis showed about a 30% decrease of vanadium. The contact angle measurements also indicated an improved surface wettability (i.e., hydrophilicity) characteristic at 35°. Finally, the cell culture studies provided a useful tool to...

Fundamentals of Biomedical Applications of Biomorphic SiC

In recent years, silicon carbide (SiC) has become an increasingly important material in numerous applications including high frequency, high power, high voltages, and high temperature devices. It is used as a structure material in applications which require hardness, stiffness, high temperature strength (over 1000° C), high thermal conductivity, a low coefficient of thermal expansion, good oxidation and corrosion resistance, some of which are characteristic of typical covalently bonded materials. It seems that SiC can create many opportunities for chemists, physicists, engineers, health professional and biomedical researches (Presas et al., 2006; Greil, 2002; Feng et al.2003). Silicon carbides are emerging as an important class of materials for a variety of biomedical applications. Examples of biomedical applications discussed in this chapter include bioceramic scaffolds for tissue engineering, biosensors, biomembranes, drug delivery, SiC-based quantum dots and etc. Although several journals exist that cover selective clinical applications of SiC, there is a void for a monograph that provides a unified synthesis of this subject. The main objective of this chapter is to provide a basic knowledge of the biomedical applications of SiC so that individuals in all disciplines can rapidly acquire the minimal necessary background for research. A description of future directions of research and development is also provided.

Evaluation of mechanical and electrochemical properties of laser surface modified Ti–6Al–4V for biomedical applications: in vitro study

Abstract The effect of Nd:YAG laser surface modification on the microtopography and physicochemical properties of Ti–6Al–4V alloy has been investigated with a view of biomedical applications. The surface roughness and hardness of laser treated samples at 140 J cm−2 were found to be 7±0·02 and 825 VHN respectively. The superior microhardness value can be attributed to grain refinement associated with laser melting and rapid solidification. The electrochemical property, mainly pitting corrosion resistance, has been carried out in Hank’s salt balanced physiological solution using standard potentiodynamic polarisation testing. A higher corrosion potential of −0·21 V was achieved for laser treated samples. At the optimum of laser fluence (140 J cm−2), energy dispersive X-ray analysis showed about a 30% decrease in vanadium content. Contact angle measurements also indicated improved surface wettability (i.e. hydrophilicity) characteristics at 35°. Finally, cell culture studies provided a useful tool to investigate the morphology and cell cytotoxicity of the laser treated surfaces.

Enhanced Entrapment and Improved in Vitro Controlled Release of N‐Acetyl Cysteine in Hybrid PLGA/Lecithin Nanoparticles Prepared Using a Nanoprecipitation/Self‐Assembly Method

To enhance the in vitro controlled release of N‐acetyl cysteine (NAC), hybrid nanoparticles (NPs) consisting of a poly(lactide‐co‐glycolide) (PLGA) hydrophobic core and a soybean lecithin mono‐layer coat were prepared. Hybrid NPs were synthesized using a nanoprecipitation combined with self‐assembly method. To characterize prepared NPs, zeta potential, diameter size, surface morphology, disparity, and lipid coating of hybrid NPs were detrmined using dynamic light scattering, scanning electron microscope and Fourier transform infrared spectroscopy techniques. High‐performance liquid chromatography was employed to evaluate drug loading yield and encapsulation efficiency and in vitro drug release of prepared NPs. The cytotoxicity of hybrid NPs was assayed on normal L929 alveolar epithelial cells using MTT method. Prepared NPs were found to disperse as individual NPs with a well‐defined spherical shape. The hydrodynamic diameter and surface charge of NAC‐loaded hybrid NPs were 81.8 ± 1.3 nm and −33.1 ± 2.1 mV, respectively. Drug loading yield and encapsulation efficiency of NAC‐loaded hybrid NPs were found to be 38 ± 2.1% and 67 ± 5.7%, respectively. Prepared hybrid NPs showed no significant cytotoxicity against normal alveolar cells. Our data suggest that the hybrid PLGA‐lecithin NPs may be An efficient controlled release drug delivery system for NAC. J. Cell. Biochem. 118: 4203–4209, 2017.

Dynamic study of PLGA/CS nanoparticles delivery containing drug model into phantom tissue using CO2 laser for clinical applications

In this study, cationic nanoparticles (NPs) were prepared by coating chitosan (CS) on the surface of PLGA NPs. To our knowledge most of the work in the field of drug delivery systems using lasers has been performed using short pulses with micron and submicron durations. We carried out an experiment using superlong PLS-R (10 ms) and CW CO₂ laser modes on simulated drug-biogelatin model where drug was encapsulated by PLGA/CS NPs. Maximum depth of drug containing cavitation was achieved faster at higher powers and shorter irradiation time in CWC mode. We believe that the main mechanism at work with superlong pulses is both photothermal due to vaporization and photomechanical due to photophoresis and cavitation collapse. In the case of CW, however, it is purely photothermal. Thus, drug molecules can be transported into tissue bulk by thermal waves which can be described by the Ficks law in 3-D model for a given cavity geometry and the mechanical waves, unlike only by pure photomechanical waves (i.e. photoacoustically) as with short pulses. Therefore, our studies could offer an alternative for currently existing method for drug delivery.

Analysis of Bioadhesivity of Osteoblast Cells on Titanium Alloy Surface Modified by Nd:YAG Laser

The surface microtopography and physical–chemical results of Ti6Al4V alloy were investigated in relation to bone cell response. Nd:YAG-laser-treated surfaces with (1.06 μm wavelength, 200 μs pulse duration, and a fluence of 140 Jcm−2 exhibited an improved hydrophilic behavior due to a lower contact angle compared with the control sample. Cell spreading on the implanted specimens was analyzed by scanning electron microscope (SEM), and their condition in a specific area was studied for 10 cells from three separate regions on the same specimen using an Image J Program software. The in vitro the in vivo tests provided some useful clinical and pathological information such as the number of adhered cells on the implant. The light microscopy assessment consisted of a complete morphological description of tissue response to the implants with different surface topography.

Silicon Carbide: A Biocompatible Semiconductor Used in Advanced Biosensors and BioMEMS/NEMS

In the last decade, there has been a tremendous development in the field of miniaturization of chemical and biochemical sensor devices. Microelectromechanical systems (MEMS) refer to microscopic devices that have a characteristic length of less than 1 mm but more than 100 nm and combine electrical and mechanical components. Nanoelectromechanical systems (NEMS) refer to nanoscopic devices that have a characteristic length of less than 100 nm and combine electrical and mechanical components. In mesoscale devices, if the functional com‐ ponents are on microor nanoscale, they may be referred to as MEMS or NEMS, respective‐ ly. These are referred to as an intelligent miniaturized system comprising sensing, processing, and/or actuating functions and combine electrical and mechanical components. The acronym MEMS originated in the USA. The term commonly used in Europe is micro system technology (MST) and in Japan, the term is micromachines. Another term generally used is micro/nanodevices.

Synthesis and release study of tissue plasminogen activators (tPA) loaded chitosan coated poly (lactide-co-glycolide acid) nanoparticles

Polyelectrolyte coated nanopatrticles (NPs) interact with bioactive molecules such as, peptides, proteins or nucleic acids and have been proposed as delivery systems for these molecules. In this study, cationic NPs were prepared by coating chitosan (CS) on the surface of PLGA NPs. The tPA encapsulated PLGA and PLGA/ CS NPs were fabricated via the W/O/W double emulsion solvent evaporation surface coating method. The CS coating was confirmed by zeta potential and FTIR. The surface morphology of NPs was also studied by TEM. In vitro drug release experiments of tPA encapsulated PLGA and PLGA/CS are determined by HPLC and showed a sustained release profile for three days with little initial burst release for PLGA/CS NPs. The mean particle size and encapsulation efficiency of tPA NPs were in the range of 280-360 nm and 46.7%±1.56, 50.8%±1.09, respectively. The encapsulation efficiency and the particles size were increased as a result of coating with CS. The release kinetics was evaluated by fitting the experimental data to standard release equation (Higuchie equation). This model was used to find the best fit for NPs. These results suggest that PLGA/CS NPs could serve as an effective vehicle for local delivery of tPA.

Fabrication, Visualization and Analysis of Fluorescein Sodium Encapsulated PLGA@CS Nanoparticles as Model for Photothermomechanical Drug Delivery Using Pulsed 532 nm Laser

PLGA/CS nanoparticles containing fluorescein sodium as drug model were synthesized and characterized to investigate the feasibility of laser-induced drug delivery using pulse 532 nm. The main objective was to investigate the photothermally-induced mechanical force for transporting the nanoparticles. An argon laser was used to excite the fluorescence of the samples after irradiation. The preliminary results indicated that the drug nanoparticles encapsulated trapped by the cavitation bubbles can be transported by photothermomechanical effect. Different regions of interactions are defined and while in our case, the thermoelastic does not apply due to higher fluences, vaporization and laser-induced thermal breakdown (LITB) including the plasma formation and shock waves played an important and major role. Threshold fluences of 2.8, 18 and 102 Jcm-2 corresponding to 0.28, 1.8 and 10 GWcm-2 and 3.8, 30, and 171 MPa are determined for ablation, vaporization and LITB mechanisms respectively. The secondary microbubbles due to explosion of the primary transient cavitation bubbles played a key role in delivery process. Despite the dominant argon laser brightness, the laser-induced fluorescence spectroscopy (LIFS) demonstrated the fluorescence emission of the cavitation bubbles carrying due to the drug nanoparticles entrapped within the biogelatin after exposure to laser radiation, the irradiation, which confirms the possibility of transport of drug nanoparticles by laser cavitation. Finally, it is suggested that the nature of such photothermal and photo non-thermal mechanical effects is governed and influenced by determining and criticizing in terms of the type of nanomaterial as well as their synthesis process engineering and fabrication as they can be made case sensitive by selecting different types of materials for a specific application.

In Vitro Assessment of Poly (Vinyl Alcohol) Film Incorporating Aloe Vera for Potential Application as a Wound Dressing

ABSTRACT Since skin tissue acts as a vital protective barrier between the body and the external atmosphere, the repair or regeneration of skin injuries serves as a great challenge in regenerative medicine. Herein, hydrogel films composed of poly vinyl alcohol (PVA) and aloe vera (AV) extracted gel were prepared and characterized for wound dressing application. The physical and morphological properties, water absorption capacity, biodegradation behavior, and water transmission rate were characterized for several variations in the AV content (0–50%). The cytocompatibility of the films, as well as cell morphology in response to different films, was assessed using MTT assay and SEM, respectively. According to the results, AV incorporation improved the surface morphology, water absorption capacity, in vitro degradation rate, and water vapor permeability of the PVA films. However, these properties were affected by the AV content. The mechanical properties of the films were enhanced by introducing AV up to 30%, and then decreased significantly with further AV increase. Evaluation of fibroblast proliferation showed that AV can positively improve the bioactivity of the films without any cytotoxicity. In conclusion, the results demonstrated that PVA/AV optimized hydrogel film can be suggested as promising wound dressings for improving wound treatment.