ABSTRACT
The present report proposes a more rational hyaluronic acid (HA) conjugation protocol that can be used to modify the surface of the superparamagnetic iron oxide nanoparticles (SPIONs) by covalently binding the targeting molecules (HA) with glutamic acid as a molecular linker on peripheral surface of SPIONs. The synthesis of HA-Glutamic Acid (GA)@SPIONs was included oxidization of nanoparticle's surface with H2O2 followed by activation of hydroxyl group and reacting glutamic acid as an intermediate molecule demonstrating transfection of lung cancer cells. Fourier transform infrared (FTIR) and zeta-potential studies confirmed the chemical bonding between amino acid linker and polysaccharides. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity assay showed that HA-SPIONs-treated cells remained 82.9% ± 2.7% alive at high particle dosage (200 µg/mL iron concentration), whereas GA-SPIONs and bare SPIONs (B-SPIONs) treated cells had only 59.3% ± 13.4% and 26.5% ± 3.1% survival rate at the same conditions, respectively. Confocal microscopy analysis showed increased cellular internalization of HA-SPIONs compared to non-interacting agarose coated SPIONs (AgA-SPIONs).
ABSTRACT
In this study, hybrid magnetofluorescent structures composed of organic moiety of poly(TMSMA-r-PEGMA) for biomolecules-resistant surfaces and methyl methacrylate for conjugation of europium complex inorganic moiety of magnetic nanoparticles are reported. Lanthanide complex of europium ion with 4,4,4-Trifluoro-1-(2-naphthyl)-1,3-butanedione (NTA) and trioctylphosphine oxide (TOPO)[Eu(NTA)3(TOPO)3] were incorporated into poly(TMSMA-r-PEGMA-r-MMA) matrix. Afterward, superparamagnetic iron oxide nanoparticles (SPIONs) were coated with as prepared polymeric europium complex (PEC) to construct hierarchical structure of magnetofluorescent probe. The PL spectra of the PEC@SPIONs excited by UV light showed characteristic emission behavior with a hypersensitive transition 5D0 --> 7F2 at 621 nm. About a 20% quenching in the intensity of the emission peak at 621 nm was found after the addition of SPIONs. Interestingly, when the concentration of PEC against SPIONs is increased, the hypersensitive transition 5D0 --> 7F2 at 621 nm is linearly increased, while 5D1 --> 7F6 at 700 nm is linearly decreased. The cytotoxic effect of PEC@SPIONs was evaluated with U373MG cell by the MTT assay of PEC@SPIONs in cell proliferation. The cell viability in the range of 10-200 ug/ml was more than 80%. No significant difference in cell proliferation until the concentration of 300 ug/ml (77.61 ± 3.33%). The cellular uptake of PEC@SPIONs evaluated by confocal microscopy showed that the magnetofluorescent nanoparticles were internalized extensively in the cytoplasmic region.
Subject(s)
Europium/chemistry , Fluorescent Dyes/chemistry , Ketones/chemistry , Magnetite Nanoparticles/chemistry , Methacrylates/chemistry , Naphthalenes/chemistry , Polyethylene Glycols/chemistry , Trimethylsilyl Compounds/chemistry , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Survival/drug effects , Fluorescent Dyes/pharmacokinetics , Fluorescent Dyes/toxicity , Humans , Magnetite Nanoparticles/toxicity , Nanotechnology , Organophosphorus Compounds/chemistryABSTRACT
A new self-assembly method for the fabrication of periodic structures using monodispersed polystyrene nanoparticles matrix was developed. The self-assembly could be formed into polystyrene nanoparticles matrix constructed by the face centered cubic (FCC) structure and hexagonally close-packed (HCP) monolayer. The polystyrene nanoparticles have been prepared by emulsion polymerization. Several aspects were investigated by using different techniques: Particle sizer, TEM and DSC etc. In this study, the feasibility of synthesizing nanoparticles of 550 nm polystyrene with a perfect spherical shape and a narrow size distribution was demonstrated. Subsequently, an investigation of the self-assembly of polystyrene nanospheres to built up an opal structure was performed. This arrangement was achieved by gravitational sedimentation under vacuum. The face centered cubic structure was identified by using SEM, thus that the different facet type {100}, {110} and {111} were composed. The self-assembly of monodispersed polystyrene nanoparticles in 2D structure was fabricated in the structure of hexagonally close-packed monolayer.
ABSTRACT
Falls are one of the main concerns of the elderly. Proper postural adjustments to maintain balance involve the activation of appropriate muscles to produce force and to relocate the center of body mass (CoM). In this study, biomechanical aspects of dynamic postural responses against forward perturbations were experimentally determined by simultaneous measurements of joint angles and EMG activations. Thirteen young and healthy volunteers took turns standing on a flat platform, and were directed to move in the forward direction by an AC servo-motor set at two different speeds (0.1 and 0.2 m/s). Joint motions were recorded, and they followed the sequence of ankle dorsiflexion, knee flexion, and then hip flexion during the later acceleration phase (AP) in order to maintain postural balance against forward perturbation. Tibialis anterior for the ankle dorsiflexion and biceps femoris for the knee flexion were activated during the second half of the AP as the primary muscles to recover balance. In addition, gastrocnemius, which was related to ankle plantarflexion, and rectus femoris, which was related to knee extension, were activated to maintain balance. Movements of the center of plantar pressure and ground reaction forces in fast-speed perturbation were significantly larger than those in slow-speed perturbation. As a result, the ankle strategy was used for slow-speed perturbation, but the mixed strategy consisting of both ankles and hip were used for fast-speed perturbation.
