Mechanical properties, biological behaviour and drug release capability of nano TiO2-HAp-Alginate composite scaffolds for potential application as bone implant material.

Nanocomposite scaffolds of TiO2 and hydroxyapatite nanoparticles with alginate as the binding agent were fabricated using the freeze drying technique. TiO2, hydroxyapatite and alginate were used in the ratio of 1:1:4. The scaffolds were characterized using X-ray diffraction, fourier transform infrared spectroscopy, and scanning electron microscopy. The biocompatibility of the scaffolds was evaluated using cell adhesion and MTT assay on osteosarcoma (MG-63) cells. Scanning electron microscopy analysis revealed that cells adhered to the surface of the scaffolds with good spreading. The mechanical properties of the scaffolds were investigated using dynamic mechanical analysis. The swelling ability, porosity, in vitro degradation, and biomineralization of the scaffolds were also evaluated. The results indicated controlled swelling, limited degradation, and enhanced biomineralization. Further, drug delivery studies of the scaffolds using the chemotherapeutic drug methotrexate exhibited an ideal drug release profile. These scaffolds are proposed as potential candidates for bone tissue engineering and drug delivery applications.

Nanomaterial-Based Approaches for Prevention of Biofilm-Associated Infections on Medical Devices and Implants.

Biofilm formation is a major problem in medical device-related infections leading to failure of implant-based therapies. Though various conventional approaches to counter biofilm formation like physical and/or mechanical removal, chemical removal, and the use of antimicrobials exist, they fail due to increased resistance of biofilms. This review discusses various nanomaterial-based approaches such as the use of metallic and metal oxide nanoparticles- and polymer-based nanocomposites, which are currently being developed for prevention and treatment of biofilms. Nanoparticles of transition metals and their oxides are toxic to microorganisms and exhibit their toxicity through the generation of reactive oxygen species at concentrations that are non-toxic to eukaryotic cells. Other approaches include the entrapment of bioactive agents in polymer/ceramic nanoparticles, for enhanced anti-biofilm activity due to the synergistic effect between them. These nanomaterial-based approaches could play an important role in control and eradication of biofilm related infections and complications associated with medical devices and implants.

Anti-biofilm efficacy of low temperature processed AgCl-TiO2 nanocomposite coating.

Biofilms are a major concern in the medical settings and food industries due to their high tolerance to antibiotics, biocides and mechanical stress. Currently, the development of novel methods to control biofilm formation is being actively pursued. In the present study, sol-gel coatings of AgCl-TiO2 nanoparticles are presented as potential anti-biofilm agents, wherein TiO2 acts as a good supporting matrix to prevent aggregation of silver and facilitates its controlled release. Low-temperature processed AgCl-TiO2 nanocomposite coatings inhibit biofilm formation by Escherichia coli, Staphylococcus epidermidis and Pseudomonas aeruginosa. In vitro biofilm assay experiments demonstrated that AgCl-TiO2 nanocomposite coated surfaces, inhibited the development of biofilms over a period of 10days as confirmed by scanning electron microscopy. The silver release kinetics exhibited an initial high release, followed by a slow and sustained release. The anti-biofilm efficacy of the coatings could be attributed to the release of silver, which prevents the initial bacterial adhesion required for biofilm formation.

Mesoporous TiO2 nanoparticles containing Ag ion with excellent antimicrobial activity at remarkable low silver concentrations.

Mesoporous Ag-TiO2 nanoparticles with TiO2 homogenous anatase crystalline phase was synthesized using a one-pot sol-gel method. The sample was calcined at 100 degrees C and characterized by XRD, HR TEM, EDAX, IR spectroscopy, DRS, N2 adsorption-desorption isotherm and Brunauer-Emmett-Teller (BET) analysis. The BET surface area of the sample was 266 m2/g and the crystallite size as calculated using Scherrer formula was 3.76 nm. The Ag-TiO2 nanoparticles exhibited excellent antimicrobial activity against representative Gram-positive and Gram-negative bacterial cultures and Candida albicans. Complete inhibition of microorganisms was achieved at a very low Ag-TiO2 concentration, in the range of 1.0 to 20 microg/mL (effective Ag concentrations were 11.7 to 234 ppb) in less than 2 h under ambient conditions, without the requirement of photoactivation. Silver ion release studies showed that about 18% of silver ions were present in solution. Thus, it may be inferred that the antimicrobial activity is due to Ag ions released from the TiO2 matrix. The mesoporous nature and antimicrobial activity at low concentrations without photoactivation are important aspects which make this material an excellent candidate for potential application as disinfectant and/or antimicrobial agent.