Advances in Science and Technology Vol. 86

Abstract: Interactive textiles have the capability to interact with the user, which means they embed sensors, local intelligence and actuators to achieve this goal. This interactivity requires to dispose of smart textiles, made of smart materials, completing the often used wording “Smart fabrics and interactive textiles” or SFIT. The term smart is used to refer to materials that sense and respond in a pre-defined way to environmental stimuli. Heath monitoring is an important field of application for smart textiles. Results and sometimes products such as shirts measuring electrocardiogram, respiration or body temperature have been achieved and are examples of state-of-the-art from the monitoring point-of-view. Making use and combining these signals to derive higher-level information and to provide feed-back in a comprehensive way to the user or to a caregiver are the starting point to interactivity. Sometimes, the textile provides itself interactivity; more often it is combined with discrete electronics and sometimes organic electronics. The convergence between textiles, smart materials and information technology is explored in the case of health monitoring. Several projects and their results are used to illustrate the progress in the field.

Abstract: Starburst triblock copolymers consisting of 8-arm poly(ethylene glycol) (8-arm PEG), poly(L-lactide) (PLLA) or its enantiomer poly(D-lactide) (PDLA) and terminal PEG, 8-arm PEG-b-PLLA-b-PEG (Stri-L) and 8-arm PEG-b- PDLA-b-PEG (Stri-D), were synthesized. An aqueous solution of a 1:1 mixture (Stri-Mix) of Stri-L and Stri-D assumed a sol state at room temperature, but instantaneously formed a physically cross-linked hydrogel in response to increasing temperature. The resulting hydrogel exhibited a high storage modulus at 37 °C. The rapid temperature-triggered hydrogel formation, high mechanical strength, and degradation behavior render this polymer system suitable for use in injectable drug delivery system or a biodegradable scaffold for tissue engineering.

Abstract: Due to the merits of zirconia ceramics such as high strength, toughness, abrasion resistance, and chemical stability in vivo, yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) are currently used in the femoral head of hip prostheses. However, this material has a limited applications range because it is a bioinert material that does not interact with bone tissue and thus does not easily integrate directly in the bone. Therefore, we need to add different material’s layer which enables in vivo formation of bone-like apatite layer that exhibits bioactivity , composite compound bioactive ceramics, and facilitates interactions and integration in bone tissue. In addition, by developing a surface structure that enhances mechanical bonding, this material can be expected to be used as an alternative aggregate under load bearing conditions. In the present study, various method were carried out with the objective of controlling interactions between zirconia ceramics and the body such as structural design of the material surface, addition of bioactivity using reagents treatment, confirmation of formation of the apatite layer using immersion in simulated body fluid, wettability testing and develop structure with mechanical properties equal to bone strength.

Abstract: In this study, nanostructured Ce- and Sm-substituted Ca10(PO4)6(OH)2 samples have been synthesized using an aqueous sol-gel chemistry route. For the characterization of obtained specimens, the XRD, SEM, UV-visible reflection and IR spectroscopy and luminescence measurements were recorded. It was shown that phase purity of the end products highly depends on the amount of lanthanide element. The reflectance of lanthanide-substituted calcium hydroxyapatite samples is wavelength independent in the wavelength range of 450-800 nm and equal almost 100%. The cerium-substituted samples show a significant decrease of transmission at ~300 nm. The characteristic samarium absorption line (~430 nm) is evident in the UV-vis reflection spectra of samarium-substituted hydroxyapatites.

Abstract: Titanium and its alloys are widely used as orthopedic and dental implant materials. However, they cannot bond with bone directly and promote new bone formation. It is desirable to provide a bone-bonding ability to Ti metal and its alloys. This ability can be achieved by surface modification such as chemical treatments. The aim of this study was to evaluate in SBF the apatite-forming ability of Ti subjected to different pre-treatments. Titanium laminated and samples Ti obtained by powder metallurgy were compared. The pretreatments studied were the alkali-treated; alkali and heat-treated; acid and alkali-treated; alkali-CaCl2-heat and hot water treatment. The groups were soaking in SBF for 1, 3, 6 and 9 days in equipment with constant agitation at 36.5°C. The obtained coatings were analyzed by diffuse reflectance spectroscopy on the infrared (DRIFT) and scanning electron microscopy (SEM). The apatite formation was present in all groups; however, the apatite-coating was more effective in samples obtained by powder metallurgy.

Abstract: In orthopaedic surgery the reattachment of tendon to bone requires suture materials that have stable and durable properties to allow healing at the tendon-bone interface. Failure rates of this type of surgery can be as high as 25%. While the tissue suture interface is a weak link, proportions of these failures are caused by in-vivo abrasion of the suture with bone and suture anchor materials. Abrasion of the suture material results from the movement of the suture through the eyelet by the surgeon during surgery, or with limb movement after surgery as the suture is not rigidly restrained within the eyelet. During movement the suture is subjected to bending and frictional forces that can lead to fatigue induced failure. This paper investigates the mechanism of bending abrasion fatigue induced failure of number two grade braided sheath only and braided sheath/multifilament core sutures. Sutures were oscillated over a stainless steel wire at low frequency under load in a dry state to simulate the bending and frictional forces between suture and eyelet. Failure mechanism was determined by video microscopy of the suture during abrasion combined with optical microscopy analysis of partially and fully abraded sutures. Braided only structures had high friction loading on the small number of fibres at the abrasion interface. This caused rapid single fibre breakages that accumulate to cause suture failure. The addition of ultra-high molecular weight polyethylene core fibres to a braided suture distributed the applied load across multiple fibres at the abrasion interface. This improved abrasion resistance by 15-20 times that of braided sheath alone.

Abstract: Although improvements have been made in implant design to increase bone formation and promote successful osseointegration using nanotechnology, the clinical diagnosis of early bone growth surrounding implants remains problematic. The development of a device allowing doctors to monitor the healing cascade and to diagnose potential infection or inflammation is necessary. Biological detection can be examined by the electrochemical analysis of electron transfer (or redox) reactions of extracellular matrix proteins involved in bone deposition and resorption. The use of nanomaterials as signal amplifiers in electrochemical sensors has greatly improved the sensitivity of detection. Nanotechnology-enabled electrochemical sensors that can be placed on the implant surface itself show promise as self-diagnosing devices in situ, possibly to detect new bone growth surrounding the implant and other cellular events to ensure implant success.

Abstract: In this paper we discuss the potential of nonspherical gold nanoparticles to serve as extremely bright light scattering labels for the detection of disease through several centimeters of tissue in humans in vivo. However, attempts to realize this important potential of gold nanoparticles have been limited by the broad spectroscopic linewidths usually observed. We identify the origin of this broadening as inhomogeneous broadening due to the extreme sensitivity of the surface plasmon resonance to the nanoparticle aspect ratio.

Abstract: Immobilizing bioactive molecules on the materials surfaces is one of the main strategies for creating functional bio-interfaces. In these kinds of bio-interfaces, the density of immobilized functional groups and the following physicochemical factors such as roughness, polarity and electrical charge have been thought important variables for regulating biological responses such as cell adhesion and differentiations. Here in this study, differences between rigidity and dynamically immobilized bioactive molecules on the biological responses will be discussed. In order to develop dynamic bio-interfaces, a polyrotaxane based block-copolymer containing clickable azide groups for conjugating various bioactive molecules was designed. Cell adhesive RGD peptide was then conjugated with the azide group by click reaction on both dynamic and rigid surfaces. As a result, cell adhesive RGD peptide immobilized on the dynamic bio-interfaces shows larger initial cell adhesion area, indicating that molecular dynamics of surface chemical groups is another important variable for the regulation of biological responses.