Nanocelluloses from jute fibers and their nanocomposites with natural rubber: Preparation and characterization.

Crosslinked natural rubber (NR) nanocomposites were prepared using cellulose nanowhiskers (CNWs) that were extracted from bamboo pulp residue of newspaper production, as the reinforcing phase. The coagulated NR latex containing bamboo nanowhiskers (master batch) was compounded with solid NR and vulcanizing agents using a two-roll mill and subsequently cured to introduce crosslinks in the NR phase. No evidence of micro-scaled aggregates of cellulose nanowhiskers in NR matrix was observed in Scanning Electron Microscopy (SEM) images. The addition of CNWs had a positive impact on the tensile strength, E-modulus, storage modulus, tan delta peak position and thermal stability of the crosslinked NR. Theoretical modeling of the mechanical properties showed a lower performance than predicated and therefore further process optimization and/or compatibilization are required to reach the maximum potential of these nanocomposites.

Crosslinked natural rubber nanocomposites reinforced with cellulose whiskers isolated from bamboo waste: Processing and mechanical/thermal properties

Chitosan as an adhesive

For the past few decades, tissue sealants and adhesives have been developed as an alternative to sutures and staples to close and seal wounds or incisions. These materials are advantageous because of their ease of use, short application time and minimal tissue damage, making them suitable for minimally invasive procedures. However, there is a large gap between the amount of research into tissue adhesives and the number of products available. To bridge this gap, there is a need to better understand the challenges to clinical translation of tissue adhesives. In particular, adhesive design must be informed by a deep understanding of the target tissue’s surface characteristics and environment, which vary considerably among tissue types. Moreover, understanding and monitoring the long-term performance of a material post-implantation is crucial; this includes monitoring the chemical and physical properties of the implanted adhesives over time, tissue responses and the resultant changes in adhesion and cohesion. In addition, early-stage consideration of the unmet clinical need and the regulatory and development paths could lower the barriers in the development cost and effort, facilitating clinical translation. In this Review, we identify challenges in the development of tissue adhesives and provide design criteria to translate tissue-adhesive technologies into clinical practice. To design and construct tissue adhesives tailored for site-specific actions, it is necessary to understand the interaction between the adhesive and the targeted tissue. In this Review, the development of adhesives for soft tissues is outlined, including discussions of in vivo properties and biocompatibility, as well as the key design criteria for accelerating their translation into clinical practice.

Overcoming the translational barriers of tissue adhesives

Hydroxyapatite is a calcium phosphate intensively proposed as a bone substitution material because of its resemblance to the constituents of minerals present in natural bone. Since hydroxyapatite’s properties are mainly adequate for nonload bearing applications, different solutions are being tested for improving these properties and upgrading them near the target values of natural bone. On the other hand, starch (a natural and biodegradable polymer) and its blends with other polymers have been proposed as constituents in hydroxyapatite mixtures due to the adhesive, gelling, and swelling abilities of starch particles, useful in preparing well dispersed suspensions and consolidated ceramic bodies. This article presents the perspectives of incorporating starch and starch blends in hydroxyapatite materials. Based on the role of starch within the materials, the review covers its use as (i) a polymeric matrix in hydroxyapatite composites used as adhesives, bone cements, bone waxes, drug-delivery devices or scaf...

Progress in Hydroxyapatite–Starch Based Sustainable Biomaterials for Biomedical Bone Substitution Applications

In the field of tissue engineering there is always a need for new engineered polymeric biomaterials which have ideal properties and functional customization. Unfortunately the demands for many biomedical applications need a set of properties that no polymers can fulfill. One method to satisfy these demands and providing desirable new biomaterials is by mixing two or more polymers. In this work, random nanofibrous blends of poly (e-caprolactone) (PCL) and polyglycolic acid (PGA) with various PCL/PGA compositions (100/0, 80/20, 65/35, 50/50, and 0/100) were fabricated by electrospinning method and characterized for soft-tissue engineering applications. Physical, chemical, thermal, and mechanical properties of PCL/PGA blend nanofibers were measured by scanning electron microscopy (SEM), porosimetry, contact angle measurement, water uptake, attenuated total reflectance Fourier transform-infrared spectroscopy (ATR-FT-IR), X-ray diffraction (XRD), differential scanning calorimetric (DSC), dynamic mechanical thermal analysis (DMTA), and tensile measurements. Morphological characterization showed that the addition of PGA to PCL results in an increase in the average diameter of the nanofibers. According to these results, when the amount of PGA in the blend solution increased, the hydrophilicity and water uptake of the nanofibrous scaffolds increased concurrently, approaching those of PGA nanofibers. Differential scanning calorimetric studies showed that the PCL and PGA were miscible in the nanofibrous structure and the mechanical characterization under dry conditions showed that increasing PGA content results in a tremendous increase in the mechanical properties. In conclusion, the random nanofibrous PCL/PGA scaffold used in this study constitutes a promising material for soft-tissue engineering. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Investigating the effect of PGA on physical and mechanical properties of electrospun PCL/PGA blend nanofibers

Bioadhesives are high molecular weight, biocompatible, biodegradable polymers used to join two surfaces where at least one of them is a living tissue. Bioadhesives are used for two main purposes, first as a replacement for surgical sutures and second as a substitute for traditional drug dosage systems. There are several considerations and issues associated with the use of biopolymers in suture-less surgery as well as in drug delivery systems. Herein is presented a review of bioadhesives; the focus being on the adhesive properties. Bioadhesives for tissue joining are considered first, along with their main characteristics and advantages. That is followed by a discussion on the use of bioadhesives as drug carriers for efficient drug delivery.

Bioadhesives: A Review

Polymer/clay nanocomposites have some unique properties due to combination of flame resistance and improved mechanical and thermal stability properties which are important to enhance the material quality and performance. The objective of this work was to investigate the effect of organically modified montmorillonite (org-MMT) on the thermal and flame retardant as well as hardness and mechanical properties of the nanocomposites based on the natural rubber (NR). It was shown that by the addition of 3 wt % of org-MMT to NR, its aging hardness rise was decreased more than 55% and the ignition time was delayed about 150%. The reduction in heat release rate peak value was equal to 54% compared to the pristine NR. Addition of org-MMT improved the thermal stability of the NR. Furthermore, nanocomposites which were calendared before curing showed much more thermal stability and fire resistance than those which contained similar amount of organoclay. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Thermal stability, aging properties, and flame resistance of NR‐based nanocomposite

The free-radical redox-initiated aqueous solution polymerization of fully and partially neutralized acrylic acid was carried out at room temperature under full exposure to air The effect of neutralization degree on the polymerization rate and product properties was studied Increasing neutralization of the reaction mixture with sodium hydroxide resulted in greater conversion of acrylic acid to sodium acrylate The rate of polymerization, determined from a gravimetric off-line water removal technique, was shown to decrease significantly with decreasing degree of neutralization Molecular weight also decreased with decreasing degree of neutralization The glass transition temperature and hydrophilicity of the polymer product decreased with increasing degree of neutralization In-line infrared monitoring was also used to monitor the reaction progress and was shown to be an effective tool for this purpose

Samaneh Khanlari

Papers

Investigating the effect of PGA on physical and mechanical properties of electrospun PCL/PGA blend nanofibers

Bioadhesives: A Review

Thermal stability, aging properties, and flame resistance of NR‐based nanocomposite

Effect of pH on Poly(acrylic acid) Solution Polymerization

Effect of surface charge and roughness on ultrafiltration membranes performance and polyelectrolyte nanofiltration layer assembly