Petroleum based plastics have been produced by the chemical industries since the early 1930s. These products are part of a very important group of materials, because their high molecular weight and low reactivity make them suitable for cases in which durable and inert materials are needed. But these advantageous properties of plastics are also their disadvantages, since they do not degrade and thus, they remain unchanged at the site of disposal. Therefore, over the past years, the use of plastics for different purposes and in various equipments has caused many problems related to disposal of solid wastes. It has been shown that petroleum based plastics accumulate in the environment at a rate of 25 million tons per year. Considering the growing problems caused by disposal of petroleum based plastics, that are non-degradable and remain in environment for many years, and in order to reduce the amount of plastic waste, worldwide programs such as recycling, incineration and source reduction have been initiated. Beside these strategies, which have their own special problems, biodegradable plastics have been the focus of extensive researches. In fact, biodegradable polymers, which are after disposal decomposed by many enzymes existing in the environment, offer the best solution to the environmental hazard caused by conventional plastics.

Synthetic polyelectrolyte are used in water and wastewater treatment systems as coagulant and filtration aids. Most of these polymers do not have a short term biodegrable property and some of them cause cancer and genetic mutation in human. In this study, the performance of different natural polyelectrolytes, as replacement materials for synthetic polyelectrolytes, in water treatment and effective parameters on their performance were evaluated. As a result, a suitable operational condition for water treatment was determined. The experimental results showed that biopolymers such as chitosan, sodium alginate and starch can be used as coagulating aid in water treatment system for reduction of turbidity. In comparison with starch and sodium alginate, chitosan has better performance for reduction of turbidity and besides, its operational range is wider. Also, the coagulated particles were bigger and stronger than those resulting from starch and sodium alginate. Therefore, using chitosan is more effective in settling and clarification operations of water treatment.

The growing need for materials suitable for sustainable development and improved healthcare has motivated scientists and engineers worldwide to investigate biopolymers. Success in this direction hinges on our ability to tailor properties of biopolymers and find cost effective processing methods.Authors applied a versatile nanofiber production technique known as electrospinning to process a variety of nanoassemblies with high specific volume and porosity from biocompatible, biodegradable and nontoxic natural biopolymers. These nanofibers and nanowebs with tailored physical, chemical, biological and mechanical properties are attractive for designing ecologically friendly products in a range of applications from personal care to healthcare such as hospital apparel, drug delivery systems, and scaffolds for tissue engineering and tissue regeneration.The present study reports on electrospinning of natural biopolymers chitosan and alginate and their blends with other biocompatible polymers. Several solvent systems and different processing conditions are investigated for effective electrospinning of biopolymers. Optimum processing conditions for producing desired electrospun nanowebs are discussed.

Hemostasis refers to the harmless practice of any surgical procedure or any other chronic ulcer which immediately requires therapy to prevent substantial blood loss and mortality from extreme hemorrhage in surgery/emergency conditions. Various natural, semi-synthetic as well as synthetic biopolymers are available with excellent hemostatic activity and further offer biodegradable and biocompatible nature with the live cells. Now a day’s biopolymers have become the most significant hemostatic agents used in emergency operations and surgical procedures. However, to date, there is no comprehensive report evaluating natural hemostatic materials based on biopolymers. Therefore, this current review attempts to combine the most advanced methods and secondly reviews various biopolymers including their preparation, origin, and composition, as well as safety and biodegradability. Insights on the various commercially available products based on biopolymers exhibiting hemostatic activity are well discussed. Thus, the paper summarizes the latest research work on commonly used biopolymers as the most widely used materials and provides an orientation for further research and development in this field.

Background and objective: Encapsulation is extensively used in food science and technology for protection of bioactive compounds by using several materials originated from different animals and plants. However, application of some of them is limited due to their suspicious halal origin. In this regard, gelatin is of concern for industrial application since it can be obtained from pork. At this review, we tried to investigate the halal biopolymers frequently used in food preparations. Results and conclusion: Biopolymers have incredible impact in the formula as gelling, stabilizing, viscosifying, and coating agent. Other than the favorable roles of biopolymers, their origin is important by some countries to find out they are derived in accordance to halal concepts. Therefore, those derived from halal animals through the process which does not threat the halal status are accepted by Islamic countries. In such cases, alternative biopolymers such as agar, pectin, and carrageenan by similar features for the specific purpose should be used instead of gelatin derived from pork.

In this study, efficient hybrid hydrogels as drug delivery platforms were synthesized using Kraft lignin, a biopolymer obtained from the alkaline paper industry, chitosan and glutaraldehyde as a crosslinker. The ratio of lignin was an important variable factor of this study and its effect on morphology and mechanical properties were studied. The characteristics such as compressive property, swelling capacity, drug release, degradation time, and SEM imaging of the hydrogels of chitosan and chitosan/ lignin with different amount of lignin were investigated. Also, paracetamol drug was selected as a drug model. The results showed that the glutaraldehyde crosslinker can effectively create a crosslinked structure, so that the durability and stability of the hydrogels in the desired conditions is up to 15 days for the pure chitosan sample and 11 days for the lignin chitosan sample, respectively. Although the shortest shelf life (5 days) corresponds to the highest amount of lignin, which was a shorter period of time, but it gives enough time for the drug to be completely released. The results showed that although the hydrogel structure is weakened by increasing the percentage of lignin, the drug was released faster with the increasing of lignin, which can be considered as a factor for changing the release rate of drug according to the intended application. The highest amount of release was observed in hydrogels with the highest amount of lignin, so that in the first two hours, its amount was about six times higher than that of pure chitosan hydrogel.

In the recent decade, biosynthesis of the degradable biopolymers polyhydroxyalkanotes in transgenic yeasts became an important research task. Most research strategies depend on either metabolic engineering or molecular approaches. In the present work, research compared PHA biosynthesis in two types of yeasts; Saccharomyces cerevisiae and a non-convenient Kloeckera spp. Yeast strains were equipped in their cytoplasm with the phaABCRe operon containing genes phbA, phbB and phbC of the PHA biosynthetic pathway of Ralstonia eutropha, which encode β-ketothiolase, NADPH-linked acetoacetyl-CoA reductase and PHA synthase, respectively. The transgenic strains Saccharomyces cerevisiae and Kloeckera sp. were able to produce PHA. The maximum content of the polymer detected in the recombinant strain INVSc1/PHA1 was 2.68 % and only poly-3-hydroxybutyrate (PHB) accumulated. However, the non-conventional transgenic strain KY1/PHA was able to accumulate as maximum of 7.06 % of the copolymer poly-(3-hydroxybutyrateco- poly-3-hydroxyvalerate) (PHV). Western blot analysis confirmed expression of the phaABCRe operon in the transgenic yeast strains. The nature of the PHA thus produced by all tested strains was analyzed by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy.

Flexibility and rigidity of biopolymers in mechanical structure have been investigated several times. Persistence length of a polymer is an exact factor to specify value of flexibility. No doubt that existence of charge on the polymers would have effect on the value of flexibility and therefore change in the persistence length of the polymer. In this study, by use of molecular dynamic simulation and Gaussian chain model (bead-spring model), we have investigated the effect of electric charge and salt concentration on the persistence length of the biopolymers in the cell. This simulation has been able to provide acceptable detail in the results.