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Topic Review
Low Molecular Weight Chitosan
Chitosan is a biopolymer with high added value, and its properties are related to its molecular weight. Thus, high molecular weight values provide low solubility of chitosan, presenting limitations in its use. Based on this, several studies have developed different hydrolysis methods to reduce the molecular weight of chitosan.
  • 2.4K
  • 13 Aug 2021
Topic Review
Natural-Drugs-Based Low-Molecular-Weight Supramolecular Gels
The utilization of paclitaxel, camptothecin, rhein, curcumin, and other natural small molecular drugs with unique rigid backbone structures and modifiable multiple sites as building blocks to form gels by self-assembly has attracted widespread attention. The obtained low-molecular-weight supramolecular gel not only retains the general characteristics of the gel but also overcomes the shortcomings of natural drugs, such as poor water solubility and low bioavailability.
  • 1.0K
  • 12 Aug 2021
Topic Review
Biomedical Applications of Quaternized Chitosan
The natural polymer chitosan is the second most abundant biopolymer on earth after chitin and has been extensively explored for preparation of versatile drug delivery systems. The presence of two distinct reactive functional groups (an amino group at C2, and a primary and secondary hydroxyl group at C3 and C6) of chitosan are involved in the transformation of expedient derivatives such as acylated, alkylated, carboxylated, quaternized and esterified chitosan. Amongst these, quaternized chitosan is preferred in pharmaceutical industries owing to its prominent features including superior water solubility, augmented antimicrobial actions, modified wound healing, pH-sensitive targeting, biocompatibility, and biodegradability. It has been explored in a large realm of pharmaceuticals, cosmeceuticals, and the biomedical arena. Immense classy drug delivery systems containing quaternized chitosan have been intended for tissue engineering, wound healing, gene, and vaccine delivery. 
  • 850
  • 11 Aug 2021
Topic Review
Functionalized Chitosan Nanomaterials
Quorum sensing (QS) is the mechanism by which the microbial colonies in a biofilm modulate and intercept communication without direct interaction. Hence, the eradication of biofilms through hindering this communication will lead to the successful management of drug resistance and may be a novel target for antimicrobial chemotherapy. Chitosan shows microbicidal activities by acting electrostatically with its positively charged amino groups, which interact with anionic moieties on microbial species, causing enhanced membrane permeability and eventual cell death. Therefore, nanoparticles (NPs) prepared with chitosan possess a positive surface charge and mucoadhesive properties that can adhere to microbial mucus membranes and release their drug load in a constant release manner. As the success in therapeutics depends on the targeted delivery of drugs, chitosan nanomaterial, which displays low toxicity, can be safely used for eradicating a biofilm through attenuating the quorum sensing (QS).
  • 508
  • 10 Aug 2021
Topic Review
Polymer Electrolyte Membrane Fuel Cell
Polymer electrolyte membrane fuel cells (PEMFCs) have been considered as electric power sources for cars, as well as stationary and portable power sources, due to their high energy efficiency, ease of operation, and environmental friendliness. Furthermore, as a promising power source, integrating PEMFCs into microgrids, which are a common structure in the smart grid framework, has been gaining traction around the world, encouraging the usage of hydrogen energy.
  • 843
  • 09 Aug 2021
Topic Review
Stimulus-Responsive Polymers and Polypeptoid Skeletons
Polypeptoids have low cytotoxicity and good biocompatibility because of their structural similarity to polypeptides. Different from polypeptides, however, polypeptoids show thermal transformation similar to synthetic thermoplastics, making them suitable for various heat treatment methods. Polypeptoids combine the properties of natural macromolecules and synthetic polymers, and become great candidates as stimulus-responsive biopolymers.
  • 527
  • 05 Aug 2021
Topic Review
Carbon Nanotube-Reinforced Polymer Composite
A novel class of carbon nanotube (CNT)-based nanomaterials has been surging since 1991 due to their noticeable mechanical and electrical properties, as well as their good electron transport properties. The development of CNT-reinforced polymer composites could contribute in expanding many areas of use, from energy-related devices to structural components. A CNT is defined as a one-atom thick sheet of graphite rolled into a tube with a diameter of one nanometer, which is classified as a single-wall carbon nanotube (SWCNT); if there are additional or multiple graphene tubes around the core of an SWCNT, this is known as a multiwalled carbon nanotube (MWCNT). Theoretical and experimental results on CNTs have showed a high modulus of elasticity: greater than 1 TPa (the elastic modulus of diamond is 1.2 TPa). In addition, CNTs also possess a strength that is 10–100 times higher than the resilient steel at a fraction of the weight. Additionally, CNTs have an excellent thermal stability of up to 2800 ◦C in vacuum and an electrical conductivity in the vicinity of 103 S/cm, with an electric-current-carrying capacity that is 1000 times higher and thermal conductivity of about 1900 W m−1 K−1 (which is about twice as high as diamond). SWCNTs in a hexagonal honeycomb structure consist of sp2 hybridized carbon in a that is rolled into a hollow tube morphology, while MWCNTs consist of multiple concentric tubes encircling one another.
  • 1.7K
  • 05 Aug 2021
Topic Review
Fully Implanted Hearing Systems
The ear and brain work together in the hearing process. Sound energy in the audible frequency range (20 Hz–20 kHz) propagates through air medium as an acoustical mechanical wave which enters from the outer ear towards the middle ear to vibrate the eardrum. 
  • 700
  • 02 Aug 2021
Topic Review
Magnetic Polymers for Microfluidic Sorting
Magnetophoresis offers many advantages for manipulating magnetic targets in microsystems. The integration of micro-flux concentrators and micro-magnets allows achieving large field gradients and therefore large reachable magnetic forces. However, the associated fabrication techniques are often complex and costly, and besides, they put specific constraints on the geometries. Magnetic composite polymers provide a promising alternative in terms of simplicity and fabrication costs, and they open new perspectives for the microstructuring, design, and integration of magnetic functions.
  • 996
  • 30 Jul 2021
Topic Review
Natural Fibre-Reinforced Polymer Composites
As one of the fastest-growing additive manufacturing (AM) technologies, fused deposition modelling (FDM) shows great potential in printing natural fibre-reinforced composites (NFRC). However, several challenges, such as low mechanical properties and difficulty in printing, need to be overcome. Therefore, the effort to improve the NFRC for use in AM has been accelerating in recent years.
  • 1.1K
  • 23 Jul 2021
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