An Insight into Advanced Nanoparticles as Multifunctional Biomimetic Systems in Tissue Engineering
Harishkumar Madhyastha, Durgesh Nandini Chauhan in Nanopharmaceuticals in Regenerative Medicine, 2022
Polymeric NPs are composed of biocompatible and nontoxic biodegradable polymers, including polysaccharides (e.g., alginate, chitosan, dextran, heparin, hyaluronic acid, and pullulan), proteins (e.g., albumin, elastin, gelatin, and silk) and synthetic polymers (e.g., polyamides, polyesters, polyanhydrides, polyacrylates, and polyurethanes) alone or in conjugation in combination with other materials to provide specific functionalities (Mosselhy et al., 2021, Choi et al., 2017). The characterisation of polymeric NPs characterisation is important to ascertain their applicability and evaluate nanotoxicology and exposure assessment. The composition and concentration, surface properties, size, shape, crystallinity, and dispersion state are characterised using several analytical techniques, including chromatography, dynamic light scattering, electrophoresis, electron microscopy, near-infrared spectroscopy, and photon correlation spectroscopy (Zong et al., 2005). The NPs’ surface area can be determined by the adsorption of inert gas (such as N2) by changing the pressure conditions to form a gas monolayer.
Peptide Structure and Analysis
Marco Chinol, Giovanni Paganelli in Radionuclide Peptide Cancer Therapy, 2016
The SPPS requires a well-solvated gel to allow the reactions to take place between reagents in the mobile phase, and functional groups on chains throughout the interior of a resin. The original resin was developed as a polystyrene polymer cross-linked with 1% of 1,3-divinylbenzene with a swelling capacity 3 fold in volume in N,N-dimethylformamide (DMF). A polyamide resin was introduced by Atherton and Sheppard (21) under the concept that the solid support and peptide backbone should be of comparable polarities. Recently, resins based on grafting of polyethylene glycol (PEG) to low cross-linked polystyrene were developed such as Tentagel (22) and PEG-PS resins (23), with a swelling capacity 5 fold in volume in DMF. More recently, resins based on cross-linked PEG have also been available such as PEGA (24) and CLERA resins (25) with a swelling capacity 11, and 6.5 fold in volume, respectively. Due to their excellent swelling property, Tentagel and PEGA resins have shown superior performance, especially on peptides with long and difficult sequences.
Innovative industrial technology starts with iodine
Tatsuo Kaiho in Iodine Made Simple, 2017
Polyamide fibers are generally known as nylon, and on account of their superior toughness, adhesiveness, and fatigue resistance, they are widely used for various industrial materials such as rubber reinforcement cords for tires, conveyor belts, transmission belts and rubber hoses, safety belts, tents, plaited cords, sewing thread, and airbags. In 2011, global production of polyamide fibers reached 6.8 million tons [36a]. Polyamides used as industrial materials are exposed to harsh environments during the processing stages of production such as heat, oxygen, and light and during use as automobile products (particularly nylon cords for tires and airbag cords). In order to prevent deterioration in these environments, various stabilizers are added.
Advances in additive manufacturing processes and their use for the fabrication of lower limb prosthetic devices
Published in Expert Review of Medical Devices, 2023
Shaurya Bhatt, Deepak Joshi, Pawan Kumar Rakesh, Anoop Kant Godiyal
Thermoplastic polymers such as polyaryletherketones have been used to fabricate spinal implants and orthopedic devices due to their temperature stability, chemical resistance, and high level of strength [37]. Polyamide is also a synthetic material widely used for the SLS process. PCL is also one of the biodegradable polymers used for the SLS process. The PCL material used for scaffold manufacturing showed that it could be a viable option for tissue engineering application to repair bone and cartilage as it provided an environment that supported cell growth [40]. Poly lactides such as PLA are also biocompatible materials produced from renewable resources and have high rigidity and strength but are brittle [37]. The strength of PLA was enhanced by introducing carbon nanotube into them. 3D-printed composite produced by polylactic acid, thermoplastic polyurethane, and graphene oxides was investigated for their compatibility in tissue scaffolds. Thermal and mechanical properties and the effect of varying printing parameters were explicitly studied. It was found that the 3D-printing process enhanced the thermal stability and to understand the effect of varying printing orientations and the effect of the addition of graphene oxide on cellular growth [41]. A correlation between the water-absorbing capability and the presence of methyl side groups in lactic acid was studied [42]. The greater water-absorbing capability was found in scaffolds with a lower ratio of lactic acid to glycolic acid.
Artificial hair implantation for hair restoration
Published in Journal of Dermatological Treatment, 2022
Aditya K. Gupta, Maanasa Venkataraman, Emma M. Quinlan
In the early days, artificial fibers consisted of synthetic fibers made of monoacrylic,polyacrylic, or polyester materials, or natural fibers, such as processed human hair (21). Manufacturers of present-day synthetic fibers (Biofibre®, Nido Z-type) state that the problems associated with earlier fibers such as non-biocompatibility, tolerability, and safety have been resolved; currently available synthetic fibers are made of polyamide material which are claimed to be inert, safe, and tolerable (21). Biofibre® medical hairs are available in 13 colors, different lengths (15, 30, or 45 cm), and various shapes (straight, wavy, and curly) (13,21). MHD® (released in 2014) is a high-density version of regular Biofibre® hairs which are implanted only in the crown area, while the lightweight regular Biofibre® hairs are used to populate the front hairline, which has thin dermal tissue (23). Besides androgenetic alopecia, the use of synthetic hair fibers has been reported in the treatment of other alopecias, for example, pharmacological, primary cicatricial (scarring alopecia due to innate hair follicle-directed causes), and secondary cicatricial (scarring alopecia due to incidental causes such as traumatic burns and surgical scars) (23,26). However, the role of artificial hair implantation in treating other types of alopecias, such as triangular temporal alopecia, has not been reported.
Selective laser sintering 3D printing – an overview of the technology and pharmaceutical applications
Published in Drug Development and Industrial Pharmacy, 2020
Naseem A. Charoo, Sogra F. Barakh Ali, Eman M. Mohamed, Mathew A. Kuttolamadom, Tanil Ozkan, Mansoor A. Khan, Ziyaur Rahman
The powder layer is usually preheated below the melting point temperature to prevent manufacturing defects such as warping and deforming in sintered parts. The heating may cause physical and chemical changes in the powder material. For instance, solid state polycondensation reduced the crystallinity of polyamide 12 powder by 6% after three recycles [42]. In another study, polyamide 12 powder was found to undergo molecular entanglement which depends on temperature and time. The high temperature and longer exposure time to high temperatures may cause the molecular chains to become larger, resulting in increase in molecular weight, decrease in fluidity, and change in mechanical and thermal properties [41]. However, pharmaceutical polymers usually degrade to smaller chain length on thermal exposure, which will dramatically change their physicochemical properties [43]. This can be prevented to a certain extent by printing in an inert gas environment. Another approach is to use a blend of used and unused powder which fulfills the thermal requirements of raw material as well as CQA of final dosage forms. Stabilizing agents such as thioethers in combination with antioxidants can also be used [11,44,45]. Alternative recycling approaches have been proposed. For example, Feng et al. recycled polyamide 12 powder after SLS into filaments for FDM and proposed it as one of the means to reduce cost and environmental impact [45]. However, this approach may not be applicable to pharmaceuticals due to adverse effect on CQAs of the dosage forms.
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