Diffusion theory: Diffusion theory describes the interpenetration of both polymer and mucin chains to a sufficient depth to create a semi-permanent adhesive bond. The adhesion force increases with the degree of penetration of the polymer chains. This penetration rate depends on the diffusion coefficient, flexibility and nature of the mucoadhesive chains, mobility and contact time. The depth of interpenetration required to produce an efficient bioadhesive bond lies in the range 0.2-0.5 μm. This interpenetration depth of polymer and mucin chains can be estimated by “I = (tDb) 1/2” Where “I” is depth of interpenetration of polymer, t is the contact time, and Db is the diffusion coefficient of the mucoadhesive …show more content…
POLYMER RELATED FACTORS: Molecular weight: For linear polymers, mucoadhesion increases with molecular weight. A large molecular weight is essential for entanglement; however, excessively long polymer chains lose their ability to diffuse and interpenetrate mucosal surfaces. Concentrated dispersions are retained on the mucous membrane for longer periods. After application such systems spread easily, since they present rheological properties of a liquid, but gellify as they come in contact with the absorption site, thus preventing their rapid removal. Chain flexibility is critical for interpenetration and entanglement with the mucus gel. Increased chain mobility leads to increased inter-diffusion and interpenetration of the polymer within the mucus …show more content…
Lectin belongs to group of structurally diverse proteins and glycoproteins that can bind reversibly to specific carbohydrate residues. After initial mucosal cell binding, lectins can remain on the cell surface or in case of receptor mediated adhesion possibly become internalized via a process of endocytosis. Lectins not only allow targeted specific attachment but also can control the drug delivery of macromolecular pharmaceuticals. Thiolated polymers derived from hydrophilic polymers such as polyacrylates. The presence of thiols group allows the formation of covalent bondwith cysteine rich mucus gel layer leading to increased residence time and improved bioavailability. Bacterial Adhesions:(39,47) :Target specific drug delivery can be achieved by adherence of pathogenic bacteria to the mucosal membrane. K-99 fimbriae , an attachment protein derived from E.coli can be attached covalently to the polyacrylic networks. TYPES OF MUCOADHESIVE DRUG DELIVERY SYSTEMS
For 8 weeks of vacation work I have been looking at preparing and characterizing nanoparticulate systems to encapsulate the antimicrobial drug mupirocin. Specifically polymeric nanoparticles and liposomes were investigated.
The main problem concerning the durability of resin-dentin is the hydrolytic degradation of the two components of the hybrid layer. These are the collagen matrix and the adhesive resin [8]. Many approaches to enhance long-term bonding were developed , these include the inhibition of dentinal endogenous proteases (matrix metalloproteinases and cysteine cathepsins)[22].Matrix metalloproteinases are thought
...degree of intermolecular association. By adjusting the formulation or the chemical moieties of the drug delivery system, the moment and the location of the release of the drug may be controlled (You e.a. 2010).
These are also very helpful for the drug encapsulation which are discharge on disintegration of polymer layer network. The factors on which the physically cross linked microgels are depends are polymer composition, ionic strength of the medium and on temperature. The physically cross linked microgels are prepared from the biopolymers such as dextron, agarose and alginate[24]. This is also very important type of microgels used in many fields.
Accardo A, Aloj L, Aurilio M, Morelli G, Tesauro D. Receptor binding peptides for target-selective delivery of nanoparticles encapsulated drugs. International journal of nanomedicine. 2014;9:1537-57. PubMed PMID: 24741304. Pubmed Central PMCID: PMC3970945. Epub 2014/04/18. eng.
Cell Adhesion: When transmembrane glycoproteins mediate interactions between cells which allow the cells to attach to a surface, a substrate, or another cell.
What is a polymer? Polymers are substances containing a hefty amount of structural units joined by the same type of linkage. The minute you hear the word polymers you assume it is manufactured with massive chemical plants. Actually, polymers have been in nature from the start. All living things plants, animals, and people are made of polymers. However, what you do not know is they are different types of polymers the Synthetic ones which use harmful toxins to be synthesized, and are those which are Natural. They are numerous polymers that fall in the natural process and are utilized in both our society and our bodies, which are cellulose; starch, rubber, proteins and both are DNA and RNA, and many more
A wide choice of constituting polymers, both natural and synthetic, delivers diverse properties which can be engineered into the hydrogel matrices, such as cell adhesiveness low-fouling behavior, etc.[219] Hydrogel immobilization of biological materials is useful because pores within the gel are in the range of
Hydrogels are defined as networks made up of polymer chains which are hydrophilic. They are in some cases found as a solid dispersed in a liquid. where water acts as the medium dispersed. Hydrogels are natural, highly porous or artificial polymeric networks. The hydrophilic structure allows hydrogels to hold the significant amount of water within their three-dimension structural systems. The extensive employment of hydrogel products in some environmental and industrial areas of applications are very high importance. As time passed, natural hydrogels were replaced with artificial ones. This was due to their long service life, the wide variety of the raw chemical resources, high capacity of water absorption, and their stability. Artificial polymers have structures that are well defined and can be modified to produce tailor powerful functionality and degradability. The artificial of hydrogels can also occur from purely artificial components. The artificial hydrogels are stable in conditions of high and sharp temperature fluctuations. Recent research describes hydrogels as a two- or multi-component systems that are made of three-dimensional
Biofilms are formed by a six step process. First is a reversible process, when an organic monolayer(made of polysaccharides or glycoproteins) absorbs to the surface, altering the chemical and physical properties of the surface. This makes the surface more conditioned and increase the chance that planktonic bacteria will attach. Secondly, also a reversible step, is when the free-floating or planktonic bacteria encounter the conditioned surface, and some attachment of the bacteria may occur. The third step is when the bacteria is left attached too long, then an irreversible attachment occurs. F...
Polymers: A great variety of polymers are used as biomaterials in medicine. Their applications vary from facial prostheses to tracheal tubes, from dentures to hip and knee joints and from kidney and liver parts to heart components. Polymeric materials are also used for medical adhesives and sealants and are also used for coatings that perform a range of functions.
As previously stated, micro-leakage is mainly caused by shrinkage of the composite during polymerization. Bulk curing of composite results in a greater leve...
Microencapsulation is the envelopment of small solid particles, liquid droplets or gases in a envelop coating. Microencapsulation is based on the embedding effect of a polymeric matrix, which creates a microenvironment in the capsule able to control the interactions between the internal part and the external one. Microencapsulation allows the protection of a wide range of materials of biological interest, from small molecules and protein to cells of bacterial, yeast and animal origin (Benita, 2005). For this reason such versatile technology is widely studied and exploited in the high technological fields of biomedicine, bio-pharmaceutics, and nutra-foods for application ranging from cell therapy to drug and bioactive molecule delivery. The
Plastic Materials for Medical devices July 2015 Table of Contents. Abstract 1 - 1. Medical Plastics Market Overview 1 2. Polymer materials 2 3. Healthcare Domain requirements 3 3.1 Sterilization compatibility 4 3.2 Biocompatibility 5 3.3 Benefits of Medical Polymer knowledge 6 4.
These functional fatty acids have an effective role in treatment/prevention a high number of diseases or disorders such as cognitive decline, Alzheimer's disease, arthritis pains, gastrointestinal cancer, and heart and cardiovascular diseases (Lecerf 2009; Gharibzahedi and others 2013a, 2013b, 2014; Abdulrazaq and others 2017; Cederholm 2017; Eltweri and others 2017; Saljoughian and others 2017). Microencapsulation protects products containing relatively high amounts of ω-3/ω-6 unsaturated fatty acids from oxidation reactions during the exposure to oxygen, metal-ions, light, and high temperatures that leads to oxidative rancidity, polymerization, and color changes. Hence, application of this technology helps in protecting the organoleptic qualities of fatty food and ensures the delivery of bioactive agents in the gut (Gharibzahedi and others 2013a, 2013b; Pourashouri and others 2014a, 2014b; Xia and others 2017). Thus, inclusion of lipophilic components into a polymeric matrix can improve their bioavailability/bioaccessibility through the prevention or reduction of unwanted interactions between PUFAs and other food ingredients (Timilsena and others 2016a;