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
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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.
... antibiotic resistance has quickly become an increasing concern in recent times due to the growing use of antibiotics. To combat this problem, we propose that healthy intestinal floras be maintained after antibiotic resistance using fecal bacteriotherapy, and that processes of lateral gene transfer be disrupted before antibiotic resistance through the use of copper surfaces and after antibiotic resistance through synthesized CSPs. Continuing research in these solutions as well as implementing these strategies into mainstream medicine will certainly reduce the frequency of antibiotic resistance along with incidences of serious disease outbreaks in hospitals. With a better understanding of the causes of antibiotic resistance and the role that patients and doctors play in these causes, it is time to move forward and attempt to eradicate this problem once and for all.
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
As previously stated, micro-leakage is mainly caused by shrinkage of the composite during polymerization. Bulk curing of composite results in a greater leve...
...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).
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...
The ingredients used in making slime contain fundamental additives that, when mixed together, cause the thick, gooey, slime every kid enjoys. Polymers are made from several smaller molecules joined by chemical bonds. The polyvinyl allows the mixture to feel slimy. Combing the polyvinyl and Borax together creates a chemical reaction. The mixture becomes cold, thicker, and elastic. This combination mixed together produces slime that is fun and safe for all ages.
When put together on a plate, the noodles then become a tangled mess. The mixtures of the polymer strands will give some viscosity, a cross-linking reactant, is also present in slime to give it the non-newtonian liquid behaviour. The tangled reactants are ions that help the polymer strands connect with weak ionic bonds for a limited time. These bonds, ironically, are strong enough to hold the polymer strands together, yet, but not strong enough to make the entire thing a
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.
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
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.
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.
Cell Adhesion: When transmembrane glycoproteins mediate interactions between cells which allow the cells to attach to a surface, a substrate, or another cell.
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