Nanomedicine and nano delivery systems are a relatively new but rapidly developing science where materials in the nanoscale range are employed to serve as means of diagnostic tools or to deliver therapeutic agents to specific targeted sites in a controlled manner Nanotechnology offers multiple benefits in treating chronic human diseases by site-specific, and target-oriented delivery of precise medicines Recently, there are a number of outstanding applications of the nanomedicine (chemotherapeutic agents, biological agents, immunotherapeutic agents etc) in the treatment of various diseases The current review, presents an updated summary of recent advances in the field of nanomedicines and nano based drug delivery systems through comprehensive scrutiny of the discovery and application of nanomaterials in improving both the efficacy of novel and old drugs (eg, natural products) and selective diagnosis through disease marker molecules The opportunities and challenges of nanomedicines in drug delivery from synthetic/natural sources to their clinical applications are also discussed In addition, we have included information regarding the trends and perspectives in nanomedicine area

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Nano based drug delivery systems: recent developments and future prospects

Chitosan—A versatile semi-synthetic polymer in biomedical applications

http://www.mtdna.or.kr/neowiz/board/up_files/files_17/Chitin_Chitosan_polymers_chemistrySolubilityFiberFormation.pdf

Chitin and chitosan polymers: Chemistry, solubility and fiber formation

Chitins and chitosans for the repair of wounded skin, nerve, cartilage and bone

Application of chitosan and its derivatives as adsorbents for dye removal from water and wastewater: a review.

Of late, the most bountiful natural biopolymer chitin and chitosan have become cynosure of all party because of an unusual combination of biological activities plus mechanical and physical properties. However applications of chitin are limited due to its inherent insoluble and intractable nature. Chitosan, alkaline hydrolytic derivative of chitin has better solubility profile, less crystallinity and is amenable to chemical modifications due to presence of functional groups as hydroxyl, acetamido, and amine. The chemical modification of chitosan is of interest because the modification would not change the fundamental skeleton of chitosan, would keep the original physicochemical and biochemical properties and finally would bring new or improved properties. In view of rapidly growing interest in chitosan its chemical aspects and chemical modification studies is reviewed. The several chemical modifications such as oligomerization, alkylation, acylation, quternization, hydroxyalkylation, carboxyalkylation, thiolation, sulfation, phosphorylation, enzymatic modifications and graft copolymerization along with many assorted modifications have been carried out. The chemical modification affords a wide range of derivatives with modified properties for specific end use applications in diversified areas mainly of pharmaceutical, biomedical and biotechnological fields. Assorted modifications including chitosan hybrids with sugars, cyclodextrin, dendrimers, and crown ethers have also emerged as interesting multifunctional macromolecules. The versatility in possible modifications and applications of chitosan derivatives presents a great challenge to scientific community and to industry. The successful acceptance of this challenge will change the role of chitosan from being a molecule in waiting to a lead player.

Chitosan-modifications and applications: Opportunities galore

Deacetylation of chitin affords chitosan, a polymer, widely studied for its pharmaceutical and nonpharmaceutical applications. The hurdle in comprehending these applications is its limited solubility. Carboxymethylation of chitosan helps to surmount this hurdle with its improved solubility in water. Though there is ample of research related to carboxymethyl chitosan (CMC) the focused review of the topic is unavailable. Hence an attempt is made in this review to cover the recent findings pertaining to synthesis, characterization of CMC and its applications especially in pharmaceutical field. CMC has been synthesized by ways as direct alkylation, reductive alkylation, Michael addition and characterized by FTIR, NMR spectroscopy, and DSC, titrimetry, viscometry, gel permeation chromatography, X-ray diffraction and capillary zone electrophoresis. The carboxymethyl group can be present at O or N or both the atoms of chitosan molecule. The CMC possess modulated physical and biological properties as chelating, sorption, moisture retention, cell functioning antioxidant, antibacterial, antiapoptotic etc. CMC is used in sustained or controlled release drug delivery, pH responsive drug delivery, DNA delivery as permeation enhancer etc. CMC can be further modified with alkylation, acylation, and grafting. Carboxyalkylation of chitosan yield carboxyethyl, carboxybutyl chitosans. These analogues of CMC may be helpful in substantiating the applications of chitosan. Copyright © 2010 VBRI press.

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Carboxymethyl chitosan and its applications

Chitosan, a polymer obtained by deacetylation of chitin is widely studied for its pharmaceutical and nonpharmaceutical applications. Recommendations about uses of this polymer although could not be always realized due to limited solubility. Chitosan, for example, has been extensively evaluated for its mucoadhesive and absorption enhancement properties. The positive charge on the chitosan molecule gained by acidic environment in which it is soluble seems to be important for absorption enhancement. However chitosan is not soluble in medium except below pH 5.6. This limits its use as permeation enhancer in body compartments where pH is high. In this regard there is a need for chitosan derivatives with increased solubility, especially at neutral and basic pH values. Trimethylation of chitosan is an effort in this direction. Despite the abundance of the research related to trimethyl chitosan (TMC), the overview of the topic is not available. Hence an attempt is made in this review to cover the recent findings pertaining to synthesis, characterization and applications of TMC especially in pharmaceutical field. TMC has been synthesized by different ways and characterized by FTIR, NMR, DSC etc. This quaternized derivative of chitosan possesses a positive charge and is soluble over a wide range of pH. TMC, being a derivative of cationic polymer enriched with positive charge shows better mucoadhesive, permeation enhancement, drug delivery and DNA delivery properties. TMC can be further derivitized or grafted for modulating properties as solubility, cytotoxicity or cell recognition ability. Apart from these applications, TMC itself and its derivatives exhibit antimicrobial properties also. Quaternization of chitosan not only with methyl group but higher group as ethyl or along with spacer or quaternization of modified chitosan can be of interest too.

Trimethyl chitosan and its applications in drug delivery.

The generation of supramolecular architectures with well-defined structures and functionalities is recently garnering attraction. Self-assemblage of amphiphilic polymers leads to the formation of polymeric micelles that demonstrate unique set of characteristics such as excellent biocompatibility, low toxicity, enhanced blood circulation time, and solubilization of poorly water-soluble drugs. In this article, we provide an up-to-date review on important aspects of polymeric micelles. Critical factors for solubilization of hydrophobic drugs in the micellar core are discussed. Polymeric micelles can be used as ‘smart’ drug carriers for targeting certain areas of the body. Here, we have especially emphasized on the recent developments in the targetability of certain tissues such as cancerous tissues using polymeric micelles. Different stimuli exploited for creating stimuli-sensitive micelles are discussed comprehensively. Application of polymeric micelles in the photodynamic therapy is also meticulously descr...

https://www.tandfonline.com/doi/pdf/10.1080/1385772X.2012.688328

Polymeric micelles: authoritative aspects for drug delivery

The most preferred route for delivering therapeutic agents is oral drug delivery However, this route is not feasible for delivery of hydrophilic macromolecules, such as therapeutic peptides, proteins, nucleotides, and efflux pump substrates, because of negligible oral bioavailability This is because of the barriers confronted by these molecules along the oral route, such as diffusion barrier of mucus, enzymatic barrier of peptidases, and permeability barrier of membranes The strategies to surmount these barriers are by utilization of permeation enhancers, enzyme inhibitors, and multi-functional polymers, ideally guaranteeing both permeation enhancement and enzyme inhibition In case of multifunctional polymers, these effects can take place only if polymers offer strong muco-adhesive features for providing a tight contact with the mucosa during the whole period of peptide drug release and absorption Among the group of multifunctional polymers exhibiting all of the aforementioned properties, thiolated polymers (designated thiomers) are the most promising The thiomers are hydrophilic macromolecules exhibiting free thiol groups on the polymeric backbone as poly(acrylates), carboxymethyl cellulose, alginate, pectin, deacetylated gellan gum, or chitosans

Nazma N. Inamdar

Papers

Chitosan-modifications and applications: Opportunities galore

Carboxymethyl chitosan and its applications

Trimethyl chitosan and its applications in drug delivery.

Polymeric micelles: authoritative aspects for drug delivery

Preparation, Properties, and Applications