Phospholipid Nanoparticles and Drug Delivery

Nanoparticles formed from materials as diverse as titanium dioxide and phospholipids are highly attractive to biomedical engineers as vehicles to deliver a variety of cosmetics, drugs, and diagnostic materials to targeted sites in the human body. Nanoparticles employed in the pharmaceutical industry are typically formed from elongated biomolecules, such as phospholipids, having one hydrophilic end and one hydrophobic end. Molecules having the latter properties are known as amphiphilic (also called amphipathic) molecules or amphiphiles. Phospholipids are typical amphiphiles with phosphatidylcholine being the favored phospholipid used to form biological nanoparticles. Phospholipid-based nanoparticles are particularly attractive as in vivo drug/diagnostic delivery devices since they are formed from nontoxic substances normally found in cells and cell membranes. Nanoparticles bioengineered from customized combinations of phospholipids with one or two fatty acid substituents, cholesterol, and other polyols are known as micelles, vesicles, or liposomes depending upon the geometry of the structure formed. Micelles are small spherical aggregates typically formed from phospholipids having one fatty acid substituent. In micelles the interior of the sphere is packed with the hydrophobic hydrocarbon chain of the fatty acid with the charged or polar end of the phospholipid exposed to the polar, aqueous environment. The hydrophobic interior allows micelles to be stably loaded with water insoluble, and/or toxic drugs, or diagnostics and injected into the blood stream where they circulate and potentially deliver the carried compounds to target sites in the body. However, due to their small size, micelles have a limited loading capacity and most lipid-based nanoparticulate delivery devices have focused on the use of vesicles or liposomes. Liposomes and vesicles are typically formed from phospholipids plus cholesterol with the phospholipid, usually phosphatidylcholine, containing two fatty acid substituents. Like micelles, liposomes and vesicles form spontaneously when the mixed lipid formulations are dispersed in a polar solvent, such as water, with the lipid formulation and method of dispersion determining the geometry of the resultant particles. Although the nomenclature is not consistent, spherical particles with the phospholipids oriented into a single welldefined bilayer membrane, much like the biological membrane illustrated in figure, are generally referred to as liposomes while particles of ambiguous shape and form are generally referred to as vesicles. The key attributes of liposomes or vesicles are that they are formed of spherically closed bilayer membranes, with the hydrophobic acyl chains of phospholipids from the two sides of the membrane oriented to the inside of the bilayer and the polar portion of the phospholipids oriented toward the aqueous/polar environments on the exterior and interior of the nanoparticles. The figure below illustrates one hemisphere of a spherical, hollow, unilamellar-membrane liposome In pharmaceutical applications, customized lipid formulations are dispersed in aqueous solutions containing a drug or diagnostic compound and liposome formation proceeds with the interior aqueous compartment trapping a few nanoliters of drug solution ready to be injected into the blood stream or other body site. Early researchers using liposome-encapsulated anticancer drugs found that higher drug levels could be delivered to solid tumors but that most of the liposomes were removed from the circulatory system by reticuloendothelial system (RES) cells (e.g., phagocytic macrophages and liver Kupffer cells). Subsequently, “stealth liposomes” cloaked or coated with compounds like polyethylene glycol have been shown to be capable of largely avoiding destruction by the RES. At the same time, animal studies have shown that by bonding targeting molecules, like immunoproteins against cell surface markers, to the liposome surface, tissue-specific targeting can be markedly improved. In the near future many new, targeted, liposome/drug formulations can be expected to appear in clinical medicine and other industries as diverse as cosmetics and nutraceuticals.

nan.emf

© Applied Cell and Molecular Biology for Engineers

Advertisements

2 thoughts on “Phospholipid Nanoparticles and Drug Delivery

  1. Hello Web Admin, I noticed that your On-Page SEO is is missing a few factors, for one you do not use all three H tags in your post, also I notice that you are not using bold or italics properly in your SEO optimization. On-Page SEO means more now than ever since the new Google update: Panda. No longer are backlinks and simply pinging or sending out a RSS feed the key to getting Google PageRank or Alexa Rankings, You now NEED On-Page SEO. So what is good On-Page SEO?First your keyword must appear in the title.Then it must appear in the URL.You have to optimize your keyword and make sure that it has a nice keyword density of 3-5% in your article with relevant LSI (Latent Semantic Indexing). Then you should spread all H1,H2,H3 tags in your article.Your Keyword should appear in your first paragraph and in the last sentence of the page. You should have relevant usage of Bold and italics of your keyword.There should be one internal link to a page on your blog and you should have one image with an alt tag that has your keyword….wait there’s even more Now what if i told you there was a simple WordPress plugin that does all the On-Page SEO, and automatically for you? That’s right AUTOMATICALLY, just watch this 4minute video for more information at. Seo Plugin

    Like

  2. Hello Web Admin, I noticed that your On-Page SEO is is missing a few factors, for one you do not use all three H tags in your post, also I notice that you are not using bold or italics properly in your SEO optimization. On-Page SEO means more now than ever since the new Google update: Panda. No longer are backlinks and simply pinging or sending out a RSS feed the key to getting Google PageRank or Alexa Rankings, You now NEED On-Page SEO. So what is good On-Page SEO?First your keyword must appear in the title.Then it must appear in the URL.You have to optimize your keyword and make sure that it has a nice keyword density of 3-5% in your article with relevant LSI (Latent Semantic Indexing). Then you should spread all H1,H2,H3 tags in your article.Your Keyword should appear in your first paragraph and in the last sentence of the page. You should have relevant usage of Bold and italics of your keyword.There should be one internal link to a page on your blog and you should have one image with an alt tag that has your keyword….wait there’s even more Now what if i told you there was a simple WordPress plugin that does all the On-Page SEO, and automatically for you? That’s right AUTOMATICALLY, just watch this 4minute video for more information at. Seo Plugin

    Like

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s