Tag Archives: gold nanoparticles

Chemotherapy Paste

Treating Melanoma with a “Chemotherapy Paste” for Better Tolerance

 According to the American Skin Cancer Foundation, melanoma is the most lethal form of cancer due to its capability of spreading from the skin to almost anywhere else in the body. For that reason, it has traditionally been necessary to take a very aggressive stance when treating skin cancers, using intravenous chemotherapy, radiation therapy, and surgery. For better tolerance and less crippling systemic side effects, scientists have developed a “chemotherapy paste” that can be applied directly to the skin to bypass the systemic treatment modality, and treat melanoma without the patient experiencing nausea and vomiting often associated with intravenous chemotherapy.

The culprits behind skin cancer are squamous cells, basal cells, and melanocytes. Melanocytes are the cells which are subject to becoming melanoma. They manufacture a brownish pigment called melanin, which imparts a tan or brown color to the skin, and protect deeper skin layers from harmful rays of the sun. When skin is exposed to the sun, melanocytes produce more melanin, which causes the skin to become darker.

Melanoma is a skin cancer which develops from melanocytes, and although it can develop anywhere on the skin surfaces, melanoma develops most commonly on the chest and on the back for men, whereas for women it most frequently develops on the legs. For both men and women, it can also develop on the face and neck. Melanoma occurs less frequently than either squamous cell cancers or basal cell cancers, but all three cells can be targets for skin cancer.

The skin is normally the first line of defense against any kind of harmful microbe or material, which would otherwise penetrate the body and wreak havoc. Unfortunately, this brilliant barrier also prevents useful drugs from being directly admitted onto the skin to treat skin diseases until recently.

A group of researchers developed a “chemotherapy paste” that incorporates nanoparticles called transfersomes to aid drug delivery through the skin to directly treat skin cancer. These transfersomes encase chemotherapy—in this case, paclitaxel—in a phospholipid bilayer-based surfactant that render the drug malleable to help penetrate the skin’s epidermal layers. A peptide was added to the transfersome complex to enhance its ability to infiltrate the skin and cancer cells and deliver paclitaxel directly to the tumor. To prolong the skin-penetrating effects, the “chemotherapy paste” was encased in a hydrogel medium to cover the “painted-on” site of the paste.

When the transfersome paste was applied to mice with melanoma, tumor sizes were reduced by half after 12 days compared to the set of mice that were receiving chemotherapy injections alone. However, it is still too early to see if the same results will transfer to humans, though a non-systemic “chemotherapy paste” approach to treating cancer will be a breakthrough that can vastly improve quality of life for cancer patients.

Gold Nanoparticle Blood Test

Gold Nanoparticle Blood Test Better at Detecting Prostate Cancer than Current Routine Method

A simple, easy-to-administer gold nanoparticle blood test, developed by a scientist at University of Central Florida (UCF), has proven to be better at detecting early stage prostate cancer than the prostate-specific antigen (PSA) test—the current routine method for prostate cancer screening.

A few drops of blood from a finger prick are mixed with gold nanoparticles that are 10,000 times smaller than a freckle. When a malignant tumor starts to grow within the body, the immune system generates antibodies, which serve as the basis of specific cancer biomarkers when testing for cancers. The gold nanoparticles attract these biomarkers, which clump together and grow in size.

Among the scientific community, gold nanoparticles are well known for their ability to absorb and scatter light efficiently. A team of researchers at UCF’s Nanoscience Technology Center developed a technique called nanoparticle-enabled dynamic light scattering assay (NanoDLSay) that evaluates the size of particles by measuring the amount of light that emanates from them. Greater the size of the particle, the greater the light measurement, which is an indicator whether a male patient has prostate cancer and how advanced it may be.

Preliminary studies indicate with 90 to 95 percent confidence results from the gold nanoparticle blood test are not false-positives compared to the PSA test, with a 50 percent confidence for false-negative results, which are considered not great but better than 20 percent with PSA. The research team is working on improving that value. Currently, the PSA test tends to procure more false-positive results that lead to more invasive procedures which can potentially be eliminated with the new test.

Even though gold is the core ingredient to run the test, a small bottle of nanoparticles suspended in water costs $250, which is enough to administer 2,500 tests, essentially rounding out the test cost to less than a dollar.

After more extensive clinical studies, long-term goal is to have patients undergo prostate cancer screenings with the gold nanoparticle blood test in physician offices, and possibly expand the reach of the new test into a universal cancer screening protocol for a wide variety of tumors.

Microneedle-Covered Capsule

Promising Microneedle-Covered Capsule to Supersede Injections?

A swallowable microneedle-covered capsule—approximately 2 centimeters long and 1 centimeter in diameter—was devised by Massachusetts Institute of Technology (MIT) researchers, working with Massachusetts General Hospital (MGH), as a way to deliver medications orally and perhaps replace injections in the future.

The prototype pill is made of acrylic—serving as a medication reservoir—and encased with tiny hollow stainless steel needles (5 millimeters in length) that are designed to “inject” drugs directly into the stomach lining. Large medications, usually consisting of proteins, are not readily absorbable and thus degraded in the stomach and rendered useless before it can be absorbed. Insulin was tested in pigs using the microneedle-covered capsule technology and was found to lower blood glucose levels more effectively than subcutaneous insulin injections.

However, the capsule took longer than a week to go through the digestive tract and evidence of tissue damage was not apparent. The scientists also claim the gastrointestinal (GI) tract has no pain receptors so no discomfort is felt as the microneedle-covered capsule moves through the GI canal.

The new medication delivery mechanism may be better suited for injecting into the gut a class of drugs called biologics that include vaccines, recombinant DNA, RNA, and antibodies, such as those for autoimmune diseases like arthritis and Crohn’s disease that often require intravenous infusions to ensure effective drug delivery.  Nanoparticles and microparticles were originally engineered for oral medication delivery for biologics but they are expensive to manufacture and a new system has to be created for a different drug. With the microneedle-covered capsule, the researchers are aiming for a universal delivery system that can be reproduced for different drugs inexpensively.

To ensure absolute safety, the scientists are working on replacing the stainless steel needles with digestible polymers and sugar that would continue to release medication into the GI lining once it breaks off from the capsule and lodges itself into the gut as it decomposes.

Gold Nanoparticles for Targeted Medication Delivery and Cancer Treatments

Cells are notoriously protective and do not easily allow particles entry into its domain unless unique transport mechanisms that the cell recognizes are in place. As a result, current medications and treatments do not target specific cell contents and end up destroying the entire cell.

In 2008, researchers discovered gold nanoparticles coated with a one-layer polymer can penetrate cell walls, and since then has recently identified the mechanism of action along with the upper size limit of the particle to effectively penetrate cell walls.

Through a series of lab experiments and computer simulations, researchers at MIT and the Ecole Polytechnique de Lausanne, Switzerland demonstrated the critical step of gold nanoparticles infiltrating the cell wall is to fuse with the phospholipid bilayer of the cell membrane, which is largely the responsibility of the coating on the particle. The coating is a mixture of hydrophobic (“water-fearing”) and hydrophilic (“water-loving”) compounds. Depending on the chemical nature of the compounds used, the upper size limit of the coating was also determined.

A bonus to the team’s discovery was that the method of delivery of gold nanoparticles also sealed the opening after its entry, preventing leaks behind the particle as well as inhibiting damage to the cell as the particle proceeded to the cell’s interior.

The team is hoping to use their discovery as a means of delivering drugs to the cell’s interior by attaching the drugs to the particle’s lipid-mixture coating once they find a way for the coating to be selective on what types of cells they attach to for targeted medication delivery.

The choice to use gold as the coating’s delivery instrument was simply convenient as a research model. However, the team has postulated on a potential health benefit of the precious metal. Gold particles are very good at absorbing x-rays. If the coating can be used to penetrate cancer cells, then the particle can be heated up by an x-ray beam and destroy the malignant cells from within.