Dear Prashanth,

I haven't checked if someone has tested ZnO NPs against these parasites/bacteria. However, I would not recommend ZnO NPs for use in malaria and tuberculosis treatment because of the following. Both, the malaria parasite and the tuberculosis bacterium are internal invaders - the malaria parasite is in the blood, and the tuberculosis bacterium is usually an intracellular microorganism. It means that any drugs that intend to cure these diseases must be taken orally or by injection - in any case the drugs need to reach the blood circulation in order to act upon the microorganisms. ZnO can not be taken orally because it will dissolve in the acidic medium in stomach (pH ~1.5). Also, I would not recommend injection of ZnO nanoparticles in the blood, because such particles would be engulfed by macrophages and would finally be toxic against these and maybe other cells, because Zn(II) ions may show toxicity to many cells in the organism. I would recommend biomedical use of ZnO only externally (not introducing it into the body, but for example applying it on the skin). Indeed, there are some formulations based on ZnO for treatment of some skin disorders. In such a way, I think that ZnO has no future as antimalarial or anti-tuberculosis drug.

Good luck!

Dear Fakhrul thanks for your reply. Can ZnO nanoparticles only be used as antimalarial or antituberculosis agents instead of conventional drugs?

Dear Prashanth,

I haven't checked if someone has tested ZnO NPs against these parasites/bacteria. However, I would not recommend ZnO NPs for use in malaria and tuberculosis treatment because of the following. Both, the malaria parasite and the tuberculosis bacterium are internal invaders - the malaria parasite is in the blood, and the tuberculosis bacterium is usually an intracellular microorganism. It means that any drugs that intend to cure these diseases must be taken orally or by injection - in any case the drugs need to reach the blood circulation in order to act upon the microorganisms. ZnO can not be taken orally because it will dissolve in the acidic medium in stomach (pH ~1.5). Also, I would not recommend injection of ZnO nanoparticles in the blood, because such particles would be engulfed by macrophages and would finally be toxic against these and maybe other cells, because Zn(II) ions may show toxicity to many cells in the organism. I would recommend biomedical use of ZnO only externally (not introducing it into the body, but for example applying it on the skin). Indeed, there are some formulations based on ZnO for treatment of some skin disorders. In such a way, I think that ZnO has no future as antimalarial or anti-tuberculosis drug.

Good luck!

Prashanth,

Please use the following links where authors have synthesized ZnO and checked its bacterial growth.

http://iopscience.iop.org/0957-4484/18/38/385702

It may be useful to you.

All the best

Thanks Dear Georgi and Dipak :)

Dr Georgi I totally agree with your opinion, but sir, how ZnO is used in anticancer treatment or as an antitumor (As chemotherapeutic nanoparticles) in drug delivery systems!!

I know that there are some publications that report cytotoxic activity of ZnO NPs against cancer cells. However, I am a little bit pessimistic about this because of the following. First, probably everything is or has been tested on cancer cells, but there is a very big gap between in vitro (tests on cells) and in vivo (tests on animals) tests with NPs. Most (if not all) tests with ZnO NPs in cancer as I know have been performed on cancer cells but not in real tumor-bearing animals. To be protected from macrophages ZnO NPs need to be covered in this case with some bio-compatible materials. Second, as I know there are some reports about selectivity in the cytotoxicity of ZnO to cancer and normal cells. Actually, cancer cells are more sensitive to cytotoxic agents than normal cells (this is in the basis of current cancer chemotherapy), so this is an expected result. But side effects from cancer chemotherapy appear as a result of cytotoxicity of substances to normal stem cells. Stem cells appear quite similar to cancer cells from metabolic point of view, but unfortunately potential cytotoxic drugs are rarely (if at all) tested on stem cells (maybe because stem cells are difficult to cultivate). So, I expect ZnO NPs to be toxic also to stem cells, which may abolish their use in cancer therapy. Third, I am usually pessimistic about the internal application of NPs that contain difficult to eliminate and toxic components (such as heavy metal ions). For example, you can find many articles about the use of gold NPs in cancer treatment. The problem in this case (although authors rarely comment on this problem) is that there is no way to get the gold out of the body after such treatment. Again, most of these studies have been performed on cells only, and long term toxicity in animals is usually not tested.

Anyway, the case of cancer is a little bit different than malaria and tuberculosis, because of two reasons, I think. First, most drugs (including NPs) used to treat cancer are toxins themselves and their use intends to kill cells. So, the use of toxic NPs in this case sometimes can work. Second, as I know there are some curative treatments for malaria and tuberculosis (unfortunately, not so effective but probably more effective than anti-cancer drugs). If you want to demonstrate the efficacy of ZnO, then you have to show that your ZnO is better than these treatments. Because the tuberculosis bacteria is an intracellular microorganism, which is sometimes inside macrophages, probably ZnO would work in this case better than for malaria. But if you are going to perform any tests I recommend you to test your NPs directly to an infected animal to see the effects.

I hope these comments help you somehow.

Kind regards,

Georgi

Dear Georgi,

Thank you very much for the detailed explanation. Thanks a lot for your suggestions :)

Dear Georgi,

Could you kindly suggest may I go for in vivo studies of my ZnO nanopowder samples (without in vivo studies) against Breast cancer (Mammary Carcinoma -DMBA induced) and lung cancer (Benzo (a) pyrene induced) ?.. Please give your opinion and suggestions.

WIth warm regards

Dear Prashanth,

I have no idea of the properties of your samples. In each case you will need to transfer the nanopowder in a stable liquid dispersion with no aggregates larger than 200-300 nm. After that you will need probably to test hemocompatibility of this dispersion to be sure that no hemolysis or thrombosis occur if you intend to inject this dispersion into animals. These are probably the most important issues. Then, your experiment will show what happens.

Kind regards,

Georgi