Applications of particles

Needle Shaped Particles

Micro particles of various shapes have recently been introduced for various drug-delivery applications. In particular the shape of particles has been shown to have an impact on various processes including circulation, vascular adhesion and phagocytosis.[4] Designing polymeric carriers for drug delivery offers numerous advantages including protection from degradation, targeted delivery, controlled release and their rapid clearance from the body, however their low targeting efficiency limit their applications.[6] Studies revealed that needle-shaped particles induced the desirable effect of disrupting the cell membranes indicated by the release of lactate dehydrogenase and uptake of extracellular calcein and thus needle-shaped calcium carbonate particles are a solution to the low targeting efficiency of other.[4] Thus such a particle can be used to target beclomethasone to the alveoli of the lungs as the particle size is small ranging from 1-10μm depending on how the particle is to be taken i.e. Nasal delivery or through respiring.[4]

The method to produce the particles of 1-10μm is expensive and includes using aqueous calcium hydroxide solution which is added to an aqueous medium bath with a temperature of not less than 60° C, into which carbon dioxide gas or a carbon dioxide containing gas is being blown to generate needle-shaped calcium carbonate particles.[5] However these production techniques have issues and can cause undesirable effects such as lowering the stability of the particle and causing chemical deposition of thermally labile molecules. Thus the needle shape particle is not as viable to produce as other particles can overcome this issue, however future developments in its production process can enable the particle to be used in most drug delivery systems as its needle shape allows for extremely fast and effective treatment of specific areas.

Octopus Shaped Particles

Octopus-shaped micro-particles belong to the class of adsorbent particles produced by joint reduction of carbon monoxide CO and iron oxides FexOy and consist of a central nucleus with ligaments branching out of them.[1] The idea of producing adsorbent particles with magnetic properties such as the Octopus shaped particle originated in connection with the detoxification of biological liquids, the protection of implants and the controlled transportations of anti-cancer medicines in tumours.[2] With such uses it requires the particle to be non-toxic and biodegradable to which the Octopus shaped particle fulfils.

Octopus-shaped particles are expensive to make, and are formed from spheres of carbon steel about 36 microns in length.[5] The formation in the plasma of octopus-shaped iron micro-particles include the following:
Firstly fluid spheres are formed in argon plasma and then are rested in vapours. The vapours then move in a circular direction around the spheres, with a molar concentration lower than the mixture of gas and vapour above. At the intersection of the sphere and the plane of movement of the vapors, distinct stagnation point is formed.[3] These create current lines which carry vapour cylinders. Over time, the vapours change of temperature causes the formation of a liquid membrane which eventually solidifies, creating the tendrils of the octopus-shaped particles.[3]

This magnetic Octopus particle can also be used to target very specific areas. The particle can be injected into the bloodstream near the target site, where then rare earth metals can be used over the area allowing the particles to be captured and extravasated at the target.[2] This particle hence allows cytotoxic drugs to be attached for chemotherapy or therapeutic DNA to correct a genetic defect. Furthermore due to its Octopus shape it is able to gain a large surface area and thus is an excellent transporter of drugs, this ability can lead to more future applications in more efficient drug delivery such as vaccines and thus be more widely used.

Bowl-Shaped Particles

The bowl-shaped micro particles are a hemisphere or a half elliptic sphere having a big opening at the central portion that have the ability to absorb water from 80 to 140 ml/100 g. The micro particle of the present invention has an excellent extending ability, adhesiveness and water uptake.[5] Micro-particles regarding adsorbents, release controlling agents and extenders and thus are used in perfumes, pharmaceuticals, agriculture and cosmetics.[5] Typically a spherical micro particle is used for these applications however the spherical micro particles have a low water uptake when used as an adsorbents and thus the bowl -shaped micro particle is better suited for such applications as its water uptake is far greater.[6]

This micro-particle varies in length from 2-100μm and is easily produced and is done so by suspension polymerization of polymerizable monomers (styrene, methylstyrene etc.) in the presence of crosslinking agents (such as divinylbenzene) and hydrophobic liquids in water.[5]The ease of production means this particle's production process can be done quickly and efficiently and hence is easier to mass produce. Therefore a mass producible particle would be ideal in commercial products such as perfumes. Future applications of this particle are being developed, which include sponges that will be able to absorb more liquid then regular household sponges.[5]

References

1. Anonymous "Magnetic nanoparticles for gene and drug delivery " 2014 (9/23/2014), .

2. Ioan Bica, "Some mechanisms for the formation of octopus-shaped iron micro-particles " J Magn Magn Mater 279 (2-3), 289 <last_page> 298 (2004).

3. Julie A. Champion, Yogesh K. Katare and Samir Mitragotri, "Particle shape: A new design parameter for micro- and nanoscale drug delivery carriers " J.Controlled Release 121 (1-2), 3 <last_page> 9 (2007).

4. N. Doshi and S. Mitragotri, "Needle-shaped polymeric particles induce transient disruption of cell membranes " Journal of The Royal Society Interface 7 (Suppl_4), S403 <last_page> S410 (2010; 2010).

5. Takuya Daikin Industries Ltd. Arase, Fumihiro Daikin Industries Ltd. Kamiya, Masayuki Daikin Industries Ltd. Tsuji, Tadashi Daikin Industries Ltd. Ino, Ikuo Daikin Industies Ltd. Kitamura, Yoshiyuki Daikin Industries Ltd. Shibuya, Shigeo Daikin Industries Ltd., Japan Patent No. EP0641738 B1 (Feb 17, 1994 Jul 30, 1997).

6. Rieke Witzleb et al., "Influence of needle-shaped drug particles on the solid lipid extrusion process " Powder Technol 207 (1-3), 407 <last_page> 413 (2011).

7. Yoshio Ota, Norifumi Goto, Iwao Motoyama, Tetsushi Iwashita, Kunio Nomura, USA Patent No. US4824654 A (Mar 17, 1988 Apr 25, 1989).