The past 200 years have witnessed a revolution in global fertility, mortality, and population growth rates, in which the demography and health of human populations have been transformed. The global demographic transition is leading inexorably to an epidemiological transition and a double burden of disease, as described by the World Health Organisation. One element is the growing burden of non-communicable disease—in both developed and developing countries—as a consequence of population ageing. Plasma has a wide range of applications and promising futures in our day and age. Plasma technologies have been employed to identify, stop, and resolve several health-related issues throughout the last 20 years of this century. These include issues with dental care, cosmetology, tissue engineering, medical diagnostics, mycoses and skin disorders, chronic and senile diseases, and hospital cleanliness in particular, as well as linked bacterial and viral illnesses. The fourth state of matter, or plasma, is well known and takes the form of ionized gas. Since non-equilibrium plasma may produce high concentrations of reactive species while keeping the gas’s overall temperature close to room temperature, it can safely come into touch with biological tissues without burning them. Because of this unique characteristic, a new field known as plasma medicine and biomedical.
Cold Atmospheric Plasma (CAP)
The CAP is generated through several mechanisms that include microwave frequencies, Radiofrequency (RF), high voltage (DC/AC). These CAP are non-equilibrium plasmas because they contain both excited and reactive species (electrons and ions), with enormous potential for plasma-based medicine and drug delivery. The temperature of the electrons is much higher than that of the ions, and their mobility is greater due to their small mass. Because cold plasma has a low power consumption and can conduct chemical reactions in gas at relatively low and ambient temperatures, its thermodynamic imbalance makes it a good choice for organic syntheses. Additionally, it works well for sterilizing medical equipment composed of materials that cannot withstand high temperatures and for treating living tissues.
Atmospheric Pressure Plasma Jet (APPJ)
An open-air, homogenous, non-equilibrium discharge that produces plasma plumes is known as an atmospheric pressure plasma jet (APPJ). UV light, ions, reactive species, and high-energy electrons are all present in the plasma plume. Because of its plasma’s sterilizing properties, atmospheric pressure plasma jets are used in the biomedical industry. Electrodes are attached to a gas nozzle to form APPJs. Ionized gas known as plasma is produced inside the nozzle and is then carried by a gas flow to the item that has to be treated. Agricultural and biological processes can benefit from the antimicrobial agents produced in plasma, including charged and excited molecules, reactive oxygen species (ROS), atomic oxygen (O), reactive forms of nitrogen (RNS), atomic nitrogen (N), nitric oxide (NO), and, in the event of electrical discharges with water admixtures, hydroxyl ions (OH) and hydrogen peroxide (H2O2). Physical and chemical phenomena that affect biological items include etching processes, heat, alternating electric fields, high-energy UV radiation, and their function in surface modification, decontamination, and sterilization treatments. The great efficacy of plasma in disinfection, sterilization, and restoration is attributed, among other things, to the wide range of plasma reactor types available for use in plasma medicine, the ability to regulate their parameters to guarantee the antimicrobial activity of plasma particles, and the ease of access to small, enclosed areas. The therapeutic applications of plasma, or ionized gas, such as wound healing, cancer therapy, and disinfection, are the main focus of the interdisciplinary discipline of plasma medicine. These applications can be broadly categorized into three groups:
• Plasma-assisted preparation of biocompatible surfaces
• Direct therapeutic application of atmospheric-pressure plasma in vivo
• Plasma decontamination and sterilization in medical environments
The list of medicine application in which non-thermal plasmas used;
• Sterilisation of human and animal tissues, blood, and surface wounds
• Assisting skin cancer therapy
• Treatment of viral, bacterial, and fungal infections due to antimicrobial plasma activity
• Odontology—caries therapy
• Coating of implants, contact optical lens, and dentures with biocompatible films
• Live tissue engineering—fabrication of bioactive agents and medicines
• Immobilisation of biological molecules, cell surface modification to control their behaviour, and improvement of blood adhesion
• Sterilisation of medical and surgical instruments, especially those made of materials and fabrics not resistant to high temperature
• Medical diagnostics—fabrication of biosensors based on polymers, and thin amorphous films for medical and biochemical analysis.
• UV sources in skin disorders like phototherapy
The scenario and the benefits
Numerous subjects are still being researched, including as blood coagulation, cancer therapy, wound healing, dentistry, cosmetics, sterilization, and decontamination. Thus far, the success of plasmas has been attributed to their adaptability and ability to produce high concentrations of charged particles, electric field, and photons (visible, infrared, and ultraviolet). The temperature properties of plasma were a major factor in some of the earliest uses of plasma in medicine. Medical professionals have traditionally used heat and high temperatures to remove tissue, sterilize equipment, and cauterize wounds. The focus of research on plasma applications in medicine has recently switched to the use of non-thermal effects. In low thermal loading settings, non-thermal air pressure plasma sources provide an effective way to produce chemically active radicals. These devices’ ability to function outside of vacuum chambers lowers installation and operating expenses overall while also enabling the treatment of mechanically sensitive materials including human tissues and biomaterials. Non-equilibrium plasmas have been shown to be safe, effective, and non-destructive to tissue when it comes to inactivating different parasites and alien species. A variety of atmospheric pressure plasma sources, such as plasma needles, floating- electrode DBDs, micro-hollow cathode discharge air plasma jets, and other types of plasma jets, have been developed for a broad range of biomedical and industrial applications. It has been demonstrated that atmospheric pressure plasma jets are appropriate generators of low-temperature, non-equilibrium atmospheric pressure plasmas. Instead of merely producing plasma plumes in small discharge gaps, the plasma jet devices also produce plasma plumes in wide space. As a result, the size of the object to be treated is not restricted when using them for direct treatment. Before being decontaminated or sterilized, the equipment needs to be well cleaned, and plasma sterilization needs to be a part of an extensive treatment process that also includes cleaning.
Summary
Non-thermal plasma is mostly employed in the biomedical and medical fields these days, and research is being done to improve its efficiency and create more useful gadgets in the future. Because of its high reactivity and other qualities—like its dependability, capacity to carry out plasma processes at atmospheric pressure, energy selectivity, and advancements in power electronics—non-thermal plasma is used. These attributes enable the development of more affordable, compact, and effective power supply plasma reactors. The CAP and APPJs have a wide range of uses and a high likelihood of being included in many more products and future improvements.
Acknowledgement: The use of information retrieved through various references/sources of internet in this article is highly acknowledged.
by Ajay Kumar Rundla and S. S. Verma S.L.I.E.T., Longowal, Distt.-Sangrur (Punjab)-148106
