State of the art in nonthermal plasma processing for biomedical applications: Can it help fight viral pandemics like COVID-19?

Plasma processing finds widespread biomedical applications, such as the design of biosensors, antibiofouling surfaces, controlled drug delivery systems, and in plasma sterilizers. In the present coronavirus disease (COVID-19) situation, the prospect of applying plasma processes like surface activation, plasma grafting, plasma-enhanced chemical vapor deposition/plasma polymerization, surface etching, plasma immersion ion implantation, crosslinking, and plasma decontamination to provide timely solutions in the form of better antiviral alternatives, practical diagnostic tools, and reusable personal protective equipment is worth exploring. Herein, the role of nonthermal plasmas and their contributions toward healthcare are timely reviewed to engage different communities in assisting healthcare associates and clinicians, not only to combat the current COVID-19 pandemic but also to prevent similar kinds of future outbreaks.

Multi-nanolayer drug delivery using radiofrequency plasma technology

BACKGROUND

It may be impossible to perform cancer surgery with free margins in the presence of an unresectable structure. Local drug treatment after surgery has been proposed to increase the rate of tumor control.

METHODS

Multi-nanolayers (10-330 nm) were generated by a low-pressure (375mTorr) inductively coupled plasma (13.56 MHz) reactor for anticancer drug delivery by the deposition of polycaprolactone-polyethylene glycol multistack barrier on the collagen membrane (100 μm thickness). Carboplatin (300 μg/cm2) was used for the in vitro and in vivo investigations. Energy-dispersive X-ray spectroscopy (15 keV), scanning electron microscopy and inductively coupled plasma mass spectrometry were used to detect the presence of carboplatin in the nanolayer, the tumor sample and the culture medium. Preclinical studies were performed on ovarian (OVCAR-3NIH) and colon (CT26) cancer cell lines as xenografts (45 days) and allografts (23 days) in Swiss-nude (n = 6) and immunocompetent BALB/cByJ mice (n = 24), respectively.

RESULTS

The loading of carboplatin or other drugs between the nanofilm on the collagen membrane did not modify the mesh complex architecture or the drug properties. Drugs were detectable on the membrane for more than 2 weeks in the in vitro analysis and more than 10 days in the in vivo analysis. Cytotoxic mesh decreased cell adherence (down 5.42-fold) and induced cancer cell destruction (up to 7.87-fold). Implantation of the mesh on the mouse tumor nodule modified the cell architecture and decreased the tumor size (50.26%) compared to the control by inducing cell apoptosis.

CONCLUSION

Plasma technology allows a mesh to be built with multi-nanolayer anticancer drug delivery on collagen membranes.

Optimization of a low pressure plasma process for fabrication of a Drug Delivery System (DDS) for cancer treatment

A low pressure ICP plasma setup was utilized to deposit thin organic barrier coatings on various substrates to fabricate DDS with encapsulated Carboplatin as a drug and Methylene Blue as a drug model. Choice of the substrates and optimal plasma parameters were discussed for the fabrication of DDS with required characteristics. Prepared thin films were analysed by FTIR, SEM, and the barrier properties were studied by measuring drug concentration released into the medium by UV-VIS and ICP-MS techniques.

Structure and Stability of C:H:O Plasma Polymer Films Co-Polymerized Using Dimethyl Carbonate

C:H:O plasma polymer films (PPFs) were deposited by means of plasma-enhanced chemical vapour deposition using the non-toxic, biodegradable organic compound dimethyl carbonate (DMC) at various plasma powers and pressures in order to control the degradation properties related to the carbonate ester group. Coating properties using pure DMC monomer vapours were compared to co-polymerized films from gaseous mixtures of DMC with either ethylene (C2H4) or carbon dioxide (CO2) affecting deposition rate and chemical composition. C:H:O film properties were found to depend primarily on the amount of oxygen in the plasma. To investigate the PPF stability during aging, changes in the composition and properties were studied during their storage both in air and in distilled water over extended periods up to 5 months. It was shown that aging of the films is mostly due to oxidation of the plasma polymer matrix yielding slow degradation and decomposition. The aging processes and their rate are dependent on the intrinsic amount of oxygen in the as-prepared C:H:O films which in turn depends on the experimental conditions and the working gas mixture. Adjustable film properties were mainly attained using a pure DMC plasma considering both gas phase and surface processes. It is thus possible to prepare C:H:O PPFs with controllable degradability both in air and in water.

Radio-frequency plasma polymerized biodegradable carrier for in vivo release of cis-platinum

A low pressure plasma process based on plasma deposition has been used to develop a drug delivery strategy. In this study, a drug delivery system based on different layers of plasma co-polymerized Poly ε-caprolactone-Polyethylene glycol (PCL-PEG) co-polymers was deposited on biocompatible substrates. Cis-platinum (118 μgm/cm2) was used as an anti-cancer drug and incorporated for local delivery of the chemotherapeutic agent. The co-polymer layers and their interaction with cancer cells were analyzed by scanning electron microscopy. Our study showed that the plasma-PCL-PEG coated cellophane membranes, in which the drug, was included did not modify the flexibility and appearance of the membranes. This system was actively investigated as an alternative method of controlling localized delivery of drug in vivo. The loading of the anti-cancer drug was investigated by UV-VIS spectroscopy and its release from plasma deposited implants against BALB/c mice liver tissues were analyzed through histological examination and apoptosis by TUNEL assay. The histological examination of liver tissues revealed that when the plasma-modified membranes encapsulated the cis-platinum, the Glisson's capsule and liver parenchyma were damaged. In all cases, inflammatory tissues and fibrosis cells were observed in contact zones between the implant and the liver parenchyma. In conclusion, low pressure plasma deposited uniform nano-layers of the co-polymers can be used for controlled release of the drug in vivo.