Development of a polystyrene-based microplastic model for bioaccumulation and biodistribution study using radiotracing and nuclear analysis method.

The investigation of micro or nano plastics behavior in the environment is essential to minimize the hazards of such pollutants on humans. While the conventional method requires sophisticated procedures and a lot of animal subjects, the nuclear technique confers a sensitive, accurate, and real-time method using radiolabeled micro or nano plastics as a tracer. In this study, polystyrene sulfonate-based microplastic (PSM) was developed with a size of around 3.6 µm, followed by radiolabeling with iodine-131 (131I) or zinc-65 (65Zn) for microplastic radiotracer model. After a stability study in seawater, phosphate buffer saline (PBS), and human serum albumin (HSA) for fifteen days, PSM-131I remained stable (>90 %), except in HSA (50-60 % after day-9), while PSM-65Zn was unstable (<50 %).

Iodine-131 radiolabeled polyvinylchloride: A potential radiotracer for micro and nanoplastics bioaccumulation and biodistribution study in organisms.

The microplastics amount in the environment is significantly increasing due to human activity, and the hazards are still being investigated. To evaluate the fate of microplastics in organisms, an accurate, fast, and sensitive method is required. Nuclear technology harnessing radiotracer is one of the most sensitive and accurate method for bioaccumulation, biodistribution and biokinetic study. Here, we developed a preparation method for radioiodinated polyvinyl chloride (PVC) as a potential radiotracer of microplastics. Iodine-131 (131I) as a potential radiotracer for microplastic was used in this experiment (activity of 98.05-221.63 MBq). The 131I-PVC was prepared using the Conant-Finkelstein reaction with a solvent combination of phosphate buffer (B), acetone (A), and tetrahydrofuran (T). Such preparation method resulted in spherical 131I-PVC with sizes ranging from 608.6 to 5457.0 nm. Our study showed that acetone is the most suitable solvent for the radioiodination process, resulting in a stable 131I-PVC for up to six days.

Aerosolised micro and nanoparticle: formulation and delivery method for lung imaging.

Purpose: The application of contrast and tracing agents is essential for lung imaging, as indicated by the wide use in recent decades and the discovery of various new contrast and tracing agents. Different aerosol production and pulmonary administration methods have been developed to improve lung imaging quality. This review details and discusses the ideal characteristics of aerosol administered via pulmonary delivery for lung imaging and the methods for the production and pulmonary administration of dry or liquid aerosol. Methods: We explored several databases, including PubMed, Scopus, and Google Scholar, while preparing this review to discover and obtain the abstracts, reports, review articles, and research papers related to aerosol delivery for lung imaging and the formulation and pulmonary delivery method of dry and liquid aerosol. The search terms used were "dry aerosol delivery", "liquid aerosol delivery", "MRI for lung imaging", "CT scan for lung imaging", "SPECT for lung imaging", "PET for lung imaging", "magnetic particle imaging", "dry powder inhalation", "nebuliser", and "pressurised metered-dose inhaler". Results: Through the literature review, we found that the critical considerations in aerosol delivery for lung imaging are appropriate lung deposition of inhaled aerosol and avoiding toxicity. The important tracing agent was also found to be Technetium-99m (99mTc), Gallium-68 (68Ga) and superparamagnetic iron oxide nanoparticle (SPION), while the essential contrast agents are gold, iodine, silver gadolinium, iron and manganese-based particles. The pulmonary delivery of such tracing and contrast agents can be performed using dry formulation (graphite ablation, spark ignition and spray dried powder) and liquid aerosol (nebulisation, pressurised metered-dose inhalation and air spray). Conclusion: A dual-imaging modality with the combination of different tracing or contrast agents is a future development of aerosolised micro and nanoparticles for lung imaging to improve diagnosis success.

Development of a Spray-Dried Formulation of Peptide-DNA Nanoparticles into a Dry Powder for Pulmonary Delivery Using Factorial Design.

BACKGROUND: Gene therapy via pulmonary delivery holds the potential to treat various lung pathologies. To date, spray drying has been the most promising method to produce inhalable powders. The present study determined the parameters required to spray dry nanoparticles (NPs) that contain the delivery peptide, termed RALA (N-WEARLARALARALARHLARALARALRACEA-C), complexed with plasmid DNA into a dry powder form designed for inhalation. METHODS: The spray drying process was optimised using full factorial design with 19 randomly ordered experiments based on the combination of four parameters and three centre points per block. Specifically, mannitol concentration, inlet temperature, spray rate, and spray frequency were varied to observe their effects on process yield, moisture content, a median of particle size distribution, Z-average, zeta potential, encapsulation efficiency of DNA NPs, and DNA recovery. The impact of mannitol concentration was also examined on the spray-dried NPs and evaluated via biological functionality in vitro. RESULTS: The results demonstrated that mannitol concentration was the strongest variable impacting all responses apart from encapsulation efficiency. All measured responses demonstrated a strong dependency on the experimental variables. Furthermore, spray drying with the optimal variables in combination with a low mannitol concentration (1% and 3%, w/v) produced functional RALA/pDNA NPs. CONCLUSION: The optimal parameters have been determined to spray dry RALA/pDNA NPs into an dry powder with excellent biological functionality, which have the potential to be used for gene therapy applications via pulmonary delivery.