DoE to improve supercoiled p53-pDNA purification by O-phospho-l-tyrosine chromatography

Understanding the adsorption of plasmid DNA and RNA molecules onto arginine-agarose chromatographic resin

Background

The production of nucleic acids (plasmid DNA or mRNA) in response to the development of new advanced vaccine platforms has greatly increased recently, mostly resulting from the pandemic situation. Due to the intended pharmaceutical use, nucleic acids preparations must fulfill all the required specifications in terms of purity and quality. Chromatography is a standard operation used to isolate these molecules from impurities, playing a central role in the manufacturing processes. However, the mechanism of nucleic acid adsorption in chromatographic resins is poorly understood, often leading to low adsorption capacities and a lack of specificity.

Methods and results

Here we investigated the adsorption of plasmid DNA and RNA molecules onto arginine-agarose, a resin with potential for large-scale application. Equilibrium batch studies were performed through pre-purified samples, using arginine-based ligands by varying the adsorption conditions in the pH value range from 6.0 to 9.0. Langmuir and Freundlich isotherm models were used to describe the adsorption equilibrium. The best fit for both nucleic acids was achieved using the Freundlich model. The correct choice of pH showed critical for controlling the efficacy of arginine-nucleic acid interaction, due to its influence on the nucleic acid structures. This type of analysis is necessary for the improvement of the selectivity and binding capacities of the resins used for plasmid DNA or mRNA purification.

Conclusions

The results presented here indicate that adsorption conditions can be tuned to enhance separation between pDNA and RNA, an important feature in the purification of nucleic acids for vaccine production.

Arginine-Affinity Chromatography for Nucleic Acid (DNA and RNA) Isolation

Nucleic acid-based therapy has been emerging as a new strategy with great potential for the treatment of numerous diseases, especially those caused by gene defects. In this context, biotechnology plays a critical role on establishing suitable processes for biopharmaceuticals manufacturing, while the purification step still imposes a major burden. Affinity chromatography using amino acids as specific ligands has been successfully applied for plasmid DNA purification. In this protocol, we describe the process for nucleic acids production and extraction, as well as the chromatographic matrix synthesis for separation between DNA and RNA. This novel arginine-macroporous support presents excellent binding capacity and great robustness for nucleic acids isolation.

Treatment of wastewater reverse osmosis concentrate using alginate-immobilised microalgae: Integrated impact of solution conditions on algal bead performance

Alginate can be used for entrapment of microalgal cells in gel beads to achieve high-rate treatment of wastewater and can overcome the difficulties of cell separation that would occur in suspended microalgae treatment systems. The potential for alginate beads to disintegrate in the presence of high ion concentrations could limit the use of alginate entrapment for treating municipal wastewater reverse osmosis concentrate (ROC). The combined effect of the pH, alkalinity, and salinity of the ROC that impact the physical stability, chemical characteristics, biomass production, and nutrient removal performance of alginate-entrapped Chlorella vulgaris for treating the ROC was investigated. Water adsorption resulting from the loss of calcium from the alginate matrix was the initiating cause of reduction of the algal bead stability. The combination of alkalinity >400 mg/L and pH ≥9.5 led to a >65% reduction in compressive strength and thus disintegration of beads during ROC treatment. However, alginate beads of C. vulgaris were sufficiently stable and were capable of nutrient remediation (up to 100% TP and 85% TN per treatment cycle of 48 h over a 10-day period) and biomass production (up to 340 mg/L/d) when salinity, pH, and alkalinity levels were <8 g TDS/L, 7-9.5, and <400 mg/L, respectively. Empirical models that were developed and validated could enable the prediction of the performance of the algal beads for various ROC compositions. This study enhances the insight and decision-making regarding the feasibility of the alginate-immobilised microalgal system for treating municipal wastewater ROC streams.

Toward QbD Process Understanding on DNA Vaccine Purification Using Design of Experiment

DNA vaccines, the third generation of vaccines, are a promising therapeutic option for many diseases as they offer the customization of their ability on protection and treatment with high stability. The production of DNA vaccines is considered rapid and less complicated compared to others such as mRNA vaccines, viral vaccines, or subunit protein vaccines. However, the main issue for DNA vaccines is how to produce the active DNA, a supercoiled isoform, to comply with the regulations. Our work therefore focuses on gaining a process understanding of the purification step which processes parameters that have impacts on the critical quality attribute (CQA), supercoiled DNA and performance attribute (PA), and step yield. Herein, pVax1/lacZ was used as a model. The process parameters of interest were sample application flow rates and salt concentration at washing step and at elution step in the hydrophobic interaction chromatography (HIC). Using a Design of Experiment (DoE) with central composite face centered (CCF) approach, 14 experiments plus four additional runs at the center points were created. The response data was used to establish regression predictive models and simulation was conducted in 10,000 runs to provide tolerance intervals of these CQA and PA. The approach of this process understanding can be applied for Quality by Design (QbD) on other DNA vaccines and on a larger production scale as well.

Dilemma on plasmid DNA purification: binding capacity vs selectivity

Plasmid DNA chromatography is a powerful field in constant development and evolution. The use of this technique is considered mandatory in the production of an efficient and safe formulation to be applied for plasmid-mediated gene therapy. Concerning this, the search for an ideal chromatographic support/ligand combination motivated scientist to pursue a continuous improvement on the plasmid chromatography performance, looking for a progression on the ligands and supports used. The present review explores the different approaches used over time to purify plasmid DNA, ambitioning both high recovery and high purity levels. Overall, it is presented a critical discussion relying on the relevance of the binding capacity versus selectivity of the supports.

Composite Central Face Design-An Approach to Achieve Efficient Alginate Microcarriers

Microparticulated drug delivery systems have been used as promising encapsulation systems for protecting drugs for in vitro and in vivo applications, enhancing its stability, providing an increased surface to volume ratio, reducing adverse effects, and hence an improvement in bioavailability. Among the studied microparticles, there is a rising interest in the research of alginate microparticles for pharmaceutical and biomedical fields confirming its potential to be used as an effective matrix for drug and cell delivery. Moreover, calcium alginate has been one of the most extensively forming microparticles in the presence of divalent cations providing prolonged drug release and suitable mucoadhesive properties. Regarding the above mentioned, in this research work, we intended to produce Ca-alginate micro-vehicles through electrospraying, presenting high encapsulation efficiency (EE%), reduced protein release across the time, reduced swelling effect, and high sphericity coefficient. To quickly achieve these characteristics and to perform an optimal combination among the percentage of alginate and CaCl2, design of Experiments was applied. The obtained model presented to be statistically significant (p-value < 0.05), with a coefficient of determination of 0.9207, 0.9197, 0.9499, and 0.9637 for each output (EE%, release, swelling, and sphericity, respectively). Moreover, the optimal point (4% of alginate and 6.6% of CaCl2) was successfully validated.

Chemometrics Approaches in Forced Degradation Studies of Pharmaceutical Drugs

Chemometrics is the chemistry field responsible for planning and extracting the maximum of information of experiments from chemical data using mathematical tools (linear algebra, statistics, and so on). Active pharmaceutical ingredients (APIs) can form impurities when exposed to excipients or environmental variables such as light, high temperatures, acidic or basic conditions, humidity, and oxidative environment. By considering that these impurities can affect the safety and efficacy of the drug product, it is necessary to know how these impurities are yielded and to establish the pathway of their formation. In this context, forced degradation studies of pharmaceutical drugs have been used for the characterization of physicochemical stability of APIs. These studies are also essential in the validation of analytical methodologies, in order to prove the selectivity of methods for the API and its impurities and to create strategies to avoid the formation of degradation products. This review aims to demonstrate how forced degradation studies have been actually performed and the applications of chemometric tools in related studies. Some papers are going to be discussed to exemplify the chemometric applications in forced degradation studies.