Exploring encapsulation mechanism of DNA and mononucleotides in sol-gel derived silica

Biodegradable silica nanoparticles for efficient linear DNA gene delivery

Targeting, safety, scalability, and storage stability of vectors are still challenges in the field of nucleic acid delivery for gene therapy. Silica-based nanoparticles have been widely studied as gene carriers, exhibiting key features such as biocompatibility, simplistic synthesis, and enabling easy surface modifications for targeting. However, the ability of the formulation to incorporate DNA is limited, which restricts the number of DNA molecules that can be incorporated into the particle, thereby reducing gene expression. Here we use polymerase chain reaction (PCR)-generated linear DNA molecules to augment the coding sequences of gene-carrying nanoparticles, thereby maximizing nucleic acid loading and minimizing the size of these nanocarriers. This approach results in a remarkable 16-fold increase in protein expression six days post-transfection in cells transfected with particles carrying the linear DNA compared with particles bearing circular plasmid DNA. The study also showed that the use of linear DNA entrapped in DNA@SiO2 resulted in a much more efficient level of gene expression compared to standard transfection reagents. The system developed in this study features simplicity, scalability, and increased transfection efficiency and gene expression over existing approaches, enabled by improved embedment capabilities for linear DNA, compared to conventional methods such as lipids or polymers, which generally show greater transfection efficiency with plasmid DNA. Therefore, this novel methodology can find applications not only in gene therapy but also in research settings for high-throughput gene expression screenings.

Sol-Gel Coatings with Azofoska Fertilizer Deposited onto Pea Seeds

Pure silica sol obtained by hydrolysis of tetraethoxysilane and the same silica sol doped with fertilizer Azofoska were used to cover the surface of pea seeds. The surface state of the coated seeds (layer continuity, thickness, elemental composition) was studied by a scanning electron microscope (SEM) and energy dispersive X-ray (EDX) detector. Different conditions such as sol mixing method, seed immersion time, effect of diluting the sol with water, and ethanol (EtOH) were studied to obtain thin continuous coatings. The coated seeds were subjected to a germination and growth test to demonstrate that the produced SiO₂ coating did not inhibit these processes; moreover, the presence of fertilizer in the coating structure facilitates the development of the seedling. The supply of nutrients directly to the grain's vicinity contributes to faster germination and development of seedlings. This may give the developing plants an advantage in growth over other undesirable plant species. These activities are in the line with the trends of searching for technologies increasing yields without creating an excessive burden on the natural environment.

Long term conservation of DNA at ambient temperature. Implications for DNA data storage

DNA conservation is central to many applications. This leads to an ever-increasing number of samples which are more and more difficult and costly to store or transport. A way to alleviate this problem is to develop procedures for storing samples at room temperature while maintaining their stability. A variety of commercial systems have been proposed but they fail to completely protect DNA from deleterious factors, mainly water. On the other side, Imagene company has developed a procedure for long-term conservation of biospecimen at room temperature based on the confinement of the samples under an anhydrous and anoxic atmosphere maintained inside hermetic capsules. The procedure has been validated by us and others for purified RNA, and for DNA in buffy coat or white blood cells lysates, but a precise determination of purified DNA stability is still lacking. We used the Arrhenius law to determine the DNA degradation rate at room temperature. We found that extrapolation to 25°C gave a degradation rate constant equivalent to about 1 cut/century/100 000 nucleotides, a stability several orders of magnitude larger than the current commercialized processes. Such a stability is fundamental for many applications such as the preservation of very large DNA molecules (particularly interesting in the context of genome sequencing) or oligonucleotides for DNA data storage. Capsules are also well suited for this latter application because of their high capacity. One can calculate that the 64 zettabytes of data produced in 2020 could be stored, standalone, for centuries, in about 20 kg of capsules.