In silico study of PEI-PEG-squalene-dsDNA polyplex formation: the delicate role of the PEG length in the binding of PEI to DNA

Multi-shell gold nanoparticles functionalized with methotrexate: a novel nanotherapeutic approach for improved antitumoral and antioxidant activity and enhanced biocompatibility

Methotrexate (MTX) is a folic acid antagonist routinely used in cancer treatment, characterized by poor water solubility and low skin permeability. These issues could be mitigated by using drug delivery systems, such as functionalized gold nanoparticles (AuNPs), known for their versatility and unique properties. This study aimed to develop multi-shell AuNPs functionalized with MTX for the improvement of MTX antitumoral, antioxidant, and biocompatibility features. Stable phosphine-coated AuNPs were synthesized and functionalized with tailored polyethylene glycol (PEG) and short-branched polyethyleneimine (PEI) moieties, followed by MTX covalent binding. Physicochemical characterization by UV-vis and Fourier-transform infrared spectroscopy (FTIR) spectroscopy, dynamic light scattering (DLS), scanning transmission electron microscopy (STEM), and X-ray photoelectron spectroscopy (XPS) confirmed the synthesis at each step. The antioxidant activity of functionalized AuNPs was determined using DPPH radical scavenging assay, ferric ions' reducing antioxidant power (FRAP), and cupric reducing antioxidant capacity (CUPRAC) assays. Biocompatibility and cytotoxicity were assessed using MTT and LDH assays on HaCaT human keratinocytes and CAL27 squamous cell carcinoma. MTX functionalized AuNPs demonstrated enhanced antioxidant activity and a pronounced cytotoxic effect on the tumoral cells compared to their individual components, highlighting their potential for improving cancer therapy.

PEI-Engineered Lipid@PLGA Hybrid Nanoparticles for Multimodal Delivery of Antigens and Immune Adjuvants to the Respiratory Mucosa

Antigen delivery via respiratory mucosal surfaces is an interesting needle-free option for vaccination. Nonetheless, it demands for the design of especially tailored formulations. Here, lipid/poly(lactic-co-glycolic) acid (PLGA) hybrid nanoparticles (hNPs) for the combined delivery of an antigen, ovalbumin (Ova), and an adjuvant, synthetic unmethylated cytosine-phosphate-guanine oligodeoxynucleotide (CpG) motifs, is developed. A panel of Ova/CpG-loaded lipid@PLGA hNPs with tunable size and surface is attained by exploiting two lipid moieties, 1,2 distearoil-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol) (DSPE-PEG) and monophosphoryl lipid A (MPLA), with or without polyethyleneimine (PEI). It is gained insights on the lipid@PLGA hNPs through a combination of techniques to analytically determine the specific moiety on the surface, the spatial distribution of the components and the internal structure of the nanoplatforms. The collected results suggest that PEI plays a role of paramount importance not only in promoting in vitro antigen escape from lysosomes and enhancing antigen cross-presentation, but also in determining the arrangement of the moieties in the final architecture of the hNPs. Though multicomponent PEI-engineered lipid@PLGA hNPs turn out as a viable strategy for delivery of antigens and adjuvant to the respiratory mucosa, tunable nanoparticle features are achievable only through the optimal selection of the components and their relative amounts.

Nucleic acid-binding bis-acridine orange dyes with improved properties for bioimaging and PCR applications

Understanding the intricate interactions of molecular dyes with nucleic acids is pivotal for advancing medical and biochemical applications. In this work, we present a comprehensive study of the interplay between a novel series of bis-acridine orange (BAO) dyes and double-stranded DNA (dsDNA). These BAO dyes were intentionally designed as two acridine orange units connected by neutral linkers featuring a 2,5-disubstituted thiophene moiety. Comparative analysis of BAO compounds with the widely utilized DNA-binding dye EvaGreen (EG) was carried out for fibroblast staining and qPCR analysis. The results show that BAO dyes outperform EG by supporting PCR amplification over a broader concentration range (0.5-5.0 μM). Furthermore, they exhibit an exceptional capability to generate consistent DNA melting curves regardless of DNA concentration fluctuations. Molecular dynamics simulations showed that BAO dyes when interacting with dsDNA unfold from the stacked conformation to the elongated one. The difference in the energy between the conformations is shown to be concomitant with fluorescence enhancement. This study enriches our understanding of the intricate interplay between innovative BAO dyes and dsDNA, fostering their applications in medical and biochemical research, particularly in qPCR methodologies and bioimaging techniques.

PEI-based functional materials: Fabrication techniques, properties, and biomedical applications

Cationic polymers have recently attracted considerable interest as research breakthroughs for various industrial and biomedical applications. They are particularly interesting due to their highly positive charges, acceptable physicochemical properties, and ability to undergo further modifications, making them attractive candidates for biomedical applications. Polyethyleneimines (PEIs), as the most extensively utilized polymers, are one of the valuable and prominent classes of polycations. Owing to their flexible polymeric chains, broad molecular weight (MW) distribution, and repetitive structural units, their customization for functional composites is more feasible. The specific beneficial attributes of PEIs could be introduced by purposeful functionalization or modification, long service life, biocompatibility, and distinct geometry. Therefore, PEIs have significant potential in biotechnology, medicine, and bioscience. In this review, we present the advances in PEI-based nanomaterials, their transfection efficiency, and their toxicity over the past few years. Furthermore, the potential and suitability of PEIs for various applications are highlighted and discussed in detail. This review aims to inspire readers to investigate innovative approaches for the design and development of next-generation PEI-based nanomaterials possessing cutting-edge functionalities and appealing characteristics.

Novel Nanotherapeutic Systems Based on PEGylated Squalene Micelles for Enhanced In Vitro Activity of Methotrexate and Cytarabine

Nanomedicine has garnered significant attention due to the advantages it offers in the treatment of cancer-related disorders, some of the deadliest diseases affecting human lives. Conventional medication formulations often encounter issues of instability or insolubility in biological environments, resulting in low bioavailability. Nanocarriers play a crucial role in transporting and safeguarding drugs at specific sites of action, enabling gradual release under particular conditions. This study focuses on methotrexate (MTx) and cytarabine (Cyt), essential antitumoral drugs, loaded into PEGylated squalene micellar structures to enhance therapeutic effectiveness and minimize drawbacks. The micelles were prepared using ultrasound-assisted methods in both water and phosphate buffer saline solutions. Evaluation of drug-loaded micelles encompassed parameters such as particle size, colloidal stability, surface charge, morphology, encapsulation efficiency, drug loading capacity, and in vitro release profiles under simulated physiological and tumoral conditions. In vitro cell inhibition studies conducted on MCF-7 and HeLa cell lines demonstrated higher antitumoral activity for the drug-encapsulated micelles compared to free drugs. The encapsulation effectively addressed the burst effect, providing sustained release for at least 48 h while enhancing the drug's protection under physiological conditions.

Immobilisation of Cellobiose Dehydrogenase and Laccase on Chitosan Particles as a Multi-Enzymatic System for the Synthesis of Lactobionic Acid

Lactobionic acid (LBA) is a bioactive compound that has become increasingly popular in medicine in recent years due to its unique properties. This chemical can be formed via the enzymatic oxidation of lactose using fungal oxidoreductive enzymes. This study aimed to intensify the synthesis of LBA using immobilised enzymes (cellobiose dehydrogenase from Phanerochaete chrysosporium (PchCDH) and laccase from Cerrena unicolor (CuLAC)) on chitosan microspheres. We used three different crosslinking agents: genipin, glutaraldehyde, and polyethyleneimine to activate the chitosan. The FTIR and CellDrop techniques were used to characterise the activated microspheres. Quantitative (HPLC) and qualitative (TLC) methods were used to determine the obtained LBA. The results show that the type of activator used influences the efficiency of the binding of the enzyme to the matrix. Furthermore, the amount of LBA formed depends on the type of system used. The use of a system in which one of the enzymes is immobilised on a PEI-activated carrier (PchCDH) and the other is free (CuLAC) proved to be the most optimal, as it yielded almost 100% conversion of lactose to lactobionic acid. Summarising the data obtained the following: lactobionic acid immobilised on chitosan microspheres has great potential for medical applications.

Multilayer gold nanoparticles as non-viral vectors for targeting MCF-7 cancer cells

Cargocomplexes play a vital role in non-viral delivery methods due to their capacity to target certain cells (or cells through the cell-division cycle) and inject their (macro)molecular "cargo" into them. The development of gene carriers that can efficiently transport and deliver genetic material into human-targeted cells with minimal toxicity is an important challenge in the field. The present study reports the straightforward preparation and testing of a modular non-viral gene carrier based on AuNPs. The design, synthesis, and in vitro evaluation of multilayer gold nanoparticles (AuNPs) as non-viral gene carriers with high transfection efficiency, reduced cytotoxicity for targeted therapeutic delivery of nucleic acids to MCF-7 cancer cells are presented. The developed non-viral vector is based on supramolecular "host-guest" inclusion complexes of β-cyclodextrin, positioned on the AuNPs surface over a layer of polyethyleneimine, and adamantyl moiety from polyethylene glycol conjugated decapeptide (WXEAAYQRFL). First, the β-CD functionalized PEI was utilized as the template for the synthesis of AuNPs of controlled sizes. The reaction produced small AuNPs with a cationic layer which is known for efficient condensation of genetic material and β-CD suitable for the decoration of the carrier with targeting moieties using "host-guest" inclusion complexation. Subsequently, adamantine-polyethylene glycol conjugated decapeptide was attached to the AuNPs. The in vitro results have validated the ability of the proposed systems to selectively target tumor cells with high efficacy and low toxicity due to the unique affinity of the aptamer-functionalized nanoparticles toward breast cancer cells. The findings of this work demonstrated that the proposed modular system may represent a very promising platform for the AuNP-based non-viral vectors mainly due to the versatility of the system, which allows for the facile exchange of several types of ligands for improving the targeting properties and transfection efficiency, or for providing better protection from the endocytotic systems.

Caging Polycations: Effect of Increasing Confinement on the Modes of Interaction of Spermidine3+ With DNA Double Helices

Polyamines have important roles in the modulation of the cellular function and are ubiquitous in cells. The polyamines putrescine²⁺, spermidine³⁺, and spermine⁴⁺ represent the most abundant organic counterions of the negatively charged DNA in the cellular nucleus. These polyamines are known to stabilize the DNA structure and, depending on their concentration and additional salt composition, to induce DNA aggregation, which is often referred to as condensation. However, the modes of interactions of these elongated polycations with DNA and how they promote condensation are still not clear. In the present work, atomistic molecular dynamics (MD) computer simulations of two DNA fragments surrounded by spermidine³⁺ (Spd³⁺) cations were performed to study the structuring of Spd³⁺ “caged” between DNA molecules. Microsecond time scale simulations, in which the parallel DNA fragments were constrained at three different separations, but allowed to rotate axially and move naturally, provided information on the conformations and relative orientations of surrounding Spm³⁺ cations as a function of DNA-DNA separation. Novel geometric criteria allowed for the classification of DNA-Spd³⁺ interaction modes, with special attention given to Spd³⁺ conformational changes in the space between the two DNA molecules (caged Spd³⁺). This work shows how changes in the accessible space, or confinement, around DNA affect DNA-Spd³⁺ interactions, information fundamental to understanding the interactions between DNA and its counterions in environments where DNA is compacted, e.g. in the cellular nucleus.

Chitosan-Crosslinked Low Molecular Weight PEI-Conjugated Iron Oxide Nanoparticle for Safe and Effective DNA Delivery to Breast Cancer Cells

Breast cancer has attracted tremendous research interest in treatment development as one of the major threats to public health. The use of non-viral carriers for therapeutic DNA delivery has shown promise in treating various cancer types, including breast cancer, due to their high DNA loading capacity, high cell transfection efficiency, and design versatility. However, cytotoxicity and large sizes of non-viral DNA carriers often raise safety concerns and hinder their applications in the clinic. Here we report the development of a novel nanoparticle formulation (termed NP-Chi-xPEI) that can safely and effectively deliver DNA into breast cancer cells for successful transfection. The nanoparticle is composed of an iron oxide core coated with low molecular weight (800 Da) polyethyleneimine crosslinked with chitosan via biodegradable disulfide bonds. The NP-Chi-xPEI can condense DNA into a small nanoparticle with the overall size of less than 100 nm and offer full DNA protection. Its biodegradable coating of small-molecular weight xPEI and mildly positive surface charge confer extra biocompatibility. NP-Chi-xPEI-mediated DNA delivery was shown to achieve high transfection efficiency across multiple breast cancer cell lines with significantly lower cytotoxicity as compared to the commercial transfection agent Lipofectamine 3000. With demonstrated favorable physicochemical properties and functionality, NP-Chi-xPEI may serve as a reliable vehicle to deliver DNA to breast cancer cells.