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Background/Objective: Cationic polymers were shown to assemble with negatively charged proteins yielding nanoparticles (NPs). Poly-diallyl-dimethyl-ammonium chloride (PDDA) combined with ovalbumin (OVA) yielded a stable colloidal dispersion (OVA/PDDA-NPs) eliciting significant anti-OVA immune response. Dendritic cells (DCs), as sentinels of foreign antigens, exert a crucial role in the antigen-specific immune response. Here, we aimed to evaluate the involvement of DCs in the immune response induced by OVA/PDDA. Methods: In vivo experiments were used to assess the ability of OVA/PDDA-NPs to induce anti-OVA antibodies by ELISA, as well as plasma cells and memory B cells using flow cytometry. Additionally, DC migration to draining lymph nodes following OVA/PDDA-NP immunization was evaluated by flow cytometry. In vitro experiments using bone marrow-derived DCs (BM-DCs) were used to analyze the binding and uptake of OVA/PDDA-NPs, DC maturation status, and their antigen-presenting capacity. Results: Our data confirmed the potent effect of OVA/PDDA-NPs inducing anti-OVA IgG1 and IgG2a antibodies with increased CD19+CD138+ plasma cells and CD19+CD38+CD27+ memory cells in immunized mice. OVA/PDDA-NPs induced DC maturation and migration to draining lymph nodes. The in vitro results showed higher binding and the uptake of OVA/PDDA-NPs by BM-DCs. In addition, the NPs were able to induce the upregulation of costimulatory and MHC-II molecules on DCs, as well as TNF-α and IL-12 production. Higher OVA-specific T cell proliferation was promoted by BM-DCs incubated with OVA/PDDA-NPs. Conclusions: The data showed the central role of DCs in the induction of antigen-specific immune response by OVA-PDDA-NPs, thus proving that these NPs are a potent adjuvant for subunit vaccine design. [ABSTRACT FROM AUTHOR]

Cationic vaccines of nanometric sizes can directly perform the delivery of antigen(s) and immunomodulator(s) to dendritic cells in the lymph nodes. The positively charged nanovaccines are taken up by antigen-presenting cells (APCs) of the lymphatic system often originating the cellular immunological defense required to fight intracellular microbial infections and the proliferation of cancers. Cationic molecules imparting the positive charges to nanovaccines exhibit a dose-dependent toxicity which needs to be systematically addressed. Against the coronavirus, mRNA cationic nanovaccines evolved rapidly. Nowadays cationic nanovaccines have been formulated against several infections with the advantage of cationic compounds granting protection of nucleic acids in vivo against biodegradation by nucleases. Up to the threshold concentration of cationic molecules for nanovaccine delivery, cationic nanovaccines perform well eliciting the desired Th 1 improved immune response in the absence of cytotoxicity. A second strategy in the literature involves dilution of cationic components in biocompatible polymeric matrixes. Polymeric nanoparticles incorporating cationic molecules at reduced concentrations for the cationic component often result in an absence of toxic effects. The progress in vaccinology against cancer involves in situ designs for cationic nanovaccines. The lysis of transformed cancer cells releases several tumoral antigens, which in the presence of cationic nanoadjuvants can be systemically presented for the prevention of metastatic cancer. In addition, these local cationic nanovaccines allow immunotherapeutic tumor treatment. [ABSTRACT FROM AUTHOR]

Antibiotic resistance requires alternatives to fight multi-drug resistant strains. Antimicrobial peptides (AMPs) act by disrupting or solubilizing microbial cell walls or membranes in accordance with mechanisms difficult to counteract from the microbe's point of view. In this review, structure–activity relationships for AMPs and their assemblies are discussed, considering not only their self-assembly but also their interactions with their carriers for optimal delivery or their combinations with other complementary antimicrobials or moieties covalently bound to their chemical structure. The effect of the formulations on AMP activity is also evaluated, revealing a myriad of possibilities. Depending on the interaction forces between the AMP, the carrier, or the elements added to the formulations, AMP activity can be reduced, enhanced, or remain unaffected. Approaches protecting AMPs against proteolysis may also reduce their activity. [ABSTRACT FROM AUTHOR]

The effect of dioctadecyldimethylammonium bromide bilayer vesicles on the wettability of planar SiO2 surfaces is due to vesicle adhesion or bilayer deposition. The adhesion or opening up of vesicles upon contact with the SiO2 surface depends on the ionic strength being 0 or 10 mM monovalent salt. The bilayer deposition usually corresponds to the lack of contact angle hysteresis and maximization of contact angles.

A study was conducted to investigate that both horse and tuna cytochrome c exhibited two types of binding to inner mitochondrial membranes that contributed to respiration. Findings suggest that site L ionization determines the participation of cytochrome c in the respiratory chain and apoptosis.