Polymer-Based Nanosystems—A Versatile Delivery Approach

Polymer-based nanoparticles of tailored size, morphology, and surface properties have attracted increasing attention as carriers for drugs, biomolecules, and genes. By protecting the payload from degradation and maintaining sustained and controlled release of the drug, polymeric nanoparticles can reduce drug clearance, increase their cargo’s stability and solubility, prolong its half-life, and ensure optimal concentration at the target site. The inherent immunomodulatory properties of specific polymer nanoparticles, coupled with their drug encapsulation ability, have raised particular interest in vaccine delivery. This paper aims to review current and emerging drug delivery applications of both branched and linear, natural, and synthetic polymer nanostructures, focusing on their role in vaccine development.

Smart Gold-Polymer Nanostructures As Promising Drug Nanocarriers For Dual-Imaging Modality And Synergistic Chemo-Photothermal Therapy in Breast Cancer Cells

To improve the efficacy of cancer therapeutics, highly sensitive imaging with precise accuracy is mandatory for timely diagnosis and selection of strategic approaches. Despite recent advances in technologies associated with tumor imaging, the application of conventional single-mode imaging is the subject of debate. Herein, two types of pH-responsive gold-polymer nanostructures, GNSts and GNRs, containing CD and MTX, GNSts-MTX@CD-Pol and GNRs-MTX@CD-Pol were designed. Dual-imaging modalities (fluorescence and CT imaging) and synergistic chemo-photothermal therapy were examined in human breast cancer MDA-MB 231 cells. MTT assay showed NIR irradiation of cells pre-treated with synthesized nanoparticles promoted tumoricidal synergy via the reduction of survival rate after 48 hours in comparison with the control group (p<0.05), indicating a high absorption coefficient in the NIR area and efficient heat production rate. Flow cytometry, real-time PCR and western blot, analyses indicated an apoptotic cell death induced by the up-regulation of Caspases 3, 6, 7, 8, and 9, Bax, and Annexin-V, confirming the activation of intrinsic and extrinsic apoptosis pathways inside the host cells. The elevation of p27 and p53 in line with the increase of cell percent at the subG1 phase showed apoptotic changes and inhibition of dynamic cell growth compared to the non-treated cells (p<0.05). Evident fluorescence intensity at lower pH values (6.3) showed pH-dependent activity of nanoparticles internalized by surface folate receptor. Of note, we showed strong capability for CT imaging in cells incubated with GNSts-MTX@CD-Pol and GNRs-MTX@CD-Pol. Taken together, all data show that gold-polymer nanostructures have considerable capability in theranostic applications like simultaneous diagnostic imaging and therapy.

Adjusting the length of supramolecular polymer bottlebrushes by top-down approaches

Controlling the length of one-dimensional (1D) polymer nanostructures remains a key challenge on the way toward the applications of these structures. Here, we demonstrate that top-down processing facilitates a straightforward adjustment of the length of polyethylene oxide (PEO)-based supramolecular polymer bottlebrushes (SPBs) in aqueous solutions. These cylindrical structures self-assemble via directional hydrogen bonds formed by benzenetrisurea (BTU) or benzenetrispeptide (BTP) motifs located within the hydrophobic core of the fiber. A slow transition from different organic solvents to water leads first to the formation of µm-long fibers, which can subsequently be fragmented by ultrasonication or dual asymmetric centrifugation. The latter allows for a better adjustment of applied shear stresses, and thus enables access to differently sized fragments depending on time and rotation rate. Extended sonication and scission analysis further allowed an estimation of tensile strengths of around 16 MPa for both the BTU and BTP systems. In combination with the high kinetic stability of these SPBs, the applied top-down methods represent an easily implementable technique toward 1D polymer nanostructures with an adjustable length in the range of interest for perspective biomedical applications.

Assessment of the Biocompatibility of Cucurbiturils in Blood Cells

Currently, cucurbiturils are being actively researched all over the world. Research is focused on the ways of improving the solubility and selectivity of cucurbiturils, increasing the stability of the complexes with other particles in various media and enhancing their ability to bind and release various substances. The most significant area of our research is the assessment of safety, studying the biological properties and synergistic effects of cucurbiturils during complexation with drugs. In this article, the hemocompatibility of erythrocytes and leukocytes with cucurbiturils was investigated. We demonstrated that cucurbiturils have no cytotoxic effect, even at high concentrations (1 mM) and do not affect the viability of PBMCs. However, cucurbiturils can increase the level of the early apoptosis of lymphocytes and cucurbit[7]uril enhances hemolysis in biologically relevant media. Despite this, cucurbiturils are fairly safe organic molecules in concentrations up to 0.3 mM. Thus, we believe that it will become possible to use polymer nanostructures as drug delivery systems in clinical practice, since cucurbiturils can be modified to improve pharmacological properties.