An efficient doxorubicin (DOX) drug delivery system with specificity against tumor cells was developed, based on multi-walled carbon nanotubes (MWCNTs) functionalized with guanidinylated dendritic molecular transporters. Acid-treated MWCNTs (oxCNTs) interacted both electrostatically and through hydrogen bonding and van der Waals attraction forces with guanidinylated derivatives of 5000 and 25,000 Da molecular weight hyperbranched polyethyleneimine (GPEI5K and GPEI25K). Chemical characterization of these GPEI-functionalized oxCNTs revealed successful decoration with GPEIs all over the oxCNTs sidewalls, which, due to the presence of guanidinium groups, gave them aqueous compatibility and, thus, exceptional colloidal stability. These GPEI-functionalized CNTs were subsequently loaded with DOX for selective anticancer activity, yielding systems of high DOX loading, up to 99.5% encapsulation efficiency, while the DOX-loaded systems exhibited pH-triggered release and higher therapeutic efficacy compared to that of free DOX. Most importantly, the oxCNTs@GPEI5K-DOX system caused high and selective toxicity against cancer cells in a non-apoptotic, fast and catastrophic manner that cancer cells cannot recover from. Therefore, the oxCNTs@GPEI5K nanocarrier was found to be a potent and efficient nanoscale DOX delivery system, exhibiting high selectivity against cancerous cells, thus constituting a promising candidate for cancer therapy.

Non-toxic carbon-based hybrid nanomaterials based on carbon nanodisks were synthesized and assessed as novel antibacterial agents. Specifically, acid-treated carbon nanodisks (oxCNDs), as a safe alternative material to graphene oxide, interacted through covalent and non-covalent bonding with guanidinylated hyperbranched polyethyleneimine derivatives (GPEI5K and GPEI25K), affording the oxCNDs@GPEI5K and oxCNDs@GPEI25K hybrids. Their physico-chemical characterization confirmed the successful and homogenous attachment of GPEIs on the surface of oxCNDs, which, due to the presence of guanidinium groups, offered them improved aqueous stability. Moreover, the antibacterial activity of oxCNDs@GPEIs was evaluated against Gram-negative E. coli and Gram-positive S. aureus bacteria. It was found that both hybrids exhibited enhanced antibacterial activity, with oxCNDs@GPEI5K being more active than oxCNDs@GPEI25K. Their MIC and MBC values were found to be much lower than those of oxCNDs, revealing that the GPEI attachment endowed the hybrids with enhanced antibacterial properties. These improved properties were attributed to the polycationic character of the oxCNDs@GPEIs, which enables effective interaction with the bacterial cytoplasmic membrane and cell walls, leading to cell envelope damage, and eventually cell lysis. Finally, oxCNDs@GPEIs showed minimal cytotoxicity on mammalian cells, indicating that these hybrid nanomaterials have great potential to be used as safe and efficient antibacterial agents.

The threat of antimicrobial resistance (AMR) and the need for sustainable disinfectants have spurred interest in natural antimicrobials such as essential oils (EOs). However, their application is limited by volatility, poor water solubility, and cytotoxicity. Herein, we present the development of bio-based core–shell sub-micro-/nanocapsules (NCs) with encapsulated oregano (OO), thyme (TO), eucalyptus (EuO), and tea tree (TTO) oils to enhance antimicrobial (AM) performance and reduce cytotoxicity. NCs were synthesized via a nanoencapsulation method using chemically modified zein or poly(methyl vinyl ether-co-maleic anhydride) (GZA) as shell polymers, with selected EOs encapsulated in their core (encapsulation efficacy > 98%). Chemical modification of zein with vanillin (VA) and GZA with either dodecyl amine (DDA) or 3-(glycidyloxypropyl)trimethoxysilane (EPTMS) resulted in improvement in particle size distributions, polydispersity indices (PDIs) of synthesized NCs, and in the stability of the NC-dispersions in water. Antibacterial testing against Staphylococcus aureus and cytotoxicity assays showed that encapsulation significantly reduced toxicity while preserving their antibacterial activity. Among the formulations, GZA-based NCs modified with EPTMS provided the best balance between safety and efficacy. Despite this, life cycle assessment revealed that zein-based NCs were more environmentally sustainable due to lower energy use and material impact. Overall, the approach offers a promising strategy for developing sustainable, effective, and safe EO-based antibacterial agents for AM applications.

Diseases caused by infection are a threat to human health and the world economy, with bacterial infections being responsible for a large portion of hospitalizations, morbidity, and mortality, which necessitates the quest for advanced medications and/or sustainable antibacterial strategies. This study aims to develop bioderived chitin nanofibers (ChNFs) and ZnO nanoparticles to produce non-toxic nanohybrid materials with improved aqueous stability and enhanced antibacterial properties. These nanohybrids were formed via either (i) an ex situ route by mixing the ChNFs with ZnO nanoparticles prepared by flame spray pyrolysis or (ii) an in situ route resulting in ZnO nanoparticles being formed and embedded into ChNFs by a simple aqueous hydrothermal process, utilizing a low-cost Zn inorganic precursor. The ChNFs, the ZnO nanoparticles, and the nanohybrids were physicochemically characterized for their size, morphology, charge and stability. Their antibacterial activity was evaluated against Gram (−) E. coli and Gram (+) S. aureus bacteria, while their cytocompatibility was assessed against mammalian cell lines. The obtained results reveal a balance between antibacterial activity and cytocompatibility, as both nanohybrids exhibited satisfactory antibacterial activity (MIC 200–300 μg/mL) combined with low cytotoxicity against mammalian cell lines (cell viability 80–100%), indicating that their further application as safe and effective antibacterial agents is promising.

Background/Objectives: Copper levels are significantly elevated in both the sera and tumor tissues of various cancers, including prostate cancer. It has therefore been suggested that targeting the elevated copper levels with copper chelators could lead to selective cancer treatment. Thus, several classes of low molecular weight copper-coordinating lipophilic compounds, as well as the newly developed copper complexes of appropriately functionalized polymers, are being investigated as promising novel anticancer therapeutics. Particularly, metal-containing polymers, or metallopolymers, are systematically investigated as anticancer agents or as drug delivery systems. This study aims to utilize the strong copper-chelating properties of hyperbranched polyethyleneimine (PEI) to develop PEI:Cu metallopolymers and evaluate their selectivity and anticancer properties against several prostate cancer cell lines. Methods: A series of PEI:Cu complexes at PEI/Cu ratios that ensure that no free copper ions are present in the solution are prepared and investigated against a human non-cancerous cell line and three prostate cancer cell lines of increasing metastatic potential. Results: PEI:Cu derivatives are cytotoxic against the human prostate carcinoma metastatic PC3 and DU145 cell lines, even at the lowest tested concentrations of 5 μg/mL, while against the non-cancerous HEK293 cells, all metallopolymer derivatives exhibit insignificant cytotoxicity up concentrations of 50 μg/mL. Their cytotoxic effect is associated with mitochondria membrane potential loss and ROS production increase. Conclusions: Hyperbranched polyethyleneimine–coordinated copper(II) metallopolymers, at low concentrations, selectively induce cytotoxicity in metastatic prostate cancer cell lines without compromising the viability of non-cancerous embryonic kidney cells.

Wool textiles with multifunctional properties such as self-cleaning, antibacterial, electrical conductivity, UV blocking etc. have recently attracted interest. Among the materials employed towards their development, carbon nanotubes (CNTs) have been widely investigated due to their unique chemical, mechanical and electrical properties, exhibiting also notable UV-blocking properties. However, their limited dispersibility in solvents, particularly in water, has hindered their extensive industrial application and diminished their significant potential. In this work, two guanidinylated derivatives of hyperbranched polyethyleneimine (GPEI5k and PEI 25K) functionalized oxCNTs (oxCNTs@GPEI5K and oxCNTs@GPEI5K), with exceptional aqueous compatibility and colloidal stability, developed in our recent publication, were evaluated as to their antibacterial activity on Gram (-) Escherichia coli and Gram (+) Staphylococcus aureus bacteria and their cytotoxicity against mammalian cells, and the most promising, i.e., oxCNTs@GPEI5K, was subsequently used as finishing agent of wool fabric. The resulting wool textiles were evaluated for color, wash fastness, antibacterial properties, and UV-blocking performance. The GPEI-functionalized oxCNTs derivative, exhibited uniform distribution and good adhesion onto the wool fabrics yielding multifunctional wool fabrics with sustained antibacterial properties even after multiple washing cycles. Additionally, the modified textiles exhibited improved ultraviolet protection, highlighting their potential for multifunctional applications in antibacterial and UV-shielding textiles.