Steadily increasing levels of antimicrobial resistance (AMR) are a continuous threat to our global public health. Antimicrobial polymers (APs) offer a promising solution, as their mechanism of action – the permeabilization of bacterial membranes – is unsusceptible toward AMR. However, their selectivity between eukaryotic and prokaryotic cells is still insufficient for clinical applications.
To guide APs and direct their activity against prokaryotic cells, a plethora of parameters can be altered. The amphiphilic balance, molecular weight, or the type of charged unit are among them. One additional important aspect in this context is the polymer architecture, as it fundamentally changes the physico-chemical properties of APs. Using bottle brush copolymers as a platform for APs, we could show that confinement and multivalence in such structures has a profound impact on their biological activity.[1-2] Indeed, optimizing structural parameters yields highly selective APs featuring increased antimicrobial activity and markedly different membrane interaction.[3-4] Systematic variation of the aspect ratio of such molecular brushes led to a further increase in bioactivity and revealed the strong influence of intramolecular self-assembly on membrane interaction.[5]
By use of advanced synthetic methods, leading to complex macromolecules, paired with the utilization of various analytical techniques, generating more insight in polymer membrane interaction we aim to open new ways to APs with increased activity and lowered unspecific toxicity paving the way to APs in biomedical applications.

The dynamics of membranes are integral to regulating biological pathways in living systems, particularly in mediating intra- and extracellular communication between membrane-less and membranized nano- and microcompartments. The membranization of membrane-less coacervates and further demembranization under control of the coacervate architecture paves the way for the exploitation of complex protocells. We present different coacervate-based protocell transformations making use of ionic interactions of charged terpolymers with the coacervate components. Two different terpolymers are used with variations in the hydrophobic blocks but the same hydrophilic block [1,2] The first transformation process is orchestrated by altering the balance of non-covalent interactions through varying concentrations of an anionic terpolymer, leading to the deposition of terpolymer nanoparticles (NPs) at the coacervate surface to fabricate membranized coacervates and, finally, giant vesicles (Scheme below).[1] Furthermore, the second strategy presents the controlled demembranization of membranized coacervate droplets.[2] After the formation of a solid-like membrane of coacervates by terpolymer-based nanospheres, the addition of an anionic polysaccharide triggers the demembranization process arising from electrostatic competition with the membrane components, resulting in demembranized polysaccharide-containing coacervate droplets. These membranization/demembranization processes not only allow for the controlled structural reconfiguration of the coacervate entities, but also varies their permeability towards (biological) (macro)molecules and nano- and micro-scale objects. Additionally, integrating a polymersome membrane facilitates the creation of bilayer and "Janus-like" membranized coacervates. This is a strong advancement toward the creation of synthetic cells with different diffusible compartments and the development of coacervate protocells with hierarchical and asymmetric membrane structures.

Amphiphilic polymeric hydrogels attract significant attention due to their unique structural properties and broad applicability across a wide range of biomedical applications. These hydrogels consist of hydrophilic and hydrophobic segments that can self-assemble into micelles leading to gel formation at concentrations above the critical gelation concentration (CGC)1. Recent studies have reported on the structural organization of thermosensitive hydrogels derived from well-defined linear triblock copolymers and star block copolymers (with 3 and 4 arms) featuring semi-crystalline blocks composed of poly(ethylene oxide) (PEO) and poly(ε-caprolactone) (PCL). These materials have been explored as sacrificial biomaterial inks in direct ink-writing printing (DIWP) applications2. Additionally, the chemical modification of alginate with alkyl chains has provided a route for preparing amphiphilic polysaccharides. Blending these modified polysaccharides with nano-fibrillated cellulose has resulted in printable hydrogels suitable for use as drug-release matrices3. In this presentation, we will showcase recent studies in our group aimed at elucidating the structure and self-assembly mechanisms in water of amphiphilic hydrogels with enhanced mechanical strength. These hydrogels have been developed from: i) aqueous dispersions of polyvinyl alcohol combined with semi-crystalline long alkyl chain alkylamines, and ii) chemically modified hydrogels derived from pectin. The findings highlight the potential of these materials for producing functional hydrogels suitable for versatile applications in biomedical and engineering fields, including their use as inks in DIWP-based applications.
This research was financially supported by the projects PID2020-113045GB-C21 and C22 and PID2023-149734NB-C21 funded by MCIU/ AEI/10.13039/501100011033.

Biocides, particularly quaternary ammonium compounds (QACs), are regarded as primary defences against pathogens [1]. The incorporation of QACs into cellulose introduces antimicrobial properties, increasing its efficacy in applications such as wound dressings and antibacterial fabrics [2]. In this work we present the synthesis of quaternized cellulose-g-poly(dimethylaminoethylmethacrylate) (PDMAEMA) copolymer via Atom Transfer Radical Polymerization (ATRP) of DMAEMA onto cellulose and subsequent quaternization, resulting in materials with both hydrophilic and cationic properties. The synthesized materials were characterized using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), Proton Nuclear Magnetic Resonance spectroscopy (1H-NMR), Thermogravimetric Analysis and X-ray Photoelectron Spectroscopy (XPS) to investigate the structural and thermal properties. ATR-FTIR spectra revealed the successful grafting of PDMAEMA onto the cellulose, demonstrated by the appearance of characteristic amine bands associated with the tertiary amine groups of PDMAEMA. 1H-NMR analysis confirmed grafting of PDMAEMA onto cellulose by showing clear chemical shifts corresponding to PDMAEMA segment. Additionally, the cellulose-g-PDMAEMA copolymer exhibited enhanced thermal stability compared to neat cellulose. Successful quaternization was confirmed by the presence of quaternary amine bands in ATR-FTIR and characteristic binding energies in XPS. To assess the potential of the quaternized cellulose-g-PDMAEMA copolymer for practical applications, antibacterial activity against the Gram-positive bacterium Staphylococcus aureus was tested. The results indicate that the quaternized copolymer exhibited promising antimicrobial properties.

Polysaccharide-based polymers offer a novel approach to enhancing micronutrient efficiency in agriculture. This study focuses on the development of biopolymer-based delivery systems that ensure the controlled and sustained release of essential micronutrients, optimizing plant uptake while reducing environmental loss. By leveraging the natural biodegradability and compatibility of polysaccharides, these polymers provide an eco-friendly alternative to conventional fertilizers.
These advanced materials regulate micronutrient availability through mechanisms such as diffusion, erosion, and swelling, ensuring nutrients are released in a targeted and efficient manner. The controlled release of micronutrients is crucial to match plant demand at different growth stages, preventing deficiencies that can hinder plant metabolism, enzyme function, and overall development [1]. Additionally, excessive application of micronutrients can lead to their leaching into the environment, causing pollution and disrupting soil and water ecosystems [2]. Particular attention is given to the role of crosslinked polysaccharides in improving nutrient retention and controlled dispersion. Systems incorporating ionic gelation techniques, such as those involving biopolymer interactions with tripolyphosphate (TPP), further enhance the stability and release profile of encapsulated micronutrients. These strategies allow for greater control over nutrient bioavailability, reducing leaching losses while maintaining soil integrity.
This approach highlights the potential of polysaccharide-based controlled-release systems to revolutionize sustainable agriculture by optimizing nutrient management. By reducing the frequency of fertilizer applications and minimizing nutrient runoff, these innovative materials contribute to improved crop productivity and environmental conservation. Future research should focus on advancing scalable and cost-effective biopolymer formulations to further support global food security and eco-friendly farming practices.

Device-related-infections are very common in clinical settings and are often accompanied by inflammation, causing pain and swelling in infected tissue. These infections not only pose a big risk to patients’ health, but also complicate post-treatment care, decreasing quality of life. Studies show that the main reason is the formation of biofilms, which act as a shelter and breeding ground to protect and further proliferate bacteria1. To address this challenge, we are aimed to develop an immobilized antibacterial coating to combat infections, without the need of antibiotics. We applied a multi-layer approach to covalently attach a contact-killing coating on the surface of different materials. Specifically, a dopamine-moiety coupling agent was used as the first layer to immobilize on the surface, which was successfully synthesized with a high yield. This was followed by a synthetic hyperbranched polyurea layer (HBP) to strengthen the coating’s mechanical properties. The molecular weight of the HBP could be well-defined and controlled to suit various purposes for different applications. The top layer consisted of a biocidal layer of PEI (Polyethyleneimine) combined with a novel salt-strengthened protonation as the core component to achieve killing of bacteria on contact 2. Both JIS assay and 3M™ Petrifilm™ Aerobic Count Plates showed complete killing on S. epidermidis ATCC 12228, while the surface wettability improved compared to the use of traditional alkylation steps that introduces long polymer chains, offering a significant step toward biocompatibility.