Thermoresponsive PNIPAAm-TiO2 hybrid aqueous lubricants containing unmodified and silane functionalized TiO2 nanoparticles were investigated under swollen (20 °C) and collapsed (40 °C) microgel conditions. Both systems reduced friction and wear compared to water; however, the functionalized formulation exhibited superior wear resistance at both temperatures. SEM-EDS, Raman spectroscopy, TOF-SIMS depth profiling, and PF-QNM revealed formation of hybrid tribofilms composed of Ti containing species and polymer derived carbonaceous fragments. At 40 °C, increased Ti deposition was observed for both systems, but improved wear performance correlated with sustained Ti+ and CN- distribution and bimodal DMT modulus values of the tribofilm. The results demonstrate that nanoparticle surface functionalization governs tribofilm stability and wear resistance beyond Ti deposition alone, enabling adaptive aqueous lubrication.

Cross-linked hydrogels incorporating supramolecular host-guest structures serve as effective biosensor transducers utilizing their swelling capabilities to detect biomarkers. This study addresses the entire development chain of a novel biosensor. Initially, stable molecular compounds were synthesized and integrated into photo-cross-linkable polymers via spin coating. The resulting networks convert chemical recognition to detectable swelling signals triggered by competitive binding. When specific analytes are present, reversible supramolecular bonds break, releasing guest molecules that alter the gel polarity and induce swelling changes. To validate this mechanism, supramolecular interactions were rigorously analyzed. The polymers were then integrated into piezoresistive sensor setups. By comparing measuring and reference sensors, the system's accuracy and reliability were demonstrated through the detection of spermine concentrations. These hydrogel-based sensors offer significant advantages: miniaturization for rapid response times, integrability, enhanced selectivity and sensitivity, and electrical outputs facilitating simple on-site diagnostics. The final sensor exhibited linear behavior within the physiologically relevant range (1-10 mu M spermine) and achieved a detection limit of 0.39 mu M. Consequently, an accurate, precise, and rapid on-site sensor was successfully created. Designed for high sensitivity, fast response, and long-term stability, these prototypes for biomedical spermine sensing hold promise for diverse applications, including noninvasive medical diagnostics, pharmaceuticals, healthcare, and environmental protection.

Synthesis of polymer nanoparticles containing α-lipoic acid derivatives, which depolymerize in response to high concentrations of glutathione, as found in breast cancer cells, for use in drug delivery systems.

Continuous flow catalysis utilizing gel-bound organocatalysts within a microfluidic reactor represents a compelling strategy in the realm of organic synthesis. In this study, a quinuclidine-based catalytic monomer (QMA) was synthesized to create polymer gel dots through the process of photopolymerization that serve as a support for the catalyst. The resulting gel-bound organocatalysts were assembled within a continuous microfluidic reactor to facilitate the Baylis-Hillman reaction between various aldehydes and acrylonitrile at a temperature of 50 °C. The conversion of the product was assessed using 1H NMR spectroscopy as an offline analytical method over a duration of 8 h. The findings indicated that highly reactive aldehydes achieved conversion rates exceeding 90%, in contrast to their less reactive counterparts. Furthermore, these results were juxtaposed with previously published data derived from alternative synthetic methodologies, revealing that the continuous microfluidic reactions employing integrated organocatalysts within polymer networks exhibited significantly higher conversions with reduced reaction times (8 h) at the same temperature (50 °C). Additionally, the influence of different geometries (round, triangular, and square) of the gel dots on catalytic activity was investigated, with round and square gel dots demonstrating slightly superior performance compared with triangular gel dots, attributed to their increased surface area. Moreover, an extended reaction period of 6 days was conducted using 4-bromobenzaldehyde and acrylonitrile, resulting in a conversion rate exceeding 70%, which remained stable for 5 days before experiencing a slight decline due to product accumulation on the gel dots.

The development of sustainable catalysts is the main objective in green chemistry approaches. In this study, a catalytically active polymer based on a tertiary amine was synthesized, functionalized with a photo-crosslinker, and structured into nanofibers via electrospinning technique with polycaprolactone (PCL) as a stabilizing additive. Subsequent photo-crosslinking yielded hierarchically porous polymers with high swelling properties and increased surface areas, thereby improving the accessibility of the immobilized catalytically active sites. The nanofiber mats were incorporated into a microfluidic reactor (MFR) setup and utilized as heterogeneous catalysts for the Knoevenagel reaction of malononitrile with different aldehydes. It was observed that the system demonstrated a substantial improvement in NMR yields (40-60%) and turnover frequencies (50-80 h-1) in comparison to catalytical systems that had been previously published. Reusability studies showed reproducibility of NMR yields over up to three cycles. The obtained results demonstrate the potential of electrospun, photo-crosslinked nanofibers as efficient heterogeneous catalysts in microfluidic synthesis, thus contributing to more sustainable production of valuable malononitrile derivatives.

Over the past decades, nanoparticulate drug carrier systems have emerged as promising tools in medicine. A persistent challenge in current pharmacotherapy is the limited selectivity of active pharmaceutical ingredients, resulting in undesirable side effects. Smart drug delivery systems, which release encapsulated active pharmaceutical ingredients in response to specific stimuli, offer a potential solution by enabling controlled drug release. This approach can be particularly relevant for exploiting biochemical differences between extracellular and intracellular environments. In this study, self-immolative polydisulfide based polymers manufactured from dithiothreitol were processed into nanoparticle formulations to respond preferentially to elevated glutathione levels, which are characteristic of intracellular environments and are often increased in tumor cells. The influence of polymer chain length on the physicochemical properties of the resulting nanoparticles was investigated. Lumogen (R) Red was incorporated as a model substance to determine the loading capacity of the carrier system. Degradation was characterized using dynamic light scattering and asymmetric flow field-flow fractionation, as well as by imaging techniques such as atomic force microscopy. Selective release of the embedded substance was demonstrated at elevated glutathione concentrations, while no significant release was observed at extracellularly relevant levels (10 & micro;M glutathione), where the behavior was comparable to the buffer control. Increased release was observed under intracellularly relevant conditions (2 - 10 mM glutathione). These findings support a redoxresponsive behavior under intracellular-like conditions. The latter was proven for primary fibroblasts and the cancer cell lines BT-474, MCF-7 and SK-BR-3 by quantification of intracellular low molecular weight thiols. The nanoparticle uptake was confirmed in the investigated cell lines by visualization via confocal laser scanning microscopy. Via lysosomal staining it was shown that nanoparticles accumulate in lysosomes. Furthermore, the carrier system itself showed no cytotoxic properties in cell culture studies against the four different cell types. The developed system is a suitable and very promising smart drug delivery system in the context of controlled drug release.

To minimize or avoid the use of antibiotics, antimicrobial polymers have emerged as a promising option to fight biomaterial‐associated infections, e.g., on titanium‐based implants. However, the challenge is to develop active polymers that exhibit an antimicrobial effect and are compatible with human cells. Different studies aiming for biocidal polymers active in soluble mode, focused on the ratio of cationic to hydrophobic groups, while only marginal knowledge is available for immobilized components. Here a strong hydrophilic electrolyte 4‐vinylbenzyltrimethylammonium chloride (TMA) is chosen as the cationic component. The block composition of the polycationic segment is modified with styrene (Sty) regarding the amphiphilic balance. To adsorb such polymers onto titanium surfaces they are equipped with a polyphosphonic acid anchor block by sequential reversible‐addition‐fragmentation chain‐transfer polymerization (RAFT) polymerization. The polymer composition affected the wetting behavior of adsorbed coatings with water contact angles ranging from 17° to 72°, while zetapotential measurements confirmed high extent of positive charges for all adsorbed polymer coatings. The fundamentally modified block composition resulted in significantly improved cytocompatibility. Antimicrobial efficacy in early bacterial adhesion is still retained from slightly antiadhesive coatings to combined antiadhesive/biocidal activity depending on Sty/TMA ratio in random polymers while a block copolymer revealed lowest antimicrobial effect.

The use of organo-catalysis in continuous-flow reactor systems is gaining attention in medicinal chemistry due to its cost-effectiveness and reduced chemical waste. In this study, bioactive curcumin (CUM) derivatives were synthesized in a continuously operated microfluidic reactor (MFR), using piperidine-based polymeric networks as catalysts. Piperidine methacrylate and piperidine acrylate were synthesized and subsequently copolymerized with complementary monomers (MMA or DMAA) and crosslinkers (EGDMA or MBAM) via photopolymerization, yielding different polymeric networks. Initially, batch reactions were optimized for the organo-catalytic Knoevenagel condensation between CUM and 4-nitrobenzaldehyde, under various conditions, in the presence of polymer networks. Conversion was assessed using offline 1H NMR spectroscopy, revealing an increase in conversion with enhanced swelling properties of the polymer networks, which facilitated greater accessibility of catalytic sites. In continuous-flow MFR experiments, optimized polymer gel dots exhibited superior catalytic performance, achieving a conversion of up to 72%, compared to other compositions. This improvement was attributed to the enhanced swelling in the reaction mixture (DMSO/methanol, 7:3 v/v) at 40 °C over 72 h. Furthermore, the MFR system enabled the efficient synthesis of a series of CUM derivatives, demonstrating significantly higher conversion rates than traditional batch reactions. Notably, while batch reactions required 90% catalyst loading in the gel, the MFR system achieved a comparable or superior performance with only 50% catalyst, resulting in a higher turnover number. These findings underscore the advantages of continuous-flow organo-catalysis in enhancing catalytic efficiency and sustainability in organic synthesis.

To address the challenges associated with poor drug solubility and uncontrolled drug release in conventional dosage forms, a combination of polymer design and advanced drug delivery approaches has been employed. The development of pH-responsive nanoparticles for controlled and selective drug release represents a notable advance in adaptive nanomedicine. This study explores the design of a pH-responsive polymer, poly(1,4-phenyleneacetone dimethylene ketal) (PPADK). Additionally, the incorporation of light-responsive ortho-nitrobenzyl groups (o-NB-PPADK) enhanced the degradation upon exposure to light. Based on the polymer, nanoparticles were prepared using the solvent displacement method. The fluorescence dye Lumogen® Red was incorporated as a model substance. The nanoparticles were characterized by dynamic light scattering to determine their hydrodynamic diameter and size distribution, and the surface charge was analyzed. Atomic force microscopy was used to visualize the surface morphology. The nanoparticles remained stable under physiological pH conditions while exhibiting accelerated degradation and substance release in acidic environment, a property potentially exploitable for tumor targeting. Further enhanced degradation and correspondingly increased release was achieved by incorporating light-responsive elements in the polymer structure. The cytotoxicity of these newly designed nanoparticles was evaluated in cell culture using a breast cancer cell line. These results support the potential of o-NB-PPADK nanoparticles as a possible candidate for selective and effective cancer therapy, combining stimuli-responsive degradation mechanisms for improved therapeutic outcomes.

The tribological behavior of thermo-responsive poly(N-isopropylacrylamide) (PNIPAAm)-based microgels is investigated for use as water-dispersible lubricant additives. Two types of microgels are synthesized using a surfactant-free emulsion polymerization method: MG0, consisting of pure PNIPAAm with a volume phase transition temperature (VPTT) of approximate to 33 degrees C, and MG16, consisting of PNIPAAm copolymerized with hydrophobic tert-butyl acrylamide, exhibiting a lower VPTT of around 23 degrees C. Swelling and lubrication performance are evaluated at 20 and 40 degrees C. Both microgels significantly reduce friction and wear compared to water alone. At 20 degrees C, MG0 remains fully swollen and provides effective wear protection through hydrated microgel lubrication. MG16, being near its VPTT, exhibits partial collapse and slightly higher wear. At 40 degrees C, MG16 demonstrates improved wear resistance, attributed to enhanced film compaction in the collapsed state. Raman spectroscopy and scanning electron microscopy-energy-dispersive X-ray spectroscopy confirm that carbon-rich tribofilms are formed via tribochemical reactions. MG0 produces more graphitic films, while MG16 generates amorphous carbon structures. These findings highlight the tunability of microgel composition for designing adaptive, water-based lubricants for temperature-sensitive applications.

Over the last few decades, nanotechnology has established to be a promising field in medicine. A remaining dominant challenge in today's pharmacotherapy is the limited selectivity of active pharmaceutical ingredients and associated undesirable side effects. Controlled drug release can be promoted by smart drug delivery systems, which release embedded API primarily depending on specific stimuli. Consequently, also the microenvironment of tumor tissue can be used advantageously. Dithiothreitol (DTT) based self-immolative polydisulfides were synthesized that preferentially respond to pathologically increased glutathione (GSH) concentrations, as found in solid tumors. The synthesis with different degrees of polymerisation was investigated as well as the synthesis of a copolymer consisting of dithiothreitol and butanedithiol (BDT). Toxicity tests were carried out on pure polymers and their degradation products. The ability to degrade was examined at pathological and physiological glutathione concentrations in order to test the suitability of the polymer as a matrix for nanoparticulate carrier systems. In addition, the processability of one polymer into nanoparticles was investigated as well as the degradation behaviour with glutathione.

A strategy for multifunctional biosurfaces exploiting multiblock copolymers and the antipolyelectrolyte effect is reported. Combining a polyzwitterionic/antifouling and a polycationic/antibacterial block with a central anchoring block for attachment to titanium oxide surfaces affords surface coatings that exhibit antifouling properties against proteins and allow for surface regeneration by clearing adhering proteins by employing a salt washing step. The surfaces also kill bacteria by contact killing, which is aided by a nonfouling block. The synthesis of block copolymers of 4-vinyl pyridine (VP), dimethyl 4-vinylbenzyl phosphonate (DMVBP), and 4-vinylbenzyltrimethyl ammonium chloride (TMA) is achieved on the multigram scale via RAFT polymerization with good end group retention and narrow dispersities. By polymer analogous reactions, poly(4-vinyl pyridinium propane sulfonate-block-4-vinylbenzyl phosphonic acid-block-4-vinylbenzyl trimethylammonium chloride) (P(VSP64-b-PA14-b-TMA64)) is obtained. The antifouling properties against the model protein pepsin and the salt-induced surface regeneration are shown in surface plasmon resonance (SPR) experiments, while independently the antibacterial and antifouling properties of coated titanium substrates are successfully tested in preliminary microbiological assays against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). This strategy may contribute to the development of long-term effective antibacterial implant surface coatings to suppress biomedical device-associated infections.

We conducted an investigation into the palladium‐catalyzed carbon‐sulfur cross‐coupling reaction involving a 2‐bromothiophene derivative and potassium thioacetate as a substitute for hydrogen sulfide. This investigation utilized kinetic and computational methods. We synthesized two palladium complexes supported by the bisphosphane ligands bis(diphenylphosphino)ferrocene (DPPF) and bis(diisopropylphosphino)ferrocene (D i PPF), as well as their tentative intermediates in the catalytic cycle. Reaction rates were measured and then compared to computational predictions.

An SPR-based dually crosslinked gel sensor for adiponitrile bearing pillar[5]arene responsive sites with a low limit of detection was developed.

The Knoevenagel reaction is a classic reaction in organic chemistry for the formation of C-C bonds. In this study, various catalytic monomers for Knoevenagel reactions were synthesized and polymerized via photolithography to form polymeric gel dots with a composition of 90% catalyst, 9% gelling agent and 1% crosslinker. Furthermore, these gel dots were inserted into a microfluidic reactor (MFR) and the conversion of the reaction using gel dots as catalysts in the MFR for 8 h at room temperature was studied. The gel dots containing primary amines showed a better conversion of about 83–90% with aliphatic aldehyde and 86–100% with aromatic aldehyde, compared to the tertiary amines (52–59% with aliphatic aldehyde and 77–93% with aromatic aldehydes) which resembles the reactivity of the amines. Moreover, the addition of polar solvent (water) in the reaction mixture and the swelling properties of the gel dots by altering the polymer backbone showed a significant enhancement in the conversion of the reaction, due to the increased accessibility of the catalytic sites in the polymeric network. These results suggested the primary-amine-based catalysts facilitate better conversion compared to tertiary amines and the reaction solvent had a significant influence on organocatalysis to improve the efficiency of MFR.

The controlled delivery of active pharmaceutical ingredients to the site of disease represents a major challenge in drug therapy. Particularly when drugs have to be transported across biological barriers, suitable drug delivery systems are of importance. In recent years responsive delivery systems have been developed which enable a controlled drug release depending on internal or external stimuli such as changes in pH, redox environment or light and temperature. In some studies delivery systems with reactivity against two different stimuli were established either to enhance the response by synergies of the stimuli or to broaden the window of possible trigger events. In the present review numerous exciting developments of pH-, light- and redox-cleavable polymers suitable for the preparation of smart delivery systems are described. The review discusses the different stimuli that can be used for a controlled drug release of polymer-based delivery systems. It puts a focus on the different polymers described for the preparation of stimuli-sensitive systems, their preparation techniques as well as their stimuli-responsive degradation. (c) 2022 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry.

Coating medical implants with antibacterial polymers may prevent postoperative infections which are a common issue for conventional titanium implants and can even lead to implant failure. Easily applicable diblock copolymers are presented that form polymer brushes via "grafting to" mechanism on titanium and equip the modified material with antibacterial properties. The polymers carry quaternized pyridinium units to combat bacteria and phosphonic acid groups which allow the linear chains to be anchored to metal surfaces in a convenient coating process. The polymers are synthesized via reversible-addition-fragmentation-chain-transfer (RAFT) polymerization and postmodifications and are characterized using NMR spectroscopy and SEC. Low grafting densities are a major drawback of the "grafting to" approach compared to "grafting from". Thus, the number of phosphonic acid groups in the anchor block are varied to investigate and optimize the surface binding. Modified titanium surfaces are examined regarding their composition, wetting behavior, streaming potential, and coating stability. Evaluation of the antimicrobial properties revealed reduced bacterial adhesion and biofilm formation for certain polymers, albeit the cell biocompatibility against human gingival fibroblasts is also impaired. The presented findings show the potential of easy-to-apply polymer coatings and aid in designing next-generation implant surface modifications.

In recent years, sequence-defined oligomers (SDOs) gained increasing interest due to their perfectly controlled molecular structure, thus providing defined properties. In order to tune the properties, different functionalities need to be incorporated into the oligomers and the chain tacticity needs to be controlled. Beside the synthesis of SDOs, suitable methods need to be found to analyze the molecular structure. In this work, oligomers exhibiting an alternating or block-wise sequence of side chain functionalities were analyzed using a hyphenation of ultra-high-performance liquid chromatography and electrospray ionization mass spectrometry enhanced by ion mobility separation (IMS). Moieties in the side chains were varied according to polarity and bulkiness. Moreover, chain tacticity was varied. Drift times in the IMS cell and the corresponding collision cross section (CCS) values were shown to be individual parameters allowing the identification of SDOs, even in the case that SDO structures only differ in sequence or tacticity of side chain functionalities. Thus, a library of CCS values was obtained as reference used for the analysis of complex mixtures of SDOs.