Cationic Hydrogels Research Articles

Development of Variable Charge Cationic Hydrogel Particles with Potential Application in the Removal of Amoxicillin and Sulfamethoxazole from Water

Cationic hydrogel particles (CHPs) crosslinked with glutaraldehyde were synthesized and characterized to evaluate their removal capacity for two globally consumed antibiotics: amoxicillin and sulfamethoxazole. The obtained material was characterized by FTIR, SEM, and TGA, confirming effective crosslinking. The optimal working pH was determined to be 6.0 for amoxicillin and 4.0 for sulfamethoxazole. Under these conditions, the CHPs achieved over 90.0% removal of amoxicillin after 360 min at room temperature, while sulfamethoxazole removal reached approximately 60.0% after 300 min. Thermodynamic analysis indicated that adsorption occurs through a physisorption process and is endothermic. The ΔH° values of 28.38 kJ mol−1, 12.39 kJ mol−1, and ΔS° 97.19 J mol−1 K−1, and 33.94 J mol−1 K−1 for AMX and SMX, respectively. These results highlight the potential of CHPs as promising materials for the removal of such contaminants from aqueous media.

A Simple Preparation of Crosslinked, Highly Alkaline Diallyldimethylammonium Hydroxide Hydrogel Particles via Inverse Static Anion Exchange.

Highly alkaline hydrogels are gaining increasing attention in building materials research. Specifically, cationic alkaline hydrogels based on diallyldimethylammonium hydroxide (DADMAOH) as the monomer have been effectively used to seal water-bearing cracks or serve as coupling media for electrochemical chloride extraction. However, the residual halogen content and challenges in scaling up monomer production have hindered broader application. Attempts to use a commercially available cation-selective membrane for ion exchange achieved up to 90% chloride-to-hydroxide switch, but the approach proved ineffective due to significant monomer decomposition during the process. By contrast, neutral gels and gel particles can be readily prepared from diallyldimethylammonium chloride (DADMAC) in large quantities and with a wide range of compositions. It is demonstrated here that these neutral gel particles undergo inverse static anion exchange when suspended in NaOH solution, generating DADMAOH particles with residual halide contents of <0.3%, without the need for ion-selective or dialysis membranes. This corresponds to an up to 100-fold reduction in residual chloride content compared to particles produced directly from alkaline monomer solutions, thereby significantly enhancing the efficiency of hydroxide ion release. The swelling behaviour of the particles is primarily influenced by the initial monomer concentration, while conductivity remains largely unaffected, indicating that charge transport occurs mainly along the particle surface. Despite the pronounced increase in swelling with decreasing particle radii, the specific conductivity of 2.8 Ω-1 m-1 is still sufficient for their use as coupling media in concrete applications. In summary, the alkaline particles prepared via inverse static anion exchange meet all necessary requirements for building materials applications, offering a broader range of tuneable properties and greater ease of production compared to gels or particles derived from DADMAOH.

Cationic hydrogel with carbon quantum dots: synthesis and methyl orange adsorption capacity

Methyl orange is one of the most commonly used acidic/anionic dyes, and its removal from wastewater is imperative to ensure environmental sustainability. This study developed a novel cationic CQDs/AM/DMC hydrogel using acrylamide (AM) and methylacryloxyethyl trimethyl ammonium chloride (DMC) as main materials, incorporating carbon quantum dots (CQDs). The hydrogel was comprehensively characterized for morphological features, chemical composition and fluorescence characteristics using FTIR, TEM, SEM, PL and XRD analyses. Moreover, as an adsorbent, the hydrogel effectively removed methyl orange (MO) dye from aqueous solutions. Notably, the CQDs/AM/DMC hydrogel exhibited a maximum adsorption capacity of 298.93 mg/g within 30 min, surpassing that of AM/DMC hydrogel (268.29 mg/g within 50 min) in 50 mg/L MO solution. The Langmuir isotherm and pseudo-second-order models had the best agreement with the experimental data, highlighting monolayer and chemical adsorption as the predominant mechanism governing dye uptake. This study contributes valuable insights into the development of an efficient adsorbent for the removal of hazardous materials from wastewater.

Balancing stretchability and conductivity: Carbon nanotube layer-enhanced non-ionic conductive hydrogels with a sandwich structure

In non-ionic conductive hydrogels, conductivity often conflicts with mechanical properties, posing a challenge in creating hydrogels that strike a balance between conductivity and mechanical properties. Here, we addressed this issue by integrating carboxylated carbon nanotube (CNT) layers in a sandwich structure onto the surface of the cationic hydrogel (P(AM-co-DMDAAC), PAD), followed by dehydration for densification. This approach simultaneously improved the conductivity of the hydrogel while maintaining its stretchability. The stability of the composite structure was ensured through electrostatic interactions, hydrogen bonding, and physical entanglement between the PAD hydrogel and the CNT layer. Additionally, adjusting the water–solid ratio of the hydrogel allows fine-tuning of its conductivity and stretchability. Remarkably, at a 500 % water–solid ratio, the hydrogel achieved a conductivity of 2.3 S/m. By further reducing the water content, the conductivity could be increased to 25 S/m, significantly higher than similar hydrogels. The PAD-CNT hydrogel found applications in swelling response, tunable resistance wires, and as strain sensors. Notably, the sandwich structure enables the PAD-CNT hydrogel to output capacitive signals, exhibiting a more sensitive response in monitoring human movement. Overall, this study introduces a novel composite structure for conductive hydrogels, holding tremendous potential in flexible conductivity and smart response fields.

A cationic hydrogel with anti-IL-17A-specific nanobodies for rheumatoid arthritis treatment via inhibition of inflammatory activities of neutrophils

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease primarily driven by inappropriate infiltration and activation of immune cells and pro-inflammatory cytokines. Among them, neutrophils with high plasticity play a pathogenic role in RA by abnormal neutrophil immune activities. As anti-IL-17A therapies failed to achieve long-term ideal therapeutic outcomes in clinical trials, we speculated that the underlying cause may be associated with the abnormal activity of neutrophils that have a direct link to IL-17A. Herein, we created a cationic hydrogel loaded with anti-IL-17A nanobodies (Nbs) capable of synergistically weakening the inflammatory activities of neutrophils and relieving inflammation in RA. Based on the host-guest interaction, the hydrogel was comprised of β-cyclodextrin-modified hyperbranched polylysine (HBPL-CD) and adamantane-modified hyaluronic acid (HA-Ad). The physical properties were adjusted to match the mechanical environment of joints and enable injection. The hydrogel with Nbs could adsorb cell-free DNA (cfDNA) persistently and slowly release anti-IL-17A Nbs, which synergistically alleviated the inflammatory activities of neutrophils via inhibiting the IL-17A stimulated neutrophil extracellular traps (NETs) of neutrophils from RA patients and mice with collagen-induced arthritis (CIA), reducing the level of pro-inflammatory cytokines, and suppressing the inflammatory phenotype of neutrophils in vitro. The ankle injection of the hydrogel with Nbs into a mouse model of CIA could alleviate the RA symptoms in vivo. This novel platform is believed to provide a guideline for treating IL-17A-related diseases by combining Nbs with the immunoregulation of neutrophils.

Controlling Alveolar Bone Loss by Hydrogel‐Based Mitigation of Oral Dysbiosis and Bacteria‐Triggered Proinflammatory Immune Response

AbstractPeriodontitis is a chronic infection where abnormal host‐microbiota interactions alter the oral microbiome, trigger a proinflammatory immune response, and cause inflammatory alveolar bone loss. While antibiotics are occasionally necessary for treating periodontitis, their use must be carefully managed to prevent the development of drug resistance and oral dysbiosis. Therefore, it's crucial to develop new treatment strategies for periodontitis that reduce antibiotic dependence while effectively controlling the inflammation triggered by bacteria. In this study, a hydrogel is engineered by grafting cationic polyamidoamine dendrimers (PAMAM‐G3) onto the oxidized carboxymethyl cellulose (OCMC) backbone, resulting in an injectable cationic hydrogel (OCMC‐PAMAM‐G3, O‐P). This hydrogel can capture anionic microbial‐associated molecular patterns (MAMPs), such as lipopolysaccharides (LPS) and cell‐free DNA (cfDNA). These findings reveal that using O‐P application circumvents the disruption of the oral mucosa microbiome caused by traditional antibiotics. Additionally, this hydrogel can mitigate inflammatory alveolar bone loss in a ligature‐induced periodontitis mouse model by alleviating the LPS/cfDNA‐TLR4/9 pathway. Moreover, topical administration of O‐P hydrogel has no significant adverse effects on the oral mucosa microbiome while improving the local subgingival microbiome. The study highlights a strategy targeting MAMPs while avoiding antibiotics, as it can mitigate the bacteria‐triggered proinflammatory immune response and potentially preserve oral dysbiosis.

Fundamental Studies on Fluids-Independent Regenerative Nanocomposite Hydrogels for Fracture Treatments of Conformance Control.

Traditional granular hydrogels showed excellent injectivity, thermal integrity, and efficient remediation of heterogeneous reservoirs. However, granular hydrogels have demonstrated their inability to adapt to fractures due to the lack of sufficient interactions. Herein, we present new nanocomposite hydrogels consisting of cationic nanogelators and anionic granular hydrogels that can chemically in situ reform bulk hydrogels in the fractures. Interestingly, our granular hydrogels showed recross-linking independence on carrying fluids, contrary to prior reported fluid-dependent recross-linking granular hydrogels. The recross-linking of nanogelators and granular hydrogels can be accomplished from room temperature to 130 °C. The nanocomposite hydrogels displayed increased shear elastic moduli compared to pristine anionic granular hydrogels, probably due to the increased covalent cross-links formed by the homogeneous regenerative approach. We found that the granular hydrogels had high salinity tolerance even in the presence of 1000 ppm divalent ions of calcium (Ca2+) since Ca2+ ions often act as the cross-linker for partially hydrolyzed acrylamide-based hydrogels. Overall, we obtained new regenerative nanocomposite hydrogels based on cationic nanogelators and anionic granular hydrogels for fracture treatments.

Tuning on passive interfacial cooling of covalent organic framework hydrogel for enhancing freshwater and electricity generation

AbstractDeveloping an efficient freshwater and electricity co‐generation device (FECGD) can solve the shortage of freshwater and electricity. However, the poor salt resistance and refrigeration properties of the materials for FECGD put big challenges in the efficient and stable operation of these devices. To address these issues, we propose the covalent organic framework (COF) confined co‐polymerization strategy to prepare COF‐modified acrylamide cationic hydrogels (ACH‐COF), where hydrogen bonding interlocking between negatively charged polymer chains and COF pores can form a salt resistant hydrogel for stabilizing tunable passive interfacial cooling (TPIC). The FECPDs based on the TPIC and salt resistance of ACH‐COF display a maximum output power density of 2.28 W m−2, which is 4.3 times higher than that of a commercial thermoelectric generator under one solar radiation. The production rate of freshwater can reach 2.74 kg m−2 h−1. Our results suggest that the high efficiency and scalability of the FECGD can hold the promise of alleviating freshwater and power shortages.

Synthesis and Evaluation of Ph and Temperature Stimuli-Responsive Magnetic Nanohydrogels for Gene Delivery

The offer of gene delivery technologies as a promising approach to treating diverse diseases has revolutionized human medicine during the last two decades. So, the application of suitable vectors, particularly polymers with substrates with unique physicochemical properties for the transfer of targeted genes to logical sites for effective treatment, plays an indispensable role for more personalized medicine and improves the safety profile in response to continuing to use new medical technologies. For this purpose, we synthesized nanocarriers with a two-block cationic hydrogel, magnetic and non-magnetic, based on N-isopropyl acrylamide (NIPAM) and quaternary alkyl ammonium halide salts of DMAEMA (DMAEMAQ) with pH and temperature responsiveness via the free radical polymerization technique. The bulk properties of these co-polymers were characterized by using Fourier transform infrared spectroscopy, 1H NMR spectroscopy, Zeta potential, lower critical solution temperature (LCST), and gel electrophoresis to show the loading of nanoparticles with the gene. In the results, magnetic P[NIPAM-DMAEMAQ] hydrogel showed controllable responsive properties determined by the nature of the cationic charge +24.7 mV incorporated, nanosize around 86.95 and 91.22 nm, and efficiency loaded with the gene more than 95%. As well, the synthesized nanohydrogel exhibited a sharp volume-phase transition in water at a LCST of ∼40 °C. So, the combination of both monomers yielded an interesting system with high transfection efficiency and compliant biocompatibility characteristics, which could effectively achieve gene loading. Also, the magnetic potential of nanohydrogel was determined as a vector to deliver genes to localized sites. Notably, the synthesized combination P[NIPAM-DMAEMAQ] nanohydrogel has been considered a transfection of the biodegradable and biocompatible magnetic nanoparticle sensitive to tunable pH and temperature responsiveness, demonstrating that it will hold a promising approach as a potential carrier to improve gene delivery therapeutic efficacy in cancer and different disease treatments.

“All-in-one” self-healing and injectable cationic guar gum hydrogel dressing functionalized by bioactive complexes composed of natural small molecules

Reducing the risk of wound infection is an urgent issue health priority. Antibacterial polysaccharide-based hydrogels have attracted great attention for infectious wounds, attributed to their safe antimicrobial performance and natural non-toxicity and biodegradability advantages. In this study, the “all-in-one” self-adaptive and injectable cationic guar gum (CG)-based polysaccharide hydrogels (FA-TOB/CG) loaded with bioactive complexes were developed for infectious wound healing. The constructed antioxidant and antibacterial ferulic acid (FA)-tobramycin (TOB) bioactive complexes (FA-TOB) were used as the cross-linking agent and introduced into the CG matrix to construct the FA-TOB/CG hydrogel with a three-dimensional porous structure. The sterilization rates of FA-TOB/CG hydrogel against S. aureus and E. coli reached 98 % and 80 % respectively. In addition, the FA-TOB/CG also exhibits enhanced antioxidant performances (DPPH: > 40 %; ABTS: > 90 %; ·OH: > 50 %). More importantly, FA-TOB/CG hydrogel also showed the ability to sustain the release of FA and TOB. These superiorities of the FA-TOB/CG hydrogel enabled it to provide a moist wound environment and promote wound healing by eliminating bacteria, modulating the local inflammatory response, and accelerating collagen deposition and vascular regeneration. Thus, this study may enlarge a new sight for developing multifunctional dressings by incorporating bioactive complexes into polysaccharide hydrogels for infected wounds.

Poly(2-isopropenyl-2-oxazoline) as a Versatile Functional Polymer for Biomedical Applications.

Functional polymers play an important role in various biomedical applications. From many choices, poly(2-isopropenyl-2-oxazoline) (PIPOx) represents a promising reactive polymer with great potential in various biomedical applications. PIPOx, with pendant reactive 2-oxazoline groups, can be readily prepared in a controllable manner via several controlled/living polymerization methods, such as living anionic polymerization, atom transfer radical polymerization (ATRP), reversible addition-fragmentation transfer (RAFT) or rare earth metal-mediated group transfer polymerization. The reactivity of pendant 2-oxazoline allows selective reactions with thiol and carboxylic group-containing compounds without the presence of any catalyst. Moreover, PIPOx has been demonstrated to be a non-cytotoxic polymer with immunomodulative properties. Post-polymerization functionalization of PIPOx has been used for the preparation of thermosensitive or cationic polymers, drug conjugates, hydrogels, brush-like materials, and polymer coatings available for drug and gene delivery, tissue engineering, blood-like materials, antimicrobial materials, and many others. This mini-review covers new achievements in PIPOx synthesis, reactivity, and use in biomedical applications.

Antibacterial Hydrogel Adhesives Based on Bifunctional Telechelic Dendritic-Linear-Dendritic Block Copolymers.

Antibiotic-resistant pathogens have been declared by the WHO as one of the major public health threats facing humanity. For that reason, there is an urgent need for materials with inherent antibacterial activity able to replace the use of antibiotics, and in this context, hydrogels have emerged as a promising strategy. Herein, we introduce the next generation of cationic hydrogels with antibacterial activity and high versatility that can be cured on demand in less than 20 s using thiol-ene click chemistry (TEC) in aqueous conditions. The approach capitalizes on a two-component system: (i) telechelic polyester-based dendritic-linear-dendritic (DLDs) block copolymers of different generations heterofunctionalized with allyl and ammonium groups, as well as (ii) polyethylene glycol (PEG) cross-linkers functionalized with thiol groups. These hydrogels resulted in highly tunable materials where the antibacterial performance can be adjusted by modifying the cross-linking density. Off-stoichiometric hydrogels showed narrow antibacterial activity directed toward Gram-negative bacteria. The presence of pending allyls opens up many possibilities for functionalization with biologically interesting molecules. As a proof-of-concept, hydrophilic cysteamine hydrochloride as well as N-hexyl-4-mercaptobutanamide, as an example of a thiol with a hydrophobic alkyl chain, generated three-component networks. In the case of cysteamine derivatives, a broader antibacterial activity was noted than the two-component networks, inhibiting the growth of Gram-positive bacteria. Additionally, these systems presented high versatility, with storage modulus values ranging from 270 to 7024 Pa and different stability profiles ranging from 1 to 56 days in swelling experiments. Good biocompatibility toward skin cells as well as strong adhesion to multiple surfaces place these hydrogels as interesting alternatives to conventional antibiotics.

Nanoparticle-hydrogel composite as dual-drug delivery system for the potential application of corneal graft rejection

Immune rejection remains the major cause of corneal graft failure. Immunosuppressants (such as rapamycin; RAPA) adjunctive to antibiotics (such as levofloxacin hydrochloride; Lev) are a clinical mainstay after corneal grafts but suffer from poor ocular bioavailability associated with severe side effects. In this study, we fabricated a Lev@RAPA micelle loaded cationic peptide-based hydrogel (NapFFKK) as a dual-drug delivery system by integrating RAPA micelles with Lev into a cationic NapFFKK hydrogel to potentially reduced the risk of corneal graft rejection. The properties of the resulting hydrogels were characterized using transmission electronmicroscopy and rheometer. Lev@RAPA micelles loaded NapFFKK hydrogel provided sustained in vitro drug release without compromising their inherent pharmacological activities. Topical instillation of Lev@RAPA micelles loaded NapFFKK hydrogel resulted in the great ocular tolerance and extended precorneal retention over 60 min, thus significantly enhancing the ocular bioavailability of both Lev and RAPA. Overall, such dual-drug delivery system might be a promising formulation for the suppression of corneal graft failure.

Preclinical assessment of an antibiotic-free cationic surfactant-based cellulose hydrogel for sexually and perinatally transmitted infections

Preclinical assessment of an antibiotic-free cationic surfactant-based cellulose hydrogel for sexually and perinatally transmitted infections

Preparation of a cationic hydrogel microsphere adsorbent for efficient removal of hexavalent chromium from aqueous solution

AbstractHerein, a cationic hydrogel microsphere (CHMS) was prepared by inverse suspension polymerization and freeze‐drying and was applied to the adsorptive removal of hexavalent chromium (Cr(VI)) from aqueous solution. Morphological characterization shows that there are lots of folds and pores on the surface of CHMS with a unique petal‐like appearance. According to the chemical structure analysis, CHMS contains plenty of functional groups such as amine and hydroxyl groups. These features give CHMS a larger specific surface area, faster adsorption rate, and higher adsorption capacity than the conventional cationic hydrogel microparticle (CHMP) adsorbent. The adsorption of Cr(VI) in water by CHMS is mainly based on the combination of electrostatic adsorption and redox reaction, with the electrostatic interaction between the protonated amine and Cr(VI) serving as the predominant adsorption mechanism. Experimental results reveal that CHMS can efficiently remove Cr(VI) from simulated wastewater in both batch and continuous adsorption modes, which is primarily due to its distinctive surface morphology and rich functional groups. Furthermore, the common coexisting metal ions in Cr(VI)‐containing wastewater have no substantial negative influence on the adsorption. Therefore, it can be concluded that CHMS has a promising application prospect in the treatment of Cr(VI)‐containing wastewater.

Versatile cationic dual-layer hydrogel filtration system for sustainable solar steam generator

Our increasing water demand has been an ongoing critical challenge due to water usages in areas such as industrial, agriculture, and domestic household. Conventional water production faces challenges, such as high investment, energy consumption, and brine discharge that may be unsustainable in the future. Solar steam generation (SSG) has been recently proposed by many researchers due to their sustainable and green water production method. Here we demonstrated the use of simple manufacturing and low-cost dual-layer hydrogel (DLH) system containing a double network of positive charged poly-[2-(acryloyloxy)ethyl] trimethyl ammonium chloride (PAETAC) and polyvinyl alcohol (PVA) bottom layer for fast water transport, as well as a broad light absorbing and heat generating PVA/graphene oxide (GO) top layer for fast water evaporation. As a result, the DLH was able to generate a high 3.12 kg m−2 h−1 water evaporation with 92% efficiency under 1 sun (kW m−2) exposure. Furthermore, this DLH design allows for a safe and passive anti-salt and bacterial property due to PAETAC cationic chain, eliminating 99% salt and bacteria via Donnan repulsion and electrostatic interaction without the need of sunlight exposure.

Cationic Hydrogels Modulate Neural Stem and Progenitor Cell Proliferation and Differentiation Behavior in Dependence of Cationic Moiety Concentration in 2D Cell Culture.

The central nervous system (CNS) has a limited regenerative capacity because a hostile environment prevents tissue regeneration after damage or injury. Neural stem/progenitor cells (NSPCs) are considered a potential resource for CNS repair, which raises the issue of adequate cultivation and expansion procedures. Cationic charge supports the survival and adhesion of NSPCs. Typically, tissue culture plates with cationic coatings, such as poly-l-ornithine (PLO), have been used to culture these cell types (NSPCs). Yet presently, little is known about the impact of cationic charge concentration on the viability, proliferation, and differentiation capacity of NSPCs. Therefore, we have recently developed well-defined, fully synthetic hydrogel systems G1 (gel 1) to G6 (gel 6) that allow for the precise control of the concentration of the cationic trimethylaminoethyl acrylate (TMAEA) molecule associated with the polymer in a range from 0.06 to 0.91 μmol/mg. When murine NSPCs were cultured on these gels under differentiation conditions, we observed a strong correlation of cationic charge concentration with NSPC survival. In particular, neurons were preferentially formed on gels with a higher cationic charge concentration, whereas astrocytes and oligodendrocytes favored weakly charged or even neutral gel surfaces. To test the properties of the gels under proliferative conditions, the NSPCs were cultivated in the presence of fibroblast growth factor 2 (FGF2). The cytokine significantly increased the number of NSPCs but delayed the differentiation toward neurons and glia cells. Thus, the hydrogels are compatible with the survival, expansion, and differentiation of NSPCs and may be useful to create supportive environments in transplantation approaches.

Fabrication of antimicrobial cationic hydrogels driven by physically and chemically crosslinking for wound healing

The wound therapy based on antibiotic delivery inevitably leads to the emergence of drug resistance. Hydrogel biomaterials with inherent antibacterial activities have emerged as promising candidates for addressing this issue. However, developing an inherently antibacterial hydrogel through simple and facile strategies to promote localized wound infection healing remains a challenge. In this study, we successfully constructed antimicrobial cationic hydrogels with self-healing and injectable properties through physically and chemically dual-crosslinked networks. The networks were formed by the copolymers poly[(di(ethylene glycol) methyl ether methacrylate)-co-(4-formylphenyl methacrylate)-co-(2-(methacryloyloxy)ethyl]trimethylammonium chloride solution)] (PDFM) and poly[(di(ethylene glycol) methyl ether methacrylate)-co-(2-aminoethyl methacrylate hydrochloride)-co-(2-(((6-(6-methyl-4[1H]pyrimidionylureido) hexyl)carbamoyl)oxy)ethyl methacrylate)] (PDAU). The hydrogel systems effectively facilitate the regeneration and healing of infected wounds through the contact bactericidal feature of quaternary ammonium cations. The presence of Schiff base bonds in the injectable hydrogels imparts remarkable pH responsiveness and self-healing properties. In vitro experiments verified their intrinsic antibacterial activities along with their favorable cytocompatibility and hemocompatibility in both in vitro and in vivo. In addition, the hydrogel significantly accelerated the healing of bacterially infected in a full-thickness skin wound. This facilely prepared dual-crosslinked hydrogel, without antibiotics loading, holds significant prospects for treating infected wounds.

Cationic and amphiphilic peptide-based hydrogels with dual activities as anticancer and antibacterial agents.

The emergence of peptide-based functional biomaterials is on the rise. To fulfil this purpose, a series of amphiphilic peptides, such as H2N-X-Met-Phe-C12H25, where X = L-lysine (CP1), X = L-histidine (CP2), and X = L-leucine (CP3), have been designed, synthesised, purified and fully characterised. Herein, we reported peptide-based supramolecular hydrogels with antibacterial and anticancer activities. An attempt has been made to investigate the antibacterial properties of these peptide-based hydrogels against Gram-positive (S. aureus and B. subtilis) and Gram-negative (E. coli and P. aeruginosa) bacteria. Investigations show that the L-lysine containing gelator, CP1, is active against both Gram-positive and Gram-negative bacteria and the L-histidine containing gelator, CP2, selectively inhibits the growth of Gram-negative bacteria. Interestingly, the L-leucine containing gelator, CP3, does not show any antibacterial properties. Moreover, the L-lysine containing gelator exhibits the best potency. Generation of reactive oxygen species (ROS) is a probable way to damage the bacterial membrane. To explore the cytotoxic properties and to determine the efficacy of the synthesized compounds in inhibiting cell viability, a comprehensive investigation was performed using three distinct cell lines: MDA-MB-231 (human triple-negative breast cancer), MDA-MB-468 (human triple-negative breast cancer) and HEK 293 (human embryonic kidney). Remarkably, the results of our study revealed a substantial cytotoxic impact of these peptide gelators on the MDA-MB-231 and MDA-MB-468 cell lines in comparison to the HEK 293 cells. Caspase 3/7 activity is the possible mechanistic path to determine the apoptotic rates of the cell lines. This finding emphasizes the promising potential of these peptide-based gelators in targeting and suppressing the growth of human triple negative breast cancer cells, while showing non-cytotoxicity towards non-cancerous HEK 293 cells. In a nutshell, these peptide-based materials are coming to light as next generation biomaterials.

Transdermal drug delivery using a porous microneedle device driven by a hydrogel electroosmotic pump.

Integrating a hydrogel electroosmotic pump with a parylene C-coated porous microneedle (PMN) is developed for transdermal drug delivery applications. The hydrogel pump is fabricated by combining an anionic and a cationic hydrogel to generate enhanced electroosmosis flow (EOF) to drive the transportation of molecules via PMN.