Polylysine Research Articles

Anti-amyloid activity of amino acid functionalized magnetic nanoparticles on αLactalbumin aggregation

Protein amyloid aggregation involves structural changes in native protein conformers and the formation of amyloid fibrils that accumulate in deposits in the human body. This study explores the effect of magnetic nanoparticles functionalized with amino acids (aaMNPs)—cysteine (Cys), poly-L-lysine (PLL), or proline (Pro)—on the amyloid aggregation of α-lactalbumin (αLA) and its amyloid fibrils (LAF). Our results from thioflavin T fluorescence assay (ThT), atomic force microscopy (AFM), and infrared spectroscopy revealed that the studied aaMNPs inhibit αLA fibrillization and destruct LAF in a concentration-dependent manner. The type of amino acid used for nanoparticle functionalization significantly influences the anti-amyloid efficacy. ProMNPs exhibit the highest inhibitory activity, with the timing of their addition being crucial Conversely, CysMNPs demonstrate the highest destructing activity. AFM image analysis through grain mapping was employed to quantify the anti-amyloid effects of aaMNPs. Cytotoxicity testing on kidney cells identified PLLMNPs as the only cytotoxic nanoparticles in our study. These findings clarify the mechanisms of inhibition and destruction of LAF in the presence of aaMNPs, which could inform the design of nanoparticles for therapeutic purposes in the future.

Versatile inulin/trans-ferulic acid/silk sericin nanoparticles-nourished probiotic complex with prolonged intestinal retention for synergistic therapy of inflammatory bowel disease

To achieve effective long-term synergistic treatment of inflammatory bowel disease (IBD) with probiotics, we developed a versatile inulin/trans-ferulic acid/silk sericin nanoparticles-nourished probiotic complex. Inulin/TFA/SS nanoparticles were fabricated by inulin, trans-ferulic acid (TFA), and silk sericin (SS), and then loaded onto the surface of poly-l-lysine (PLL) and poly-glutamic acid (PGA)-coated Bifidobacterium longum (BL) to obtain BL@PLL-PGA-Inulin/TFA/SS NPs (BL@PP-NPs). This design simultaneously endowed the complex with excellent gastrointestinal resistance, antioxidant, and anti-inflammation abilities. Moreover, the inulin in the nanoparticles acts as a prebiotic, promoting the Bifidobacterium's rapid proliferation to exert effects within a short period. Compared with uncoated BL, BL@PP-NPs exhibited excellent gastric acid tolerance and up to 31.32-fold colonic colonization, and the ROS scavenging and proliferative capacity were increased by 5.61- and 1.39-fold, respectively. In a mouse model of dextran sulfate sodium (DSS)- and trinitrobenzene sulfonic acid (TNBS)-induced colitis, the components of Inulin/TFA/SS NPs synergized with probiotics to efficiently treat IBD by attenuating oxidative stress, decreasing inflammation, repairing intestinal barrier, and promoting the rapid proliferation of probiotics to reverse gut microbial disorders. Collectively, food-grade BL@PP-NPs represent a novel approach to probiotic modification that offers an effective, safe, and synergistic therapy for IBD.

Poly(L-lysine)-block-poly(ethylene glycol)-block-poly(L-lysine) triblock copolymers for the preparation of flower micelles and their irreversible hydrogel formation

ABSTRACT Poly(L-lysine)-block-poly(ethylene glycol)-block-poly(L-lysine) (PLys-block-PEG-block-PLys) triblock copolymers formed polyion complex (PIC) with poly(acrylic acid) (PAAc) or sodium poly(styrenesulfonate) (PSS), leading to the formation of flower micelle-type nanoparticles (NanoLys/PAAc or NanoLys/PSS) with tens of nanometers size in water at a polymer concentration of 10 mg/mL. The flower micelles exhibited irreversible temperature-driven sol-gel transitions at physiological ionic strength, even at low polymer concentrations such as 40 mg/mL, making them promising candidates for injectable hydrogel applications. Rheological studies showed that the chain length of PLys segments and the choice of polyanions significantly impacted irreversible hydrogel formation, with PSS being superior to PAAc for the formation. The incorporation of silica gel nanoparticles into the PIC flower micelles also resulted in irreversible gelation phenomena. The highest storage modulus exceeded 10 kPa after gelation, which is sufficient for practical applications. This study demonstrates the potential of these PIC-based hydrogels as biomaterials with tunable properties for biomedical applications.

Bone‐Induced Nanocomposite Coating with a “Sandwich” Structure

AbstractInfection‐induced bone defects present significant challenges in clinical bone regeneration, frequently leading to poor bone induction, recurring infections, and complications such as pain and chronic inflammation. This study introduces a novel Ti/Lignin‐Ag@PLL composite coating with a “sandwich” structure, designed to integrate pro‐adhesion, photothermal‐photodynamic antibacterial, and osteogenic properties. The Ti/Lignin‐Ag@PLL composite coating is fabricated using self‐assembly technology, in which Ag+ is reduced to silver nanoparticles (Ag‐NPs) by lignin, followed by Polylysine (PLL) grafting. Photothermal conversion efficiency is evaluated under near‐infrared (NIR) laser irradiation, while antibacterial activity is tested against E. coli and S. aureus. Biocompatibility is also assessed using vascular endothelial cells (VECs) and osteoblasts (OBs). The results indicate that the Ti/Lignin‐Ag@PLL coating demonstrates a 31% photothermal conversion efficiency and nearly 100% antibacterial efficacy against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) under NIR irradiation for 10 min. Without irradiation, the antibacterial rates are 85% and 94%, respectively, after 24 h. Additionally, the coating significantly promotes cell adhesion, proliferation, and osteogenesis, as evidenced by the upregulation of Runx2 and Collagen I. This study uniquely contributes to the development of a multifunctional composite coating that effectively combines robust antibacterial properties with enhanced osteogenic potential, offering a promising solution for bone tissue repair and infection prevention.

Hyperbranched polylysine/oxidized carboxymethyl cellolose integrated gelatin composite for wound treatment

Herein, we report the preparation and evaluation of a new composite consisting of gelatin matrix, oxidized carboxymethyl cellulose (OCMC), and hyperbranched polylysine (PL) components for full-thickness wound treatment. To enhance the antimicrobial activity of the gelatin matrix, OCMC/PL was successfully combined with this matrix via the Schiff base reaction. Moreover, allantoin (Alla) as a drug model was loaded by this composite and the optimal formulation for wound healing (PLOCG-Alla) was obtained. The structural properties, thermal stability, crystallinity and interactions between materials were investigated using SEM, TGA, XRD and FTIR techniques. Cytotoxicity and antibacterial capacity were evaluated by MTT assay and colony counting methods, respectively. The release behavior was investigated at two different pH values. Blood coagulation and wound healing potential were also evaluated in vivo. PLOCG-Alla exhibited high antibacterial capacity, pH-dependent release behavior, biocompatibility and high blood clotting ability. It also accelerated wound healing in vivo.

Exploring the adhesion properties of extracellular vesicles for functional assays.

The "stickiness" of extracellular vesicles (EVs) can pose challenges for EV processing and storage, but adhesive properties may also be exploited to immobilize EVs directly on surfaces for various measurement techniques, including super-resolution microscopy. Direct adhesion to surfaces may allow examination of broader populations of EVs than molecular affinity approaches, which can also involve specialized, expensive affinity reagents. Here, we report on the interaction of EVs with borosilicate glass and quartz coverslips and on the effects of pre-coating coverslips with poly-L-lysine (PLL), a reagent commonly used to facilitate interactions between negatively charged surfaces of cells and amorphous surfaces. Additionally, we compared two mounting media conditions for super-resolution microscopy (SRM) imaging and used immobilized EVs for a B-cell interaction test. Our findings suggest that borosilicate glass coverslips immobilize EVs better than quartz glass coverslips. We also found that PLL is not strictly required for EV retention but contributes to the uniform distribution of EVs on borosilicate glass coverslips. Overall, these findings suggest that standard lab materials like borosilicate glass coverslips, with or without PLL, can be effectively used for the immobilization of EVs in specific imaging techniques.

Synergistic coating of Laponite swollen-layer and heparin composite for enhanced antifouling and antithrombotic performance

When implantable medical devices come into contact with blood, acute thrombosis and inflammation often occur due to the adhesion and denaturation of plasma proteins, ultimately degrading device performance. To address this issue, we developed a gel-like coating with superhydrophilic properties, incorporating a heparin based outer layer designed to minimize foreign body reactions and enhance hemocompatibility. The coating was engineered using a layer-by-layer (LbL) assembly of poly-l-lysine (PLL), laponite (Lap), and heparin (Hep), utilizing electrostatic interactions. The successful formation of stable layers was confirmed by QCM-D analysis. The inner layer, composed of PLL/Lap multilayers, formed a gel-like structure that maintained superhydrophilicity and effectively prevented cell adhesion. The outermost PLL/Hep multilayers significantly suppressed thrombus formation by inhibiting plasma protein and red blood cell adsorption as well as platelet activation. The coating exhibited excellent stability, retaining its superhydrophilic properties and heparin functionality even after 7 days of immersion in DPBS. Additionally, in vitro hemocompatibility and cytocompatibility tests confirmed its non-toxicity and overall biocompatibility. These results highlight the potential application of this coating to various implantable medical devices, providing a robust solution for improving device performance and safety.

Inflammation-responsive PCL/gelatin microfiber scaffold with sustained nitric oxide generation and heparin release for blood-contacting implants

Delayed endothelialization, the excessive proliferation of smooth muscle cells (SMCs), and persistent inflammation are the main reasons for the implantation failure of blood-contacting materials. To overcome this problem, an inflammation-responsive, core-shell structured microfiber scaffold is developed using polycaprolactone (PCL), selenocystamine-modified gelatin (Gel-Se), L-ascorbyl 6-palmitate (AP), and dexamethasone as the fiber shell, with poly (l-lysine) (PLL) and heparin incorporated in the fiber core. Superhydrophilic microfiber scaffolds exhibit antifouling properties that inhibit protein adsorption and blood cell adhesion, thereby effectively mitigating the risk of acute thrombosis. The continuous release of heparin and sustained generation of nitric oxide (NO) through the catalytic decomposition of S-nitrosothiols by selenocystamine lead to a biomimetic endothelial function for the enhancement of blood compatibility. The inflammation-responsive compound AP can detoxify excess reactive oxygen species (ROS) while controlling the release of dexamethasone to reduce chronic inflammation. We demonstrate the ability of microfiber scaffolds to reduce thrombotic and inflammatory complications, inhibit SMC proliferation, and promote rapid endothelialization both in vitro and ex vivo. Hence, microfiber scaffolds are robust and promising for blood-contacting implants with enhanced antithrombogenicity and anti-inflammatory capabilities.

One-pot synthesis of monodisperse silver-lignin particles: Enhanced antibacterial agents against antibiotic-resistant bacteria

Lignin-based supports for metal nanoparticles (NPs) have attracted significant attention due to their abundant functional groups that facilitate NPs loading. However, many studies involve a two-step process: fabricating lignin particles and then reducing metal ions to NPs using physical energy consumption or chemical reduction. A one-step in-situ reduction method for NP synthesis on carrier surfaces, eliminating energy consumption, is needed for environmentally friendly and sustainable approach. Herein, we demonstrate that poly-l-lysine (PL) controls the self-assembly kinetics of kraft lignin (KL), and reduces silver ion (Ag+) to silver nanoparticles (AgNPs), forming highly monodisperse, co-self-assembled PL-KL particles (Ag@PL-KLPs) without chemical reducing agents or energy consumption. PL facilitated rapid KL desolvation, promoting intermolecular interactions and silver ion adsorption, followed by an efficient, separate nucleation and growth process yielded Ag@PL-KLPs approximately 270 nm in size with a narrow distribution. Notably, Ag@PL-KLPs exhibited enhanced bacteriostatic and bactericidal properties against antibiotic-resistant bacteria (ARB), including both Gram-negative and Gram-positive strains, at concentrations of 250 μg/mL. Leveraging biomass-derived lignin and this cost-effective, one-step green synthesis approach offers a sustainable method for avoiding antibiotic overuse and environmental contamination.

Shear-Thinning Extrudable Hydrogels Based on Star Polypeptides with Antimicrobial Properties.

Hydrogels with low toxicity, antimicrobial potency and shear-thinning behavior are promising materials to combat the modern challenges of increased infections. Here, we report on 8-arm star block copolypeptides based on poly(L-lysine), poly(L-tyrosine) and poly(S-benzyl-L-cysteine) blocks. Three star block copolypeptides were synthesized with poly(S-benzyl-L-cysteine) always forming the outer block. The inner block comprised either two individual blocks of poly(L-lysine) and poly(L-tyrosine) or a statistical block copolypeptide from both amino acids. The star block copolypeptides were synthesized by the Ring Opening Polymerization (ROP) of the protected amino acid N-carboxyanhydrides (NCAs), keeping the overall ratio of monomers constant. All star block copolypeptides formed hydrogels and Scanning Electron Microscopy (SEM) confirmed a porous morphology. The investigation of their viscoelastic characteristics, water uptake and syringe extrudability revealed superior properties of the star polypeptide with a statistical inner block of L-lysine and L-tyrosine. Further testing of this sample confirmed no cytotoxicity and demonstrated antimicrobial activity of 1.5-log and 2.6-log reduction in colony-forming units, CFU/mL, against colony-forming reference laboratory strains of Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, respectively. The results underline the importance of controlling structural arrangements in polypeptides to optimize their physical and biological properties.

A Multifunctional Nanodrug Increases the Therapeutic Sensitivity of Lenvatinib to Hepatocellular Carcinoma by Inhibiting the Stemness of Hepatic Cancer Stem Cells.

Drug resistance resulting from diverse mechanisms including the presence of cancer stem cells (CSCs) is the main obstacle for improving therapeutic efficacy of lenvatinib in hepatocellular carcinoma (HCC). Herein, a nanomedicine (siCD24-Len-MnO@PLAP) is developed by incorporating manganese oxide (MnO), lenvatinib (Len), and siRNA against CD24 (siCD24) into micelles composed of methoxypolyethylene glycol (mPEG), poly-L-lysine (PLLys), and polyasparagyl(N-(2-Aminoethyl)piperidine) (PAsp(PIP)) triblock copolymer. The nanomedicine can respond to the tumor microenvironment (TME) to release lenvatinib, and produce Mn2+ and O2, accompanied by changes in nanoparticle charge, which facilitates cellular endocytosis of siCD24-loaded nanoparticles. The released siCD24 and lenvatinib synergistically reduces CD24 expression, resulting in a more pronounced inhibition of stemness of CSCs. In the mouse models of HCC using Huh7-derived CSCs and Hepa1-6-derived CSCs, the nanomedicine shows remarkable anti-cancer effect by enhancing the therapeutic effects of lenvatinib against HCC via reducing the expression level of CD24 and decreasing the expression of hypoxia inducible factor-1α (HIF-1α). Moreover, in situ production of paramagnetic Mn2+ from the nanomedicine serves as an excellent contrast agent for magnetic resonance imaging (MRI) to monitor the therapeutic process. This study demonstrates that this multifunctional MRI-visible siCD24- and lenvatinib-loaded nanodrug holds great potential in enhancing therapeutic sensitivity for HCC lenvatinib therapy.

Miktoarm Star-polypept(o)ide-Based Polyion Complex Micelles for the Delivery of Large Nucleic Acids.

Miktoarm star polymers exhibit a captivating range of physicochemical properties, setting them apart from their linear counterparts. This study devised a synthetic pathway to synthesize cationic miktoarm stars utilizing polypept(o)ides (PeptoMiktoStars), comprising 3 or 6 polysarcosine (pSar) arms (AB3×100, AB6×50, overall 300) for shielding and a cross-linkable poly(S-ethylsulfonyl-l-homocysteine) (pHcy(SO2Et)20) block and a poly(l-lysine) ((pLys)20) block for nucleic acid complexation. Precise control over the DPn and narrow molecular weight distributions (D̵ ≈ 1.2) were achieved for both structures. Both PeptoMiktoStars efficiently complexed mRNA and pDNA into polyion complex micelles (PICMs). AB6-PICMs provided modest (mRNA) to high (pDNA) stability against glutathione and heparin sulfate (HS), while even cross-linked AB3-PICMs were susceptible to HS. All PICMs delivered pDNA and mRNA into D1 cells (over 80%) and Jurkat T cells (over 50%) in vitro. Despite payload- and cell-dependency, AB3 showed overall higher transfection efficiency, while AB6 demonstrated better shielding and enhanced stability.

Shield-armed probiotic delivery system based on co-deposition of poly-dopamine and poly-l-lysine helps Lactiplantibacillus plantarum relieve hyperuricemia

Hyperuricemia (HUA) is a disease characterized by an abnormal metabolism of purine. Lactic acid bacteria (LAB) have attracted much attention for their safe and effective treatment of HUA by inhibiting xanthine oxidase (XOD) and regulating gut microbiota. However, the effectiveness of probiotics can be compromised by the harsh environment of the gastrointestinal tract. In preliminary experiments, Lactiplantibacillus plantarum DY1, which is generally regarded as safe (GRAS), can lower uric acid. We have devised a straightforward and efficient technique for encapsulating DY1 using a coating comprising polydopamine (PDA) co-deposited with poly-l-lysine (PLL) to obtain DY1@PDLL. TEM, SEM, FT-IR and DLS tests showed that DY1 was successfully coated. Incubate at SGF or SIF for 3 h, the number of viable bacteria of free probiotics and DY1@PDLL decreased by 0.92 and 0.46 log cfu/mL, 1.66 and 0.66 log cfu/mL, respectively. The fluorescence intensity of the intestines of the DY1@PDLL treated mice was 3.96 times that of free probiotic. Notably, DY1@PDLL can reduce the uric acid levels of HUA mice by 31.63 % and free probiotics by 18.72 % (≈1.69 times). DY1@PDLL could also regulate gut microbiota and serum metabolic profile. These findings unequivocally highlight the remarkable potential of DY1@PDLL as an exceptional oral probiotic delivery system.

Antimicrobial spectrum against wound pathogens and cytotoxicity of star-arranged poly-l-lysine-based antimicrobial peptide polymers.

Introduction. As growing numbers of patients are at higher risk of infection, novel topical broad-spectrum antimicrobials are urgently required for wound infection management. Robust pre-clinical studies should support the development of such novel antimicrobials.Gap statement. To date, evidence of robust investigation of the cytotoxicity and antimicrobial spectrum of activity of antimicrobial peptides (AMP)s is lacking in published literature. Using a more clinical lens, we address this gap in experimental approach, building on our experience with poly-l-lysine (PLL)-based AMP polymers.Aim. To evaluate the in vitro bactericidal activity and cytotoxicity of a PLL-based 16-armed star AMP polymer, designated 16-PLL10, as a novel candidate antimicrobial.Methods. Antimicrobial susceptibilities of clinical isolates and reference strains of ESKAPE (Enterococcus spp., Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp.) pathogens, to 16-PLL10 were investigated. Human erythrocyte haemolysis and keratinocyte viability assays were used to assess toxicity. Modifications were made to 16-PLL10 and re-evaluated for improvement.Results. Minimum bactericidal concentration of 16-PLL10 ranged from 1.25 µM to ≥25 µM. At 2.5 µM, 16-PLL10 was broadly bactericidal against ESKAPE strains/wound isolates. Log-reduction in colony forming units (c.f.u.) per millilitre after 1 h, ranged from 0.3 (E. cloacae) to 5.6 (K. pneumoniae). At bactericidal concentrations, 16-PLL10 was toxic to human keratinocyte and erythrocytes. Conjugates of 16-PLL10, Trifluoroacetylated (TFA)-16-PLL10, and Poly-ethylene glycol (PEG)ylated 16-PLL10, synthesised to address toxicity, only moderately reduced cytotoxicity and haemolysis.Conclusions. Due to poor selectivity indices, further development of 16-PLL10 is unlikely warranted. However, considering the unmet need for novel topical antimicrobials, the ease of AMP polymer synthesises/modification is attractive. To support more rational development, prioritising clinically relevant pathogens and human cells, to establish selective toxicity profiles in vitro, is critical. Further characterisation and discovery utilising artificial intelligence and computational screening approaches can accelerate future AMP nanomaterial development.

Polarized ATR-FTIR studies of DPPC/DPPG lipid bilayers doped with PLL

The structural characterization of lipid bilayers is crucial for understanding various biological processes and designing effective systems of drugs. Attenuated Total Reflection Fourier Transformed Infrared (ATR-FTIR) spectroscopy is a powerful technique for probing lipid membrane properties, but conventional methods face challenges in discerning molecular orientation and intermolecular interactions. The polarized ATR-FTIR spectroscopy combined with Principal Component Analysis (PCA) was used to investigate the interactions between positively charged peptide (poly-L-lysine (PLL)) and anionic lipid bilayers (dipalmitoylphosphatidylcholine/dipalmitoylphosphatidylglycerol, DPPC/DPPG). This integrated approach offers deeper insight into mutual interactions between proteins and lipids of membrane, providing a comprehensive understanding of structure of both protein and lipid bilayers components. The findings of this study shed light on the orientational order of lipid molecules in DPPC/DPPG membrane structure as well as secondary strictures of PPL peptides. It was shown that the presence of PLL peptide disrupts lipid molecule ordering within the lipid bilayer, primarily through electrostatic and H-bond interactions. The utility of polarized ATR-FTIR spectroscopy supported by PCA calculations in elucidating molecular organizations within complex membrane systems is emphasized.

Dual contrasting ability of NaGd0.7Eu0.3F4 nanocrystals tuned by their hydrophilic coating mode

This work introduces non-covalent hydrophilic coating of NaGd0.7Eu0.3F4 nanocrystals by polylysine (PL) and polyethyleneimine (PEI) for MRI and fluorescent imaging purposes. PL- and PEI-stabilized nanocrystals exhibit high colloidal stability, cell internalization, fluorescent contrasting of nuclei and cytoplasm, low cytotoxicity, and relaxivity (r1= 0.17 dm3 mmol–1 s–1 and r1 = 0.23 dm3 mmol–1 s–1).

Development of an automated high-content immunofluorescence assay of pSmads quantification: Proof-of-concept with drugs inhibiting the BMP/TGF-β pathways.

Bone morphogenetic proteins (BMPs) and transforming growth factors (TGF-β) are members of the TGF-β superfamily, known for their roles in several physiological and pathological processes. These factors are known to bind in vivo to BMP and TGF-β receptors, respectively, which induces the phosphorylation of Smad (pSmad) transcription factors. This pathway is generally studied with Western blot and luciferase bioluminescence assay, which presents some limitations. In this work, we developed and optimized a high-throughput assay to study pSmad pathways using immunofluorescence (IF) as an alternative to Western blot. We aimed to overcome the technical challenges usually faced in the classical IF assay in image acquisition, analysis, and quantification. We used C2C12 cells as a cellular model. The cells were stimulated with BMP-2 and TGF-β1 that were delivered either in solution (soluble) or via a biomaterial presenting the growth factor (GF), that is in a "matrix-bound" manner. Image acquisition parameters, analysis methods, and quantification of pSmads using IF were optimized for cells cultured on two types of supports: on bare glass and on a biomimetic coating made by self-assembly of the biopolymers hyaluronic acid and poly(l-lysine), which was crosslinked and then loaded with the GFs. We performed high-content kinetic studies of pSmad expression for cells cultured in 96-well microplates in response to soluble and matrix-bound BMP-2 and TGF-β1. The detection limit of the IF-based assay was found to be similar to Western blot. Additionally, we provide a proof-of-concept for drug testing using inhibitors of BMP and TGF-β receptors, under conditions where specific signaling pathways are engaged via the ligand/receptor interactions. Altogether, our findings offer perspectives for future mechanistic studies on cell signaling and for studies at the single cell level using imaging methods.

Flexible electrochemical sensor with 2D-on-2D layered structure for real-time on-site intelligent detection of carbendazim residues on fresh tea leaves

Excessive use of carbendazim (CBZ) for controlling fungal disease may result in pesticide residues in growth environments. There is an urgent requirement for real-time detection of CBZ content to enable rapid assessment of pesticide residues. Herein, a novel electrochemical sensor was created, which utilizes a laser-induced graphene (LIG) electrode modified with two-dimensional (2D) tungsten disulfide (WS2) nanosheets and a poly(L-lysine) (PLL) film to construct a 2D-on-2D layered structure. The PLL/WS2/LIG electrode exhibits strong charge transfer, excellent electrocatalytic performance, and high CBZ adsorption capacity, thus leading to enhanced sensitivity. As a result, the sensor exhibits a low detection limit of 1.2 ng/mL (6.2 nM), high sensitivity up to 135.1 μA(μg/mL)−1cm−2, and a wide response range of 0.01 to 1.5 μg/mL. Moreover, an intelligent analysis system, consisting of a portable device that connects to an online cloud platform equipped with a machine learning model and visualization software, has been developed for the real-time detection of CBZ residues on tea leaves in tea plantations. This study demonstrates that the PLL/WS2/LIG sensor and the intelligent analysis system have great potential to monitor pesticide residues to guarantee food safety.

Self-adhesive poly-l-lysine/tannic acid hybrid hydrogel for synergistic antibacterial activity against biofilms

Biomedical implants are crucial for enhancing various human physiological functions. However, they are susceptible to microbial contamination after implantation, posing a risk of implant failure. To address this issue, hydrogel-based coatings are used, but achieving both effective antibacterial properties and stable adhesion remains challenging. This study introduces a hybrid hydrogel network made from Tannic Acid (TA) and Poly-l-Lysine (PLL), cross-linked through ionic and hydrogen bonds, which imparts adhesive and anti-infective properties. The physicochemical analysis revealed that the hydrogels exhibited significant porosity, favorable mechanical characteristics, and demonstrated in vitro enzymatic biodegradation. Moreover, the hydrogels demonstrated adhesion to various substrates, including Ti alloy with an adhesive strength of 42.5 kPa, and retained their integrity even after immersion in water for a minimum of 10 days. The modified Ti surfaces significantly reduced protein adsorption (∼70 %), indicating antifouling properties. The hydrogels prevented bacterial adhesion on titanium surfaces through a “contact-kill” mode of action and inhibited biofilm formation by around 94.5 % for Staphylococcus aureus and 90.8 % for Pseudomonas aeruginosa. The modified Ti retained biofilm inhibitory effects for at least six days without significant performance decline. In vitro cytotoxicity assay confirmed the biocompatibility of the hydrogels with NIH3T3 cells. Overall, these results highlight the competence of hybrid hydrogels as effective coatings for Ti implants, offering strong adhesion and biofilm prevention to mitigate implant-related infections.

Portable surface acoustic wave device platform coupled with a paper-based capillary fluidics for real-time biosensing applications

Surface acoustic wave (SAW) sensors have emerged as prominent real-time, label-free biosensors with diverse applications in immunoassays and nucleic acid detection. However, widespread adoption in diagnostics has been impeded by challenges such as miniaturization of instrumentation, microfluidics fabrication and high attenuation in liquid environments. In this study we address these limitations by presenting a portable platform capable of real-time monitoring of a SAW microarray chip comprising up to four sensing channels, combined with a novel paper-based capillary flow channel. For the fabrication of a portable, automated and versatile sensor platform, we integrated a microcontroller, RF components, and a micropump for flow control. Calibration procedures ensured accurate measurements for both amplitude and phase, with a low drift rate (0.72 mdB/h and 1.00 mdeg./h, respectively) and high resolution (2.10 mdB and 6.10 mdeg.), indicating stable operation with minimal interface electronics. The capillary flow channel, implemented by confining the fluid on the sensing surface using a nitrocellulose strip, facilitated laminar and continuous sample flow with minimum damping of the acoustic signal. The sensor system was evaluated with two SAW devices at 100 and 200 MHz using glycerol dilutions within the range of 1 % and 70 %, demonstrating real-time monitoring capabilities and linear correlations between amplitude and phase changes. To prove the biosensing and clinical validity of the SAW newly developed system, DNA adsorption on a poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) functionalized SAW-surface was demonstrated with a detection limit of 0.001 μg/mL. Our study demonstrates the feasibility of a portable SAW sensor system coupled with a low-cost and replaceable capillary flow channel for real-time monitoring and biomolecular detection.