Search Results (155)

Polylactic acid (PLA) is a biopolymer made from starch that is both sustainable and low-cost. But its chemical inertness limits its application in the removal of heavy metals from aqueous environments. This study addresses the limitations by functionalizing PLA with N-hydroxysuccinimide (NHS) and N-sulfosuccinimide (S-NHS). It is hypothesized that introducing the sulfonate group using S-NHS increases the electron-donating capabilities of PLA, optimizing its adsorption capabilities for heavy metals. Density Functional Theory (DFT) calculations of energy, optimization, frequencies and NBOs in Gaussian 16 (M05-2X/LanL2DZ) and Multiwfn 4.0 were used for the electronic properties of the pristine and functionalized polymer and their interactions with a simplified system of hexahydrated ions of nickel (Ni²⁺), arsenic (As³⁺), and lead (Pb²⁺) cations were analyzed. The results indicated that PLA-S-NHS has an energy gap (Egap) of 3.31 eV, being lower than that of PLA (5.51 eV) and PLA-NHS (4.42 eV), signaling an increase in its adsorption capabilities. Its total dipole moment (TDM) reached 196.16 Debye. The metal–polymer complexes exhibit high TDMs, such as 1104.78 Debye with Pb in PLA-S-NHS, confirming greater interactions. The NBO analysis shows that S-NHS functionalization strengthens the donor–acceptor interactions with the sulfonate group oxygens acting as a primary donor, enhancing the adsorption of heavy metals; this is shown by the adsorption energies (Eads), confirming that functionalization with S-NHS enhances the interaction with metal ions, with negative Eads values observed for all complexes, especially for Pb²⁺, indicating thermodynamically favorable adsorption. The functionalization with S-NHS optimizes the electronic properties of PLA for heavy-metal adsorption, thereby validating the hypothesis and providing a molecular basis for the rational design of advanced bioadsorbents. These results indicate the potential application of these functionalized PLA polymers, especially as membranes, for the selective extraction of heavy metals from aqueous solutions. Full article

Biosensors based on electrolyte-gated organic field-effect transistors (EGOFETs) have attracted considerable attention due to their advantages, including low cost, inherent signal amplification, and low-voltage operation. A critical step influencing sensing performance is the integration of specific receptors onto the device surface. Among various strategies, the covalent immobilization of biorecognition elements onto gold surfaces via thiol chemistry is one of the most widely used approaches. In this study, we report the optimization of a mixed self-assembled monolayer (SAM) composed of 11-mercaptoundecanoic acid (11-MUA) and 3-mercaptopropionic acid (3-MPA) for label-free detection of human IgG using EGOFETs. The quality of the SAM was systematically modulated by varying the total concentration from 10 to 400 mM and characterized using X-ray Photoelectron Spectroscopy (XPS), Electrochemical Impedance Spectroscopy (EIS), Cyclic Voltammetry (CV), and Atomic Force Microscopy (AFM). The results revealed that a concentration of 50 mM yielded a densely packed and well-ordered monolayer. After covalent immobilization of anti-IgG antibodies via 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) chemistry and subsequent blocking with ethanolamine and bovine serum albumin (BSA), the functionalized gate electrodes were integrated into poly(3-hexylthiophene) (P3HT)-based EGOFETs. Electrical measurements demonstrated that EGOFET biosensors functionalized with the 50 mM SAM achieved optimal sensing performance. The devices exhibited a highly linear response (R² = 0.998) over a wide concentration range from 1 fM to 10 nM, with a LOD of 2.82 fM, and showed excellent selectivity against non-target immunoglobulins A and M (IgA and IgM). This SAM concentration optimization strategy provides a versatile approach for engineering high-performance EGOFET biosensors, with potential applicability to a broad range of disease biomarkers. Full article

Silk fibroin (SF) is an ideal biomaterial for next-generation clinical wound dressings due to its biocompatibility and tunable mechanical properties. Cell therapies for wound healing have explored using SF as the base for delivering beneficial cargo; however, retention is poor due to exudate “wash out.” To address concerns with the premature release of cargo from SF-fabricated wound dressings, we utilized amine-reactive chemistry to conjugate SF mats with azido-reactive dibenzocyclooctyne (DBCO) that can then attach complementary azido-tagged cargo through chemoselective immobilization. SF mats were made using electrospinning of a 1:1 SF/PCL solution and were then conjugated with N-Hydroxysuccinimide-dibenzocyclooctyne ester (DBCO). PBS soaking was used for control SF mats. SF mats were then imaged and characterized using the following metrics: pore size, fiber alignment, fiber distribution, fiber diameter, ultimate tensile strength, tangent modulus, proteolytic degradation, absorption, and retention. Successful DBCO conjugation of SF mats was confirmed through the presence of the Az-Cy5 dye while exhibiting no significant changes to the DBCO SF mats in any of the tested metrics compared to controls. Our results provide evidence that the amine chemistry responsible for the DBCO conjugation does not alter important SF mat properties. This confirms that DBCO augmentation paired with Az-Cy5 tags may be a viable approach for immobilizing different therapeutic cargoes to aid wound healing efforts. Full article

The increasing demand for continuous physiological monitoring has accelerated the development of high-sensitivity wearable electrochemical platforms. This study reports the fabrication of a multi-analyte electrochemical sensor based on single-walled carbon nanotubes (SWCNTs) for the detection of sweat-associated metabolites. To facilitate efficient heterogeneous electron transfer, glucose oxidase (Gox), lactate oxidase (Lox), and urease (Ure) were immobilized onto the SWCNT network through π–π interaction using 1-pyrenebutanoic acid succinimidyl ester (PBSE), followed by additional stabilization via 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)/N-hydroxysuccinimide (NHS) coupling. The developed platform exhibited concentration-dependent resistance responses within the ranges of 0.02–0.20 mM for glucose, 20–100 mM for lactate, and 50–400 mM for urea under controlled experimental conditions. The resistance-based configuration enabled stable and reproducible signal modulation across these concentration intervals. Although direct testing with human sweat was not performed, the electrochemical behavior of key sweat-related metabolites was systematically evaluated as a preparatory step toward future wearable integration. Full article

Collagen sponges are widely used for oral tissue regeneration, due to their extracellular matrix-mimetic architecture and excellent biocompatibility. However, in practical biomedical applications, collagen sponges may exhibit hydration-induced structural instability, and there can be associated inflammatory responses under physiological conditions, potentially compromising their regenerative performance. In this study, we investigated how two cross-linking strategies—transglutaminase (TG) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-hydroxysuccinimide (EDC/NHS)—modulate the structural stability and inflammatory profiles of collagen sponges. TG-cross-linked sponges exhibited microstructural collapse, associated with macrophage activation and engagement of the Itgαvβ3/5–Src–RhoC–NF-κB signaling axis. In contrast, EDC/NHS-cross-linked sponges preserved a stable porous architecture, effectively suppressing this signaling cascade and establishing a low-inflammatory microenvironment. These findings elucidate a key mechanism by which cross-linking regulates the microstructural integrity of collagen scaffolds and provides in vitro-derived preliminary design principles for developing next-generation collagen biomaterials with low-inflammatory properties. Full article

The objective of this study was to develop multifunctional chitosan (CT) derivatives by conjugating oleic acid (OLA) and caffeic acid (CAF) to improve water solubility at neutral pH, enhance interfacial activity, and provide antioxidant protection in oil-in-water emulsions. Two CAF-incorporation strategies—1-(3-dimethylaminopropyl)-3-ethylcarbodiimide·HCl/N-hydroxysuccinimide (EDC/NHS)-mediated amide coupling and ascorbic acid/H₂O₂-initiated free radical grafting—were employed to functionalize the CT–OLA backbone. The CT–OLA–CAF conjugates generated via the free radical pathway exhibited markedly lower viscosity and interfacial tension than those produced through EDC/NHS coupling, thereby highlighting the respective advantages and limitations associated with these two synthesis approaches. Chemically, CAF incorporation substantially enhanced the antioxidant capacity of the conjugates—surpassing that of both CT and CT—OLA and conferred excellent protection to photo-oxidatively labile β-carotene in o/w emulsions. Full article

Pancreatic function tests are used to determine the presence of chronic pancreatitis, particularly in the early stage of the disease. Chymotrypsin is an indicator of pancreatic function and is thus related to pancreatic diseases. However, these methods often require specific equipment and cannot always meet on-site analysis requirements. Consequently, a highly sensitive detection method needs to be developed. This research employed graphene oxide modified with NHS sensors and peptides (RRHFFGC: Arginine-Arginine-Histidine-Phenylalanine-Phenylalanine-Glycine-Cysteine) tagged with gold nanoclusters (Au NCs) for the detection of chymotrypsin. The N-Hydroxysuccinimide-(Polyethylene Glycol)₄-Dibenzocyclooctyne (NHS-PEG₄-DBCO) and graphene oxide (GO)-N₃ click reaction yielded GO-NHS material, appropriate for fluorescence quenching. The peptide chain was accurately broken with the introduction of chymotrypsin, and the Au NCs were situated far from the GO-NHS surface. The detection limit was 2.014 pg/mL. The results showed that the detection method had high sensitivity in comparison with the previous studies. This method is relevant to real samples due to its potential efficacy. Therefore, it is a promising method in the biomedical field. Full article

Tecovirimat is an antiviral agent approved for the treatment of orthopoxvirus infections including smallpox, cowpox and monkeypox. A key challenge in its synthesis lies in the generation of maleimide intermediates, which traditionally requires high-temperature thermal rearrangement and often results in low-to-moderate yields. Classical methods rely on heating in toluene above 70 °C, limiting scalability and efficiency. Herein, we present a mild and efficient organocatalytic approach to the synthesis of tecovirimat intermediates, using a room-temperature Mumm rearrangement of isomaleimide precursors. The reaction is catalyzed by 10 mol% imidazole and N-hydroxysuccinimide. As a representative example for one of the tecovirimat synthesis methods, intermediate N-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)-4-(trifluoromethyl)benzamide was synthesized from p-trifluoromethylbenzohydrazide at a 71% yield over two steps. Additionally, N-(2,5-dioxopyrrol-1-yl)(tert-butoxy)formamide was obtained from Boc-hydrazide at a 37% yield. The methodology was sufficiently extended to other benzohydrazide-derived isomaleimides. To support the mechanistic rationale, preliminary PM7 semiempirical computational studies were performed, highlighting the electronic features facilitating the transformation. This work offers a practical and scalable route to tecovirimat intermediates, overcoming key synthetic bottlenecks and enhancing the efficiency of antiviral drug production. Full article

Alzheimer’s Disease (AD) is one of the most commonly seen neurodegenerative disorders, where early detection of its biomarkers is crucial for effective management. Conventional diagnostic methods are often expensive, time-consuming, and highly complex, which highlights an urgent need for point-of-care biosensing technology. In this work, we developed assays on three-dimensional (3D) graphene foam electrodes by functionalising them with a 1-Pyrenebutyric acid N-hydroxysuccinimide ester (Pyr-NHS) to enable effective antibody immobilisation for the detection of amyloid beta peptides (Aβ42 and Aβ40), key biomarkers for AD. Pyr-NHS linkers were used for stable functionalisation, followed by binding with Aβ42 and Aβ40 antibodies, and then bovine serum albumin (BSA) was employed as a blocking agent to minimise non-specific bindings on the electrode surface. Differential Pulse Voltammetry (DPV) measurements showed satisfactory stability over 12 days (RDS upper limit was <10%) and highly sensitive and specific detection of Aβ42 and Aβ40, with insignificant interference of tau217 protein. The biosensor exhibited a low limit of detection (LOD) with 252 aM for Aβ42 and 395 aM for Aβ40, covering 0.125 fM–1 nM and 0.125 fM–100 pM linear ranges, respectively. Further validation was conducted on spiked-diluted human plasma. This excellent analytical performance was attributed to the stable Pyr-NHS functionalisation, the 3D graphene foam enabling superior conductivity and a larger surface area on the working electrode, and the optimisation of antibody concentration for immobilisation. These promising results suggest that 3D graphene foam-based biosensors have considerable potential for early detection of AD biomarkers and developing cost-effective, portable, and reliable point-of-care devices. Full article

Background/Objectives: This study aimed to further enhance the properties of paclitaxel (PTX) and honokiol (HNK) through encapsulation in planetary ball-milled nanoparticles (PBM NPs) and specific targeting of breast cancer (BrCa) cells via MUC1 targeting using an aptamer (S2.2) coating. Methods: Tissue microarray (TMA) analysis was utilized to measure MUC1 expression in stages 1, 2, 3, and 4 BrCa tissue samples. Pharmacokinetic simulations were performed to explore the potential advantages of using PTX and HNK in combination while targeting MUC1 for BrCa treatment. To investigate the efficacy of the PBM NPs for MUC1 targeting, we synthesized the aptamer-conjugated PTX and HNK PBM NPs (PTX-S2.2-PBM NPs, HNK-S2.2-PBM NPs) using N-hydroxysuccinimide (NHS) coupling. Dynamic light scattering (DLS), Fourier-transform infrared (FTIR), and high-performance liquid chromatography (HPLC) were utilized to characterize the NPs. MTT and live/dead cell assays were used to evaluate the cytotoxicity of the NPs. Results: TMA sample analysis confirmed the upregulation of MUC1 in BrCa tissues, which increased with the stage of BrCa. DLS analysis revealed that the PTX-S2.2 and HNK-S2.2 NPs have a desirable size (83.4 nm and 163 nm, respectively) and zeta potential (−9.74 mV and −7.16 mV, respectively), which are suitable for systemic circulation and improved therapeutic outcomes. FTIR and HPLC analysis suggest proper conjugation was achieved, and an encapsulation efficiency of PTXS2.2 and HNKS2.2 NPs at 77% and 84%, respectively, was achieved. Cell viability assays demonstrated that PTX-S2.2-PBM and HNK-S2.2-PBM NPs exhibit cytotoxicity comparable to or greater than free PTX and HNK, respectively. Conclusions: These findings support the belief that using PTX-S2.2 and HNK-S2.2 PBM NPs could be a promising treatment option for BrCa. Full article

Natural polysaccharides are used for very different applications and are particularly exploited for preparing hydrogel materials. For instance, gels based on different carbohydrate polymers have been applied to remove unwanted materials from the surface of cultural heritages items. This study was focused on the preparation of novel physical hydrogels suitable for the cleaning of sensitive materials like wood and paper, i.e., to remove the soil from their surface. For this purpose, alginate biopolymer was used and ionically crosslinked with six different amines, in the presence of N-hydroxysuccinimide as a co-gelling agent. All the synthetized gel materials were characterized by a multianalytical approach, using different techniques such as FT-IR, thermal analysis, SEM-EDS, mechanical tests, and evaluation of moisture properties. All the results showed that the introduction of the investigated amines improved the original properties of alginate and provided good cleaning properties when applied to sensitive surfaces. Full article

Surgical dead spaces are challenging to handle with current preventive methods. Tissue adhesives show promise in obliterating ‘dead spaces’, but the drawbacks of currently available adhesives prevent them from being used for dead space elimination. An adhesive powder based on N-Hydroxysuccinimide-poly(2-oxazoline), NHS-POx, combines robust adhesive strength in moist environments with favorable biocompatibility and biodegradability, which makes this an interesting candidate for eliminating spaces that remain between tissues after surgery. The current study evaluates the swelling, crosslinking speed, and degradation properties of this novel tissue adhesive. These results were then used to design multiple adhesive variants differing in pH, surfactant addition, and particle size, which were subsequently examined based on their wetting rates, adhesive strength, and durability. The powder displayed minimal swelling and rapid crosslinking properties, by which the latter could be increased by a basic buffer or surfactant addition and reduced by increasing particle size. The wetting rate of the powder increased when a surfactant (Pluronic F68) was added to the mix. The adhesive strength, as measured by tensile and shear strength measurements of different prototypes of the adhesive powder, was significantly better than that of a commercially available fibrin glue. The addition of both buffer and Pluronic F68 led to a breakdown of adhesive force after 14 days of incubation, while the prototype containing neither buffer nor Pluronic F68 still had measurable adhesive force after 14 days of incubation. The current study results display several characteristics of the NHS-POx-based tissue adhesive that are favorable for tissue approximation, preventing the occurrence of dead spaces. The most effective and usable adhesive prototype will be identified in further ex vivo and in vivo animal model studies. Full article

Plasma-derived fibrin hydrogels are widely used in tissue engineering because of their excellent biological properties. Specifically, human plasma-derived fibrin hydrogels serve as 3D matrices for autologous skin graft production, skeletal muscle repair, and bone regeneration. Nevertheless, for advanced applications such as in vitro skin equivalents and engineered grafts, the intrinsic limitations of native fibrin hydrogels in terms of long-term mechanical stability and resistance to degradation need to be addressed to enhance the usefulness and application of these hydrogels in tissue engineering. In this study, we chemically modified plasma-derived fibrin by incorporating succinimidyl alginate (SA), a version of alginate chemically modified to introduce reactive succinimidyl groups. These NHS ester groups (N-hydroxysuccinimide esters), attached to the alginate backbone, are highly reactive toward the primary amine groups present in plasma proteins such as fibrinogen. When mixed with plasma, the NHS groups covalently bond to the amine groups in fibrin, forming stable amide linkages that reinforce the fibrin network during hydrogel formation. This chemical modification improved mechanical properties, reduces contraction, and enhanced the stability of the resulting hydrogels. Hydrogels were prepared with a final fibrinogen concentration of 1.2 mg/mL and SA concentrations of 0.5, 1, 2, and 3 mg/mL. The objective was to evaluate whether this modification could create a more stable matrix suitable for supporting skin tissue development. The mechanical and microstructure properties of these new hydrogels were evaluated, as were their biocompatibility and potential to create 3D skin models in vitro. Dermo-epidermal skin cultures with primary human fibroblast and keratinocyte cells on these matrices showed improved dermal stability and better tissue structure, particularly SA concentrations of 0.5 and 1 mg/mL, as confirmed by H&E (Hematoxylin and Eosin) staining and immunostaining assays. Overall, these results suggest that SA-functionalized fibrin hydrogels are promising candidates for creating more stable in vitro skin models and engineered skin grafts, as well as for other types of engineered tissues, potentially. Full article

Our study develops two configurations of MoS₂ and graphene heterostructures—MoS₂ on graphene (MG) and graphene on MoS₂ (GM)—to investigate biomolecule sensing in field-effect transistor (FET) biosensors. Leveraging MoS₂ and graphene’s distinctive properties, we employ specialized functionalization techniques for each configuration: graphene with MoS₂ on top uses a silane-based method with triethoxysilylbutyraldehyde (TESBA), and MoS₂ with graphene on top utilizes 1-pyrenebutyric acid N-hydroxysuccinimide ester (PBASE). Our research explores the application of MoS₂–Graphene heterostructures in biosensors, emphasizing the roles of synthesis, fabrication, and material functionalization in optimizing sensor performance. Through our experimental investigations, we have observed that doping MoS₂ and graphene leads to noticeable changes in the Raman spectrum and shifts in transfer curves. Techniques such as XPS, Raman, and AFM have successfully confirmed the biofunctionalization. Transfer curves were instrumental in characterizing the biosensing performance, revealing that GM configurations exhibit higher sensitivity and a lower limit of detection (LOD) compared to MG configurations. We demonstrate that GM heterostructures offer superior sensitivity and specificity in biosensing, highlighting their significant potential to advance biosensor technologies. This research contributes to the field by detailing the creation process of vertical MoS₂–graphene heterostructures and evaluating their effectiveness in accurate biomolecule detection, advancing biosensing technology. Full article

Due to their catalytic performance, laccases constitute one of the most promising groups of enzymes for potential applications in modern biotechnology. In this study, we aimed to chemically modify Ensifer meliloti (Sinorhizobium meliloti) and Cerrena unicolor laccase and comparatively characterize the structures of both enzymes. The most characteristic feature was the spatial localization of lysine residues, predominantly positioned distal to the active site region for both compared enzymes. The solvent-accessible surface area (SASA) analysis showed that bacterial laccase was characterized by a larger hydrophobic SASA than the fungal enzyme. The pK_a prediction identified only one Lys in the E. meliloti laccase structure susceptible to modification. Modifications were achieved by using mono- and bifunctional crosslinking agents, and glycosylations were also performed. The degree of protein modification ranged from 0% for glucose- and galactose-modified E. meliloti laccase and citraconic anhydride-modified (CA) C. unicolor laccase to 62.94% for the palmitic acid N-hydroxysuccinimide ester-modified E. meliloti enzyme. The stability of covalently modified laccases over a wide pH and temperature ranges and in the presence of inhibitors was investigated. Protein modifications with polymeric sucrose (PS) and ethylene glycol bis-(succinimidyl succinate) (EGNHS) significantly increased the activity of the bacterial and fungal laccases by 15 and 19%, respectively. Although pH optima remained relatively unchanged by modifications, certain variants, especially CA-modified bacterial protein and EGNHS-modified C. unicolor enzyme, exhibited improved stability at near-neutral pH (6–7). Modification of the bacterial enzyme with glutaraldehyde-carbodiimide (GA-CDI-ver) and of the fungal enzyme with CA was the most effective in improving its thermal stability. Chemical modifications using GA, CDI, GA-CDI, and PS allowed E. meliloti L 3.8 laccase to retain full activity in the presence of 5 mM NaI, whereas CA-, PS-, and EGNHS-modified C. unicolor variants retained their activity even at elevated NaCl concentrations. The results clearly demonstrate that the outcome of chemical modifications is closely linked to enzyme-specific structural features and that selecting an appropriate modification strategy is critical to achieving the desired effect. Full article