Magnetite nanoparticles coated with chitosan and polyethylenimine as anion exchanger for sorptive enrichment of phosphopeptides

Nitrophenyl Thiourea-Modified Polyethylenimine Colorimetric Sensor for Sulfate, Fluorine, and Acetate

A thiourea-based colorimetric sensor incorporating polyethyleneimine (PEI) and chromophoric nitrophenyl groups was synthesized and utilized for detecting various anions. Structural characterization of the sensor was accomplished using FTIR and 1H-NMR spectroscopy. The sensor's interactions and colorimetric recognition capabilities with different anions, including CI-, Br-, I-, F-, NO3-, PF6-, AcO-, H2PO4-, PO43-, and SO42-, were investigated via visual observation and UV/vis spectroscopy. Upon adding SO42-, F-, and AcO- anions, the sensor exhibited distinct color changes from colorless to yellow and yellowish, while other anions did not induce significant color alterations. UV/vis spectroscopic titration experiments conducted in a DMSO/H2O solution (9:1 volume ratio) demonstrated the sensor's selectivity toward SO42-, F-, and AcO-. The data revealed that the formation of the main compounds and anion complexes was mediated by hydrogen bonding, leading to signal changes in the nitrophenyl thiourea-modified PEI spectrum.

Enrichment of phosphopeptides by arginine-functionalized magnetic chitosan nanoparticles

One of the most crucial and prevalent post-translational modifications is the phosphorylation of proteins. The study and examination of protein phosphorylation hold immense importance in comprehending disease mechanisms and discovering novel biomarkers. However, the inherent low abundance, low ionization efficiency, and coexistence with non phosphopeptides seriously affect the direct analysis of phosphopeptides by mass spectrometry. In order to tackle these problems, it is necessary to carry out selective enrichment of phosphopeptides prior to conducting mass spectrometry analysis. Herein, magnetic chitosan nanoparticles were developed by incorporating arginine, and were then utilized for phosphopeptide enrichment. A tryptic digest of β-casein was chosen as the standard substance. After enrichment, combined with matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS), the detection limit of the method was 0.4 fmol. The synthesized magnetic material demonstrated great potential in the detection of phosphopeptides in complex samples, as proven by its successful application in detecting phosphopeptides in skim milk and human saliva samples.

Influence of the Type of Biocompatible Polymer in the Shell of Magnetite Nanoparticles on Their Interaction with DPPC in Two-Component Langmuir Monolayers

Magnetite nanoparticles (MNPs) are attractive nanomaterials for applications in magnetic resonance imaging, targeted drug delivery, and anticancer therapy due to their unique properties such as nontoxicity, wide chemical affinity, and intrinsic superparamagnetism. Their functionalization with polymers such as chitosan or poly(vinyl alcohol) (PVA) can not only improve their biocompatibility and biodegradability but it also plays an important role in their interactions with biological cells. In this work, the effect of the functionalization of MNPs with chitosan, PVA, and their blend on model cell membranes formed from 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine (DPPC) using a Langmuir technique was studied. The studies performed showed that the type of biocompatible polymer in the MNP shell plays a crucial role in the effectiveness of its adsorption process into the model cell membrane. Modification of MNPs with chitosan facilitates significantly more effective adsorption than coating them with PVA or with a chitosan and PVA blend. The presence of all the investigated MNPs in the DPPC monolayer at low concentrations does not affect its thermodynamic state, fluidity, or morphology, which is promising in terms of their biocompatibility. On the other hand, their high concentration (molar fraction above ≈0.05) exerts a disruptive effect on the model cell membrane and results in their aggregation, leading probably to the loss of their superparamagnetic properties essential for nanomedicine.

Synthesis, Characterization, and Application of Magnetite Nanoparticles Coated with Hydrophobic Polyethyleneimine for Oil Spill Cleaning

Pollution with oil spills, a major contributor to water contamination, has a remarkable effect on the economy, biodiversity, and environment. To protect marine species and environment, efforts should be undertaken for developing efficient ways to remove oil spills. The current work discusses the oil spill removal using magnetite nanoparticles (MNPs) functionalized with hydrophobic polyethyleneimine (HPEA). In this respect, nonylphenol pentaethylenehexamine (NTEPA) and nonylphenol triethylenetetramine (NDETA) were prepared by a simple one-step method and used as capping agents in the synthesis of hydrophobically modified magnetite nanoparticles designated as NDETA/Fe3O4 (magnetite as a core and NDETA as a shell) and NTEPA/Fe3O4 (magnetite as a core and NTEPA as a shell). The prepared MNPs were characterized using FTIR, XRD, TEM, DLS, TGA, and DSA to determine their physical and chemical properties. Additionally, MNPs were applied as oil spill collectors with high efficiencies that reached 93% and 90% for NDETA/Fe3O4 and NTEPA/Fe3O4, respectively, at low magnetite to oil ratios.

Cost-effective fabrication, antibacterial application and cell viability studies of modified nonwoven cotton fabric

In the present work, nonwoven cotton fabric was modified for antibacterial applications using low-cost and eco-friendly precursors. The treatment of fabric with alkali leads to the formation of active sites for surface modification, followed by dip coating with silver nanoparticles and chitosan. The surface was chlorinated in the next step to transform amide (N-H) groups in chitosan into N-halamine (N-Cl). The modified and unmodified surfaces of the nonwoven cotton fabric have been characterized by FTIR, SEM, and XRD. The active chlorine loading is measured with iodine/sodium thiosulphate. The antimicrobial activity and cell toxicity assay were carried out with and without modifications of nonwoven cotton fabric. The antimicrobial efficacies of loaded fabric were evaluated against four bacterial species (Micrococcus luteus, Staphylococcus aureus, Enterobacter aerogenes, and E.coli). It was found that modified fabric exhibited superior efficiency against gram-positive and gram-negative bacterial strains as compared to their bulk counterparts upon exposure without affecting strength and integrity of fabric. The overall process is economical for commercial purposes. The modified fabric can be used for antimicrobial, health, and food packaging industries, and in other biomedical applications.

Melamine foam assisted in-tip packed amine-functionalized titanium metal-organic framework for the selective enrichment of endogenous glycopeptides

Endogenous glycopeptides are significantly important in diverse pathological and physiological systems, but their direct analysis is severely hampered by their low abundance and presence of interfering species in biological fluids. In this study, we synthesized the amine-functionalized titanium metal-organic framework (NH₂-MIL-125(Ti)) by a simple hydrothermal method, characterized and used for glycopeptides enrichment. The designed separation media is highly hydrophilic and stable which is suitable for hydrophilic interaction chromatography (HILIC). To make the process smooth, simple, reliable, and robust, NH₂-MIL-125(Ti) crystals were packed in pipette-tip using hydrophilic melamine foam, as supporting frit. Free amine groups, present in the structure imparted hydrophilicity and a unique pattern of porosity, contributing to the size exclusion effect that excluded the large-sized proteins up to 1:700 peptide to protein ratio. The prepared MOF particles possessed regular porosity, high surface area, good hydrophilicity, and offered an in-tip flow-based set-up enhanced the enrichment performance for N-linked glycopeptides. The affinity material showed a detection limit of 1 fmol.µL^-1 and selectivity up to 1:1000 (HRP digest to BSA digest). Moreover, repeatability and reusability were evaluated up to five rounds of enrichment using the same affinity tip, and scanning electron microscopic images revealed no structural changes in the MOF crystals. Finally, the MOF packed in pipette tip was applied to selectively capture the N-linked endogenous glycopeptides from a healthy saliva sample and 64 unique endogenous glycopeptides were identified. These results demonstrated the excellent potential of NH₂-MIL-125(Ti) based affinity tip for glycopeptides which can be used to enrich trace glycopeptide biomarkers from the biological fluids.

Modification of Luffa Sponge for Enrichment of Phosphopeptides

The enrichment technique is crucial to the comprehensive analysis of protein phosphorylation. In this work, a facile, green and efficient synthetic method was set up for quaternization of luffa sponge. The resultant luffa sponge showed strong anion-exchange characteristics and a high adsorption ability for phosphate ions. Along with the unique physical properties, e.g., tenacity and porous texture, quaternized luffa sponge was demonstrated to be a well-suited solid-phase extraction (SPE) material. The quaternized luffa sponge-based SPE method was simple, cost-effective and convenient in operation, and was successfully applied to the capture of phosphopeptides from protein digests. The enrichment approach exhibited exceptionally high selectivity, sensitivity and strong anti-interference ability. Four phosphopeptides were still detected by using the digest mixture of β-casein and bovine serum albumin with a molar ratio of 1:100. 21 phosphopeptides were identified from the tryptic digest of non-fat milk.