Polyethylenimine-Assisted Generation of Optical Nanoprobes for Biosensing Applications

PEI-based functional materials: Fabrication techniques, properties, and biomedical applications

Cationic polymers have recently attracted considerable interest as research breakthroughs for various industrial and biomedical applications. They are particularly interesting due to their highly positive charges, acceptable physicochemical properties, and ability to undergo further modifications, making them attractive candidates for biomedical applications. Polyethyleneimines (PEIs), as the most extensively utilized polymers, are one of the valuable and prominent classes of polycations. Owing to their flexible polymeric chains, broad molecular weight (MW) distribution, and repetitive structural units, their customization for functional composites is more feasible. The specific beneficial attributes of PEIs could be introduced by purposeful functionalization or modification, long service life, biocompatibility, and distinct geometry. Therefore, PEIs have significant potential in biotechnology, medicine, and bioscience. In this review, we present the advances in PEI-based nanomaterials, their transfection efficiency, and their toxicity over the past few years. Furthermore, the potential and suitability of PEIs for various applications are highlighted and discussed in detail. This review aims to inspire readers to investigate innovative approaches for the design and development of next-generation PEI-based nanomaterials possessing cutting-edge functionalities and appealing characteristics.

Schiff base synergized with protonation of PEI to achieve smart antibacteria of nanocellulose packaging films

Microbial growth and reproduction can cause food spoilage. Developing the controlled release packaging films for food is an ideal solution. In this study, polyethyleneimine (PEI) was grafted to cellulose nanofibers (CNF) films by Schiff base, and when the CNF/PEI films were stimulated by pH, PEI released from the CNF/PEI films due to Schiff base hydrolysis, improving the antibacterial efficiency of PEI. Stimulated by acid with pH of 4, the PEI cumulative release rate of the CNF/PEI₈₀₀ and the CNF/PEI₂₀₀₀ films reached to 92.90 % and 87.28 %, respectively. At the same time, the amino groups of PEI protonated by obtaining H⁺, the charge density increased, and PEI molecular chains extended, enhancing the antibacterial activity of films. The Zeta potential value on the surface of the CNF/PEI film increased with the decrease of pH value. Schiff base synergized with protonation of PEI to achieve smart antibacteria of CNF packaging films. The antibacterial rates of the film against L. monocytogenes and E. coli were 94.7 % and 90.6 % at pH 4, but 29.5 % and 23.6 % at pH 8, respectively. The developed films also had good barrier properties of oxygen, visible light and mechanical properties, and had an attractive application prospect in food preservation to control release of antibacterial agent.

Automated Parameterization of Coarse-Grained Polyethylenimine under a Martini Framework

As a versatile polymer in many applications, synthesized polyethylenimine (PEI) is polydisperse with diverse branched structures that attain pH-dependent protonation states. Understanding the structure-function relationship of PEI is necessary for enhancing its efficacy in various applications. Coarse-grained (CG) simulations can be performed at length and time scales directly comparable with experimental data while maintaining the molecular perspective. However, manually developing CG forcefields for complex PEI structures is time-consuming and prone to human errors. This article presents a fully automated algorithm that can coarse-grain any branched architecture of PEI from its all-atom (AA) simulation trajectories and topology. The algorithm is demonstrated by coarse-graining a branched 2 kDa PEI, which can replicate the AA diffusion coefficient, radius of gyration, and end-to-end distance of the longest linear chain. Commercially available 25 and 2 kDa Millipore-Sigma PEIs are used for experimental validation. Specifically, branched PEI architectures are proposed, coarse-grained using the automated algorithm, and then simulated at different mass concentrations. The CG PEIs can reproduce existing experimental data on PEI's diffusion coefficient and Stokes-Einstein radius at infinite dilution as well as its intrinsic viscosity. This suggests a strategy where probable chemical structures of synthetic PEIs can be inferred computationally using the developed algorithm. The coarse-graining methodology presented here can also be extended to other polymers.

Intelligent visual detection of OTC enabled by a multicolor fluorescence nanoprobe: Europium complex functionalized carbon dots

It is of great significance to realize ultra-sensitive and visual detection of oxytetracycline (OTC) residues, especially for public health and environmental safety. In this study, a multicolor fluorescence sensing platform (CDs-Cit-Eu) for OTC detection was constructed by using rare earth europium complex functionalized carbon dots (CDs). The blue-emitting CDs (λ_em = 450 nm) prepared by one-step hydrothermal method using nannochloropsis were not only the scaffold of Eu³⁺ ion coordination, but also the recognition unit of OTC. After adding OTC to the multicolor fluorescent sensor, the emission intensity of CDs decreased slowly, and the emission intensity of Eu³⁺ ions (λ_em = 617 nm) enhanced significantly, accompanying by a significant color change of the nanoprobe from blue to red. The detection limit of the probe for OTC was calculated to be 3.5 nM, manifesting ultra-high sensitivity towards OTC detection. In addition, OTC detection in real samples (honey, lake water, tap water) was successfully achieved. Moreover, a semi-hydrophobic luminescent film SA/PVA/CDs-Cit-Eu was also prepared for OTC detection. With the help of smartphone color recognition APP, real-time intelligent detection of OTC was realized.

Reactive oxygen species in biological media are they friend or foe? Major In vivo and In vitro sensing challenges

The role of Reactive Oxygen Species (ROS) on biological media has been shifting over the years, as the knowledge on the complex mechanism that lies in underneath their production and overall results has been growing. It has been known for some time that these species are associated with a number of health conditions. However, they also participate in the immunoactivation cascade process, and can have an active role in theranostics. Macrophages, for example, react to the presence of pathogens through ROS production, potentially allowing the development of new therapeutic strategies. However, their short lifetime and limited spatial distribution of ROS have been limiting factors to the development and understanding of this phenomenon. Even though, ROS have shown successful theranostic applications, e.g., photodynamic therapy, their wide applicability has been hampered by the lack of effective tools for monitoring these processes in real time. Thus the development of innovative sensing strategies for in vivo monitoring of the balance between ROS concentration and the resultant immune response is of the utmost relevance. Such knowledge could lead to major breakthroughs towards the development of more effective treatments for neurodegenerative diseases. Within this review we will present the current understanding on the interaction mechanisms of ROS with biological systems and their overall effect. Additionally, the most promising sensing tools developed so far, for both in vivo and in vitro tracking will be presented along with their main limitations and advantages. This review focuses on the four main ROS that have been studied these are: singlet oxygen species, hydrogen peroxide, hydroxyl radical and superoxide anion.

pH-Regulated Single and Double Charge Inversions on PEI-Coated Surfaces

The pH-regulated charge inversions on polyethylenimine (PEI)-coated surfaces are indispensable to their applications in biomaterials and nanomaterials. Various PEI-coated surfaces, where single charge inversion happens, have been extensively investigated, while the surfaces where double charge inversion appears are less reported. Here, using a molecular theory, we systematically study the pH-regulated charge density of PEI-coated surfaces. The results suggest whether single or double charge inversion happens depends on PEI affinity to the surface and the bare surface charge density. The region of double charge inversion is much smaller than that of single charge inversion, revealing the reason why double charge inversion is less observed in experiments. Besides, the charge inversions are significantly influenced by the solution condition. The present work provides a useful guideline to the selection of the coated materials and the parameters of PEI solution in the design of PEI-coated surfaces aiming to promote their applications in multifunctional nanomaterials.

An environment-friendly dip-catalyst with xylan-based catalytic paper coatings

Replacing catalyst supports with sustainable and degradable materials is an urgent task. Xylan is a type of abundant natural polymers with potential applications in dispersing, anchoring, and coating materials, but its material values have always been underestimated. In this study, polyethyleneimine modified dialdehyde xylan (DAX-PEI) was used as a dispersing and anchoring agent to bind Pd nanoparticles onto paper surface to produce a DAX-PEI-Pd coated paper, which was used to catalyze Suzuki-Miyaura reactions. The catalytic coated paper exhibited a good catalytic activity with a yield of 91% and a high turnover frequency (TOF) of 3300 h^-1. Besides, it showed an excellent recyclability with the same catalytic coated paper being used 15 times and still having a yield of nearly 90%. This environment-friendly catalytic coated paper owns its great prospect in organic synthesis.

TOCNC-g-PEI nanoparticle encapsulated oregano essential oil for enhancing the antimicrobial activity of cellulose nanofibril packaging films

A nanocellulose-based film with excellent antimicrobial and antioxidant activity was developed by adding Pickering emulsion which was stabilized by functionalized particles. First, TOCNC-g-PEI nanoparticles were prepared by grafting polyethyleneimine (PEI) onto TEMPO-oxidized cellulose nanocrystals (TOCNCs) and used to stabilize oregano essential oil (OEO) Pickering emulsions. The contact angle of TOCNC-g-PEI nanoparticles was 79.7°, and the minimum inhibitory concentration against L.monocytogenes and E.coli was 0.50 mg/mL. Second, the emulsion droplets were stably dispersed in cellulose nanofibril (CNF) suspensions owing to the depletion stability of CNFs. Finally, the films were dried and emulsion droplets formed oil core/CNF shell microcapsules in active CNF films and completely encapsulated OEO in active CNF films. The inhibition rates of the film against L.monocytogenes and E.coli were 97.28% and 97.23%, respectively. The influence of Pickering emulsion on the active CNF films was discussed. The developed active CNF films have promising application in food preservation and active packaging.

Modification of Branched Polyethyleneimine Using Mesquite Gum for Its Improved Hemocompatibility

In the present study, the modification of branched polyethyleneimine (b-PEI) was carried out using mesquite gum (MG) to improve its hemocompatibility to be used in biomedical applications. In the copolymer synthesis process (carboxymethylated mesquite gum grafted polyethyleneimine copolymer (CBX-MG-PEI), an MG carboxymethylation reaction was initially carried out (carboxymethylated mesquite gum (CBX-MG). Subsequently, the functionalization between CBX-MG and b-PEI was carried out using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) as crosslinking agents. The synthesis products were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). Thermogravimetric analysis showed that CBX-MG and CBX-MG-PEI presented a lower decomposition temperature than MG. The CBX-MG-PEI has a high buffer capacity in the pH range of 4 to 7, similar to the b-PEI. In addition, the CBX-MG-PEI showed an improvement in hemocompatibility in comparison with the b-PEI. The results showed a non-hemolytic property at doses lower than 0.1 µg/mL (CBX-MG-PEI). These results allow us to propose that this copolymer be used in transfection, polymeric nanoparticles, and biomaterials due to its physicochemical and hemocompatibility properties.

Layer-by-layer assembly strategy for fabrication of polydopamine-polyethyleneimine hybrid modified fibers and their application to solid-phase microextraction of bioactive molecules from medicinal plant samples followed by surface plasmon resonance biosensor validation

A solid-phase microextraction method is introduced to overcome limitations of classical phytochemical pattern of identifying bioactive compounds, including tedious and time-consuming separation and purification step and consumption of large amounts of organic solvents, which was non-environmentally- friendly. In this proposed method for solid-phase microextraction, polyvinylidene fluoride fibers@polydopamine@polyethyleneimine@receptor as a solid part of the extractors were pushed into sample solution of medicinal plants, and the procedure was followed by stirring and easily dissociation of receptor binding ligands in organic solvent through pulling out of the functionalized fibers. Xanthine oxidase was chosen as the model receptor, while isoacteoside was selected as the model inhibitor. Several effecting parameters were optimized by experimental design, including temperature, ion strength and pH. Nine bioactive components were obtained from extract of Plantago depressa by using the established solid-phase micro-extraction method. The limit of detection and limit of quantification of the nine components ranged from 0.0008 to 0.03 mg mL^-1 and from 0.001 to 0.016 mg mL^-1, respectively. The RSD values of intra-day and inter-day precisions ranged from 0.24% to 2.19% and 0.62%-2.84%, respectively. The average recoveries of the nine components were from 95.06 to 104.03% with relative standard deviation (RSD) values from 1.02 to 2.90% for Plantago depressa. The RSD values of stability of the nine components ranged from 1.36% to 2.74%, which satisfied the requirements of an analytical method. In addition, surface plasmon resonance biosensor was utilized to corroborate the binding affinity between these compounds and receptor. The avidity values of these ligands corresponded well with their IC₅₀ values. The results confirmed that polydopamine and polyethyleneimine hybrid modified polyvinylidene fluoride fibers based solid-phase microextraction method was successfully utilized for locating bioactive compounds of medicinal plants.

Parallel Multiparameter Study of PEI-Functionalized Gold Nanoparticle Synthesis for Biomedical Applications: Part 2. Elucidating the Role of Surface Chemistry and Polymer Structure in Performance

Elucidating the polyethyleneimine (PEI) chemistry to predictively and reproducibly synthesize gold nanoparticle (AuNP)-PEI conjugates with desired properties has been elusive despite evaluation in numerous studies and reported enhanced properties. The lack of reproducible methods to control the core size and stability has led to contradictory results for performance and safety; thus, advancement of the conjugate platform for commercial use has likely been hindered. Recently, we reported a robust, reproducible method for synthesizing PEI-functionalized AuNPs (Au-PEIs), providing an opportunity to investigate structure-function relationships and to further investigate synthesis parameters affecting performance, where only materials stable in biological media are candidates for use. The properties of Au-PEIs prepared by the optimized reduction of HAuCl₄ using four different structural variants of PEI changed significantly with the PEI molar mass and backbone form (branched or linear). In the present study using our previously reported synthesis procedure, comprehensive analysis of properties such as size distribution, surface plasmon resonance (SPR), morphological state, surface functionality, and the shelf life has been systematically evaluated to elucidate the role of surface chemistry and reactive groups involved in conjugation, as a function of conjugate size and morphology. Being important for commercial adoption, the chemistry was related to the observed colloidal stability of the product in relevant media, including exposure to physiological variables such as salt, pH, proteins, and thermal changes. Overall, this work advances progress toward smart design of engineered nanoscale drug delivery systems and devices by providing unreported details of contributions affecting formation, stability, and fate.