Colloidal Solution Of Nanoparticles Research Articles

A polyelectrolyte-induced highly processable pigment-like photonic crystal ink

Developing a straightforward strategy for constructing highly processable photonic crystals (PCs) is crucial for various applications, yet remains a challenge. Here, we present a simple polyelectrolyte-induced self-assembly strategy for producing novel photonic crystal (PC) inks with outstanding processing flexibility by adding the polyelectrolytes into the ultralow concentration of colloidal nanoparticle solution. The polyelectrolyte can cover the nanoparticles through the hydrogen bond interaction to induce the aggregation and mutual repulsion of them simultaneously, enabling the self-assembly of ultralow concentration (0.01–1.0 v/v%) of nanoparticles into short-range ordered arrays with angle-independent structural colors. The resulting PC inks present unprecedented pigment-like color modulation capacity, as well as ultrahigh freedom in processing methods due to the fact that the rheological behaviors of PC inks can be widely adjusted by varying the properties of polyelectrolytes. Consequently, the PC inks can be easily shaped into complex and exquisite multicolor patterns/3D structures using various techniques, including injection molding, writing, drawing, and 3D printing. This general approach paves the way for quick and scalable production of advanced PC materials deeply required in practical applications.

Development of AgNPs-PVP/TPU based flexible strain sensors for structural health monitoring of composite structures

Real-time in-stu structural health monitoring (SHM) of composite structure developed through highly sensitive and flexible smart sensors based on colloidal solution of Silver Nano Particles (AgNPs). Synthesis of AgNPs through chemical reduction method by citrate and then in Haxen phase transferred by using surfactant Cetyltrimethylammonium bromide (CTAB). Colloidal solution of AgNPs-Haxen and Polyvinylpyrrolidone (PVP) - Haxen has been followed by mixed, calcined and deposited that thick paste on flexible Thermoplastic Polyurethane (TPU) film. These sensors become more sensitive than metallic foil made sensors and farther this sensor pasted on polymer composite for monotonic loading like tensile loading. The data extracted from sensors was monitored effectively by data acquisitioning technique using Keithley KUSB-3100. This research based on chemical synthesis of metallic nanoparticles like silver, its functionalization, protection of these nanoparticles from environment by capping agents and by creating inert atmosphere respectively. Then these functionalized capped nanoparticles are embedded on the surface of thermoplastic Urethane (TPU) film to make piezo resistive semi conductive strips which serve as flexible strain gauge/smart sensor. One other technique is also being used to make sensor is that colloidal solution of metallic Nanoparticles sprays over TPU substrate using Connective Self Assembly (CSA) method. The sensor then properly attached to Glass fabric reinforced polymer (GFRP) composite and calibrated using data acquisitioning (DAQ) under different mode of testing.

PHOTOREGULATION OF THE BIOSYNTHETIC ACTIVITY OF LARICIFOMES OFFICINALIS USING COLLOIDAL SOLUTIONS OF METAL NANOPARTICLES AND LASER IRRADIATION

The aim of the work was to study the influence of biogenic metal nanoparticles on the growth characteristics and biosynthetic activity of the fungus Laricifomes officinalis, as well as the effects of photocatalytic activity of NPs after exposure to low-intensity laser radiation under deep cultivation conditions. Material and Methods. Traditional mycological methods, colloidal solutions of nanoparticles biogenic metals, and unique photobiological methods were used. Results. Treatment of the inoculum with colloidal solutions of nanoparticles of all used metals ncreased the growth of L. officinalis by 31–54%, while irradiation of the fungal inoculum with laser light in a medium with nanoparticles reduced the growth activity of the L. officinalis mycelium by 14.4–22.6%. All nanoparticles suppressed the biosynthesis of extracellular polysaccharides, whereas treatment of the inoculum with colloidal solutions of FeNPs and MgNPs stimulated the synthesis of endopolysaccharides. At the same time, laser light irradiation in the presence of AgNPs increased the amount of endopolysaccharides, while FeNPs and MgNPs slightly inhibited their synthesis. Treatment of the inoculum with colloidal metal solutions and laser light affected the total phenolic content (TPC) in the mycelial mass. The highest TPC values in ethanol extracts with AgNPs and laser light irradiation were 97.31Ѓ}3.7 mg of GAEs/g of dry mass. Conclusions. The research results gave ground to consider nanoparticles of biogenic metals (AgNPs, FeNPs, MgNPs) and low-intensity laser light as a promising regulators of the biosynthetic activity of L. officinalis in the biotechnology of its cultivation.

Fabrication of metallic titanium nanoparticles through ultrasonication assisted by electric current flow

This study was aimed at characterizing metallic Ti electrodes and nanoparticles fabricated from a titanium chloride/deep eutectic solvent (DES) solution by applying electric current between metallic Ti plates used as the anode and cathode under ultrasonic irradiation at room temperature. The cathode was not damaged during the flow of electric current, whereas the anode deteriorated to produce a nanoparticle colloidal solution. The nanoparticle size ranged from 5.3 to 12.2 nm. X-ray diffraction measurements revealed that the Ti nanoparticle powder exhibited a hexagonal crystal structure without any crystalline Ti oxide. However, X-ray photoelectron spectroscopy results indicated the presence of O. Furthermore, the metallic Ti nanoparticles were noted to be covered with Ti oxide layers. These layers acted as a physical barrier, protecting the metallic Ti nanoparticles against further oxidation by exposure to water and air.

Gold nanoparticle-based biosensor for Lysozyme-DNA detection utilizing decomposition Mueller matrix polarimetry

Lysozyme serves as a crucial biomarker in the identification of several diseases, that includes breast cancer, Alzheimer’s disease, meningitis, and rheumatoid arthritis. This study proposes an innovative method for the detection of Lysozyme using a gold nanoparticle based biosensor and decomposition Muller matrix polarimetry. In the proposed study, the DNA aptamer is used as the recognition element, while the gold nanoparticles are used as a sensing element. The sensed signal is taken as the input to a Mueller matrix calculation process, which determines three optical characteristics that yield optimal results of the gold nanoparticle colloidal solution, namely the degree of depolarization, the linear diattenuation, and the depolarization index. The results have shown that all three optical parameters vary linearly with the concentration of Lysozyme throughout a broad dynamic range spanning from 0.01 to 500 pM with a limit of detection of 1.24 fM. Overall, the proposed technique provides potential tool for the detection of Lys.

Nano Formulation and Evaluation of Atorvastatin Mouth Dissolving Tablets

Atorvastatin calcium is an anti-hyperlipidemic drug that competitively inhibit HMG-CoA reductase and decrease production of cholesterol in liver. This statin derivative is highly metabolized in gut wall and liver so that it produces only 14% oral bioavailability. In this study we aim to improve the bioavailability of BCS II drug atorvastatin calcium in the formulation of mouth dissolving tablet, which enters the blood stream via facial, jugular artery and vein, by penetrating the lipid membrane when the tablet disintegrates. The Atorvastatin – chitosan nanoparticles was formulated by freeze drying of colloidal solution of nanoparticles. Super disintegrant like croscarmellose sodium, crospovidone, and sodium starch glycolate were added and tested for its dispersion properties. The prepared formulation shows enhanced rate of dissolution and may helpful by avoiding first pass metabolism and to achieve maximum bioavailability. Further the polymeric nano formulation (atorvastatin-chitosan nano particle) allows drug to penetrate much faster and dissolve the drug in saliva. Finally, the prepared formulation is evaluated by pre formulation studies, pre compression evaluation, post compression evaluation and the result of the study revealed that atorvastatin chitosan nanoparticles with size of 406 nm and PDI 0.246 had 118% dissolute in 10 min and shows enhance bioavailability.

Functionalization of three-dimensional epitaxial graphene with metal nanoparticles.

We demonstrate the first successful functionalization of epitaxial three-dimensional graphene with metal nanoparticles. The functionalization is obtained by immersing three-dimensional graphene in a nanoparticle colloidal solution. This method is versatile and demonstrated here for gold and palladium, but can be extended to other types of nanoparticles. We have measured the nanoparticle density on the top surface and in the porous layer volume by scanning electron microscopy and scanning transmission electron microscopy. The samples exhibit a wide coverage of nanoparticles with minimal clustering. We demonstrate that high-quality graphene promotes the functionalization, leading to higher nanoparticle density both on the surface and in the pores. X-ray photoelectron spectroscopy shows the absence of contamination after the functionalization process. Moreover, it confirms the thermal stability of the Au- and Pd-functionalized three-dimensional graphene up to 530 °C. Our approach opens new avenues for utilizing three-dimensional graphene as a versatile platform for catalytic applications, sensors, and energy storage and conversion.

Laser fragmentation of amorphous and crystalline selenium of various morphologies and assessment of their antioxidant and protection properties.

Introduction: The process of laser-induced breakdown of amorphous and crystalline selenium nanoparticles (Se NPs) of various shapes during nanosecond laser fragmentation of aqueous colloidal solutions of nanoparticles with different concentrations has been studied. Methods: The methods of studying the characteristics of plasma and acoustic oscillations induced by optical breakdown are applied. The methods of assessing the concentration of hydrogen peroxide and hydroxyl radicals, the amount of long-lived reactive species of protein and 8-oxoguanine are applied. Results: It has been established that in the process of laser fragmentation of selenium nanoparticles at a wavelength of 532nm, corresponding to the maximum absorption of selenium, the highest probability of breakdown, the number of plasma flashes, their luminosity and the amplitude of acoustic signals are achieved at concentrations of the order of 109NPs/mL. It has been shown that the use of selenium nanoparticles of various shapes and structures leads to a change in the photoacoustic signal during laser-induced breakdown. When crystalline selenium nanoparticles are irradiated, the intensity of the photoacoustic response during breakdown turns out to be greater (1.5 times for flash luminosity and 3 times for acoustics) than when amorphous particles are irradiated at the same concentration. It has been shown that selenium nanoparticles exhibit significant antioxidant properties. Selenium nanoparticles effectively prevent the formation of reactive oxygen species (ROS) during water radiolysis, eliminate radiation-induced long-lived reactive species of protein, and reduce the radiation-chemical yield of a key marker of oxidative DNA damage - 8-oxoguanine. Discussion: In general, the intensity of processes occurring during laser fragmentation of amorphous and crystalline selenium nanoparticles differs significantly. The antioxidant properties are more pronounced in amorphous selenium nanoparticles compared to crystalline selenium nanoparticles.

Green Synthesis Of Silver Nanoparticles Using Ketapang Leaf Extract (Terminalia Catappa L.) Assisted By Ultrasound

Green synthesis of silver nanoparticles using plants has been interesting in recent years. In the present study, the silver nanoparticles were synthesized using a bioreductor from ketapang leaf extract (Terminalia catappa L.) assisted by sonochemical methods. This green synthesis provides an economic, eco-friendly, and clean synthesis route for silver nanoparticles. Different concentrations of AgNO3 precursors (0.5; 1.0 and 1.5 mM) were initially reacted with ketapang leaf extract with PVA 1% solution as stabilizers that were sonicated for 30 minutes. Silver nanoparticle colloidal solutions were characterized using UV-Vis spectrophotometers, Particle Size Analyzers (PSA), and Transmission Electron Microscopes (TEM). Maximum absorption of silver nanoparticles was obtained at wavelength 420-450 nm. Based on UV data, the silver nanoparticles showed stability for up to 3 weeks. The XRD peaks indicated that the (111) crystallographic plane was more predominant than other planes. The average size of the silver nanoparticles was 79.7 nm from the PSA result. TEM imaging depicted that the nanoparticles were spherical. Finally, the result proved that the silver nanoparticles effectively removed the methylene blue up to 76.43% within optimum conditions (3 ppm of methylene blue, 15 minutes contact time, and 8% nanoparticle concentration).

Acute toxicity of zinc carbonate nanocrystals on white mice model

Zinc-based nanoparticles (NPs) are successfully used to meet the mineral needs of animals and poultry, capable of increasing the growth rate and the efficiency of their use of feed. Nanoparticles of zinc oxide are widely used, which are superior to conventional sources of zinc in terms of pharmacological activity and bioavailability, have a positive effect on productivity and antioxidant protection, and increase reproductive potential. However, a detailed investigation of their toxicological parameters showed the risks of their introduction into the body, as a result of which a large number of zinc oxide NPs were synthesized by the methods of “green chemistry”, the main drawback of which is a complex methodology and a high level of costs. We investigated the acute toxicity of a colloidal solution of zinc carbonate nanocrystals in a model of white mice. The experiment was conducted on 42 female non-linear white mice, 3–4 months old, with a live weight of 21–23 g, kept under optimal vivarium conditions. According to the principle of analogues, 6 experimental groups were formed: mice were injected with a colloidal solution of zinc carbonate nanoparticles in doses (by absolute weight of the drug) of 15,000.0; 20000.0; 25000.0; 30000; 35000.0 and 40000.0 mg/kg of body weight based on the absolute weight of the drug, which according to the active substance (zinc carbonate nanoparticles) was (37.5; 50.0; 62.5; 75.0; 87.5 and 100, 0 mg/kg of body weight), orally using an esophageal-gastric tube. Mice of the control group were injected with distilled water in a volume of 0.2 cm3 according to the same protocol. The clinical condition of the experimental animals was observed for 14 days, noting the appearance and development of clinical signs of poisoning, the time of death or recovery to the physiological norm. After the death (diagnostic slaughter) of the animals, a pathological autopsy was performed. Clinical observations showed that a single intragastric administration of the drug to mice of experimental groups 1-6 did not cause acute poisoning. The deaths of mice in all experimental groups were not observed during the 14-day observation period, as a result of which the LD50 indicator could not be calculated. At the same time, the maximum possible injected dose of the colloidal solution of zinc carbonate nanoparticles (by absolute weight) was 40,000.0 mg/kg of body weight (100.0 mg/kg by active substance), which allows the drug to be assigned to the VI class of toxicity – substances are relatively harmless (LD50 > 15000.0 mg/kg of body weight), and according to the degree of danger up to IV class – low-hazardous substances (LD50 > 5000.0 mg/kg of body weight).

Carbon-supported Ternary Nanocatalyst Palladium-Vanadium-Cobalt for Hydrodechlorination of 2,4-Dichlorophenol

M ultimetallic nanocatalysts have remarkably revealed activities in various catalytic applications. Herein, the ternary nanocatalysts based on palladium-vanadium-cobalt were successfully synthesized through the reduction of their salts with the combination of sodium borohydride and ethylene glycol as reducing agents, including impregnating of activated carbon (AC) substrate with colloid solution of metallic nanoparticles (PdVCo/C). The immobile of trimetallic PdVCo on AC was evidenced by XRD, EDX analysis, transmission electron microscopy (TEM) and specific surface area (BET). Therein, TEM imaging showed that the PdVCo particles size is about 7 nm. The trimetallic nanocatalysts were evaluated in the hydrodechlorination of dichlorinated substrates which was defined by GC (FID detector). The obtained result was that the conversion of 2,4-dichlorophenol was over 91% in the case of PdVCo nano-catalyst in the presence of potassium hydroxide and the high catalytic stability was observed.

High-Precision Optical Excited Heaters Based on Au Nanoparticles and Water-Soluble Porphyrin

Gold nanoparticles are widely used as local heaters under optical excitation. Hybrid molecular-plasmon nanostructures based on gold nanoparticles and water-soluble porphyrin have been developed. A colloidal solution of gold nanoparticles was obtained by laser ablation of metallic gold in water, ensuring its highest chemical purity. The hybrid nanostructures formation was performed due to the Coulomb interaction of cationic porphyrin and gold nanoparticles. The revealed functional properties of hybrid nanostructures make them promising for controllable nano-heater applications (for example, photothermal therapy). Gold nanoparticles act as heaters, whereas porphyrin serves as a fluorescent thermometer with a single optical excitation.

Experimental aggregative stability study of Ag/PVP nanoparticles in colloidal solutions, based on the water, propylene glycol-water, and isopropanol systems

Experimental aggregative stability study of Ag/PVP nanoparticles in colloidal solutions, based on the water, propylene glycol-water, and isopropanol systems

Handheld UV spectrophotometer device for detection of methamphetamine hydrochloride based on supramolecular sensing platform

The realization of drug detection in drug-using crime sites can provide law enforcement officials with direct evidence. This research has developed and demonstrated an easy-to-use handheld sensor that can quickly detect methamphetamine (MA) in the field. The core of the handheld UV spectrophotometer device (HUVSD) is the STM32F103 series of single-chip micro-controller, which has a 32-bit microcontroller and two embedded 12-bit high-precision analog-to-digital converter (ADC) modules. Through Bluetooth-wireless transmission protocol, the spectral information can be displayed in the cell phone's app, and it is possible to visually determine whether the test sample contains methamphetamine hydrochloride substances based on the characteristic peak at 410 nm. The readily available and inexpensive inducible compound 3A and the phosphate pillar[5]arene@silver nanoparticle (PP5@AgNPs) colloidal solution were used as the reactants. The PP5@AgNPs colloidal solution and 3A were mixed and reacted at room temperature, and the color changed to gray-black. The color change was caused by the aggregation of AgNPs induced by the molecular recognition between the induction compound 3A and PP5 on the AgNPs surface. After continuing to add the drug MA, the color of the colloidal solution turned yellow again. This is due to the occurrence of competitive molecular recognition, and the interaction between PP5 and 3A/MA was investigated by molecular docking simulations. The HUVSD has high sensitivity, simple equipment, time-saving, color change visualization and suitable for on-site deployment. It only needs a Pasteur pipette, which has great potential to realize rapid on-site detection.

Molecular Dynamics Modeling of Pulsed Laser Fragmentation of Solid and Porous Si Nanoparticles in Liquid Media.

The production of non-toxic and homogeneous colloidal solutions of nanoparticles (NPs) for biomedical applications is of extreme importance nowadays. Among the various methods for generation of NPs, pulsed laser ablation in liquids (PLAL) has proven itself as a powerful and efficient tool in biomedical fields, allowing chemically pure silicon nanoparticles to be obtained. For example, laser-synthesized silicon nanoparticles (Si NPs) are widely used as contrast agents for bio visualization, as effective sensitizers of radiofrequency hyperthermia for cancer theranostics, in photodynamic therapy, as carriers of therapeutic radionuclides in nuclear nanomedicine, etc. Due to a number of complex and interrelated processes involved in the laser ablation phenomenon, however, the final characteristics of the resulting particles are difficult to control, and the obtained colloidal solutions frequently have broad and multimodal size distribution. Therefore, the subsequent fragmentation of the obtained NPs in the colloidal solutions due to pulsed laser irradiation can be utilized. The resulting NPs' characteristics, however, depend on the parameters of laser irradiation as well as on the irradiated material and surrounding media properties. Thus, reliable knowledge of the mechanism of NP fragmentation is necessary for generation of a colloidal solution with NPs of predesigned properties. To investigate the mechanism of a laser-assisted NP fragmentation process, in this work, we perform a large-scale molecular dynamics (MD) modeling of FS laser interaction with colloidal solution of Si NPs. The obtained NPs are then characterized by their shape and morphological properties. The corresponding conclusion about the relative input of the properties of different laser-induced processes and materials to the mechanism of NP generation is drawn.

Green synthesis of silver nanoparticles from discarded shells of velvet tamarind (Dialium cochinchinense) and their antimicrobial synergistic potentials and biofilm inhibition properties.

In the field of nanomedicine, biogenic metal nanoparticles are commonly synthesized using edible plant products as bio-reducing or stabilizing agents. In this study, discarded shell of velvet tamarind fruit is explored as a potent reducing agent for biogenic synthesis of silver nanoparticles (VeV-AgNPs). Silver nanoparticles were formed in minutes under sunlight exposure, which was considerably fast compared to under ambient conditions. The optical, structural and morphological studies revealed that the nanoparticle colloidal solution consisted of particles with quasi-spherical and rodlike morphologies. To investigate antimicrobial properties, eight microorganisms were exposed to the VeV-AgNPs. The results indicated that VeV-AgNPs had enhanced antimicrobial activity, with a recorded minimum inhibitory concentration (MIC) of 3.9µg/mL against E. coli. Further studies were conducted to examine the biofilm inhibition properties and synergistic effect of the VeV-AgNPs. The findings showed a biofilm inhibition potential of around 98% against E. coli, and the particles were also found to increase the efficacy of standard antimicrobial agents. The combinatory effect with standard antifungal and antibacterial agents ranged from synergistic to antagonistic effects against the tested microorganisms. These results suggest that silver nanoparticles produced from discarded shells of velvet tamarind are potent and could be used as a potential drug candidate to combat antimicrobial resistance.

Application of Fluorescent Carbon Nanoelectronic Materials in Combining Partial Differential Equations for Fingerprint Development and Its Image Enhancement

Fluorescent developers play a crucial role when dealing with objects with complex patterns or color interference against their background due to their excellent photoluminescent properties. In recent years, fluorescent nanoelectronic materials have emerged as a novel class of fluorescent materials for fingerprint development research. Here, carbon quantum dots (CQDs) are synthesized using an electrochemical method and utilized as fluorescent nanoelectronic materials in combination with gold nanoparticles (AuNPs) to form a composite (Au/CQDs). The photoelectric properties of Au/CQDs are verified, and a precursor solution for Au/CQDs is prepared using the Wessling method. After the addition of a surfactant and subsequent elimination processes, an Au/CQDs fluorescent nanocolloidal solution is obtained. This solution is applied for the development of visible fingerprints and latent fingerprints on adhesive surfaces. The resulting development images are subjected to enhancement processes such as sharpening, smoothing, and noise reduction using partial differential equations to improve their visual quality. In experiments, under light exposure, Au/CQDs exhibit a higher conversion rate with cyclohexane compared to conditions without light. In the Au/NPs system, the fluorescence of CQDs is effectively quenched due to the rapid electron transfer process within the Au/CQDs system. Moreover, the electrode modified with Au/CQDs shows significantly improved efficiency in decomposing H2O2 compared to conditions without light exposure. After the development with Au/CQDs nanoparticle colloid solution, bright fingerprint patterns are visible under ultraviolet light. As the age of the fingerprint increases, the developed fingerprint has a higher resolution than fresh fingerprints. Image enhancement through partial differential equations results in satisfactory sharp edges and smooth contours in the images.

Bioinspired palladium-doped manganese oxide nanocorns: a remarkable antimicrobial agent targeting phyto/animal pathogens

Microbial pathogens are known for causing great environmental stress, owing to which emerging challenges like lack of eco-friendly remediation measures, development of drug-resistant and mutational microbial strains, etc., warrants novel and green routes as a stepping stone to serve such concerns sustainably. In the present study, palladium (Pd) doped manganese (II, III) oxide (Mn3O4) nanoparticles (NPs) were synthesized using an aqueous Syzygium aromaticum bud (ASAB) extract. Preliminary phytochemical analysis of ASAB extract indicates the presence of polyphenolics such as phenols, alkaloids, and flavonoids that can act as potential capping agents in NPs synthesis, which was later confirmed in FTIR analysis of pure and Pd-doped Mn3O4 NPs. XRD, Raman, and XPS analyses confirmed the Pd doping in Mn3O4 NPs. FESEM and HRTEM study reveals the mixed morphologies dominated by nanocorns appearance. Zeta potential investigation reveals high stability of the synthesized NPs in colloidal solutions. The developed Pd-doped Mn3O4 NPs were tested against two fungal phytopathogens, i.e., Sclerotinia sclerotiorum and Colletotrichum gloeosporioides, known for causing great economic losses in yield and quality of different plant species. The antifungal activity of synthesized Pd‐doped Mn3O4 NPs displayed a dose‐dependent response with a maximum of ~92%, and ~72% inhibition was recorded against S. sclerotiorum and C. gloeosporioides, respectively, at 1000 ppm concentration. However, C. gloeosporioides demonstrated higher sensitivity to Pd‐doped Mn3O4 NPs upto 500 ppm) treatment than S. sclerotiorum. The prepared NPs also showed significant antibacterial activity against Enterococcus faecalis. The Pd-doped Mn3O4 NPs were effective even at low treatment doses, i.e., 50–100 ppm, with the highest Zone of inhibition obtained at 1000 ppm concentration. Our findings provide a novel, eco-benign, and cost-effective approach for formulating a nanomaterial composition offering multifaceted utilities as an effective antimicrobial agent.

Critical nanomaterial attributes of iron-carbohydrate nanoparticles: Leveraging orthogonal methods to resolve the 3-dimensional structure

Intravenous iron-carbohydrate nanomedicines are widely used to treat iron deficiency and iron deficiency anemia across a wide breadth of patient populations. These colloidal solutions of nanoparticles are complex drugs which inherently makes physicochemical characterization more challenging than small molecule drugs. There have been advancements in physicochemical characterization techniques such as dynamic light scattering and zeta potential measurement, that have provided a better understanding of the physical structure of these drug products in vitro. However, establishment and validation of complementary and orthogonal approaches are necessary to better understand the 3-dimensional physical structure of the iron-carbohydrate complexes, particularly with regard to their physical state in the context of the nanoparticle interaction with biological components such as whole blood (i.e. the nano-bio interface).

Development of Positively Charged Poly-L-Lysine Magnetic Nanoparticles as Potential MRI Contrast Agent.

A colloidal solution of magnetic nanoparticles (MNPs) modified with biocompatible positively charged poly-L-lysine (PLL) with an oleate (OL) layer employed as an initial coating was produced as a potential MRI contrast agent. The effect of various PLL/MNPs' mass ratios on the samples' hydrodynamic diameter, zeta potential, and isoelectric point (IEP) was studied by the dynamic light-scattering method. The optimal mass ratio for MNPs' surface coating was 0.5 (sample PLL0.5-OL-MNPs). The average hydrodynamic particle size in the sample of PLL0.5-OL-MNPs was 124.4 ± 1.4 nm, and in the PLL-unmodified nanoparticles, it was 60.9 ± 0.2 nm, indicating that the OL-MNPs' surface became covered by PLL. Next, the typical characteristics of the superparamagnetic behavior were observed in all samples. In addition, the decrease in saturation magnetizations from 66.9 Am2/kg for MNPs to 35.9 and 31.6 Am2/kg for sample OL-MNPs and PLL0.5-OL-MNPs also confirmed successful PLL adsorption. Moreover, we show that both OL-MNPs and PLL0.5-OL-MNPs exhibit excellent MRI relaxivity properties and a very high r2(*)/r1 ratio, which is very desirable in biomedical applications with required MRI contrast enhancement. The PLL coating itself appears to be the crucial factor in enhancing the relaxivity of MNPs in MRI relaxometry.