Successful application of a magnetophoretic separation technique for harvesting biological cells often relies on the need to tag the cells with magnetic nanoparticles. This study investigates the underlying principle behind the attachment of iron oxide nanoparticles (IONPs) onto microalgal cells, Chlorella sp. and Nannochloropsis sp., in both freshwater and seawater, by taking into account the contributions of various colloidal forces involved. The complex interplay between van der Waals (vdW), electrostatic (ES) and Lewis acid-base interactions (AB) in dictating IONP attachment was studied under the framework of extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) analysis. Our results showed that ES interaction plays an important role in determining the net interaction between the Chlorella sp. cells and IONPs in freshwater, while the AB and vdW interactions play a more dominant role in dictating the net particle-to-cell interaction in high ionic strength media (≥100 mM NaCl), such as seawater. XDLVO predicted effective attachment between cells and surface functionalized IONPs (SF-IONPs) with an estimated secondary minimum of -3.12 kT in freshwater. This prediction is in accordance with the experimental observation in which 98.89% of cells can be magnetophoretically separated from freshwater with SF-IONPs. We have observed successful magnetophoretic separation of microalgal cells from freshwater and/or seawater for all the cases as long as XDLVO analysis predicts particle attachment. For both the conditions, no pH adjustment is required for particle-to-cell attachment.
Matched MeSH terms: Nanoparticles/chemistry*; Metal Nanoparticles/chemistry
Layered hydroxides (LHs) have recently fascinated researchers due to their wide application in various fields. These inorganic nanoparticles, with excellent features as nanocarriers in drug delivery systems, have the potential to play an important role in healthcare. Owing to their outstanding ion-exchange capacity, many organic pharmaceutical drugs have been intercalated into the interlayer galleries of LHs and, consequently, novel nanodrugs or smart drugs may revolutionize in the treatment of diseases. Layered hydroxides, as green nanoreservoirs with sustained drug release and cell targeting properties hold great promise of improving health and prolonging life.
This review presents an introduction to the synthesis of metallic nanoparticles by radiation-induced method, especially gamma irradiation. This method offers some benefits over the conventional methods because it provides fully reduced and highly pure nanoparticles free from by-products or chemical reducing agents, and is capable of controlling the particle size and structure. The nucleation and growth mechanism of metallic nanoparticles are also discussed. The competition between nucleation and growth process in the formation of nanoparticles can determine the size of nanoparticles which is influenced by certain parameters such as the choice of solvents and stabilizer, the precursor to stabilizer ratio, pH during synthesis, and absorbed dose.
Different biological methods are gaining recognition for the production of silver nanoparticles (Ag-NPs) due to their multiple applications. One of the most important applications of Ag-NPs is their use as an anti-bacterial agent. The use of plants in the synthesis of nanoparticles emerges as a cost effective and eco-friendly approach. In this study the biosynthesis of silver nanoparticles using Vitex negundo L. extract and its antimicrobial properties has been reported. The resulting silver particles are characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-Visible (UV-Vis) spectroscopic techniques. The TEM study showed the formation of silver nanoparticles in the 10-30 nm range and average 18.2 nm in size. The XRD study showed that the particles are crystalline in nature, with a face centered cubic (fcc) structure. The silver nanoparticles showed the antimicrobial activity against Gram positive and Gram negative bacteria. Vitex negundo L. was found to display strong potential for the synthesis of silver nanoparticles as antimicrobial agents by rapid reduction of silver ions (Ag+ to Ag0).
Matched MeSH terms: Metal Nanoparticles/toxicity; Metal Nanoparticles/ultrastructure; Metal Nanoparticles/chemistry*
This proof-of-concept study proposes a novel sensing mechanism for selective and label-free detection of 2,4,6-trinitrotoluene (TNT). It is realized by surface chemistry functionalization of silica nanoparticles (NPs) with 3-aminopropyl-triethoxysilane (APTES). The primary amine anchored to the surface of the silica nanoparticles (SiO2-NH2) acts as a capturing probe for TNT target binding to form Meisenheimer amine-TNT complexes. A colorimetric change of the self-assembled (SAM) NP samples from the initial green of a SiO2-NH2 nanoparticle film towards red was observed after successful attachment of TNT, which was confirmed as a result of the increased separation between the nanoparticles. The shift in the peak wavelength of the reflected light normal to the film surface and the associated change of the peak width were measured, and a merit function taking into account their combined effect was proposed for the detection of TNT concentrations from 10-12 to 10-4 molar. The selectivity of our sensing approach is confirmed by using TNT-bound nanoparticles incubated in AptamerX, with 2,4-dinitrotoluene (DNT) and toluene used as control and baseline, respectively. Our results show the repeatable systematic color change with the TNT concentration and the possibility to develop a robust, easy-to-use, and low-cost TNT detection method for performing a sensitive, reliable, and semi-quantitative detection in a wide detection range.
Hybrid reinforcement's novel composite (Al-Fe3O4-SiC) via powder metallurgy method was successfully fabricated. In this study, the aim was to define the influence of SiC-Fe3O4 nanoparticles on microstructure, mechanical, tribology, and corrosion properties of the composite. Various researchers confirmed that aluminum matrix composite (AMC) is an excellent multifunctional lightweight material with remarkable properties. However, to improve the wear resistance in high-performance tribological application, hardening and developing corrosion resistance was needed; thus, an optimized hybrid reinforcement of particulates (SiC-Fe3O4) into an aluminum matrix was explored. Based on obtained results, the density and hardness were 2.69 g/cm3, 91 HV for Al-30Fe3O4-20SiC, after the sintering process. Coefficient of friction (COF) was decreased after adding Fe3O4 and SiC hybrid composite in tribology behaviors, and the lowest COF was 0.412 for Al-30Fe3O4-20SiC. The corrosion protection efficiency increased from 88.07%, 90.91%, and 99.83% for Al-30Fe3O4, Al-15Fe3O4-30SiC, and Al-30Fe3O4-20SiC samples, respectively. Hence, the addition of this reinforcement (Al-Fe3O4-SiC) to the composite shows a positive outcome toward corrosion resistance (lower corrosion rate), in order to increase the durability and life span of material during operation. The accomplished results indicated that, by increasing the weight percentage of SiC-Fe3O4, it had improved the mechanical properties, tribology, and corrosion resistance in aluminum matrix. After comparing all samples, we then selected Al-30Fe3O4-20SiC as an optimized composite.
Cellulose nanomaterial with rod-like structure and highly crystalline order, usually formed by elimination of the amorphous region from cellulose during acid hydrolysis. Cellulose nanomaterial with the property of biocompatibility and nontoxicity can be used for enzyme immobilization. In this work, urease enzyme was used as a model enzyme to study the surface modification of cellulose nanomaterial and its potential for biosensor application. The cellulose nanocrystal (CNC) surface was modified using 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation to introduce the carboxyl group at C6 primary alcohol. The success of enzyme immobilization and surface modification was confirmed using chemical tests and measured using UV-Visible spectrophotometer. The immobilization strategy was then applied for biosensor application for urea detection. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were used for electroanalytical characterization of the urea biosensor.
Many papers have been written on the synthesis of gold nanoparticles but very few included pictures of the process, and none of them used video to show the whole process of synthesis. This paper records the process of synthesis of gold nanoparticles using video clips. Every process from cleaning of glassware, an important step in the synthesis of metallic nanoparticles, to the dialysis process is shown. It also includes the preparation of aqua regia and the actual synthesis of gold nanoparticles. In some papers, the dialysis process was omitted, but in this paper, it is included to complete the whole process as it is being used for purification.
Nanoparticles of undoped and copper doped with Fe3
O4 of three concentrations (0.5, 1.0 and 1.5) are synthesized by
sonochemical method. Structural, optical and morphological properties of these compounds were studied. Fe2+/Fe3+
ratio is found to be 2.36. Crystalline structure, lattice parameters, surface morphologies, direct and indirect band gap
energies of the synthesized compounds were estimated and the results are discussed in detail. The XDR analysis indicates
the Cu doped Fe3
O4
nanoparticles have higher crystallinity than undoped samples. Average crystallite size is found
to increase as Cu concentration increased. The FTIR results are proven by the presence of mixed magnetite-hematite
nanostructures and it is complement to the XRD results. The presence of spherical, polygonal and agglomeration forms
of the particles are visually seen in the SEM images. Direct and indirect band gap energy is found to be decreased as the
copper concentration was increased.
Bacterial cellulose (BC) is a highly pure and crystalline material generated by aerobic bacteria, which has received significant interest due to its unique physiochemical characteristics in comparison with plant cellulose. BC, alone or in combination with different components (e.g., biopolymers and nanoparticles), can be used for a wide range of applications, such as medical products, electrical instruments, and food ingredients. In recent years, biomedical devices have gained important attention due to the increase in medical engineering products for wound care, regeneration of organs, diagnosis of diseases, and drug transportation. Bacterial cellulose has potential applications across several medical sectors and permits the development of innovative materials. This paper reviews the progress of related research, including overall information about bacterial cellulose, production by microorganisms, mechanisms as well as BC cultivation and its nanocomposites. The latest use of BC in the biomedical field is thoroughly discussed with its applications in both a pure and composite form. This paper concludes the further investigations of BC in the future that are required to make it marketable in vital biomaterials.
The development of microwave absorbing materials based on recycled hematite (α-Fe2O3) nanoparticles and polycaprolactone (PCL) was the main focus of this study. α-Fe2O3 was recycled from mill scale and reduced to nanoparticles through high energy ball milling in order to improve its complex permittivity properties. Different compositions (5% wt., 10% wt., 15% wt. and 20% wt.) of the recycled α-Fe2O3 nanoparticles were melt-blended with PCL using a twin screw extruder to fabricate recycled α-Fe2O3/PCL nanocomposites. The samples were characterized for their microstructural properties through X - ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The complex permittivity and microwave absorption properties were respectively measured using the open ended coaxial (OEC) probe and a microstrip in connection with a vector network analyzer in the 1-4 GHz frequency range. An average α-Fe2O3 nanoparticle size of 16.2 nm was obtained with a maximum imaginary (ε") part of permittivity value of 0.54 at 4 GHz. The complex permittivity and power loss values of the nanocomposites increased with recycled α-Fe2O3 nanofiller content. At 2.4 GHz, the power loss (dB) values obtained for all the nanocomposites were between 13.3 dB and 14.4 dB and at 3.4 GHz, a maximum value of 16.37 dB was achieved for the 20 % wt. nanocomposite. The recycled α-Fe2O3/PCL nanocomposites have the potential for use in noise reduction applications in the 1-4 GHz range.
There is an increasing demand for lithography methods to enable the fabrication of diagnostic devices for the biomedical and agri-food sectors. In this regard, scanning probe lithography methods have emerged as a possible approach for this purpose, as they are not only convenient, robust and accessible, but also enable the deposition of "soft" materials such as complex organic molecules and biomolecules. In this report, the use of polymer pen lithography for the fabrication of DNA oligonucleotide arrays is described, together with the application of the arrays for the sensitive and selective detection of Ganoderma boninense, a fungal pathogen of the oil palm. When used in a sandwich assay format with DNA-conjugated gold nanoparticles, this system is able to generate a visually observable result in the presence of the target DNA. This assay is able to detect as little as 30 ng of Ganoderma-derived DNA without any pre-amplification and without the need for specialist laboratory equipment or training.
The migration process of magnetic nanoparticles and colloids in solution under the influence of magnetic field gradients, which is also known as magnetophoresis, is an essential step in the separation technology used in various biomedical and engineering applications. Many works have demonstrated that in specific situations, separation can be performed easily with the weak magnetic field gradients created by permanent magnets, a process known as low-gradient magnetic separation (LGMS). Due to the level of complexity involved, it is not possible to understand the observed kinetics of LGMS within the classical view of magnetophoresis. Our experimental and theoretical investigations in the last years unravelled the existence of two novel physical effects that speed up the magnetophoresis kinetics and explain the observed feasibility of LGMS. Those two effects are (i) cooperative magnetophoresis (due to the cooperative motion of strongly interacting particles) and (ii) magnetophoresis-induced convection (fluid dynamics instability originating from inhomogeneous magnetic gradients). In this feature article, we present a unified view of magnetophoresis based on the extensive research done on these effects. We present the physical basis of each effect and also propose a classification of magnetophoresis into four distinct regimes. This classification is based on the range of values of two dimensionless quantities, namely, aggregation parameter N* and magnetic Grashof number Grm, which include all of the dependency of LGMS on various physical parameters (such as particle properties, thermodynamic parameters, fluid properties, and magnetic field properties). This analysis provides a holistic view of the classification of transport mechanisms in LGMS, which could be particularly useful in the design of magnetic separators for engineering applications.
The three dimensional free convection boundary layer flow near a stagnation point region is embedded in viscous nanofluid with the effect of g-jitter is studied in this paper. Copper (Cu) and aluminium oxide (Al2O3) types of water base nanofluid are cho- sen with the constant Prandtl number, Pr=6.2. Based on Tiwari-Das nanofluid model, the boundary layer equation used is converted into a non-dimensional form by adopting non- dimensional variables and is solved numerically by engaging an implicit finite-difference scheme known as Keller-box method. Behaviors of fluid flow such as skin friction and Nusset number are studied by the controlled parameters including oscillation frequency, amplitude of gravity modulation and nanoparticles volume fraction. The reduced skin friction and Nusset number are presented graphically and discussed for different values of principal curvatures ratio at the nodal point. The numerical results shows that, in- crement occurs in the values of Nusset number with the presence of solid nanoparticles together with the values of the skin friction. It is worth mentioning that for the plane stagnation point there is an absence of reduced skin friction along the y-direction where as for axisymmetric stagnation point, the reduced skin friction for both directions are the same. As nanoparticles volume fraction increased, the skin friction increased as well as the Nusset number. The results, indicated that skin frictions of copper are found higher than aluminium oxide.
In this work, Ni nanoparticles were directly decorated on graphene (G) nanosheets via mechanical ball milling. Based on transmission electron microscopy observations, the Ni nanoparticles were well dispersed and attached to the G nanosheet without any agglomerations. Electrochemical results showed that the capacitance of a G/Ni nanocomposite was 275 F g(-1) at a current density of 2 A g(-1), which is higher than the capacitance of bare G (145 F g(-1)) and bare Ni (3 F g(-1)). The G/Ni electrode also showed superior performance at a high current density, exhibiting a capacitance of 190 F g(-1) at a current density of 5 A g(-1) and a capacitance of 144 F g(-1) at a current density of 10 A g(-1). The equivalent series resistance for G/Ni nanocomposites also decreased. The enhanced performance of this hybrid supercapacitor is best described by the synergistic effect, i.e. dual charge-storage mechanism, which is demonstrated by electrical double layer and pseudocapacitance materials. Moreover, a high specific surface area and electrical conductivity of the materials enhanced the capacitance. These results indicate that the G/Ni nanocomposite is a potential supercapacitor.
INTRODUCTION: The effectiveness of conventional cancer chemotherapy is hampered by the occurrence of multidrug resistance (MDR) in tumor cells. Although many studies have reported the development of novel MDR chemotherapeutic agents, clinical success is lacking owing to the high associated toxicity. Nanoparticle-based delivery of chemotherapeutic drugs has emerged as alternative approach to treat MDR cancers via exploitation of leaky vasculature in the tumor microenvironment. Accordingly, functionalization of nanoparticles with target specific ligands can be employed to achieve significant improvements in the treatment of MDR cancer. Areas covered: This review focuses on the recent advances in the functionalization of nanocarriers with specific ligands, including antibodies, transferrin, folate, and peptides to overcome MDR cancer. The limitations of effective ligand-functionalized nanoparticles as well as therapeutic successes in ligand targeting are covered in the review. Expert opinion: Targeting MDR tumors with ligand-functionalized nanoparticles is a promising approach to improve the treatment of cancer. With this approach, higher drug concentrations at targeted sites would be achieved with lower dosage frequencies and reduced side effects in comparison to existing formulations of chemotherapeutic drugs. However, potential toxicities and immunological responses to ligands should be carefully reviewed for viable options in for future MDR cancer treatment.
Inhalation therapy of lipid-based carriers has great potential in direct target towards the root of respiratory diseases, which make them superior over other drug deliveries. With the successful entry of lipid carriers into the target cells, drugs can be absorbed in a sustained release manner and yield extended medicinal effects. Nevertheless, translation of inhalation therapy from laboratory to clinic especially in drug delivery remains a key challenge to the formulators. An ideal drug vehicle should safeguard the drugs from any premature elimination, facilitate cellular uptake, and promote maximum drug absorption with negligible toxicity. Despite knowing that lung treatment can be done via systemic delivery, pulmonary administration is capable of enhancing drug retention within the lungs, while minimizing systemic toxicity with local targeting. Current inhalation therapy of lipid-based carriers can be administered either intratracheally or intranasally to reach deep lung. However, the complex dimensions of lung architectural and natural defense mechanism poise major barriers towards targeted pulmonary delivery. Delivery systems have to be engineered in a way to tackle various diseases according to their biological conditions. This review highlights on the developmental considerations of lipid-based delivery systems cater for the pulmonary intervention of different lung illnesses.
Green porous and ecofriendly scaffolds have been considered as one of the potent candidates for tissue engineering substitutes. The objective of this study is to investigate the biocompatibility of hydroxyethyl cellulose (HEC)/silver nanoparticles (AgNPs), prepared by the green synthesis method as a potential host material for skin tissue applications. The substrates which contained varied concentrations of AgNO3(0.4%-1.6%) were formed in the presence of HEC, were dissolved in a single step in water. The presence of AgNPs was confirmed visually by the change of color from colorless to dark brown, and was fabricated via freeze-drying technique. The outcomes exhibited significant porosity of >80%, moderate degradation rate, and tremendous value of water absorption up to 1163% in all samples. These scaffolds of HEC/AgNPs were further characterized by SEM, UV-Vis, ATR-FTIR, TGA, and DSC. All scaffolds possessed open interconnected pore size in the range of 50-150μm. The characteristic peaks of Ag in the UV-Vis spectra (417-421nm) revealed the formation of AgNPs in the blend composite. ATR-FTIR curve showed new existing peak, which implies the oxidation of HEC in the cellulose derivatives. The DSC thermogram showed augmentation in Tgwith increased AgNO3concentration. Preliminary studies of cytotoxicity were carried out in vitro by implementation of the hFB cells on the scaffolds. The results substantiated low toxicity of HEC/AgNPs scaffolds, thus exhibiting an ideal characteristic in skin tissue engineering applications.
This study utilized the incorporation of nanoparticle filler into an epoxy system to study the effect of different nanosized
montmorillonite (MMT) fillers on the thermal stability and mechanical properties of epoxy. The sample was prepared
using diglycidyl ether of bisphenol A (DGEBA) with different surface treatments of montmorillonite filler by mechanical
stirring. The results of thermal stability and mechanical properties of epoxy/clay system obtained from thermal gravimetric
analyzer (TGA), universal testing machine (UTM) and scanning electron microscopy (SEM) were discussed. With the same
amount of filler introduced into the system, different thermal stability of epoxy composite can be observed. Bentonite,
which contained other contaminant components, can downgrade the enhanced properties of the filler.
With the increasing clinical use of titanium dioxide nanoparticles (nano-TiO2), a better understanding of their safety in the human use is critical. The present study aims to review the potential application of nano-TiO2 as targeted cancer therapy based on their toxicity risk which highly dependent on their physio-chemical properties. Methods: This review was performed based on PRISMA-P protocol that begin with literature searching on the selected databases; PubMed, Springer Link, Science Direct and general search engine; Google Scholar from 2013 to 2018. Studies retrieved by the pre-determined keywords (titanium dioxide nanoparticles, toxicity, genotoxicity, cytotoxicity, targeted cancer therapy) that assessed toxicity risk of nano-TiO2 in cancer therapeutics were included. Results: The search retrieved 252 articles. Assessment of eligibility by application of inclusion criteria yielded 14 articles. Nano-TiO2 induced cytotoxicity and genotoxicity in dose and time-dependent manner killing the cancerous cells. All studies used primary particles size < 100 nm with mean of 39.38 and standard deviation of 30.47 which is lower than the mean denoting diameter distribution from selected studies are concentrated from the mean. Conclusion: This review suggest that TiO2 nanoparticles can be considered as an ideal candidate for drug-delivery vehicle for targeted cancer therapy by specifically tailored their physio-chemical properties of this nanoparticles according to desired target site and functions to ensure its optimal efficacy.