Water-soluble Nanocomposites Research Articles

Scalable, Semicontinuous Production of Micelles Encapsulating Nanoparticles via Electrospray

Nanoparticle encapsulation within micelles has been demonstrated as a versatile platform for creating water-soluble nanocomposites. However, in contrast to typical micelle encapsulants, such as small molecule drugs and proteins, nanoparticles are substantially larger, which creates significant challenges in micelle synthesis, especially at large scale. Here, we describe a new nanocomposite synthesis method that combines electrospray, a top-down, continuous manufacturing technology currently used for polymer microparticle fabrication, with bottom-up micellar self-assembly to yield a scalable, semicontinuous micelle synthesis method: i.e., micellar electrospray. Empty micelles and micellar nanocomposites containing quantum dots (QDs), superparamagnetic iron oxide nanoparticles (SPIONs), and their combination were produced using micellar electrospray with a 30-fold increase in yield by weight over batch methods. Particles were characterized using dynamic light scattering, transmission electron microscopy, and scanning mobility particle sizing, with remarkable agreement between methods, which indicated size distributions with variations of as little as ~5%. In addition, new methodologies for qualitatively evaluating nanoparticle loading in the resultant micelles are presented. Micellar electrospray is a broad, scalable nanomanufacturing approach that should be easily adapted to virtually any hydrophobic molecule or nanoparticle with a diameter smaller than the micelle core, potentially enabling synthesis of a vast array of nanocomposites and self-assembled nanostructures.

Development of polyaniline–multiwalled carbon nanotube (PANI–MWCNT) nanocomposite for optical pH sensor

A highly transparent and water soluble nanocomposite of a conducting polymer, polyaniline (PANI) plus multiwalled carbon nanotubes (MWCNTs), was prepared by in situ chemical polymerisation method using sulphonic acid as a dopant. Initially, MWCNTs were functionalised by acid treatment and then dispersed in the monomer, aniline and the resultant MWCNTs coated aniline was polymerised using ammonium per sulphate as an oxidising agent to form PANI–MWCNT nanocomposite. The synthesised nanocomposite was characterised by using spectroscopic (ultraviolet–visible and Fourier transform infrared spectroscopy), field emission scanning electron microscopy and thermal analyses. The ultraviolet–visible spectrum of the salt phase (dark green) of the PANI–MWCNT nanocomposite shows a free carrier tail with increasing absorption at higher wavelength, which confirms the presence of conducting emeraldine salt phase of the PANI; whereas, the base form (deep blue) of the nanocomposite shows a sharp peak at 600 nm representing insulating pernigraniline phase of the polymer. The synthesised nanocomposite was then demonstrated for optical pH sensing.

Studies of conducting polyaniline (PANI) wrapped-multiwalled carbon nanotubes (MWCNTs) nanocomposite and its application for optical pH sensing

Highly transparent and water soluble nanocomposite of conducting polyaniline wrapped-multiwalled carbon nanotubes (PANI-MWCNTs) was synthesized by in situ chemical polymerization method using sulphonic acid as a dopant. MWCNTs were functionalized prior to their use and then polymerized using ammonium per sulphate as an oxidizing agent. The nanocomposite was subjected for physico-chemical characterization using spectroscopic (UV–vis and FT-IR), FE-SEM and HR-TEM analysis. The UV–vis spectrum of the salt phase (dark green) of the PANI-MWCNTs nanocomposite shows a free carrier tail with increasing absorption at higher wavelength, which confirms the presence of conducting emeraldine salt phase of the polyaniline and is further supported by FT-IR analysis. However, the base form (deep blue) of the nanocomposite shows a sharp peak at 600nm representing an insulating emeraldine base phase of the polymer. The FE-SEM images show the uniform wrapping/coating of the polyaniline over the functionalized MWCNTs and this is further supported by HR-TEM analysis. The synthesized nanocomposite was then successfully used for the determination of pH of the solution (pH 1–12) and found to be a potential candidate for optical pH sensing.

Photoinduced relaxation processes in self-assembling complexes from CdSe/ZnS water-soluble nanocrystals and cationic porphyrins

Particular features and quenching mechanisms of exciton luminescence of water-soluble nanocomposites that are formed as a result of the interaction of surface charged semiconductor quantum dots (QDs) CdSe/ZnS (dCdSe = 2.8 nm) and cationic porphyrins (H2TMPyrP4+ and ZnTMPyrP4+) have been studied theoretically and experimentally. It has been found that, in CdSe/ZnS⊕Porphyrin conjugates, there occurs long-range inductive resonance electronic excitation energy transfer from surface modified (with thioglycolic or mercaptoundecanoic acid) QDs to porphyrins, which is accompanied by quenching of the exciton luminescence of QDs and an increase in the fluorescence intensity of porphyrin. It has been shown that, when mercaptoundecanoic acid is used as a QD shell, the QD luminescence quenching efficiency by porphyrins follows the Forster-Galanin theory and depends on the overlap integral between the CdSe/ZnS luminescence band and the absorption spectra of free-base porphyrin H2TMPyrP4+ and its metal complex ZnTMPyrP4+. It has been revealed that, as the QDs ↔ Zn-porphyrin intercenter distance decreases from 39.1 (mercaptoundecanoic acid) to 30.1), a considerable QD luminescence quenching is observed; however, the energy transfer efficiency substantially decreases, from 55% in the former case to 23% in the latter one. Based on the spectral-luminescent data and quantum-chemical calculations, it has been found that the chemical change of H2TMPyrP4+ in the structure of the complex with CdSe/ZnS QDs passivated by thioglycolic or mercaptoundecanoic acid is caused by the formation of a metal complex ZnTMPyrP4+. Based on calculations of the redox-potentials, it has been concluded that the low luminescence quantum yield of CdSe/ZnS QDs passivated by residues of mercaptocarboxylic acids S−(CH2)nCOO− and its dependence on the number of CH2 groups are related to the possibility of photoinduced electron transfer from the HOMO of passivating molecules to QDs (QD* ⇐ S−(CH2)nCOO− hole transfer). It has been shown that the quenching of the exciton luminescence of QDs in heterogeneous structures CdSe/ZnS(thioglycolic acid)⊕ZnTMPyrP4+, which is complementary to the energy transfer, can be caused by the photoinduced electron transfer that involves the participation of the LUMO of the ZnTMPyrP4+ molecule (QD* ⇒ ZnTMPyrP4+).

A simplistic one-pot method to produce magnetic graphene-CdS nanocomposites

Abstract A simple, yet novel process was developed where magnetic graphene-CdS (Fe 3 O 4 -CdS/G) nanocomposites were prepared by a one-pot solvothermal route in which the reduction of graphite oxide (GO) into graphene was accompanied by the generation of CdS and Fe 3 O 4 nanoparticles. The results of TEM and XRD studies indicate the formation of Fe 3 O 4 -CdS/G nanocomposites. Besides vibration sample magnetometry, fluorescence spectra and loading of doxorubicin (DOX) reveal that this new nanocomposite possesses good superparamagnet (44.85 emu/g), good fluorescent properties and a high loading efficiency (0.98 mg/mg). The efficient, stable, and water soluble nanocomposites are confirmed to be suitable for biomedical applications.

Nanocomposites of silver and copolymers of 2,2-Diallyl-1,1,3,3-tetraethylguanidinium chloride with vinyl acetate

New water-soluble nanocomposites consisting of silver nanoparticles and copolymers of 2,2-diallyl-1,1,3,3-tetraethylguanidinium chloride with vinyl acetate were prepared. These nanocomposites show promise for the development of new water-soluble antiseptics and biocides.

Ultrafast nonlinear optical response of carbon nanotubes functionalized with water soluble porphyrin

A new nanocomposite is obtained by functionalizing carbon nanotubes (CNTs) with a water soluble metalloprophyrin using a simple chemical technique and characterized by optical absorption, IR, and Raman spectroscopy. Results from spectroscopic studies indicate the noncovalent nature of interaction between CNTs and porphyrin. The ultrafast nonlinear response is characterized by measuring the nonlinear absorption coefficient and refractive index by z-scan technique in the femtosecond pulse regime. The nanocomposite is found to exhibit two-photon absorption (TPA) with a reasonably large nonlinear optical coefficient, whereas pure CNTs is known to exhibit saturable absorption. Design of such water soluble nanocomposites offers scope for obtaining materials with enhanced ultrafast optical nonlinearity.

A novel approach for adding smart functionalities to cellulosic fabrics.

A water soluble nanocomposite, based on Ag-nanoparticles (Ag-NPs) loaded on hyperbranched poly (amide-amine, HBPAA) was prepared, characterized and utilized in functional finishing as well as in combined reactive dyeing/and functional finishing of linen, cotton and viscose fabrics. Incorporation of the nanocomposite alone and in combination with reactive dyes in easy care finishing formulations brought about an outstanding antibacterial functionality of the finished and the dyed/finished fabrics even after 15 laundering cycles along with a slight negative impact on other performance properties. Improvement or decrement in the functional, comfort, and dyeing properties is governed by the type of cellulosic substrate.

Antimicrobial activity of silver—poly(1-vinyl-1,2,4-triazole) nanocomposites

Novel water-soluble nanocomposites containing 1–26 nm silver nanoparticles stabilized with poly(1-vinyl-1,2,4-triazole) were prepared. They possess plasmon absorption with the maxima at 412 and 415 nm and exhibit the antimicrobial activity against Gram-negative reference and nosocomial strains, oxacillin/methicillin-susceptible staphylococci, micrococci, and streptococci, as well as fungi.

Palladium nanoparticle/chitosan-grafted graphene nanocomposites for construction of a glucose biosensor

Graphene (GR) was covalently functionalized with chitosan (CS) to improve its biocompatibility and hydrophilicity for the preparation of biosensors. The CS-grafted GR (CS-GR) rendered water-soluble nanocomposites that were readily decorated with palladium nanoparticles (PdNPs) using in situ reduction. Results with TEM, SEM, FTIR, Raman and XRD revealed that CS was successfully grafted without destroying the structure of GR, and PdNPs were densely decorated on CS-GR sheets with no aggregation occurring. A novel glucose biosensor was then developed through covalently immobilizing glucose oxidase (GOD) on a glassy carbon electrode modified with the PdNPs/CS-GR nanocomposite film. Due to synergistic effect of PdNPs and GR, the PdNPs/CS-GR nanocomposite film exhibited excellent electrocatalytical activity toward H 2O 2 and facilitated high loading of enzymes. The biosensor demonstrated high sensitivity of 31.2 μA mM −1 cm −2 for glucose with a wide linear range from 1.0 μM to 1.0 mM as well as a low detection limit of 0.2 μM (S/N = 3). The low Michaelis–Menten constant (1.2 mM) suggested enhanced enzyme affinity to glucose. These results indicated that PdNPs/CS-GR nanocomposites held great potential for construction of a variety of electrochemical biosensors.

Silver-containing nanocomposites based on galactomannan and carrageenan: synthesis, structure, and antimicrobial properties

Water-soluble silver-containing nanocomposites based on biocompatible polysaccharides, galactomannan and carrageenan, were synthesized for the first time. A complex of physicochemical methods was employed to establish the phase composition, the average size of metal nanoparticles, and the morphology of new nanobiocomposites. The obtained nanomaterials possess high antimicrobial activity.

Synthesis and Characterization of Processable Multi-Walled Carbon Nanotubes—Sulfonated Polydiphenylamine Graft Copolymers

Water soluble and processable nanocomposites composed of multi-walled carbon nanotubes (MWNTs) and poly(diphenylamine sulfonic acid) (PDPASA) are synthesized and characterized. Two types of methodologies are adopted. MWNTs are covalently functionalized with 2,5-diaminobenzene sulfonic acid (DABSA) and further in situ polymerized with diphenylamine-4-sulfonic acid (DPASA). This results in the formation of nanocomposites, MWNT(DABSA)-g-PDPASA, in which PDPASA is presented as the graft chains onto MWNTs. In another approach, DPASA is in situ polymerized in presence of unfunctionalized MWNTs, results in a nanocomposite in which MWNTs are present as entrapped mass in PDPASA matrix. Both nanocomposites are found to be water soluble and can form free standing films. The conductivity of MWNT(DABSA)-g-PDPASA and MWNT/PDPASA is found to be 1.25 mS x cm(-1) and 0.65 mS x cm(-1), respectively, which is higher than that of pristine PDPASA (0.25 x 10(-5) S x cm(-1)). The nanocomposites are characterized for their structure, morphology, optical and thermal properties.

Water-soluble Poly(3,4-ethylenedioxythiophene) Nanocomposites Created by a Templating Effect of β-1,3-Glucan Schizophyllan

Abstract Chemical polymerization of 3,4-ethylenedioxythiophene (EDOT) in the presence of single-chain schizophyllan (s-SPG) gave water-soluble nanocomposites with the very uniform globular structure. The findings indicate that s-SPG is capable of acting not only as a one-dimensional host to create fibrous architectures but also as a neutral host to create nanoparticles. The mechanism is reasonably explained by the difference in the hydrophobicity of guest polymers or assemblies.

Toward Understanding and Optimizing the Template-Guided Synthesis of Chiral Polyaniline Nanocomposites

Previously we reported synthesis and characterization of water-soluble chiral conducting polymer nanocomposites via template-guided synthesis. Experimental procedures and parameters need to be carefully controlled to achieve synthesis of water-soluble nanocomposites. Here, we describe a modified synthetic procedure with higher molecular weight poly(acrylic acid) (PAA) (MW ∼ 250 000) as a template. This new system allows synthesis of chiral water-soluble nanocomposites over a more broad range of conditions making the synthesis more reproducible and easier to carry out at large scale. Another objective of this work is to further understand the underlying formation mechanism of chiral polyaniline nanocomposites. We carried out a detailed study of how temperature, template, and solvent affect the final morphology and properties of these nanocomposites. We found that the extent of interaction and stability of the template/monomer/acid adduct (nanocomposite precursor) and population density of monomer surrounding the template are crucial in determining the degree of nanocomposite chirality. Detailed characterization of the nanocomposites and their precursors was carried out by circular dichroism (CD), UV−vis, FTIR, NMR, and TEM spectroscopy. On the basis of experimental results and synthetic procedures, a simplified model for the formation mechanism of chiral polyaniline nanocomposite is proposed.

Water-Soluble Nanocomposites of Zerovalent Metallic Silver with Enhanced Antimicrobial Activity

Water-Soluble Nanocomposites of Zerovalent Metallic Silver with Enhanced Antimicrobial Activity