CdS semiconductor nanoparticles in silica sonogel matrices

SiO₂ gels obtained by sonocatalytic method combined with DCCA were used as host-matrices for extremely fine dispersions of CdS semiconductor particles. Small crystallites were produced in situ by H₂S gas diffusion method. The particles were characterized by TEM and HRTEM, EXAFS, UV-Vis and Raman spectroscopies. The size of crystallites ranged from 5 to 10 nm. The optical transmission spectra showed the characteristic blue shift as a function of the particles size, as predicted by the theory. The optical and mechanical qualities of the samples were substantially improved by an infiltration method using a sono-sol which sealed the superficial pores thus ensuring greater longevity and the possibility of obtaining transparent gels by polishing.     

Syntheses of semiconductor nanoparticles using single-molecular precursors

Methods for the preparation of II-VI, III-V, and II-V as well as other compound semiconductor nanoparticles using main group single-molecular precursors have been developed. The work involves the design and synthesis of compounds containing all the elements required within the desired nanoparticulate material. Precursors are tailored to give reproducible, clean decomposition at moderate temperatures, leading to high quality, defect free, mono-dispersed nanoparticles. In this article we cover key aspects of precursor and nanoparticle synthesis. One of the more successful and reproducible series of single-source precursors used, and the one on which we have concentrated our research efforts, is the bis(dialkyldithio-/diseleno-carbamato)cadmium(II)/zinc(II) compounds, M(E(2)CNR(2))(2) (M = Zn or Cd, E = S or Se, and R = alkyl) for the preparation of chalcogenide nanoparticulate materials. Preliminary mechanistic studies suggest that the precursor to nanoparticle deposition route is strongly influenced by the alkyl substituent groups present, and may well determine the phase and quality of the final metal chalcogenide nanoparticles produced. Herein we discuss the synthesis of semiconductor nanoparticles using such single-molecular precursors.     

Luminescent Carbon Nanodots: Emergent Nanolights

Similar to its popular older cousins the fullerene, the carbon nanotube, and graphene, the latest form of nanocarbon, the carbon nanodot, is inspiring intensive research efforts in its own right. These surface‐passivated carbonaceous quantum dots, so‐called C‐dots, combine several favorable attributes of traditional semiconductor‐based quantum dots (namely, size‐ and wavelength‐dependent luminescence emission, resistance to photobleaching, ease of bioconjugation) without incurring the burden of intrinsic toxicity or elemental scarcity and without the need for stringent, intricate, tedious, costly, or inefficient preparation steps. C‐dots can be produced inexpensively and on a large scale (frequently using a one‐step pathway and potentially from biomass waste‐derived sources) by many approaches, ranging from simple candle burning to in situ dehydration reactions to laser ablation methods. In this Review, we summarize recent advances in the synthesis and characterization of C‐dots. We also speculate on their future and discuss potential developments for their use in energy conversion/storage, bioimaging, drug delivery, sensors, diagnostics, and composites.     

Incorporation into paper of cellulose triacetate films containing semiconductor nanoparticles

CdSe/ZnS quantum dots (QDs) were embedded in films of cellulose triacetate (CTA) to give clear films with the broad absorbance and well-defined, size-tunable fluorescence characteristic of QDs. The relative quantum yields of the QDs in polymer were compared to that of the initial QDs dispersed in toluene. Alkaline hydrolysis of the film surfaces to regenerated cellulose rendered the previously hydrophobic CTA film surfaces hydrophilic and compatible with aqueous papermaking. Films containing combinations of different sized QDs gave more complex emission patterns. Small pieces of fluorescent films were added to pulp slurries and incorporated into laboratory paper sheets through hydrogen bonding between the regenerated cellulose film surfaces and cellulosic pulp fibers. The film system (cellulose ester bulk/cellulose surface) can be used to incorporate hydrophobic particles or molecules compatible with solutions of cellulosic polymers into paper products at both high and low loadings. QDs in paper may prove useful for security applications, such as sheets with unique optical signatures.     

Sustainable preparation of gold nanoparticles via green chemistry approach for biogenic applications

Novel premises of ‘Green Nanotechnology’ have tremendous impacts towards industrial scale revolution. The furtive extracted from natural precursors have driven to the generation of biogenic resources for the fabrication of cutting-edge nanomaterials in simple and cost-effective process. This inspection is an intension of the coupling hypothesis of Nanotechnology via ‘Green-Chemistry’ avenue. So, as to diminish the negative effects of technological applications in the health of human beings and the environment, society is focused towards a greener future. Nanoscience assures a promising future by its improvement in green chemistry to develop the 'Greenary Nanoscience and Nanotechnology'. The improvement and execution of chemical assisted processes in order to reduce the usage of harmful substances, the ‘Green Chemistry’ approach is one and only remarkable authentication, which attributed to long range surface area and higher pore volume of gold-nanoparticles. As of now, the efficient biogenic mechanism dramatically reduces the utilization and hazardous reagents have been employed to low-price natural and waste products to yield value-added nanomaterials with extensive relevance, suggesting an economical and green solution to environmental issues. In depth investigation of this critical review illustrates, novel biogenic screening platform was also conducted against antimicrobial strains and degradation of gold-nanoparticles products well explored-from selection precursors evolved from natural extracts, as well as eventually disintegration into bio-degradable yet potentially recyclable byproducts.     

Fluorescent nanoparticles for chemical and biological sensing

Fluorescent nanoparticles (NPs), including quantum dots (QDs), dye-doped NPs, and rare earth-based NPs, etc., have been a major focus of research and development during the past decade. The impetus behind such endeavors can be attributed to their unique chemical and optical properties, such as bright fluorescence, high photostability, large Stocks shift and flexible processability. The introduction of fluorescent NPs into analytical chemistry has opened up new venues for fluorescent analysis. In this review...     

Synthesis and characterization of monodisperse CdSe quantum dots in different organic solvents

Nearly monodisperse CdSe quantum dots (QDs) have been prepared by a soft solution approach using air-stable reagents in different organic solvents. This scheme is a supplement to the conventional thermal decomposition of organometallic compounds at higher temperatures. CdSe nanocrystals of different sizes could be obtained by simply changing the solvent. This method is reproducible and simple and thus can be readily scaled up for industrial production. The reaction process was monitored by the temporal evolution of the UV-Vis absorption and room temperature photoluminensce spectra. The structures of the CdSe quantum dots were determined by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The phase-transfer of oleic acid-stabilized CdSe nanocrystals into PBS buffer solutions was also studied for their potentials in biological applications. __________ Translated from Journal of Shanghai Jiaotong University, 2005, 39(1) (in Chinese)     

基于PbS量子点和金纳米颗粒的可卡因适体传感器的研究

本文采用水热法合成了硫化铅量子点,将其与壳聚糖混合后修饰在玻碳电极上,利用PbS与巯基之间的强烈的键和作用,直接将所合成的带巯基的与可卡因适体互补的DNA固定到电极上,将金纳米颗粒标记在可卡因适体作为示踪物检测可卡因,研制了一种新型的用于快速测定可卡因的适体传感器.该适体传感器与不同浓度的可卡因培育时,可卡因适体与可卡...     

Toward a comprehensive understanding of textiles functionalized with silver nanoparticles

This article provides a comprehensive understanding of development of textiles functionalized with silver nanoparticles (AgNPs). There are three established methods to fabricate textiles functionalized with AgNPs, namely, solution‐immersion, layer‐by‐layer deposition, and sonochemical. In addition, several textile types such as cotton, wool, polyester, silk, cotton/polyester blend, polyamide, and regenerated cellulose have been used for the fabrication. The AgNP deposition mechanism on textiles is mainly due to electrostatic interaction between AgNPs and textile constituents. It was exhibited that the deposition of AgNPs on textiles can transform their textiles colors. In addition, it was demonstrated that the deposition of AgNPs on textiles is not permanent, particularly against washing treatment. Textiles modified with AgNPs have several promising applications such as antibacterial, antifungal, catalyst, electronic devices, water treatment, sun protection, air treatment, and surface‐enhanced Raman scattering, which are comprehensively discussed in this article. Future challenges in fabricating textiles functionalized with AgNPs remain on how this can be carried out to improve long‐term stabilization of AgNPs on textiles to achieve their permanent deposition by employing greener approaches.