The n-type Ge photodetectors with gold nanoparticles deposited to enhance the responsivity

Gold nanoparticles (AuNPs) have been deposited on n-type Ge photodetectors to improve the responsivity. Two different coverage ratios, including 10.5 and 30.3% of AuNPs have been prepared, and the fabricated photodetectors are compared with the control sample. The 1,310-nm responsivities at -2 V of the control, 10.5% AuNPs, and 30.3% AuNPs samples are 465, 556, and 623 mA/W, respectively. The AuNPs could increase the responsivities due to the plasmon resonance. The reflectance spectra of these samples have been measured to verify that plasmon resonance contributes to the forward scattering of incident light. The reflectance decreases with AuNP deposition, and a denser coverage results in a smaller reflectance. The smaller reflectance indicates more light could penetrate into the Ge active layer, and it results in a larger responsivity.     

Synthesis of β-cyclodextrin functionalized gold nanoparticles for the selective detection of Pb2+ ions from aqueous solution

In the present study we carried out the synthesis of β-cyclodextrin (β-CD) functionalized gold nanoparticles (AuNPs) using a microwave assisted heating method in alkaline media. Stable dispersion of β-CD stabilized AuNPs was obtained at an optimized pH of 10.5. At this pH value the deprotonated secondary hydroxyl group of β-CD shows the highest chelating affinity toward Pb²⁺ ions thereby inducing AuNP aggregation. The Pb²⁺ induced aggregation in β-CD-AuNP solution is monitored by both colorimetric response and UV-Vis spectroscopy. TEM, DLS and FTIR analyses were carried out to confirm the Pb²⁺ ion induced aggregation behaviour of β-CD-AuNPs under alkaline conditions. Furthermore at the experimental pH the response of the β-CD-AuNP system towards Pb²⁺ ions is selective when compared with other interfering metal cations.     

纳米技术在生物传感器中的应用研究进展

纳米材料因其特殊物理结构和电化学性质在生物传感器中有着广泛的应用,以纳米技术为基础的生物传感器的研究为生命科学及其相关领域的研究提供了许多新的方法。介绍了生物传感器的研究进展,分析了固定化酶时引入纳米颗粒的作用,探讨了金纳米粒子和碳纳米管的结构、特性、功能,评述了纳米粒子在生物传感器中的具体应用,展望了纳米技术的介入对生物传感器的发展所带来的美好前景。     

Nanoscopic observation of a gold nanoparticle-conjugated protein using near-field scanning optical microscopy

This study describes a single gold nanoparticle (AuNP)-based observation of biomolecular interaction using a near-field scanning microscope (NSOM) in transmission mode. To observe streptavidin molecules, a glass surface was first patterned with a micro-scale line of (3-aminopropyl)trimethoxysilane (APTMS) by micro-contact printing (μCP) with a subsequent reaction of N-hydroxysuccinimide (NHS)-biotin. The AuNP-conjugated streptavidin was then applied to the biotin-modified glass surface and NSOM was employed to detect the resulting specific interaction between streptavidin and biotin on the glass surface. Using the optical and topological images generated from the NSOM analysis, the interaction could be observed at the nanoscopic scale. This study demonstrates that the NSOM is a powerful tool for the detection of protein interactions at the nanoscopic level when the protein is conjugated with AuNPs.     

Polymers with platinum drugs and other macromolecular metal complexes for cancer treatment

Metal-based anticancer drugs, in particular platinum-drugs, have been investigated for the treatment of cancer for the last 40 years. A small set of platinum-based drugs have meanwhile received FDA approval for the treatment of various cancer. Cisplatin and its relatives are currently one of the most widely used anticancer drugs. The use is however associated with significant side effects and rising drug resistance. To combat these problems, drug delivery carriers have been developed to increase the protection of the drug and increase efficacy. Metal-based drugs represent a rather unique drug delivery challenge. Most anticancer drugs are either physically encapsulated into a polymer matrix or they can be conjugated to the polymer via a degradable linker. While both pathways are possible for metal-based drugs, the conjugation to the polymer can be carried via labile or permanent ligands. In addition, the prodrug strategy using the drug in the higher oxidation state is a common approach that has been widely tested for platinum drug. The delivery of platinum drugs is now a mature field and the various conjugation techniques have been combined with a range of drug carriers including dendrimers, micelles and solid polymer nanoparticles. Hybrids of macromolecular metal complexes with inorganic nanoparticles have been tested in recent years to combine the ability to deliver the drug with imaging properties. An emerging trend is the surface decoration of the polymeric nanoparticles with targeting ligands such as folates. The advanced state of this field is evident by the fact that some macromolecular platinum drugs even advanced to the clinic. While the delivery of platinum drugs has been well explored, the delivery of other metal-based drugs based on gold, ruthenium or cobalt is still in their infancy.     

Graphene-DNA hybrid materials: Assembly, applications, and prospects

Among the carbon-based nanomaterials such as carbon nanotubes, fullerenes, graphene and nanodiamonds, graphene received recently widespread attention owing to its exceptional structural, electronic and mechanical properties and potential applications in various domains. However, all currently known forms of graphene materials are not well dispersible or soluble in most common solvents. This limitation deters to explore the chemistry of graphene at the molecular level and its nanobio device applications. One well known solution to this problem is the use of dispersing agents such as polymers, biopolymers, or surfactants in conjunction with the appropriate experimental conditions. Among the various biomolecules, deoxyribonucleic acid (DNA) has emerged as an appealing biomacromolecule for functional materials due to its biocompatibility and renewability in addition to its very interesting double helix structure, which guarantees a range of unique properties that are difficult to detect in other molecules and polymers. Hence, the combination of graphene (a carbon-based nanomaterial), showing exceptional electronic properties, and DNA (a nanostructured biomolecule), having extraordinary recognition properties, demonstrates a new type of nanobio hybrid material. This, in turn, leads to a successful incorporation of the properties of the two different components in new hybrid materials that present important features for potential applications that range from advanced biomedical systems by means of very sensitive electrochemical sensors and biosensors to highly efficient electronics- and optics-based biochips. This article will focus on the recent advancement of the methods available for the chemical functionalization of graphene using DNA by different interactions (covalent or non-covalent and insertion of DNA through graphene nanopore or nanogap), various types of assemblies, and future prospects. Furthermore, the various potential applications of the resulting new nanobio hybrid materials are also highlighted.