The main goal of our research is to develop new types of technologically important optically acti... more The main goal of our research is to develop new types of technologically important optically active quantum dot (QD) based materials, study their properties and explore their biological applications. For the first time chiral II-VI QDs have been prepared by us using microwave induced heating with the racemic (Rac), D- and L-enantiomeric forms of penicillamine as stabilisers. Circular dichroism (CD) studies of these QDs have shown that D- and L-penicillamine stabilised particles produced mirror image CD spectra, while the particles prepared with a Rac mixture showed only a weak signal. It was also demonstrated that these QDs show very broad emission bands between 400 and 700 nm due to defects or trap states on the surfaces of the nanocrystals. These QDs have demonstrated highly specific chiral recognition of various biological species including aminoacids. The utilisation of chiral stabilisers also allowed the preparation of new water soluble white emitting CdS nano-tetrapods, which demonstrated circular dichroism in the band-edge region of the spectrum. Biological testing of chiral CdS nanotetrapods displayed a chiral bias for an uptake of the D- penicillamine stabilised nano-tetrapods by cancer cells. It is expected that this research will open new horizons in the chemistry of chiral nanomaterials and their application in nanobiotechnology, medicine and optical chemo- and bio-sensing.
ABSTRACT Recently, the use of stereospecific chiral stabilising molecules has also opened another... more ABSTRACT Recently, the use of stereospecific chiral stabilising molecules has also opened another avenue of interest in the area of quantum dot (QD) research. The main goal of our research is to develop new types of technologically important quantum dot materials containing chiral defects, study their properties and explore their applications. The utilisation of chiral penicillamine stabilisers allowed the preparation of new water soluble white emitting CdS quantum nanostructures which demonstrated circular dichroism in the band-edge region of the spectrum. It was also demonstrated that all three types of QDs (D-, L-, and Rac penicillamine stabilised) show very broad emission bands between 400 and 700 nm due to defects or trap states on the surfaces of the nanocrystals. In this work the chiral CdS based quantum nanostructures have also been doped by copper metal ions and new chiral penicilamine stabilized CuS nanoparticles have been prepared and investigated. It was found that copper doping had a strong effect at low levels in the synthesis of chiral CdS nanostructures. We expect that this research will open new horizons in the chemistry of chiral nanomaterials and their application in biotechnology, sensing and asymmetric synthesis.
ABSTRACT Quantum dots (QDs) are fluorescent semiconductor (e.g. II-VI) nanocrystals, which have a... more ABSTRACT Quantum dots (QDs) are fluorescent semiconductor (e.g. II-VI) nanocrystals, which have a strong characteristic spectral emission. This emission is tunable to a desired energy by selecting variable particle size, size distribution and composition of the nanocrystals. QDs have recently attracted enormous interest due to their unique photophysical properties and range of potential applications in photonics and biochemistry. The main aim of our work is develop new chiral quantum dots (QDs) and establish fundamental principles influencing their structure, properties and biosensing behaviour. Here we present the synthesis and characterisation of chiral CdSe semiconductor nanoparticles and their utilisation as new chiral biosensors. Penicillamine stabilised CdSe nanoparticles have shown both very strong and very broad luminescence spectra. Circular dichroism (CD) spectroscopy studies have revealed that the D- and Lpenicillamine stabilised CdSe QDs demonstrate circular dichroism and possess almost identical mirror images of CD signals. Studies of photoluminescence and CD spectra have shown that there is a clear relationship between defect emission and CD activity. We have also demonstrated that these new QDs can serve as fluorescent nanosensors for various chiral biomolecules including nucleic acids. These novel nanosensors can be potentially utilized for detection of various chiral biological and chemical species with the broad range of potential applications.
Chirality plays an important role in the fields of chemistry, pharmacology, biology and medicine.... more Chirality plays an important role in the fields of chemistry, pharmacology, biology and medicine. Recently, chirality has also been envisaged to play an important role in nano-biotechnology. This review presents some recent years’ advances in the production and potential applications of various chiral nanostructured inorganic materials, including metallic (plasmonic), semiconducting, metal oxide and silica based chiral nanomaterials as well as chiral hybrid nanostructures. Chiral plasmonic nanostructures have deserved major attention due to their ability to enhance chiral signals and their consequent development as highly sensitive chiral plasmonic sensors. Also, significant advancements were made in the synthesis of chiral quantum dots (QDs) and development of their applications including sensing of various chiral organic drug molecules and catalysis of asymmetric aldol condensation reactions. The preparation of chiral metal oxide based nanomaterials such as chiral TiO2 nanofibres, chiral ZrO2 nanotubes and chiral mesoporous silica can lead to important applications in catalysts and separation of enantiomeric compounds. Finally, recently fabricated novel types of chiral hybrid nanostructures containing combinations of plasmonic and other nanomaterials in one system may find many potential applications ranging from chiral sensing to asymmetric catalysis.
The main goal of our research is to develop new types of technologically important optically acti... more The main goal of our research is to develop new types of technologically important optically active quantum dot (QD) based materials, study their properties and explore their biological applications. For the first time chiral II-VI QDs have been prepared by us using microwave induced heating with the racemic (Rac), D- and L-enantiomeric forms of penicillamine as stabilisers. Circular dichroism (CD) studies of these QDs have shown that D- and L-penicillamine stabilised particles produced mirror image CD spectra, while the particles prepared with a Rac mixture showed only a weak signal. It was also demonstrated that these QDs show very broad emission bands between 400 and 700 nm due to defects or trap states on the surfaces of the nanocrystals. These QDs have demonstrated highly specific chiral recognition of various biological species including aminoacids. The utilisation of chiral stabilisers also allowed the preparation of new water soluble white emitting CdS nano-tetrapods, which demonstrated circular dichroism in the band-edge region of the spectrum. Biological testing of chiral CdS nanotetrapods displayed a chiral bias for an uptake of the D- penicillamine stabilised nano-tetrapods by cancer cells. It is expected that this research will open new horizons in the chemistry of chiral nanomaterials and their application in nanobiotechnology, medicine and optical chemo- and bio-sensing.
ABSTRACT Recently, the use of stereospecific chiral stabilising molecules has also opened another... more ABSTRACT Recently, the use of stereospecific chiral stabilising molecules has also opened another avenue of interest in the area of quantum dot (QD) research. The main goal of our research is to develop new types of technologically important quantum dot materials containing chiral defects, study their properties and explore their applications. The utilisation of chiral penicillamine stabilisers allowed the preparation of new water soluble white emitting CdS quantum nanostructures which demonstrated circular dichroism in the band-edge region of the spectrum. It was also demonstrated that all three types of QDs (D-, L-, and Rac penicillamine stabilised) show very broad emission bands between 400 and 700 nm due to defects or trap states on the surfaces of the nanocrystals. In this work the chiral CdS based quantum nanostructures have also been doped by copper metal ions and new chiral penicilamine stabilized CuS nanoparticles have been prepared and investigated. It was found that copper doping had a strong effect at low levels in the synthesis of chiral CdS nanostructures. We expect that this research will open new horizons in the chemistry of chiral nanomaterials and their application in biotechnology, sensing and asymmetric synthesis.
ABSTRACT Quantum dots (QDs) are fluorescent semiconductor (e.g. II-VI) nanocrystals, which have a... more ABSTRACT Quantum dots (QDs) are fluorescent semiconductor (e.g. II-VI) nanocrystals, which have a strong characteristic spectral emission. This emission is tunable to a desired energy by selecting variable particle size, size distribution and composition of the nanocrystals. QDs have recently attracted enormous interest due to their unique photophysical properties and range of potential applications in photonics and biochemistry. The main aim of our work is develop new chiral quantum dots (QDs) and establish fundamental principles influencing their structure, properties and biosensing behaviour. Here we present the synthesis and characterisation of chiral CdSe semiconductor nanoparticles and their utilisation as new chiral biosensors. Penicillamine stabilised CdSe nanoparticles have shown both very strong and very broad luminescence spectra. Circular dichroism (CD) spectroscopy studies have revealed that the D- and Lpenicillamine stabilised CdSe QDs demonstrate circular dichroism and possess almost identical mirror images of CD signals. Studies of photoluminescence and CD spectra have shown that there is a clear relationship between defect emission and CD activity. We have also demonstrated that these new QDs can serve as fluorescent nanosensors for various chiral biomolecules including nucleic acids. These novel nanosensors can be potentially utilized for detection of various chiral biological and chemical species with the broad range of potential applications.
Chirality plays an important role in the fields of chemistry, pharmacology, biology and medicine.... more Chirality plays an important role in the fields of chemistry, pharmacology, biology and medicine. Recently, chirality has also been envisaged to play an important role in nano-biotechnology. This review presents some recent years’ advances in the production and potential applications of various chiral nanostructured inorganic materials, including metallic (plasmonic), semiconducting, metal oxide and silica based chiral nanomaterials as well as chiral hybrid nanostructures. Chiral plasmonic nanostructures have deserved major attention due to their ability to enhance chiral signals and their consequent development as highly sensitive chiral plasmonic sensors. Also, significant advancements were made in the synthesis of chiral quantum dots (QDs) and development of their applications including sensing of various chiral organic drug molecules and catalysis of asymmetric aldol condensation reactions. The preparation of chiral metal oxide based nanomaterials such as chiral TiO2 nanofibres, chiral ZrO2 nanotubes and chiral mesoporous silica can lead to important applications in catalysts and separation of enantiomeric compounds. Finally, recently fabricated novel types of chiral hybrid nanostructures containing combinations of plasmonic and other nanomaterials in one system may find many potential applications ranging from chiral sensing to asymmetric catalysis.
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Papers by Joseph Govan