Muhit Rana | MD Anderson Cancer Center, UT Texas, Houston (original) (raw)

Papers by Muhit Rana

A typical lock-and-key sensing strategy, relying only on the most dominant interactions between t... more A typical lock-and-key sensing strategy, relying only on the most dominant interactions between the probe and target, could be too limiting. In reality, the information received upon sensing is much richer. Non-specific events due to various intermolecular forces contribute to the overall received information with different degrees, and when analyzed, could provide a much more powerful detection opportunity. Here, we have assembled a highly selective universal sensor array using water-soluble two-dimensional nanoparticles (nGO, MoS 2 and WS 2) and fluorescent DNA molecules. The array is composed of 12 fluorescently silent non-specific nanoreceptors (2D-nps) and used for the identification of three radically different systems; five proteins, three types of live breast cancer cells and a structure-switching event of a macromolecule. The data matrices for each system were processed using Partial Least Squares (PLS) discriminant analysis. In all of the systems, the sensor array was able to identify each object or event as separate clusters with 95% confidence and without any overlap. Out of 15 unknown entities with unknown protein concentrations tested, 14 of them were predicted successfully with correct concentration. 8 breast cancer cell samples out of 9 unknown entities from three cell types were predicted correctly. During the assembly of each nanoprobe, the intrinsic non-covalent interactions between unmodified 2D nanoparticles and ssDNAs were exploited. The unmodified 2D materials offer remarkable simplicity in the layout and the use of ssDNAs as probes provides limitless possibilities because the natural interaction of a ssDNA and 2D surface can be fine-tuned with the nucleobase composition, oligonucleotide length and type of 2D nanomaterial. Therefore, the approach described here can be advanced and fine-tuned indefinitely for meeting a particular sensing criterion. Though we have only studied three distinct elements, this approach is universal enough to be applied to a wide-range of systems.

The EPA's recommended maximum allowable level of inorganic mercury in drinking water is 2 ppb (10... more The EPA's recommended maximum allowable level of inorganic mercury in drinking water is 2 ppb (10 nM). To our knowledge, the most sensitive colorimetric mercury sensor reported to date has a limit of detection (LOD) of 800 pM. Here, we report an instrument-free and highly practical colorimetric methodology, which enables detection of as low as 2 ppt (10 pM) of mercury and/or silver ions with the naked eye using a gold nanoprobe. Synthesis of the nanoprobe costs less than $1.42, which is enough to perform 200 tests in a microplate; less than a penny for each test. We have demonstrated the detection of inorganic mercury from water, soil and urine samples. The assay takes about four hours and the color change is observed within minutes after the addition of the last required element of the assay. The nanoprobe is highly programmable which allows for the detection of mercury and/or silver ions separately or simultaneously by changing only a single parameter of the assay. This highly sensitive approach for the visual detection relies on the combination of the signal amplification features of the hybridization chain reaction with the plasmonic properties of the gold nanoparticles. Considering that heavy metal ion contamination of natural resources is a major challenge and routine environmental monitoring is needed, yet time-consuming, this colorimetric approach may be instrumental for on-site heavy metal ion detection. Since the color transition can be measured in a variety of formats including using the naked eye, a simple UV-Vis spectrophotometer, or recording using mobile phone apps for future directions, our cost-efficient assay and method have the potential to be translated into the field.

In this study, we have coupled the DNA polymerization capability of hybridization chain reaction ... more In this study, we have coupled the DNA polymerization capability of hybridization chain reaction (HCR) with the plasmonic properties of gold nanoparticles to develop a reprogrammable and multiplexed detection of three circulating oncomiRs (miR-10b, miR-21 and miR-141) dysregulated in various disease states of breast cancer. We have demonstrated that by simply changing the initiator (label-free short single stranded DNA) content of the HCR, while keeping everything else unchanged, the same nanoparticle assembly can be reprogrammed for the detection of the target oncomiRs individually or simultaneously in all possible combinations. We have shown that as little as 20 femtomoles of each oncomiR can be detected visually without using any analytical instrument. Furthermore, we demonstrated that the target oncomiR can be detected in an RNA pool isolated from a liquid biopsy mimic of breast cancer.

Analytical Chemistry, 2016

In this study, we have investigated the intrinsic peroxidase-like activity of citrate-capped AuNP... more In this study, we have investigated the intrinsic peroxidase-like activity of citrate-capped AuNPs (perAuxidase) and demonstrated that the nanozyme function can be multiplexed and tuned by integrating oligonucleotides on a nanoparticle surface. Systematic studies revealed that by controlling the reaction parameters, the mutiplexing effect can be delayed or advanced and further used for aptasensor applications.

African Journal of Traditional, Complementary and Alternative Medicines

... 2012 Corresponding Authors: Trishna Das, Girijananda Chowdhury Institute of Pharmaceutical Sc... more ... 2012 Corresponding Authors: Trishna Das, Girijananda Chowdhury Institute of Pharmaceutical Sciences, Guwahati (Assam), India. 16 ... Region Trishna Das, Shanti Bhushan Mishra, Dipankar Saha and Shivani Agarwal 1 2 1 3 ...

Journal of Biomolecular Structure and Dynamics, 2015

ABSTRACT Targeting, silencing or imaging miRNA molecules have been considered promising methods f... more ABSTRACT Targeting, silencing or imaging miRNA molecules have been considered promising methods for fighting cancer at the molecular level. microRNAs (miRNAs) are small noncoding RNA molecules (~22 nucleotides) that regulate gene expression at the post-transcriptional level. miR-10b has been found over-expressed in metastatic breast cancer. Inhibiting the functions of miR-10b using single stranded synthetic anti-sense Locked Nucleic Acid (LNA) molecules has shown effective therapeutic results for metastatic breast cancer. The objective of this study was to understand the interaction between miR-10b with its complementary natural or unnatural anti-sense strands using two-dimensional graphene (nGO) and Molybdenum disulfide (MoS2). Here we used nGO and MoS2 to investigate the interaction between an LNA modified antisense oligonucleotide and its target oncomiR (miR-10b). In this study, nGO and MoS2 serve as a firm nano-platform for nucleic acids with or without base modification, while providing rich kinetic and spectroscopic information about their interaction. Moreover, we were able to validate the stability of the oligonucleotide and nGO or MoS2 nanoassemblies (nGO/ssDNA or MoS2/ssDNA) at different temperatures. In conclusion, we demonstrate that two-dimensional nanomaterials serve as a superb nano-platform for monitoring nucleic acid interactions, which have essential implications in miRNA imaging and therapeutic technologies. We were able to observe the similarities and differences in interactions between miR-10b and its LNA or DNA complementary strands using rapid quenching and adsorbing properties of nGO and MoS2. The stability of the nGO/ssDNA or MoS2/ssDNA nanoassemblies in a wide range of temperatures suggests that it is an attractive nanomaterial for monitoring hybridization and de-hybridization of oligonucleotides.

Bioconjugate Chemistry, 2015

Here we have demonstrated that graphene serves as a remarkable platform for monitoring the multit... more Here we have demonstrated that graphene serves as a remarkable platform for monitoring the multitask activity of an enzyme with fluorescence spectroscopy. Our studies showed that four different simultaneous enzymatic tasks of DNase I can be observed and measured in a high throughput fashion using graphene oxide and oligonucleotide nanoassemblies. We have used phosphorothioate modified oligonucleotides to pinpoint the individual and highly specific functions of DNase I with single stranded DNA, RNA, and DNA/DNA and DNA/RNA duplexes. DNase I resulted in fluorescence recovery in the nanoassemblies and enhanced the intensity tremendously in the presence of sequence specific DNA or RNA molecules with different degrees of amplification. Our study enabled us to discover the sources of this remarkable signal enhancement, which has been used for biomedical applications of graphene for sensitive detection of specific oncogenes. The significant difference in the signal amplification observed for the detection of DNA and RNA molecules is a result of the positive and/or reductive signal generating events with the enzyme. In the presence of DNA there are four possible ways that the fluorescence reading is influenced, with two of them resulting in a gain in signal while the other two result in a loss. Since the observed signal is a summation of all the events together, the absence of the two fluorescence reduction events with RNA gives a greater degree of fluorescence signal enhancement when compared to target DNA molecules. Overall, our study demonstrates that graphene has powerful features for determining the enzymatic functions of a protein and reveals some of the unknowns observed in the graphene and oligonucleotide assemblies with DNase I.

Circulating oncomiRs are highly stable diagnostic, prognostic, and therapeutic tumor biomarkers, ... more Circulating oncomiRs are highly stable diagnostic, prognostic, and therapeutic tumor biomarkers, which can reflect the status of the disease and response to cancer therapy. miR-141 is an oncomiR, which is overexpressed in advanced prostate cancer patients, whereas its expression is at the normal levels in the early stages of the disease. On the other hand, miR-21 is significantly elevated in the early stage, but not in the advanced prostate cancer. Here, we have demonstrated simultaneous detection of exogenous miR-21 and miR-141 from human body fluids including blood, urine and saliva using nanographene oxide. Our system enables us to specifically and reliably detect each oncomiR at different fluorescence emission channels from a large population of RNAs extracted from body fluids. We were also able to determine the content and the ratio of the miR-21 and miR-141 in 10 different miRNA cocktails composed of various, but unknown, concentrations of both oncomiRs. A strong agreement (around 90%) between the experimental results and the actual miRNA compositions was observed. Moreover, we have demonstrated that overexpressed miR-21 or miR-141 increases the fluorescence only at their signature wavelengths of 520 and 670 nm, respectively. The approach in this study combines two emerging fields of nanographene in biomedicine and the role of circulating miRNAs in cancer. Our strategy has the potential to address the current challenges in diagnosis, prognosis and staging of prostate cancer with a non- or minimally invasive approach

The interaction of locked nucleic acid (LNA)-modified antisense miR-10b oligonucleotides and its ... more The interaction of locked nucleic acid (LNA)-modified antisense miR-10b oligonucleotides and its complementary DNA (cDNA) analog is studied using gold nanoparticles. We demonstrate that LNA shows a slower hybridization rate with complementary DNA molecules, however improves the melting temperature (∼15 °C) and duplex stability significantly. The dramatic difference in melting temperatures between the LNA–cDNA and DNA–cDNA duplexes is examined through the change in aggregation of gold nanoparticles by monitoring the absorbance values at 525, 570, and 600 nm. Furthermore, the difference in melting temperatures enables us to control gold nanoparticle assembly/disassembly with free DNA/LNA oligonucleotides at various temperatures. This heat-induced rearrangement of gold nanoparticles and oligonucleotides is monitored by naked eye and UV–Vis spectroscopy. Owing to the remarkable duplex stability with complementary oligonucleotides, LNA not only plays an important role in medicine but also is a significant tool in biomaterials science.

We report the facile and non-covalent construction of a graphene oxide-based functional hybrid ma... more We report the facile and non-covalent construction of a graphene oxide-based functional hybrid material with gold and fluorescently labeled superparamagnetic iron oxide nanoparticles [GO–MNcy5.5–AuNP]. The obtained [GO–MNcy5.5–AuNP] hybrid exhibits the physical properties of each component. The relaxivity of the magnetic nanoparticles was improved, cy5.5 fluorescence was completely quenched and the surface plasmon peak of the gold nanoparticles at 520 nm was observed in the hybrid complex. The hybrid exhibits an ultra-high doxorubicin loading capacity of 6.05 mg mg−1 at 0.32 mg ml−1 drug concentration. This material could serve as a promising platform for theranostics, due to its contrast agent composition and anticancer drug loading capacity.

Graphene oxide has gained significant attention due to its exceptional physical properties at bio... more Graphene oxide has gained significant attention due to its exceptional physical properties at biological interfaces. It has extraordinary quenching, fast adsorption and desorption properties that are suitable for detection of molecular interactions in nucleic acids. Here we studied the interaction between locked nucleic acid (LNA) modified oligonucleotides and its complementary miR-10b DNA analog. We demonstrate that LNA modification does not alter the hybridization yield, despite a slight difference in the rate, however it does increase the duplex stability dramatically. The noncovalent nucleic acid–graphene oxide complex maintained the stability between 25 and 90 °C in the absence of oligonucleotide-induced desorption. The melting temperatures of duplexes with or without LNA base modification were determined due to remarkable fluorescence quenching and fast oligonucleotide adsorption with graphene oxide. The difference in melting temperatures was used to control the release of surface adsorbed nucleic acids at 70 °C. Finally, a mutation in the oligonucleotide sequence is detected by the complementary oligonucleotides on the graphene oxide surface. Due to its extraordinary physical properties, graphene oxide represents a remarkable platform for studying nucleic acid interactions and serves as a promising material for biomedical applications.

African Journal of …, 2009

African Journal of Traditional, Complementary and Alternative medicines (AJTCAM), ABSTRACTS OF TH... more African Journal of Traditional, Complementary and Alternative medicines (AJTCAM), ABSTRACTS OF THE WORLD CONGRESS ON MEDICINAL AND AROMATIC PLANTS, CAPE TOWN NOVEMBER 2008. ...

We controlled the fluorescence emission of a fluorescently labeled iron oxide nanoparticle using ... more We controlled the fluorescence emission of a fluorescently labeled iron oxide nanoparticle using three different nanomaterials with ultraefficient quenching capabilities. The control over the fluorescence emission was investigated via spacing introduced by the surface-functionalized single-stranded DNA molecules. DNA molecules were conjugated on different templates, either on the surface of the fluorescently labeled iron oxide nanoparticles or gold and nanographene oxide. The efficiency of the quenching was determined and compared with various fluorescently labeled iron oxide nanoparticle and nanoquencher combinations using DNA molecules with three different lengths. We have found that the template for DNA conjugation plays significant role on quenching the fluorescence emission of the fluorescently labeled iron oxide nanoparticles. We have observed that the size of the DNA controls the quenching efficiency when conjugated only on the fluorescently labeled iron oxide nanoparticles by setting a spacer between the surfaces and resulting change in the hydrodynamic size. The quenching efficiency with 12mer, 23mer and 36mer oligonucleotides decreased to 56%, 54% and 53% with gold nanoparticles, 58%, 38% and 32% with nanographene oxide, 46%, 38% and 35% with MoS2, respectively. On the other hand, the presence, not the size, of the DNA molecules on the other surfaces quenched the fluorescence significantly with different degrees. To understand the effect of the mobility of the DNA molecules on the nanoparticle surface, DNA molecules were attached to the surface with two different approaches. Covalently immobilized oligonucleotides decreased the quenching efficiency of nanographene oxide and gold nanoparticles to ∼22% and ∼21%, respectively, whereas noncovalently adsorbed oligonucleotides decreased it to ∼25% and ∼55%, respectively. As a result, we have found that each nanoquencher has a powerful quenching capability against a fluorescent nanoparticle, which can be tuned with surface functionalized DNA molecules.

A typical lock-and-key sensing strategy, relying only on the most dominant interactions between t... more A typical lock-and-key sensing strategy, relying only on the most dominant interactions between the probe and target, could be too limiting. In reality, the information received upon sensing is much richer. Non-specific events due to various intermolecular forces contribute to the overall received information with different degrees, and when analyzed, could provide a much more powerful detection opportunity. Here, we have assembled a highly selective universal sensor array using water-soluble two-dimensional nanoparticles (nGO, MoS 2 and WS 2) and fluorescent DNA molecules. The array is composed of 12 fluorescently silent non-specific nanoreceptors (2D-nps) and used for the identification of three radically different systems; five proteins, three types of live breast cancer cells and a structure-switching event of a macromolecule. The data matrices for each system were processed using Partial Least Squares (PLS) discriminant analysis. In all of the systems, the sensor array was able to identify each object or event as separate clusters with 95% confidence and without any overlap. Out of 15 unknown entities with unknown protein concentrations tested, 14 of them were predicted successfully with correct concentration. 8 breast cancer cell samples out of 9 unknown entities from three cell types were predicted correctly. During the assembly of each nanoprobe, the intrinsic non-covalent interactions between unmodified 2D nanoparticles and ssDNAs were exploited. The unmodified 2D materials offer remarkable simplicity in the layout and the use of ssDNAs as probes provides limitless possibilities because the natural interaction of a ssDNA and 2D surface can be fine-tuned with the nucleobase composition, oligonucleotide length and type of 2D nanomaterial. Therefore, the approach described here can be advanced and fine-tuned indefinitely for meeting a particular sensing criterion. Though we have only studied three distinct elements, this approach is universal enough to be applied to a wide-range of systems.

The EPA's recommended maximum allowable level of inorganic mercury in drinking water is 2 ppb (10... more The EPA's recommended maximum allowable level of inorganic mercury in drinking water is 2 ppb (10 nM). To our knowledge, the most sensitive colorimetric mercury sensor reported to date has a limit of detection (LOD) of 800 pM. Here, we report an instrument-free and highly practical colorimetric methodology, which enables detection of as low as 2 ppt (10 pM) of mercury and/or silver ions with the naked eye using a gold nanoprobe. Synthesis of the nanoprobe costs less than $1.42, which is enough to perform 200 tests in a microplate; less than a penny for each test. We have demonstrated the detection of inorganic mercury from water, soil and urine samples. The assay takes about four hours and the color change is observed within minutes after the addition of the last required element of the assay. The nanoprobe is highly programmable which allows for the detection of mercury and/or silver ions separately or simultaneously by changing only a single parameter of the assay. This highly sensitive approach for the visual detection relies on the combination of the signal amplification features of the hybridization chain reaction with the plasmonic properties of the gold nanoparticles. Considering that heavy metal ion contamination of natural resources is a major challenge and routine environmental monitoring is needed, yet time-consuming, this colorimetric approach may be instrumental for on-site heavy metal ion detection. Since the color transition can be measured in a variety of formats including using the naked eye, a simple UV-Vis spectrophotometer, or recording using mobile phone apps for future directions, our cost-efficient assay and method have the potential to be translated into the field.

In this study, we have coupled the DNA polymerization capability of hybridization chain reaction ... more In this study, we have coupled the DNA polymerization capability of hybridization chain reaction (HCR) with the plasmonic properties of gold nanoparticles to develop a reprogrammable and multiplexed detection of three circulating oncomiRs (miR-10b, miR-21 and miR-141) dysregulated in various disease states of breast cancer. We have demonstrated that by simply changing the initiator (label-free short single stranded DNA) content of the HCR, while keeping everything else unchanged, the same nanoparticle assembly can be reprogrammed for the detection of the target oncomiRs individually or simultaneously in all possible combinations. We have shown that as little as 20 femtomoles of each oncomiR can be detected visually without using any analytical instrument. Furthermore, we demonstrated that the target oncomiR can be detected in an RNA pool isolated from a liquid biopsy mimic of breast cancer.

Analytical Chemistry, 2016

In this study, we have investigated the intrinsic peroxidase-like activity of citrate-capped AuNP... more In this study, we have investigated the intrinsic peroxidase-like activity of citrate-capped AuNPs (perAuxidase) and demonstrated that the nanozyme function can be multiplexed and tuned by integrating oligonucleotides on a nanoparticle surface. Systematic studies revealed that by controlling the reaction parameters, the mutiplexing effect can be delayed or advanced and further used for aptasensor applications.

African Journal of Traditional, Complementary and Alternative Medicines

... 2012 Corresponding Authors: Trishna Das, Girijananda Chowdhury Institute of Pharmaceutical Sc... more ... 2012 Corresponding Authors: Trishna Das, Girijananda Chowdhury Institute of Pharmaceutical Sciences, Guwahati (Assam), India. 16 ... Region Trishna Das, Shanti Bhushan Mishra, Dipankar Saha and Shivani Agarwal 1 2 1 3 ...

Journal of Biomolecular Structure and Dynamics, 2015

ABSTRACT Targeting, silencing or imaging miRNA molecules have been considered promising methods f... more ABSTRACT Targeting, silencing or imaging miRNA molecules have been considered promising methods for fighting cancer at the molecular level. microRNAs (miRNAs) are small noncoding RNA molecules (~22 nucleotides) that regulate gene expression at the post-transcriptional level. miR-10b has been found over-expressed in metastatic breast cancer. Inhibiting the functions of miR-10b using single stranded synthetic anti-sense Locked Nucleic Acid (LNA) molecules has shown effective therapeutic results for metastatic breast cancer. The objective of this study was to understand the interaction between miR-10b with its complementary natural or unnatural anti-sense strands using two-dimensional graphene (nGO) and Molybdenum disulfide (MoS2). Here we used nGO and MoS2 to investigate the interaction between an LNA modified antisense oligonucleotide and its target oncomiR (miR-10b). In this study, nGO and MoS2 serve as a firm nano-platform for nucleic acids with or without base modification, while providing rich kinetic and spectroscopic information about their interaction. Moreover, we were able to validate the stability of the oligonucleotide and nGO or MoS2 nanoassemblies (nGO/ssDNA or MoS2/ssDNA) at different temperatures. In conclusion, we demonstrate that two-dimensional nanomaterials serve as a superb nano-platform for monitoring nucleic acid interactions, which have essential implications in miRNA imaging and therapeutic technologies. We were able to observe the similarities and differences in interactions between miR-10b and its LNA or DNA complementary strands using rapid quenching and adsorbing properties of nGO and MoS2. The stability of the nGO/ssDNA or MoS2/ssDNA nanoassemblies in a wide range of temperatures suggests that it is an attractive nanomaterial for monitoring hybridization and de-hybridization of oligonucleotides.

Bioconjugate Chemistry, 2015

Here we have demonstrated that graphene serves as a remarkable platform for monitoring the multit... more Here we have demonstrated that graphene serves as a remarkable platform for monitoring the multitask activity of an enzyme with fluorescence spectroscopy. Our studies showed that four different simultaneous enzymatic tasks of DNase I can be observed and measured in a high throughput fashion using graphene oxide and oligonucleotide nanoassemblies. We have used phosphorothioate modified oligonucleotides to pinpoint the individual and highly specific functions of DNase I with single stranded DNA, RNA, and DNA/DNA and DNA/RNA duplexes. DNase I resulted in fluorescence recovery in the nanoassemblies and enhanced the intensity tremendously in the presence of sequence specific DNA or RNA molecules with different degrees of amplification. Our study enabled us to discover the sources of this remarkable signal enhancement, which has been used for biomedical applications of graphene for sensitive detection of specific oncogenes. The significant difference in the signal amplification observed for the detection of DNA and RNA molecules is a result of the positive and/or reductive signal generating events with the enzyme. In the presence of DNA there are four possible ways that the fluorescence reading is influenced, with two of them resulting in a gain in signal while the other two result in a loss. Since the observed signal is a summation of all the events together, the absence of the two fluorescence reduction events with RNA gives a greater degree of fluorescence signal enhancement when compared to target DNA molecules. Overall, our study demonstrates that graphene has powerful features for determining the enzymatic functions of a protein and reveals some of the unknowns observed in the graphene and oligonucleotide assemblies with DNase I.

Circulating oncomiRs are highly stable diagnostic, prognostic, and therapeutic tumor biomarkers, ... more Circulating oncomiRs are highly stable diagnostic, prognostic, and therapeutic tumor biomarkers, which can reflect the status of the disease and response to cancer therapy. miR-141 is an oncomiR, which is overexpressed in advanced prostate cancer patients, whereas its expression is at the normal levels in the early stages of the disease. On the other hand, miR-21 is significantly elevated in the early stage, but not in the advanced prostate cancer. Here, we have demonstrated simultaneous detection of exogenous miR-21 and miR-141 from human body fluids including blood, urine and saliva using nanographene oxide. Our system enables us to specifically and reliably detect each oncomiR at different fluorescence emission channels from a large population of RNAs extracted from body fluids. We were also able to determine the content and the ratio of the miR-21 and miR-141 in 10 different miRNA cocktails composed of various, but unknown, concentrations of both oncomiRs. A strong agreement (around 90%) between the experimental results and the actual miRNA compositions was observed. Moreover, we have demonstrated that overexpressed miR-21 or miR-141 increases the fluorescence only at their signature wavelengths of 520 and 670 nm, respectively. The approach in this study combines two emerging fields of nanographene in biomedicine and the role of circulating miRNAs in cancer. Our strategy has the potential to address the current challenges in diagnosis, prognosis and staging of prostate cancer with a non- or minimally invasive approach

The interaction of locked nucleic acid (LNA)-modified antisense miR-10b oligonucleotides and its ... more The interaction of locked nucleic acid (LNA)-modified antisense miR-10b oligonucleotides and its complementary DNA (cDNA) analog is studied using gold nanoparticles. We demonstrate that LNA shows a slower hybridization rate with complementary DNA molecules, however improves the melting temperature (∼15 °C) and duplex stability significantly. The dramatic difference in melting temperatures between the LNA–cDNA and DNA–cDNA duplexes is examined through the change in aggregation of gold nanoparticles by monitoring the absorbance values at 525, 570, and 600 nm. Furthermore, the difference in melting temperatures enables us to control gold nanoparticle assembly/disassembly with free DNA/LNA oligonucleotides at various temperatures. This heat-induced rearrangement of gold nanoparticles and oligonucleotides is monitored by naked eye and UV–Vis spectroscopy. Owing to the remarkable duplex stability with complementary oligonucleotides, LNA not only plays an important role in medicine but also is a significant tool in biomaterials science.

We report the facile and non-covalent construction of a graphene oxide-based functional hybrid ma... more We report the facile and non-covalent construction of a graphene oxide-based functional hybrid material with gold and fluorescently labeled superparamagnetic iron oxide nanoparticles [GO–MNcy5.5–AuNP]. The obtained [GO–MNcy5.5–AuNP] hybrid exhibits the physical properties of each component. The relaxivity of the magnetic nanoparticles was improved, cy5.5 fluorescence was completely quenched and the surface plasmon peak of the gold nanoparticles at 520 nm was observed in the hybrid complex. The hybrid exhibits an ultra-high doxorubicin loading capacity of 6.05 mg mg−1 at 0.32 mg ml−1 drug concentration. This material could serve as a promising platform for theranostics, due to its contrast agent composition and anticancer drug loading capacity.

Graphene oxide has gained significant attention due to its exceptional physical properties at bio... more Graphene oxide has gained significant attention due to its exceptional physical properties at biological interfaces. It has extraordinary quenching, fast adsorption and desorption properties that are suitable for detection of molecular interactions in nucleic acids. Here we studied the interaction between locked nucleic acid (LNA) modified oligonucleotides and its complementary miR-10b DNA analog. We demonstrate that LNA modification does not alter the hybridization yield, despite a slight difference in the rate, however it does increase the duplex stability dramatically. The noncovalent nucleic acid–graphene oxide complex maintained the stability between 25 and 90 °C in the absence of oligonucleotide-induced desorption. The melting temperatures of duplexes with or without LNA base modification were determined due to remarkable fluorescence quenching and fast oligonucleotide adsorption with graphene oxide. The difference in melting temperatures was used to control the release of surface adsorbed nucleic acids at 70 °C. Finally, a mutation in the oligonucleotide sequence is detected by the complementary oligonucleotides on the graphene oxide surface. Due to its extraordinary physical properties, graphene oxide represents a remarkable platform for studying nucleic acid interactions and serves as a promising material for biomedical applications.

African Journal of …, 2009

African Journal of Traditional, Complementary and Alternative medicines (AJTCAM), ABSTRACTS OF TH... more African Journal of Traditional, Complementary and Alternative medicines (AJTCAM), ABSTRACTS OF THE WORLD CONGRESS ON MEDICINAL AND AROMATIC PLANTS, CAPE TOWN NOVEMBER 2008. ...

We controlled the fluorescence emission of a fluorescently labeled iron oxide nanoparticle using ... more We controlled the fluorescence emission of a fluorescently labeled iron oxide nanoparticle using three different nanomaterials with ultraefficient quenching capabilities. The control over the fluorescence emission was investigated via spacing introduced by the surface-functionalized single-stranded DNA molecules. DNA molecules were conjugated on different templates, either on the surface of the fluorescently labeled iron oxide nanoparticles or gold and nanographene oxide. The efficiency of the quenching was determined and compared with various fluorescently labeled iron oxide nanoparticle and nanoquencher combinations using DNA molecules with three different lengths. We have found that the template for DNA conjugation plays significant role on quenching the fluorescence emission of the fluorescently labeled iron oxide nanoparticles. We have observed that the size of the DNA controls the quenching efficiency when conjugated only on the fluorescently labeled iron oxide nanoparticles by setting a spacer between the surfaces and resulting change in the hydrodynamic size. The quenching efficiency with 12mer, 23mer and 36mer oligonucleotides decreased to 56%, 54% and 53% with gold nanoparticles, 58%, 38% and 32% with nanographene oxide, 46%, 38% and 35% with MoS2, respectively. On the other hand, the presence, not the size, of the DNA molecules on the other surfaces quenched the fluorescence significantly with different degrees. To understand the effect of the mobility of the DNA molecules on the nanoparticle surface, DNA molecules were attached to the surface with two different approaches. Covalently immobilized oligonucleotides decreased the quenching efficiency of nanographene oxide and gold nanoparticles to ∼22% and ∼21%, respectively, whereas noncovalently adsorbed oligonucleotides decreased it to ∼25% and ∼55%, respectively. As a result, we have found that each nanoquencher has a powerful quenching capability against a fluorescent nanoparticle, which can be tuned with surface functionalized DNA molecules.