Roger M. Leblanc

Professor

rml@miami.edu

Phone:
(305) 284-2194
Locator Code:
0431
Address:
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Career

Education

1968-70Post Doctoral , Davy Faraday Research Laboratory
1967Ph.D. , Universite Laval

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Research

Brief description of research

Our research group aims at understanding the surface chemistry, spectroscopic and microscopic investigation of organic and biological supramolecular complexes. The chemistry of monolayers of supramolecular complexes is of paramount importance on account of many potential applications in diverse fields such as manufacture of new polymers, bio- and chemisensors, protective surface coatings, conductive films, optoelectronic devices, etc.

 

  • Specifically we are focusing on:
  • Combinatorial chemistry
  • Molecular recognition
  • Development of chemi- and biosensors
  • Tissue engineering
  • Aggregation studies regarding amyloidogenesis

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LIST OF SPECIALTIES: Molecular recognition, surface chemistry and spectroscopy

RESEARCH PROFILES

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Publications

Pardo, J., Peng, Z. & Leblanc, R. Cancer targeting and drug delivery using carbon-based quantum dots and nanotubes 37823, 2 (Molecules. 2018). [Link]

SUMMARY: Currently cancer treatment is in large part non-specific with respect to treatment. Medication is often harsh on patients, whereby they suffer several undesired side effects as a result. Carbon-based nanoparticles have attracted attention in recent years due to their ability to act as a platform for the attachment of several drugs and/or ligands. Relatively simple models are often used in cancer research, wherein carbon nanoparticles are conjugated to a ligand that is specific to an overexpressed receptor for imaging and drug delivery in cancer treatment. These carbon nanoparticles confer unique properties to the imaging or delivery vehicle due to their nontoxic nature and their high fluorescence qualities. Chief among the ongoing research within carbon-based nanoparticles emerge carbon dots (C-dots) and carbon nanotubes (CNTs). In this review, the aforementioned carbon nanoparticles will be discussed in their use within doxorubicin and gemcitabine based drug delivery vehicles, as well as the ligand-mediated receptor specific targeted therapy. Further directions of research in current field are also discussed.

Mintz, K., Waidely, E., Zhou, Y., Peng, Z., Al-Youbi, A. O., Bashammakh, A. S., El-Shahawi, M. S. & Leblanc, R. Carbon dots and gold nanoparticles based immunoassay for detection of alpha-L-fucosidase 114-1211041 (Analytica Chimica Acta. 2018). [Link]

SUMMARY:

Hepatocellular carcinoma (HCC) is among the leading causes of mortality in the world. The detection of HCC in its early stage is the key for early treatment and thus the improvement of the chances of survival. Among the various methods of HCC screening, assays based on the detection of biomarker that is specific to HCC such as alpha-l-fucosidase (AFU) have been regarded as the most prominent methods. In this regards, a new assay for the detection of AFU to screen HCC was developed. This assay was based on the energy transfer between carbon dots (C-dots) and gold nanoparticles (AuNPs), the concentration of AFU could be monitored by the degree of C-dots fluorescence quenching due to the energy transfer. With this assay, a limit of detection of 3.4 nM (well below the diagnostic cutoff point of 80 nM), and a broad linear range of detection from 11.3 to 200 nM were achieved. We also demonstrate the determination of the concentration of AFU in human blood serum.

Zhou, Y., Peng, Z., Seven, E. S. & Leblanc, R., Crossing the blood-brain barrier with nanoparticles 290-303270 (Journal of Controlled Release. 2018).

Zhou, Y., Mintz, K. J., Oztan, C. Y., Hettiarachchi, S. D., Peng, Z., Seven, E. S., Liyanage, P. Y., De La Torre, S., Celik, E. & Leblanc, R. Embedding carbon dots in superabsorbent polymers for additive manufacturing 92110, 8 (Polymers. 2018).

Zhou, Y., Liyanage, P. Y., Geleroff, D. L., Peng, Z., Mintz, K. J., Hettiarachchi, S. D., Pandey, R. R., Chusuei, C. C., Blackwelder, P. L. & Leblanc, R. Photoluminescent Carbon Dots: A Mixture of Heterogeneous Fractions 2589-259719 (ChemPhysChem. 2018). [Link]

SUMMARY: Photoluminescent carbon dots (CDs) fractions have been isolated from a gel‐like material (GM), which was synthesized using a convenient one‐step solvothermal route. In terms of purification, size exclusion chromatography (SEC) and dialysis were compared with acetone wash, which revealed the advantage of acetone wash. The pre‐purified GM with acetone wash (A‐GM) was further isolated by the reversed‐phase preparative thin layer chromatography (TLC) with acetonitrile−water mixture (7 : 3; va/vw) as the developing solvent. As a result, there were four photoluminescent bands on the TLC plate, which indicated the presence of four photoluminescent fractions. Detailed characterization measurements such as UV/Vis absorption, fluorescence emission, attenuated total reflection Fourier‐transform infrared spectroscopy, X‐ray photoelectron spectroscopy, zeta potential, dynamic light scattering, atomic force microscopy, and TEM measurements were performed on all fractions to analyze their heterogeneous optical, structural, electrical, and morphological properties. Considering the comprehensive analysis, all isolated fractions were CDs. In addition, excitation wavelength‐independent CDs were obtained with a mean size of 2.5 nm and high quantum yield (55 %). Furthermore, the study demonstrates that the excitation wavelength‐dependent photoluminescence of GM could result from the mixture of different surface states of each CD fraction rather than multiple surface states of uniform CDs nanoparticles.

Peng, Z., Li, J., Li, S., Pardo, J., Zhou, Y., Al-Youbi, A. O., Bashammakh, A. S., El-Shahawi, M. S. & Leblanc, R. Quantification of Nucleic Acid Concentration in the Nanoparticle or Polymer Conjugates Using Circular Dichroism Spectroscopy 2255-226290, 3 (Anal. Chem.. 2018). [Link]

SUMMARY: The interface of nucleic acids and nanomaterials is among the most promising fields in recent years. Considerable efforts have been devoted to the development of novel systems based on the two components for various promising applications such as sensing, bioimaging, drug delivery, and theranostics. However, the determination of nucleic acid concentration in these systems remains as a challenge due to the interference of nanoparticles. To this end, we developed a simple, yet reliable, method to quantify the nucleic acid concentration in their nanoparticle or polymer conjugates based on circular dichroism (CD) spectroscopy. In this paper, three nucleic acids, namely, DNA sodium salt from calf thymus (NaDNA), DNA from herring sperm (hsDNA), and ribonucleic acid from torula yeast (tyRNA), were noncovalently conjugated to three nanoparticles. The concentrations of the three nucleic acids in their nanoparticle conjugates were successfully determined on the basis of CD spectra calibration curves.

Sharma, S. K., Seven, E. S., Micic, M., Li, S. & Leblanc, R. Surface Chemistry and Spectroscopic Study of a Cholera Toxin B Langmuir Monolayer 2557-256434, 7 (Langmuir. 2018). [Link]

SUMMARY: In this article, we explored the surface chemistry properties of a cholera toxin B (CTB) monolayer at the air–subphase interface and investigated the change in interfacial properties through in situ spectroscopy. The study showed that the impact of the blue shift was negligible, suggesting that the CTB molecules were minimally affected by the subphase molecules. The stability of the CTB monolayer was studied by maintaining the constant surface pressure for a long time and also by using the compression–decompression cycle experiments. The high stability of the Langmuir monolayer of CTB clearly showed that the driving force of CTB going to the amphiphilic membrane was its amphiphilic nature. In addition, no major change was detected in the various in situ spectroscopy results (such as UV–vis, fluorescence, and IR ER) of the CTB Langmuir monolayer with the increase in surface pressure. This indicates that no aggregation occurs in the Langmuir monolayer of CTB.

Han, X., Shokri Kojori, H., Leblanc, R. & Kim, S. J. Ultrasensitive Plasmonic Biosensors for Real-Time Parallel Detection of Alpha-L-Fucosidase and Cardiac-Troponin-I in Whole Human Blood 7795-779990, 13 (Analytical Chemistry. 2018). [Link]

Waidely, E., Al-Youbi, A. O., Bashammakh, A. S., El-Shahawi, M. S. & Leblanc, R. Alpha- l -Fucosidase Immunoassay for Early Detection of Hepatocellular Carcinoma 9459-946689, 17 (Analytical Chemistry. 2017). [Link]

SUMMARY: Detection of alpha-l-fucosidase has been shown to have relevance in diagnosing hepatocellular carcinoma. Few assays have been developed to measure this enzyme, with most relying on colorimetric techniques involving the enzyme’s kinetics. While these assays are facile and quick, the sensitivity is not always sufficient for early tumor detection. To improve upon previous assays for alpha-l-fucosidase, a fluorescence based immunoassay was produced implementing an alpha-l-fucosidase specific antibody (FUCA2). The immobilization of the alpha-l-fucosidase-specific antibody onto a quartz slide was investigated with several bioconjugation approaches and an immunoassay for detection of alpha-l-fucosidase was produced. The immunoassay was utilized to produce calibration curves for quantifying alpha-l-fucosidase concentrations in both PBS and human blood serum. A detection limit of 10 nM was found using human blood serum, which is well below the diagnostic cutoff point of 80 nM.

Han, X., Park, J., Wu, W., Malagon, A., Wang, L., Vargas, E., Wikramanayake, A., Houk, K. N. & Leblanc, R. A resorcinarene for inhibition of Aβ fibrillation 2003-20098, 3 (Chemical Science. 2017). [Link]

SUMMARY: Amyloid-β peptides (Aβ) fibrillation is the hallmark of Alzheimer's disease (AD). However, it has been challenging to discover potent agents in order to inhibit Aβ fibrillation. Herein, we demonstrated the effect of resorcinarene on inhibiting Aβ fibrillation in vitro via experimental and computational methods. Aβ were incubated with different concentrations of resorcinarene so as to monitor the kinetics by using thioflavin T binding assay. The results, which were further confirmed by far-UV CD spectroscopy and atomic force microscopy, strongly indicated that the higher concentration of resorcinarene, the more effective the inhibition of Aβ fibrillation. A cytotoxicity study showed that when sea urchin embryos were exposed to the resorcinarene, the majority survived due to the resorcinarene low toxicity. In addition, when the resorcinarene was added, the formation of toxic Aβ 42 species was delayed. Computational studies of Aβ fibrillation, including docking simulations and MD simulations, illustrated that the interaction between inhibitor resorcinarene and Aβ is driven by the non-polar interactions. These studies display a novel strategy for the exploration of promising antiamyloiddogenic agents for AD treatments.

Han, X., Jing, Z., Wu, W., Zou, B., Peng, Z., Ren, P., Wikramanayake, A., Lu, Z. & Leblanc, R. Biocompatible and blood-brain barrier permeable carbon dots for inhibition of Aβ fibrillation and toxicity, and BACE1 activity 12862-128669, 35 (Nanoscale. 2017). [Link]

Sharma, S. K. & Leblanc, R. Biosensors based on β-galactosidase enzyme: Recent advances and perspectives 1-11535 (Analytical Biochemistry. 2017). [Link]

SUMMARY:

Many industries are striving for the development of more reliable and robust β-galactosidase biosensors that exhibit high response rate, increased detection limit and enriched useful lifetime. In a newfangled technological atmosphere, a trivial advantage or disadvantage of the developed biosensor may escort to the survival and extinction of the industry. Several alternative strategies to immobilize β-galactosidase enzyme for their utilization in biosensors have been developed in recent years in the quest of maximum utility by controlling the defects seen in the previous biosensors. The overwhelming call for on-line measurement of different sample constituents has directed science and industry to search for best practical solutions and biosensors are witnessed as the best prospect. The main objective of this paper is to serve as a narrow footbridge by comparing the literary works on the β-galactosidase biosensors, critically analyze their use in the construction of best biosensor by showing the pros and cons of the predicted methods for the practical use of biosensors.

Peng, Z., Han, X., Li, S., Al-Youbi, A. O., Bashammakh, A. S., El-Shahawi, M. S. & Leblanc, R. Carbon dots: Biomacromolecule interaction, bioimaging and nanomedicine 256-277343 (Coordination Chemistry Reviews. 2017). [Link]

Peng, Z., Miyanji, E. H., Zhou, Y., Pardo, J., Hettiarachchi, S. D., Li, S., Blackwelder, P. L., Skromne, I. & Leblanc, R. Carbon dots: Promising biomaterials for bone-specific imaging and drug delivery 17533-175439, 44 (Nanoscale. 2017). [Link]

Liu, W., Li, S., Wang, Z., Yan, E. C. Y. & Leblanc, R. Characterization of Surface-Active Biofilm Protein BslA in Self-Assembling Langmuir Monolayer at the Air-Water Interface 7548-755533, 30 (Langmuir. 2017). [Link]

Zhou, Y., Desserre, A., Sharma, S. K., Li, S., Marksberry, M. H., Chusuei, C., Blackwelder, P. L. & Leblanc, R. Gel-like Carbon Dots: Characterization and their Potential Applications 890-89718 (ChemPhysChem.. 2017). [Link]

Zhou, Y., Sharma, S. K., Peng, Z. & Leblanc, R. Polymers 679, 2 (Polymers in carbon dots: A review. 2017). [Link]

Peng, Z., Li, S., Han, X., Al-Youbi, A. O., Bashammakh, A. S., El-Shahawi, M. S. & Leblanc, R. Recent Progress Toward the Spectroscopic Analysis of Biomacromolecule-Nanoparticle Interactions 649-6664 (Bioinspired and Biomimetic Supramolecular Chemistry. 2017). [Link]

Ji, Y., Zhou, Y., Waidely, E., Desserre, A., Marksberry, M. H., Chusuei, C. C., Dar, A. A., Chat, O. A., Li, S. & Leblanc, R. Rheology of a carbon dot gel 119-124468 (Inorganica Chimica Acta. 2017). [Link]

Han, X., Tian, C., Gandra, I., Eslava, V., Galindres, D., Vargas, E. & Leblanc, R. The Investigation on Resorcinarenes towards either Inhibiting or Promoting Insulin Fibrillation 17903-1790723, 71 (Chemistry - A European Journal. 2017). [Link]

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