Featured paper: Clay Labyrinth in Hydrogel Matrix for Controlled Drug Release.


[Paper: Highly Controlled Diffusion Drug Release from Ureasil–Poly(ethylene oxide)–Na+–Montmorillonite Hybrid Hydrogel Nanocomposites. ACS Appl. Mater. Interfaces, 2018, 10 (22), pp 19059–19068. DOI: 10.1021/acsami.8b04559]

Clay Labyrinth in Hydrogel Matrix for Controlled Drug Release

By combining a clay and a polymer gel at the nanoscale, a brazilian scientific team with members of the São Paulo State University (UNESP) and the University of Franca (UNIFRAN) developed a new material that can carry drugs and release them in a gradual and controlled manner.

The team tested in vitro – that is, in the laboratory, in containers that simulate the biological conditions – the performance of the material in the release of sodium diclofenac. This drug is an anti-inflammatory, given orally or by injection, widely used to relieve swelling and pain from, for example, arthritis, rheumatism, muscle injuries, surgeries or gout.

The material developed is a nanocomposite that includes polymeric hydrogel, clay and the drug. The hydrogel (gel that absorbs water amounts higher than normal without dissolving) is composed of an organic-inorganic hybrid material known as siloxane-polyether or ureasil. The clay is known as montmorillonite, and is present in the nanocomposite in the form of nanometric lamellae homogeneously dispersed in the hydrogel. The diclofenac sodium, which appears encapsulated within the nanocomposite, is incorporated into the material during its preparation, as if it were another “ingredient”.

The nanocomposite was obtained by the São Paulo team through the sol-gel process. This preparation method is based on a series of chemical reactions with the transformation of a “sol” (liquid with nanometric particles in suspension) into a gel (rigid three-dimensional network with interstices in which the liquid remains immobilized).

In this nanocomposite the main function of the hydrogel, which is hydrophilic, is absorbing water from the external environment and storing it in its interstices. In this aqueous environment, the drug molecules disperse due to the physical diffusion process until they cross the pores of the hydrogel and exit into the external environment, in this case the human body if the material were being used to release drugs into real patients.

clay hydrogelThe main novelty of the material is the use of clay, which is impermeable, to control how the drug is released. In fact, in the material developed by the São Paulo team, the nanometric clay lamellae acted as a physical barrier to the passage of the molecules of water and drug.

As shown in the image below, the lamella set formed a real labyrinth that slowed the movement of these molecules, determining a specific rhythm to water absorption and the release of diclofenac sodium.

“The main contribution of this work was to develop a barrier system based on an organic-inorganic hybrid material containing polymer-clay for the fine control of the diclofenac sodium release,” says Eduardo Ferreira Molina, corresponding author of an article on the subject, recently published in the journal ACS Applied Materials & Interfaces. Molina is currently a professor at the University of Franca (SP).

In the work reported in this journal, the authors prepared a series of samples of the nanocomposite using different proportions of montmorillonite clay, as well as samples of the clayless hydrogel. The scientists used different characterization techniques to analyze the structure of the nanocomposites and their phases (hydrogel and clay) and also to study water absorption and release of the drug in the material. The team was able thus to verify that the presence of the clay was essential to control the way the drug was released. By adjusting the clay percentage used in nanocomposite preparation, the researchers were able to prevent the early release of a large dose of sodium diclofenac (a common problem in drug delivery systems). They also succeeded in releasing it slowly and at a steady and predictable rate.

The results of this work may constitute a first step towards the use of this nanocomposite as a drug release system for prolonged treatments of arthritis, migraine, postoperative pain and etc. With a system like this, medication could be released gradually at the most appropriate doses and rates, keeping the ideal concentration of the drug in the bloodstream.

Celso R. N. Jesus (left), first author of the paper and Eduardo F. Molina, corresponding author.
Celso R. N. Jesus (left), first author of the paper and Eduardo F. Molina, corresponding author.

The work, which received funding from the Brazilian federal agencies CAPES and CNPq and the São Paulo State agency FAPESP, was carried out at the Chemistry Institute of UNESP, in the city of Araraquara, with the exception of small-angle X-ray scattering (SAXS) measurements, performed at the Brazilian Synchrotron Light Laboratory (LNLS), in the city of Campinas.

The research was developed between 2010 and 2014 in the doctorate in Chemistry of Celso Ricardo Nogueira Jesus, under the supervision of Professor Celso Valentim Santilli (UNESP) and Professor Sandra Helena Pulcinelli (UNESP). The idea, previously unpublished, of developing these nanocomposites to function as barriers to controlled drug release arose at the beginning of the doctoral research of Nogueira Jesus. The theme brought together themes developed in two other postgraduate works. On the one hand, Eduardo Molina’s doctoral research, guided by Professor Santilli, on siloxane-polyether for controlled release of drugs. In 2010, this work was in the final phase. And on the other hand, Márcia Hikosaka’s master’s work, guided by Professor Pulcinelli and completed a few years ago, on the preparation of nanocomposites with polymers and montmorillonite clay.

B-MRS members named editors of international scientific journals.


Prof. Novais de Oliveira Jr (left), associate editor of ACS Appl. Mater. Interfaces with editor-in -chief Prof. Schanze at XVI B-MRS Meeting.
Prof. Novais de Oliveira Jr (left), associate editor of ACS Appl. Mater. Interfaces with editor-in -chief Prof. Schanze at XVI B-MRS Meeting.

B-MRS President Osvaldo Novais de Oliveira Junior is the newest associate editor of ACS Applied Materials and Interfaces, an ACS Publications journal with an impact factor of 7,504. The full professor of IFSC – USP (Institute of Physics of São Carlos of the University of São Paulo) assumed this post in early September. At B-MRS, Oliveira Junior has been administrative director and counselor, and has been chairing the society since early 2016.

The Solar Energy journal (impact factor 4,018) also recently incorporated a member of B-MRS among its editors, Carlos Frederico de Oliveira Graeff, full professor and pro-rector of research at Unesp (Universidade Estadual Paulista Júlio de Mesquita Filho). Graeff was named associate editor in the area of Photovoltaics in this periodical of the publisher Elsevier. A member of B-MRS since its beginning, Graeff was scientific director of the society and served on the scientific committee of the B-MRS Newsletter.

Finally, Carlos José Leopoldo Constantino, also a professor at Unesp and a member of the B-MRS community, took over as Associate Editor in the Nanomaterials area of the Journal of Nanoscience and Nanotechnology (Impact Factor 1,483) from American Scientific Publishers.

Prof. Graeff (left) and Constantino, associate editors of international journals.
Prof. Graeff (left) and Constantino, associate editors of international journals.

Interview with Prof. Kirk Schanze (UTSA, USA), editor-in-chief of ACS Applied Materials & Interfaces.


Kirk Schanze
Kirk Schanze

In the research group of Professor Kirk Schanze, conjugated polyelectrolytes (CPEs) have been the subject of both fundamental studies and applications. The group has already explore CPEs as fluorescent sensors, in solar cells and as biocidal materials.

On September 13, in Gramado, Kirk Schanze, who is a Professor at the University of Texas at San Antonio (UTSA) and editor-in-chief of ACS Applied Materials & Interfaces, will take some time out of his busy schedule to deliver a plenary lecture on CPEs in the XVI B-MRS Meeting.

Schanze graduated in Chemistry from Florida State University in 1979. Four years later, he earned his Ph.D., also in Chemistry, from the University of North Carolina at Chapel Hill. Soon after, he was appointed a Miller Postdoctoral Fellow at the University of California, Berkeley. In 1986, he joined the University of Florida (UF) as a professor of the Department of Chemistry. There, he chaired the Division of Organic Chemistry, held the Prominski Chair of Chemistry, and founded the Schanze Group, which today continues its research activities at UTSA. In 2016, Schanze left UF to hold the Robert A. Welch Distinguished University Chair in Chemistry at UTSA.

Between 2000 and 2008, Schanze served as senior editor of the prestigious journal Langmuir. Shortly thereafter, he became the first editor-in-chief of ACS Applied Materials & Interfaces, which had just been released.

Prof. Schanze has authored about 300 papers and 20 patents. According to Google Scholar, his scientific production has more than 16,000 citations and his h index is 71. He is fellow of the American Chemical Society (ACS). He was a visiting professor at the Harbin Institute of Technology (China) and the Tokyo Metropolitan University (Japan) in 2011, at the Ecole Normale Supérieure Cachan (France) in 2008 and at the Chemical Research Promotion Center (Taiwan) in 2007. He has received distinctions from the American Chemical Society, National Science Foundation, University of Florida, Japan Society for Promotion of Science, and Japanese Photochemical Association, among other entities.

Here follows an interview with the scientist.

B-MRS newsletter: – In your opinion, what are your main scientific and/ or technological contributions to the field of conjugated polyelectrolytes? Describe them briefly and feel free to share a few references of your papers, patents or books.

Kirk Schanze: – We were among the first groups to study conjugated polyelectrolytes, which are water soluble conjugated polymers.  Following are some of the key contributions from our group to this field:

a) Our lab was the first to report the synthesis of a water soluble, fluorescent poly(phenylene ethynylene) sulfonate (PPE-SO3) and describe the application to fluorescence sensing of ions in water at ultralow concentration.[1]

b) We were the first to report the use of a fluorescent conjugated polyelectrolyte as a sensor for enzyme activity, which is an important biosensing application.[2]

c) Our lab has developed the applications of cationic conjugated polyelectrolytes to sensing phosphatase enzyme activity. These enzymes are important in a number of biologically significant processes. [3,4]

d) Working in collaboration with Prof. David Whitten of the University of New Mexico, we have developed cationic conjugated polyelectrolytes as a novel class of antibacterial agents.[5,6]

References:

[1] C. Tan, M. R. Pinto and K. S. Schanze, “Photophysics, Aggregation and Amplified Quenching of a Water-Soluble poly(Phenylene ethynylene)”, Chem. Commun. 2002, 446-447, 10.1039/B109630C.

[2] M. R. Pinto and K. S. Schanze, “Amplified Fluorescence Sensing of Protease Activity with Conjugated Polyelectrolytes”, Proc. Nat. Acad. Sci. USA, 2004, 101, 7505, 10.1073/pnas.0402280101.

[3] Zhao, X.; Liu, Y.; Schanze, K. S., “A Conjugated Polyelectrolyte Based Fluorescence Sensor for Pyrophosphate”, Chem. Commun. 2007, 2914-2916, 10.1039/b706629e.

[4] Zhao, X. Y.; Schanze, K. S., “Fluorescent Ratiometric Sensing of Pyrophosphate via Induced Aggregation of a Conjugated Polyelectrolyte”, Chem. Commun. 2010, 46, 6075-6077, 10.1039/c0cc01332c.

[5] Ji, E.; Corbitt, T. S.; Parthasarathy, A.; Schanze, K. S.; Whitten, D. G., “Light and Dark-Activated Biocidal Activity of Conjugated Polyelectrolytes”, ACS Appl. Mater. Interfaces 2011, 3, 2820-2829, 10.1021/am200644g.

[6] 299. Huang, Y.; Pappas, H. C.; Zhang, L.; Wang, S.; Cai, R.; Tan, W.; Wang, S.; Whitten, D. G.; Schanze, K. S., “Selective Imaging and Inactivation of Bacteria over Mammalian Cells by Imidazolium Substituted Polythiophene”, Chem. Mater. 2017, 2017, 29, 6389–6395, 10.1021/acs.chemmater.7b01796.

B-MRS Newsletter: – You have been the Editor-in-Chief of ACS Applied Materials & Interfaces since its release, haven´t you? In less than 10 years, the journal hit an impact factor of 7,504. To what factors do you attribute this good result?

Kirk Schanze: – ACS Applied Materials & Interfaces (AMI) publishes papers that come from a currently very active area of materials research, specifically applied materials/interfaces.  There is a large community of scientists and engineers around the globe who are working in this field.  AMI has a global community of editors and editorial board members who represent their regions.  Indeed, the newest editor who has joined our editorial board is Prof. Osvaldo Oliveira Jr. of the University of Sao Paulo!

B-MRS Newsletter: – We often see papers from the Brazilian Materials Community at ACS Applied Materials & Interfaces. Could you share with our readers some numbers about the participation of Brazilian authors in the journal?

Kirk Schanze: – ACS Applied Materials & Interfaces has published more than 100 papers with authors or co-authors from Brazil.  Many of these papers have been highly cited in the field of materials science.   Examples of highly cited papers are:

  • K. Poznyak†, J. Tedim†, L. M. Rodrigues†‡, A. N. Salak†, M. L. Zheludkevich*†, L. F. P. Dick‡ and M. G. S. Ferreira†§ Novel Inorganic Host Layered Double Hydroxides Intercalated with Guest Organic Inhibitors for Anticorrosion Applications, ACS Appl. Mater. Interfaces, 2009, 1 (10), pp 2353–2362, DOI: 10.1021/am900495r (co-author from Rio Grande do Sul Federal University in Porto Alegre)
  • Heberton Wender*†, Adriano F. Feil†, Leonardo B. Diaz†, Camila S. Ribeiro‡, Guilherme J. Machado†, Pedro Migowski§, Daniel E. Weibel‡, Jairton Dupont§, and Sérgio R. Teixeira*† Self-Organized TiO2 Nanotube Arrays: Synthesis by Anodization in an Ionic Liquid and Assessment of Photocatalytic Properties, ACS Appl. Mater. Interfaces, 2011, 3 (4), pp 1359–1365, DOI: 10.1021/am200156d

B-MRS Newsletter: – Please, leave an invitation to your plenary talk.

Kirk Schanze: – Everyone is invited to attend my talk which will highlight our work of conjugated polyelectrolyte as applied in the field of energy- and bio- materials chemistry.

More information

On XVI B-MRS Meeting website, click on the photo of Kirk Schanze and see his mini CV and the abstract of his plenary lecture: http://sbpmat.org.br/16controter/home/

ACS Publications will award prizes to the best student contributions of the XVI B-MRS Meeting.


Until August 14, undergratudate and graduate students who are authors of accepted abstracts can apply for the student awards of the XVI B-MRS Meeting. In addition to the traditional “Bernhard Gross Award” from the Brazilian Materials Research Society, this edition of the event will feature awards from the publisher of the American Chemical Society (ACS Publications), responsible for a number of very prestigious peer-reviewed scientific journals in the materials field.

The Bernhard Gross Award was established by SBPMat in honor of the pioneer of Brazilian materials research Bernhard Gross, and it distinguish the best works (up to 1 oral and 1 poster) from each symposium.

Among the winners of the Bernhard Gross Award, the three best posters and the three best oral presentations will receive the “ACS Publications Best Poster Prize” and the “ACS Publications Best Oral Presentation Prize” respectively. The prizes will consist of US $ 500 for each winning work, in addition to the certificate. The ACS awards will be sponsored by the following ACS’s journals: ACS Applied Materials & Interfaces, ACS Nano, Nano Letters, Chemistry of Materials, JACS and ACS Omega.

In order to compete for the prizes, students have to submit through the website of the event, an extended abstract, elaborated according to the template that is available in the instructions for authors.

The papers will be evaluated considering the quality of the extended abstracts and presentations, as well as the scientific contribution of the research work.

The Student Awards Ceremony will take place at the closing of the XVI B-MRS Meeting, on September 14. Prizes will only be given if the winner students are present at the ceremony.

Seis periódicos da ACS patrocinarão os prêmios para  as melhores contribuições de estudantes.
                                       Six ACS journals will sponsor the prizes for the best student contributions.