INSTITUTE OF BIOLOGY, MEDICINAL CHEMISTRY & BIOTECHNOLOGY
 
  Drug Discovery
  Molecular Analysis
  Organic and Organometallic Chemistry
  Medicinal Chemistry
  Synthetic Medicinal Chemistry and Chemical Biology
  Structural Biology & Chemistry
  Molecular Endocrinology
  Signal Mediated Gene Expression
  Molecular & Cellular Ageing
  Biomedical Applications
  Holistic Approaches in Health
  Chemical Carcinogenesis and Genetic Toxicology
  Metabolic Engineering-Bioinformatics
  Biotechnology
  Enzyme and Synthetic Biotechnology
  Biomimetics & Nanobiotechnology
  Conjugated Polymers for Healthcare, Bioelectronics and Bioimaging

 

Conjugated Polymers for Healthcare, Bioelectronics and Bioimaging

The strategic plan of the Laboratory of Conjugated Polymers for Healthcare, Bioelectronics and Bioimaging is the study of conjugated polymers optoelectronic properties for imaging, diagnosis and therapeutic application in order to enhance existing processes and produce innovate new products. The activities of the Laboratory are focusing on the interplay between the science of conjugated polymers and their biological function towards healthcare, bioelectronics and bioimaging applications.

 

Research Team

Dr. Christos Chochos, Associate Researcher

 

Research activities

  • Research activity A. Conjugated polymer nanoparticles for cancer theranostics
  • Research activity B. In vitro and ex vivo monitoring of biological activities with organic photodetectors

 

Research activity A. Conjugated polymer nanoparticles for cancer theranostics

Cancer represents a serious public health concern and, for centuries, has been a leading cause of death around the globe. To improve the clinical outcome and survival rate of cancer patients, regular screening, surveillance programs, and early intervention are widely recognized as the best methods used in cancer diagnosis and therapy. Conventional tumor therapies such as chemotherapy, radiotherapy, and surgery have proved successful, but also cause a variety of serious side effects to cancer patients during treatment. To improve treatment efficacy and reduce side effects, further efforts are now devoted to better identify different cancer therapeutic options that are effective, affordable, and acceptable to patients. Meanwhile, the development of non-invasive imaging technologies and image-guided tumor therapies is indispensable to improve the survival rate of cancer patients.

Conjugated polymer nanoparticles for cancer theranostics

The development of nanoscaled theranostic agents that integrate diagnosis and therapy for effective personalized precision medicine has obtained tremendous attention in the past several decades. By virtue of their real-time diagnostic capability, theranostic platforms can identify the location of a tumor, detect the accumulation of theranostic agents, and monitor the therapeutic response as well as destroy tumors with higher specificity and sensitivity.

Among these emerging techniques, photothermal therapy (PTT) has been developed into a powerful tool for noninvasive cancer theranostics owing to its high selectivity, generally low systemic toxicity, and negligible drug resistance. PTT strongly depends on the use of photothermal agents (PTAs) that provide an efficient conversion from light energy to heat in the thermal ablation of cancer cells and tumors.

Interestingly, PTAs may also serve as contrast agents for the emerging diagnostic technique of photoacoustic (PA) tomography imaging. The latter has been reported as a method obtain functional information of biological tissues with higher resolution, higher contrast, and deeper penetration depth compared to other optical imaging modalities.

Thus, synergistically combining PAI and PTT into one theranostic system has emerged as a powerful tool in cancer treatment owing to its non-invasiveness, deep penetration, high selectivity, and high effectiveness without systemic side effects.

Up to now, the most widely developed PA/PTT agents are inorganic nanomaterials such as noble metal nanomaterials (e.g., Au and Pd), transition metal dichalcogenides (e.g., MoS2, WS2 nanosheets, and CuS2 nanoparticles), and carbon nanomaterials (e.g., graphene and carbon nanotubes). However, a potential concern is that these typical non-biodegradable inorganic nanomaterials could remain in the body for a long period of time, which could lead to potential long-term biotoxicity and significantly hindering potential in vivo applications.

In contrast, compared to inorganic nanomaterials, organic PA/PTT agents represent more promising candidates for pre-clinical or clinical PA/PTT due to the generally favorable biodegradability and biocompatibility characteristics. For example, indocyanine green (ICG), an FDA-approved contrast agent, has been extensively studied in the development of theranostic nanomedicines. ICG has been shown to eliminate the effects of toxicity induced by exogenous probes. Although organic theranostic nanomaterials produced from near-infrared dyes can be produced via encapsulation strategies, they often show disadvantages of unstable nanostructures and insufficient photothermal conversion efficiencies.

Therefore, new biocompatible PA/PTT agents with high photothermal conversion efficiency and good photostability are highly desired.

To date, conjugated polymers as organic π-conjugated macromolecules have been explored as optically and electronically active materials for versatile optoelectronic devices and as nanoprobes for various biomedical applications. Specifically, as a novel category of photonic nanomaterials, π-conjugated polymer nanoparticles, also known as semiconducting polymer nanoparticles (SPNs) have attracted great interest as fluorescent probes for cell tracking, tumor imaging, ultrafast hemodynamic imaging, and chemiluminescence imaging of drug-induced injury and neuroinflammation. This series of applications is most notably due to the excellent properties of high absorption, control dimensions, and good biocompatibility. More importantly, π-conjugated polymer nanoparticles exhibit a high photothermal conversion efficiency, responsible for converting light energy to thermal energy and heat deposition in tumors, ultimately allowing for PTT. Meanwhile, π-conjugated polymer nanoparticles exhibit an extraordinary ability to convert light energy into acoustics. Therefore, they may also serve as a flexible nanoplatforms for in vivo PA of tumors by responsive to reactive oxygen species (ROS), enzyme, and pH.

In collaboration with German Cancer Research Center (DKFZ)
Supported by the following selected research grants
:

  • “Strategic Relationship between the DKFZ/NCT Heidelberg and the Athens Comprehensive Cancer Center (ACCC) in Athens, Greece for Individualized Cancer Medicine” Helmholtz Association. Funding: 1.500.000Euros (2017-2019) PI. V. G. Gregoriou (Collaborator C. L. Chochos)

  • “Materials for Energy Applications and Creating of a Comprehensive Cancer Research Center in the City of Athens” GSRT-SIEMENS Program. Funding: 1.000.000Euros (2015-2017) PI. V. G. Gregoriou (Collaborator C. L. Chochos)

 

Research activity B. In vitro and ex vivo monitoring of biological activities with organic photodetectors

a) Development of conjugated polymers for the fabrication of efficient organic photodetectors (OPDs) and their applicability in the detection of weak fluorescent biological signals involved in studies of cellular activity function.
This is achieved by manifested the OPDs sensitivity and temporal resolution in the measurement of calcium signals from chemical fluorophores (Fluo-4) and genetically encoded calcium indicators (GECI) associated to changes in intracellular calcium concentration in physiological and pathophysiological conditions in-vitro and ex-vivo for the first time.

b) Integration of OPDs in miniaturized implantable device designs made of flexible mechanical properties for targeting specific brain regions. Detection of optical events in specific areas, from a population to individual cells, will improve our understanding of metabolic and physiological activities, as well as disease progression in vivo.

 

MAJOR achievements

In collaboration with Dr. Vasilis Gregoriou (President of NHRF and Director of Research), we have recently completed the establishment of a new research infrastructure at NHRF in the framework of the national project “SIEMENS” of the GSRT [Materials for Energy Applications and Establishment of Athens Comprehensive Cancer Center (ACCC)]. This newly developed infrastructure is consisting of:

  • an organic synthesis laboratory (traditional organic synthesis, microwave synthesis, pumps, rotary evaporator, balance, stirrer, heaters, etc.)
  • a bioimaging suite (including a Field Emission high resolution scanning electron microscope (SEM) and a micro-RAMAN spectrometer)
  • a materials analysis suite (including a preparative gel permeation chromatography and an automated chromatography column for the analysis of the molecular characteristics of the polymers, a potensiostat for the electrochemical characterization).

 

 

 

 

 

 

 
 

 

   
       

 

 

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