Optoelektronik nöral arayüzleri için yeni biyouyumlu kuantum noktaları ve nanoteknolojik birleşimler

Colloidal semiconductor quantum dots offer high potency in the realm of targetable and remotely addressable biointerfaces due to their low-cost solution-processability, wide spectral tunability and high photostability. But most popular and well-studied quantum dots contain cadmium and lead, which are known to be highly toxic and carcinogenic for biomedical applications. For that reason, the search for appropriate biocompatible quantum dots and their utilization is an important challenge in the development of quantum dot based bioelectronic devices. This thesis addresses efficient neural interfaces based on nanoengineered assemblies of novel and biocompatible quantum dots. In the first part of the thesis, we synthesized type-II indium phosphide/zinc oxide core/shell quantum dots for the first time. These quantum dots were incorporated into photoelectrode structure and induced bioelectrical current that triggered the firing of a single neural cell at 4 μW mm−2, 26-fold lower than the ocular safety limit for continuous exposure to visible light. Next, we inspired by the nonradiative energy transfer used by photosynthetic systems and developed quantum funnels based on indium-based rainbow quantum dots that are assembled in a graded energy profile. The novel nanoengineered assembly facilitated optical neuromodulation of a single cell and enhanced bioelectric current 215% per unit absorbance in comparison with the control sample. In the second part of the thesis, we reported colloidal aluminum antimonide quantum dots for the first time. The synthesis was performed via controlled reaction of aluminum chloride and antimony bis(trimethylsilyl)amide in the presence of superhydride. These quantum dots showed excitonic transitions in the UV-A region and tunable band-edge emission in the blue spectral range (quantum yield of up to 18%). Among all III-V quantum dots, aluminum antimonide quantum dots showed the brightest core emission in the blue spectral region. Finally, we used aluminum antimonide quantum dots as biointerfacing layer in a photovoltaic device for neural stimulation. This type of neural interface generated capacitive bioelectrical current with a rise time of ~55 μs and with a magnitude over 600 μA.cm-2, pointing out the most sensitive quantum dot based capacitive biointerface. This biointerface did not exhibit any toxic effect on the cells and demonstrated operational lifetime of one year in aqueous environment. These findings show that novel cadmium-free quantum dots can induce a biocompatible and effective biological junction and introduce a new route in the use of quantum dots in optoelectronic device architectures for light-triggered bioelectrical devices for applications such as artificial retinal prostheses.