Periodic Reporting for period 1 - APSIM (Artificial Photosynthetic Stomatocyte for Intelligent Movement)
Periodo di rendicontazione: 2020-10-01 al 2022-09-30
The discovery of the first centimeter-sized chemical motors has brought great interest in the field of catalytic micro/nanomotors fabrication. By harnessing chemical energy from active fuels, nanomotors with the long-range and sustainable movement have been achieved, promising their biomedical application. Nevertheless, despite the progress, two major problems are still prevalent for traditional nanomotors: 1) the potential side effect of active fuels in biomedical applications, and 2) limited motion control due to the interference of Brownian motion. By keeping these challenges in mind, our ultimate goal was to exploit artificial photosynthetic reactions to drive the motion of stomatocyte nanomotor, which has not been explored before. Using biocompatible chemicals and abundant solar energy to drive the motion will enable a nanomachine that can perform tasks at the nanometer scale. Our design is immobilizing water oxidation catalyst and water-reduction catalyst on the inner stomach and outer surface of the stomatocyte, respectively. The organometallic complex is attached to the surface of the stomatocyte to connect the two half-reactions for motion.
The main objectives of this project were divided into three steps, which correspond to respective work packages (WPs). The following are the brief objectives of the project.
• Objective 1: Drive translational motion to control the speed of stomatocyte nanomotor by PS II catalyzed water-oxidation (WP1).
• Objective 2: Drive rotational motion to control the direction of stomatocyte nanomotor by GQD-catalyzed water-reduction (WP2).
• Objective 3: Couple the translational and rotational motion to drive intelligent movement of stomatocyte nanomotor by artificial photosynthetic water splitting (WP3).
We envision, the as-fabricated nanomotors driven by biocompatible chemicals and abundant solar energy, to be optimized as carriers for cargo delivery and as nanoreactors for solar energy conversion. Moreover, the results of this project challenged the hydrophilic understanding of polyethylene glycol (PEG), one of the most widely used polymers in the biomedical field. This allowed 1) the adaptive loading of molecular probes onto the nanomotors for cargo delivery, and 2) the efficient loading of molecular catalysts and photosensitizer for next-generation photosynthetic nanomotors. These results will benefit society with a great impact on the biomedical field and renewable energy conversion in the future.
The main objectives of this project were divided into three steps, which correspond to respective work packages (WPs). The following are the brief objectives of the project.
• Objective 1: Drive translational motion to control the speed of stomatocyte nanomotor by PS II catalyzed water-oxidation (WP1).
• Objective 2: Drive rotational motion to control the direction of stomatocyte nanomotor by GQD-catalyzed water-reduction (WP2).
• Objective 3: Couple the translational and rotational motion to drive intelligent movement of stomatocyte nanomotor by artificial photosynthetic water splitting (WP3).
We envision, the as-fabricated nanomotors driven by biocompatible chemicals and abundant solar energy, to be optimized as carriers for cargo delivery and as nanoreactors for solar energy conversion. Moreover, the results of this project challenged the hydrophilic understanding of polyethylene glycol (PEG), one of the most widely used polymers in the biomedical field. This allowed 1) the adaptive loading of molecular probes onto the nanomotors for cargo delivery, and 2) the efficient loading of molecular catalysts and photosensitizer for next-generation photosynthetic nanomotors. These results will benefit society with a great impact on the biomedical field and renewable energy conversion in the future.
During the fellowship, objective 1 was met without deviation, and objective 2 was slightly changed by using nicotinamide adenine dinucleotide (NAD+), an important cofactor in cells, as the electron acceptor for biomedical application of nanomotor in the future. Due to the influence of positively charged osmium complex (Os) on the self-assembly of block-copolymer, we developed a post-functionalization method to attach Os onto the nanomotors. In brief, for all the objectives, functionalized block copolymers were synthesized and assembled into a stomatocyte structure.
For objective 1 (WP1), PS II enriched thylakoid membrane fragments (PSII-BBY) were successfully extracted from spinach and encapsulated into the stomatocyte during the shape transforming of polymersome, and visible light (680 nm) was used to drive the water-oxidation reaction catalyzed by PS II for translational motion.
For objective 2 (WP2), nitrogen-doped graphitic carbon dots and amorphous carbon dots were prepared and immobilized onto stomatocyte, and visible light (450 nm) was used to drive the reduction of NAD+ catalyzed by co-immobilized rhodium complex (Rh) for directional movement. To study the rotation, we successfully engineered polymersomes into different shapes, including nanorods, discs, rod-modified stomatocytes, etc.
For objective 3 (WP3), a molecular probe comprising Os as the functional module, pyrene as the anchor, and PEG as the spacer is synthesized. By harnessing the non-covalent interaction between pyrene and PEG corona of the nanomotors, Os is efficiently loaded onto the surface of the nanomotors. The length of the PEG spacer is manipulated to optimize the electron transfer between reduction and oxidation reactions.
The results from WP3 are published by Nature Chemistry. The results from WP2 are in preparation. The results from WP1 and WP3 are in preparation. In terms of collaborative work, I was able to publish a preprint version of our research work on nanomotors with programmable positive and negative chemotaxis as the third author paper, and one paper was submitted to Nature Materials as the third author. All the publications resulting from this fellowship include references to the EU funding.
In terms of exploitation and dissemination, we built international collaboration with Prof. Dr. Michael L. Klein (National Academy of Sciences) and Prof. Dr. Vincenzo Carnevale from Temple University on understanding the loading mechanism of Os complex by molecular dynamics simulation. We built a collaboration with the Electron Microscopy Center of Utrecht University on characterizing the nanomotors. Apart from this, the results were also disseminated in conferences of sIMMposium, NWO CHAINS, and FMS Annual meeting. The results were also disseminated in “Supramolecular and Systems Chemistry Course” at Nijmegen by the supervisor.
In terms of outreach activities, I joined the ‘open house’ organized by the Faculty of Science, Radboud University. Presentation, demo experiment, and Lab tour were given to communicate the project results and research activities of the host with a general audience, including primary school students. Moreover, a website (http://apsimproject.com/(si apre in una nuova finestra)) and YouTube channels are built to communicate project activities to different audiences. The project results are also communicated with the Twitter accounts of the departments.
For objective 1 (WP1), PS II enriched thylakoid membrane fragments (PSII-BBY) were successfully extracted from spinach and encapsulated into the stomatocyte during the shape transforming of polymersome, and visible light (680 nm) was used to drive the water-oxidation reaction catalyzed by PS II for translational motion.
For objective 2 (WP2), nitrogen-doped graphitic carbon dots and amorphous carbon dots were prepared and immobilized onto stomatocyte, and visible light (450 nm) was used to drive the reduction of NAD+ catalyzed by co-immobilized rhodium complex (Rh) for directional movement. To study the rotation, we successfully engineered polymersomes into different shapes, including nanorods, discs, rod-modified stomatocytes, etc.
For objective 3 (WP3), a molecular probe comprising Os as the functional module, pyrene as the anchor, and PEG as the spacer is synthesized. By harnessing the non-covalent interaction between pyrene and PEG corona of the nanomotors, Os is efficiently loaded onto the surface of the nanomotors. The length of the PEG spacer is manipulated to optimize the electron transfer between reduction and oxidation reactions.
The results from WP3 are published by Nature Chemistry. The results from WP2 are in preparation. The results from WP1 and WP3 are in preparation. In terms of collaborative work, I was able to publish a preprint version of our research work on nanomotors with programmable positive and negative chemotaxis as the third author paper, and one paper was submitted to Nature Materials as the third author. All the publications resulting from this fellowship include references to the EU funding.
In terms of exploitation and dissemination, we built international collaboration with Prof. Dr. Michael L. Klein (National Academy of Sciences) and Prof. Dr. Vincenzo Carnevale from Temple University on understanding the loading mechanism of Os complex by molecular dynamics simulation. We built a collaboration with the Electron Microscopy Center of Utrecht University on characterizing the nanomotors. Apart from this, the results were also disseminated in conferences of sIMMposium, NWO CHAINS, and FMS Annual meeting. The results were also disseminated in “Supramolecular and Systems Chemistry Course” at Nijmegen by the supervisor.
In terms of outreach activities, I joined the ‘open house’ organized by the Faculty of Science, Radboud University. Presentation, demo experiment, and Lab tour were given to communicate the project results and research activities of the host with a general audience, including primary school students. Moreover, a website (http://apsimproject.com/(si apre in una nuova finestra)) and YouTube channels are built to communicate project activities to different audiences. The project results are also communicated with the Twitter accounts of the departments.
During the implementation of the project, we developed a new surface functionalization method inspired by a serendipitous discovery during our experiment which led to the realization of the dual nature phenomena of the PEG layer. This helped us to efficiently attach Os onto the stomacotyte to connect two half-reactions. As compared with traditional covalent and non-covalent binding, the new surface functionalization strategy has the following advantages: (i) one step in water; (ii) short functionalization time (2 minutes); (iii) spatial-temporal selective loading; and (iv) precise orientation control. The unexpected results have the following potential impact: 1) PEG, one of the most widely used polymers in the biomedical field, can potentially be used to load hydrophobic cargo molecules, which will build the new designing principle of drug carriers, 2) molecular catalyst and photosensitizer can be loaded onto stomatocyte for the second generation photosynthetic nanomotors, 3) we challenged the “stealth” nature belief of the PEG corona which is used in many biomedical applications and demonstrate that by design we can engineer the corona of the particles to be responsive under specific conditions. This can lead to the design of better carriers in the future as well as an understanding of the behavior of this system in complex environments.