Application of Nanoparticle Antioxidants to Enable Hyperstable Chloroplasts for Solar Energy Harvesting

Abstract

The chloroplast contains densely stacked arrays of light‐harvesting proteins that harness solar energy with theoretical maximum glucose conversion efficiencies approaching 12%. Few studies have explored isolated chloroplasts as a renewable, abundant, and low cost source for solar energy harvesting. One impediment is that photoactive proteins within the chloroplast become photodamaged due to reactive oxygen species (ROS) generation. In vivo, chloroplasts reduce photodegradation by applying a self‐repair cycle that dynamically replaces photodamaged components; outside the cell, ROS‐induced photodegradation contributes to limited chloroplast stability. The incorporation of chloroplasts into synthetic, light‐harvesting devices will require regenerative ROS scavenging mechanisms to prolong photoactivity. Herein, we study ROS generation within isolated chloroplasts extracted from Spinacia oleracea directly interfaced with nanoparticle antioxidants, including dextran‐wrapped nanoceria (dNC) previously demonstrated as a potent ROS scavenger. We quantitatively examine the effect of dNC, along with cerium ions, fullerenol, and DNA‐wrapped single‐walled carbon nanotubes (SWCNTs), on the ROS generation of isolated chloroplasts using the oxidative dyes, 2’,7’‐ dichlorodihydrofluorescein diacetate (H2DCF‐DA) and 2,3‐bis(2‐methoxy‐4‐nitro‐5‐sulfophenyl)‐2H‐tetrazolium‐5‐carboxanilide sodium salt (XTT). Electrochemical measurements confirm that chloroplasts processed from free solution can generate power under illumination. We find dNC to be the most effective of these agents for decreasing oxidizing species and superoxide concentrations whilst preserving chloroplast photoactivity at concentrations below 5 μM, offering a promising mechanism for maintaining regenerative chloroplast photoactivity for light‐harvesting applications.

Plant nanobionics approach to augment photosynthesis and biochemical sensing

“…Previous studies demonstrated the potential of dextran-wrapped nanoceria as ROS scavengers for isolated chloroplasts 2 and microalgae 29 despite their inability to move through lipid bilayers and cell walls. According to our uptake mechanism, dextran-wrapped nanoceria do not interact with the chloroplast membrane owing to their neutral zeta potential 30 .…”

“…By capturing atmospheric CO 2 , these plant organelles convert light energy into three major forms of sugars that fuel plant growth: maltose, triose phosphate, and glucose 1 . Whereas photosystems interfaced with nanomaterials are extensively studied, nanoengineering chloroplast photosynthesis for enhancing solar energy harnessing remains unexplored 2 . One major deterrent in using chloroplast photosynthetic power as an alternative energy source is that these organelles are no longer independently living organisms.…”

Lipid Exchange Envelope Penetration (LEEP) of Nanoparticles for Plant Engineering: A Universal Localization Mechanism

“…14 The chloroplast is responsible for CO 2 reduction to valuable and energy rich sugars and sugar precursors and as such has been extensively studied due to the potential to exploit plastome (genetic material of plastids) engineering for biotechnological applications, 15−17 as well as the potential for the chloroplast to serve as an engineering material. 18 Chloroplasts are similar to Gram-negative bacteria and mitochondria in that they are surrounded by two membranes, an outer membrane and an inner membrane. 19 Glycerolipids (galactolipids and sulfolipids) account for 52% of the total lipids in the outer membrane, while the inner membrane contains nearly 85% of glycerolipids such as Monogalactosyldiacylglycerol.…”

Noncovalent Protein and Peptide Functionalization of Single-Walled Carbon Nanotubes for Biodelivery and Optical Sensing Applications

“…SWCNTs have proven to be among the most versatile materials today, enabling a breadth of novel hybrid materials in fields spanning healthcare, 2−4 molecular biology, 5,6 energy, 7,8 and catalysis. 9 A large fraction of this recent research has focused on exploiting intrinsic SWCNT optical properties as a means of signal transduction in bio-optical devices.…”