Table 1.

Strengths and weaknesses of nanotechnology approaches for chloroplast biotechnology advancements.

Chloroplast nanobiotechnology applications	Strengths	Weaknesses	Areas of improvement
Chemical delivery	Targeted delivery Less runoff into environment Improvement of agrochemical suspensions	Environmental impact of biocompatible nanomaterials for targeted delivery is unknown	Biodegradability studies of targeted nanomaterials Controlled chemical release
Gene delivery	Species independent Gene delivery without specialized equipment In situ gene delivery	Potential limitation of plasmid DNA size per nanoparticle Only transient expression shown Only proof of concept, with GFP expression	Stable plastid genome transformation enabled by nanomaterials Targeted gene delivery to chloroplasts for applied research Inducible expression of exogenous DNA Overcoming the bottleneck of selectable markers
Nanosensors	Real-time monitoring of plant signaling molecules High sensitivity down to single molecule level Do not photobleach Near infrared imaging Species independent	Available for only a few plant signaling molecules to date Most studies performed in laboratory conditions	Targeted sensor delivery to chloroplasts Multiplexed sensing of plant signaling molecules
Photosynthesis	Enhancement of light and carbon reactions of photosynthesis Protecting chloroplast photosynthetic machinery from oxidative stress	Environmental toxicity of some types of nanomaterials used to boost photosynthesis Most studies performed in laboratory conditions	Targeted delivery of nanoparticles to chloroplasts Develop more biocompatible and biodegradable nanomaterials that improve photosynthesis
Biomanufacturing	Use of plants as widely accessible, solar powered manufacturing technology Scalable, low cost manufacturing of biopharmaceuticals and bioplastics in situ	Research and development at very early stage	Proof of concept of turning plants into biomanufacturing devices using nanotechnology