SMART Discovers Breakthrough Way to Look at the Surface of Nanoparticles

The discovery will enable SMART researchers in precision agriculture to develop new plant sensors for hormones and nanoparticle carriers for gene engineering

Researchers from SMART, MIT’s research enterprise in Singapore, have made a ground-breaking discovery that allows scientists to ‘look’ at the surface density of dispersed nanoparticles. This revolutionary technology enables researchers to ‘characterise’ or understand the properties of nanoparticles without disturbing the nanoparticle, and also at a much lower cost and far quicker too. New method to explore the surface of nanoparticles will accelerate Nano-engineering of materials and can be used to ‘characterise’ nanoparticles with any geometric shape as a universal characterisation technique.

The new process is explained in a paper titled “Measuring the Accessible Surface Area within the Nanoparticle Corona using Molecular Probe Adsorption”, published this month in the prestigious academic journal, Nano Letters. It was led by Michael Strano, co-lead principal investigator of DiSTAP and Carbon P. Dubbs Professor at MIT, and Minkyung Park, Graduate Student at MIT. DiSTAP, the Disruptive & Sustainable Technologies for Agricultural Precision Interdisciplinary Research Group (IRG) is a part of the Singapore-MIT Alliance for Research and Technology (SMART), MIT’s research enterprise in Singapore. DiSTAP IRG develops new technologies to enable Singapore, a city-state which is dependent upon imported food and produce, to improve its agriculture yield to reduce external dependencies.

The Molecular Probe Adsorption (MPA) method is based on non-invasive adsorption of a fluorescent probe on the surface of colloidal nanoparticles in an aqueous phase. Researchers are able to calculate the surface coverage of dispersants on the nanoparticle surface – which are used to make it stable at room temperature – by the physical interaction between the probe and nanoparticle surface. The method is substantially faster and cheaper than existing chemical methods and does not damage the nanoparticle being studied. MPA will also aid researchers across all sectors to push nanoparticle research boundaries and current limits.

“We can now characterise the surface of the nanoparticle through its adsorption of the fluorescent probe. This allows us to understand the surface of the nanoparticle without damaging it, which is, unfortunately, the case with chemical processes widely used today,” said Park. “This new method also uses machines that are readily available in labs today, opening up a new easy method for the scientific community to develop nanoparticles that can help revolutionise different sectors and disciplines.”

The MPA method is also able to characterise a nanoparticle within minutes compared to several hours that the best chemical methods require today. Because it uses only fluorescent light, it is also substantially cheaper.

DiSTAP has started to use this method for nanoparticle sensors in plants and nanocarriers for delivery of molecular cargo into plants.

“We are already using the new MPA method within DiSTAP to aid us in creating sensors and nanocarriers for plants,” said Strano. “It has enabled us to discover and optimise more sensitive sensors, and understand the surface chemistry, which in turn allows for greater precision when monitoring plants. With higher quality data and insight into plant biochemistry, we can ultimately provide optimal nutrient levels or beneficial hormones for healthier plants and higher yields.”

The discovery will enable SMART researchers in

Repeats in genetic patterns triggers autoimmunity in hybrid plants

NUS researchers in Singapore reported that the genes responsible for providing defence responses against powdery mildew (RPW8) in the Arabidopsis thaliana plant, when duplicated as multiple copies in the genome, can misregulate immune receptors to trigger autoimmunity in hybrid plants.

Genomic information from plants can be used to enhance agricultural production and improve food security in a sustainable manner. Through a better understanding of the relationship between a plant’s genetic information and the resulting behaviour, improved crops with better traits (resistance to diseases, tolerance to drought, etc.) can be developed. This can be achieved through cross-pollinating plants with selected traits to produce a hybrid with the desired characteristics.

A research team led by Prof Eunyoung CHAE from the Department of Biological Sciences, NUS has discovered that in selective plant breeding, the genes responsible for providing defence responses against powdery mildew (RPW8) in the Arabidopsis thaliana plant, when duplicated as multiple copies in the genome, can misregulate immune receptors to trigger autoimmunity in hybrid plants. This can cause the premature gradual death of the foliage in these hybrids, known as hybrid necrosis.

The researchers applied a technique known as the genome-wide association mapping study (GWAS) to the model plant Arabidopsis thaliana in this research. GWAS is an important tool to identify genetic variation in plants which are associated with a particular trait. It allows the researchers to identify Single Nucleotide Polymorphisms (SNPs) which mark the causal natural variation in the genome responsible for growth-immunity trade-off. These SNPs are like postal codes showing the genetic information that is associated with autoimmune symptoms in plants. The SNPs were found to be located adjacent to a multi-gene cluster which is known to confer resistance to powdery mildew (a fungal disease that affects a wide range of plants). The team found that having multiple copies of this set of genetic codes (RPW8) in Arabidopsis thaliana is detrimental as it triggers its autoimmunity mechanism even in the absence of pathogens.

Prof Chae said, “The plant Arabidopsis thaliana used in our study belongs to the Brassicaceae family, and the family members include vegetables such as broccoli, kale, cabbage, mustard and bok choy. Our team is currently assessing the variability of the plant immune system, particularly on the powdery mildew resistance gene clusters in this family, and if the variability is associated with heightened resistance and/or trade-off between immunity and growth.”

NUS researchers in Singapore reported that the