It must be known which trace elements are useful for the plant under experiment so that the same nanoparticles are used to increase the yield. The B. juncea seedlings on treatment with gold nanoparticles in the field (foliar spray) showed changes both in growth and yield of seed [99]. Like CuO nanoparticle in wheat [100], gold nanoparticle was also accumulated in Brassica [99]. The percentage of germination increased when B. juncea seedling were sprayed/inoculated with 25-ppm gold nanoparticles. However, as the concentration of gold nanoparticles LCZ696 increases, the rate of germination is slowed down. The authors have suggested that the antagonistic effect of gold nanoparticles slows

down the effect of ethylene; as a result of which, an increase in the number of leaves of B. juncea occurs. In fact, it is not the antagonism of gold nanoparticles but the complexation of ethylene with gold or adsorption of ethylene on gold nanoparticles. An average 19% increase in the seed of B. juncea was noted after treating the

plant with about 10-ppm gold nanoparticles. However, it is not economically feasible as the cost of gold nanoparticles (10 mg L-1) Selleck JNK-IN-8 sprayed seems greater than the yield of the crop nevertheless; it is an attempt towards a bright future for increased food crop produced with engineered gold nanoparticles. Nickel, platinum and palladium nanoparticles Bali et al. [101] eFT508 cell line have studied the formation of platinum nanoparticles from Pt(II) by M. sativa and B. juncea plant biomass.

The conversion of Pt(II) to metallic platinum was studied in acidic medium between pH 2 and 3. However, such high pH amongst plant kingdom is never achieved. This process can be used to extract metals from clinical disposal sites to prevent recycling in the soil. Generally, the metals in the soil or at mining sites exist in the form of salts rather than a co-reduction compound. The platinum metal concentration in this study showed the accumulation of platinum between 0.77 and 36.83 mg of platinum per gram of dry biomass of Org 27569 M. sativa. Spherical-shaped palladium nanoparticles have also been obtained using peel extract of Annona squamosa [102]. It is a useful study of platinum metal uptake by plants which can be extended to other metal ions of this group of metals, viz. Ni, Pt and Pd. Both the living and dead organisms are equally useful in producing nanosized crystal of metal [103]. Reduction of Pd(II) to elemental palladium has been achieved by formate or hydrogen [104]. Beneficial and adverse effects of metal nanoparticles Nanoparticles of specific size are capable of penetrating and migrating to different regions of plant cells [105]. These nanoparticles can be stopped at certain point or their movement may be accelerated by the use of small magnets provided that the nanoparticle is magnetic in nature as the non-transition metal ions are not attracted towards a magnet.