Green synthesis and characterization of palladium nanoparticles and its conjugates from solanum trilobatum leaf extract

1Reader, Department of Biochemistry, Sathyabama University Dental College and Hospitals, Chennai, India 2Research Scholar, Department of Biotechnology, Sathyabama University, Chennai, India 3Lecturer, Department of Microbiology, Sathyabama University Dental College and Hospitals, Chennai, India *Corresponding author. E-mail: kanchibms@yahoo.co.in; Phone No: 9444158175 Green synthesis and characterization of palladium nanoparticles and its conjugates from solanum trilobatum leaf extract Amarnath Kanchana1,*, Saveetha Devarajan2 and Senniyanallur Rathakrishnan Ayyappan3

In modern nanoscience and nanotechnology the production of nanomaterials with the preferred quality is one of the most stimulating aspects. In addition, nanoparticles refer to nanoscale materials that have an aerodynamic equivalent diameter of 100 nm or less [1] yet, it has been shown that there is a strong tendency with several nanoscale materials sold commercially of agglomerating and therefore existing as much larger micrometer scale particles further complicating studies regarding exposure and effect. An important area of research in nanotechnology deals with the synthesis of metallic nanoparticles of different chemical compositions, sizes and controlled monodispersity [2].
To date, metallic nanoparticles are mostly prepared from nobel metals (ie. Ag, Pt, Au and Pd) [3]. Recently, the advances in fabrication of palladium nanoparticles (PdNPs) have gained great importance owing to their application both in heterogeneous and homogeneous catalysis, their high surfaceto-volume ratio and their high surface energy [4].
Biosynthetic methods employing either biological microorganisms or plant extracts have been suggested as possible ecofriendly alternatives to chemical and physical DOI: 10.5101/nml.v2i3.p169-176 http://www.nmletters.org methods [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. The rate of reduction of metal ions in the method of using plants has been found to be much faster than the method of using micro-organisms and stable. The synthesis of nanoparticles can be carried out by both intracellular and extracellular methods such as leaf broth, sundried leaves, fruits, growing plants on metal-rich soil, gold-rich agar media, etc. and the results obtained were positive in all cases. Extracellular nanoparticle synthesis using plant leaf extracts rather than whole plants would be more economical owing to easier downstream processing.
Biological processes using microorganisms, plants, and plant extracts have been used to synthesize nanoparticles of gold and silver with wide applications in the field of medicine, cancer treatment, drug delivery, commercial appliances, sensors, etc.
There is relatively little knowledge in literatures concerning the biological synthesis of palladium nanoparticles. The only success was the recent findings on the production of PdNPs using coffee and tea extract [20]. It has also been found that the antioxidants such as geniposide, chlorogenic acid, crocins and crocetin were the reducing and stabilizing agents for synthesizing palladium nanoparticles (3 to 5 nm) in water crude extract of Gardenia jasminoides Ellis' [21]. This study appeared to be a new promising biosynthetic nanocatalyst for the development of an industrial process. An extremely simple green approach that generated by Mallikarjuna et al., 2008 [22] in bulk quantities of nanocrystals (2060 nm) of noble metals such as silver (Ag) and palladium (Pd) using coffee and tea extract at room temperature is noteworthy. Currently, however, the exact mechanism for the synthesis of palladium nanoparticles is unclear. Our protocol for the phyto-synthesis of palladium nanoparticles under moderate pH and room temperature offers a new means to develop environmentally benign nanoparticles.
Palladium Lipoic Acid (LAPd) is a formulation used in a prescription version called DNA Reductase and a dietary supplement called Poly MVA. The active ingredient is the palladium-lipoic acid polymer, which exists as a trimer of palladium-lipoic acid joined to thiamine. This arrangement is unique in that it allows the molecule to be both water and lipid soluble, as well as exist as a liquid crystal. This liquid crystalline structure allows it to store a great deal of energy and thus serve as a semiconductor [23][24][25]. "Palladium Lipoic Compounds" a specific class of compounds has become the centre piece of nontoxic cancer therapy in recent research.
It acts by modulating cellular energy helping the human body to build up the immune system and have an energetic life.
Hence Poly-MVA that is a variant of Palladium Lipoic Acid (LAPd) acts as an anti-oxidant supplement and helps us lead a life free from many diseases [26]. Poly-MVA is one of the first available formulations of Palladium Lipoic acid in the market which helps in fighting many diseases such as diabetic neuropathy, retinopathy which causes blindness, controls blood sugar levels in the body; prevent cardiomyopthay and helps in slowing the aging process by normalizing the free radicals in the body [27]. The palladium lipoic complexes in Poly-MVA work in novel ways that do not harm the body as a whole only the cancer cells specifically, partially by converting free radicals into a usable form of energy [28][29].
To the best of our knowledge, there are no reports on the reduction of aqueous palladium chlorate ions from the leaves of The vitamin (Vitamins B1, B2, and B12) was added to the leaf extract containing palladium lipoic acid complex and kept for incubation at room temperature for 24 hours. Then after the incubation period the colour of the leaf extract was changed from yellow to brown colour. The mixture was centrifuged at 4,500 rpm to separate the capped PdNPs. The resulting palldium nanoparticle solution was purified by repeated centrifugation at 15,000 rpm for 20 min, with the pellet produced by this process redispersed in deionized water.

UV-Vis spectroscopic Studies
The

Results and Discussion
The We also made an attempt of conjugating palladium to lipoic acid, a thiol rich molecule which exhibited a dark brown colour than that of unconjugated palladium (see Fig. 1c). Chen et al., 1984 [32] in his study used a shorter chain thiol (C 6  of the medium and surface-adsorbed species [37]. Based on Mie's theory, spherical nanoparticles give rise to a single surface plasmon resonance band in the absorption spectra, whereas anisotropic particles confer two or more surface plasmon resonance bands depending on the shape of the particles [38]. In present investigation, all reaction mixtures show a single surface plasmon resonance band revealing spherical shape of silver nanoparticles, which is addressed through SEM images. The λmax shift in the absorbance spectra observed in Fig respectively. SEM measurements on these particles expelled a spherical shape within the size range of 6070 nm (see Fig. 4a).
6580 nm (see Fig. 4b) and 75100 nm (see Fig. 4c) which can be assigned to bioorganic compounds present in the leaf broth [32]. Such size distribution analysis of capped (PdNPs capped with lipoic acid and vitamins) and non-capped PdNPs confirms that the particles are well dispersed.
The analysis of IR spectra gives an idea about biomolecules bearing different functionalities which are present in underlying system. The FTIR spectra of samples containing PdNPs and its conjugates are illustrated in Fig. 4a- heterocyclic components on to the particle surface in stabilizing the nanoparticles [42]. Therefore it appears more likely that the reduction of palladium ions and stabilization of synthesized palladium nanoparticles is the responsibility of many functional groups, including amines, alcohols, ketones, aldehydes, alkenes and carboxylic acids, that are present in various plant metabolites and reducing sugars.

Conclusion
The rapid biological synthesis of palladium nanoparticles