Cultivating Eco-Friendly Nanomaterials: Mimosa Pudica-Enhanced Zinc Oxide Nanoparticles for Enhanced Health and Environmental Well-being

In this work, we report the development of ZnO NPs by using environmentally friendly SCS using Mimosa pudica (MP) leaves. The obtained ZnO-MP-NPs were subjected to extensive characterization techniques such as PXRD, BET, SEM, & TEM. Further, ZnO-MP-NPs were evaluated for their antioxidant ability by DPPH method. Their anticancer capability was assessed by MTT assay on human breast cancer cell ine MCF-7. The results indicated the potential applications of ZnO-MP-NPs both as antioxidant and anticancer agents.


Introduction
Due to their numerous uses in a variety of fields, such as environmental remediation, biology, and materials research, NPs have gained significant attention [1,2].Several NPs have been developed and studied extensively for their innumerable applications.Among various NPs, ZnO NPs find various applications in cosmetics [3,4], antimicrobials [5][6], food packaging [7], conductive coatings [8], sensors [9], catalysis [10], photovoltaics [11,12], anticarcinogenic [13][14][15], anti-tubercular agent [16], drug delivery [16], biomedical imaging [17], water purification [18], energy storage [19], antifouling coatings [20] etc.The conventional methods employed for ZnO-MP-NPs synthesis often entail the use of chemical precursors and energyintensive high-temperature processes, raising concerns about their adverse environmental impact.As environmental consciousness grows, there is an urgent need to explore sustainable and eco-friendly approaches for the synthesis of advanced nanomaterials.Using biologically produced materials as environmentally benign substitutes in nanoparticle synthesis is one possible way to address these environmental issues.Studies show that plant extracts as a powerful option in the synthesis of NPs [13][14][15].This study focuses on the synthesis of ZnO-MP-NPs using an environmentally friendly solution combustion method, where the aqueous extract of M. pudica leaves serves as a biofuel.The choice of M. pudica leaves for this purpose is particularly intriguing, as this plant extract is recognized for its abundant phytochemical constituents, which may contribute to the synthesis and stabilization of NPs [13][14][15].

With this background the research undertaken highlights the development of ZnO-MP-NPs
and their characterization by PXRD, SEM, TEM, and BET.We also explored the potential application of the synthesized ZnO-MP-NPs as an an antioxidant agant by DPPH assay .
Further, the developed NPs were also evaluated for their anti-carcinogenic potential on MCF-

Chemicals and reagents
This investigation used only analytical-grade chemicals and reagents, all of which were used without further purification.The leaves came from the Sir MVIT campus of our institute, which is located in Hunasamaranahalli, Bengaluru.Following a thorough washing in copious amounts of water, they were allowed to air-dry for three weeks.

Preparation of aqueous extract from M. pudica leaves
To obtain the aqueous extract from M. pudica leaves, fifteen grams of desiccated foliage were subjected to a Soxhlet extraction process, employing 125 mL of distilled water as the extracting solvent.The extraction process took place over the course of 72 hours.

ZnO-MP-NPs synthesis by green technique
The synthesis of ZnO-MP-NPs was performed following a protocol documented in prior studies [13][14][15].Initially, 2 g of Zn(NO3)2•6H2O was successfully dissolved in 10 mL of distilled water.Subsequently, 6 milliliters of a leaf extract were The ensuing blend underwent comprehensive agitation using a magnetic stirrer.It was later kept into a muffle furnace, where it was subjected to a controlled temperature of 375±10°C.The solution underwent a dehydration, got converted into gel that lead into the formation of finely powdered ZnO-MP-NPs.

Characterization
. A detailed qualitative phytochemical analysis of the aqueous plant leaf extract was conducted, adopting established methods [21][22][23], with the goal of identifying components related to combustion.The structural properties of the ZnO-MP-NPs were evaluated through PXRD, employing a PANalytical IX'pert diffractometer with Cu Kα radiation (λ=1.5418Å).
Morphology was examined using a Carl Zeiss Ultra 55 microscope with a silver coating for SEM.Particle shape and size were determined using a Philips 200 TEM.The Quantachrome ASiQwin instrument was utilized to quantify the surface area.

Assessment of anticarcinogenic potential using MTT assay
To evaluate the effectiveness of ZnO-MP-NPs in combating cancer, MTT assay was employed, a method previously described in our earlier research [13-15, 24, 25].To assess cell viability, the absorbance at 590 nm was determined using a microplate reader.The percentage of inhibition was then calculated as per the following formula: [Absorbance of test sample-Absorbance of control] × 100 Absorbance of control

Assessment of antioxidant activity using the DPPH assay
To evaluate the antioxidant potential of ZnO-MP-NPs standard DPPH method was followed with few changes [26].To calculate the DPPH scavenging activity, following formula was used: DPPH scavenging activity (%) = [1 -(As/Ac)] × 100, where As represents the intensity of peaks at 517 nm for the DPPH solution after the reaction, and Ac denotes the intensity of peaks for the control.

Crystallography
In Figure 1, the PXRD pattern from ZnO-MP-NPs reveals a distinct broadening of XRD peaks, indicating the formation of NPs.The diffraction peaks were definitively recognized as indicative of the hexagonal Wurtzite phase of ZnO, aligning with the ICDD card No. 80-0074.
To estimate the ZnO-MP-NPs' crystallite diameter, the Debye-Scherrer formula [27] was employed, with =0.89/cos........ (1), where 0.89 represents Scherrer's constant,  is the Xray wavelength,  is the Bragg diffraction angle, and  is the FWHM of the diffraction peak corresponding to the ⟨101⟩ plane.Calculations based on this formula determined the average crystallite size of the sample to be in the 26 nm range.indicates that the ZnO-MP-NPs have a comparatively large surface area, an important characteristic to comprehend their possible uses.These nanoparticles are advantageous for a variety of applications due to their high surface area, which suggests that they provide a significant area for interactions with other materials.The BET finding highlights how promising these ZnO-MP-NPs are in a variety of scientific and industrial applications where having a large surface area is useful.

Anticarcinogenic activity
The data in Figure 4 illustrates the cytotoxic effects of ZnO-MP-NPs on the MCF-7 cell line.
To ascertain the IC50 value, indicating the concentration of ZnO-MP-NPs needed to hinder cell growth by 50%, we utilized nonlinear regression analysis, employing a sigmoid dose-response curve model.The IC50 for the MCF-7 cell line was determined to be 78.81µg/mL (Figure 3).Literature indicates that ZnO-NPs induce cytotoxicity in a manner that is cellspecific and dependent on the rate of cell proliferation, with rapidly dividing cancer cells being more susceptible, and quiescent cells being less sensitive [29,30].Nevertheless, the precise mechanism underlying the induction of apoptosis in cancer cells by ZnO-MP-NPs remains an area of ongoing investigation, and additional investigation is needed to elucidate this mechanism further.

Radical scavenging activity
The IC50 value for the scavenging activity of ZnO-MP-NPs was obtained via a non-linear regression analysis employing a sigmoidal dose-response curve model.The computation was executed utilizing GraphPad Prism 5 software and yielded an IC50 value of 140.5 μg/mL (as presented in Figure 5).The antioxidative potential of ZnO-MP-NPs could be attributed to the transfer of electron density from oxygen to the unpaired electron at the nitrogen atom in DPPH, resulting in a reduction in the intensity of the n → π* transition [31].