The size of nanoparticles (NPs) allows them to accumulate in plants, and they affect plant growth by altering the size of leaves and roots and affecting their photosynthetic reactions by altering the composition of proteins in the electron transport chain, chlorophyll biosynthesis, and carbohydrate synthesis reactions. Plants play an important role on Earth as nutrient producers in all trophic food webs by producing oxygen, absorbing carbon dioxide, and synthesizing edible carbohydrates during photosynthesis. In this study, Fe₃O₄ and ZnO NPs at various concentrations (0, 1, 2, and 4mg/l) were used to investigate the effect of NPs on plant morphological parameters and photosynthesis intensity, determining the amount of chlorophyll and the absorption of their light spectrum in common wheat (Triticum aestivum L.). Fe₃O₄ (25nm, 2mg/l, and 4mg/l) and ZnO (32nm, 4mg/l) significantly increased the leaf length of common wheat seedlings. However, Fe₃O₄ NPs (25nm, 1mg/l, and 4mg/l) significantly reduced light absorption at 645 and 663nm and the content of chlorophyll b, chlorophyll a, and total chlorophyll, but Fe₃O₄ (25nm, 2mg/l) significantly reduced the chlorophyll a content. In addition, ZnO NPs (32nm, 1mg/l) significantly increased the chlorophyll b content. This study has made a major contribution to understanding the effect of low concentrations of NPs on plant seedlings. Currently, NPs with high concentrations, starting at 10mg/l, have been analysed in other studies, but in the environment, NPs enter plants in low concentrations as dust or through water droplets. Therefore, it is important to determine the potential impact of small concentrations of NPs on crops that are important for agriculture.

Biological synthesis of nanoparticles (NPs) using alfalfa (Medicago sativa L.) and other plants has several advantages such as lower costs, reduction of pollution, and improvement of the environment and human health. Often, biosynthesis is used to synthesize Ag, Au, and ZnO NPs. Less often are also synthesized Cu and Fe NPs. Synthesis with plant extracts from their parts or callus cultures is a widely used method since extracts contain the most significant number of biomolecules. Synthesis with living plants (in vivo) provides NPs with improved properties for better interactions with plants but is used less often due to the long realization time, the need to control the plants growing conditions, and difficulty in controlling the size and shape of the synthesized NPs. Here, we performed a systematic review of various methods for the biological synthesis of different metal NPs with different plants, to highlight advantages and disadvantages of mentioned methods. For discussion, results showed that biosynthesis of NPs allows obtaining NPs with reduced toxicity, and their size and shape depend on the type and number of biomolecules present in plants. Plant biomolecules determine the antibacterial and anticancer properties of NPs, as well as increasing the use of NPs in biomedicine, for better drug transport, therefore medicinal plants or sea plants are mostly used for biosynthesis. NPs which were synthesized in marine plants could be a very effective agent against water bacteria; therefore, if NP biosynthesis takes place in water, biological water purification is possible. Limitations of the study included a great methodological diversity of the synthesis, it is still difficult to systematize the synthesis methods, and it seems that each described study uses a different synthesis protocol; therefore, in future studies, it is necessary to clarify which method can provide the most efficient biosynthesis and develop a unified approach.

Gold (Au) and silver (Ag) nanoparticles (NPs) are used for drug transport and plant protection due to their insoluble nature and unique properties. To produce health-friendly NPs, toxic solvents should be replaced with plant-based synthesis. Plants, such as alfalfa (Medicago sativa L.), release biomolecules that reduce metal ions and form nanoclusters without free radicals, showing anti-inflammatory and antioxidant properties. In this study, callus cultures of two M. sativa genotypes, ‘Kometa’ and ‘La Bella Campagnola’, were exposed to two precursors (AgNO₃ and HAuCl₄) for 24 and 48 h to assess the feasibility of biological NP synthesis. Spectrophotometry showed significant (p ≤ 0.05) changes in light absorbance compared with the control. Dynamic light scattering and zeta potential measurements indicated a change in the composition of the liquid compared with the control. To improve image quality and obtain more accurate data, transmission electron microscopy (TEM) analysis was repeated, confirming the presence of quasi-spherical nanoparticles with diameters in the range of 5–25 nm for both AuNPs and AgNPs in the callus culture extracts of both genotypes. Nanoparticle Tracking Analysis demonstrated that the AgNPs and AuNPs from both genotypes displayed polydisperse size distributions, with a mean particle size ranging from 220 to 243 nm. Elemental analysis provided clear evidence that Ag and Au were present only in treated samples, confirming effective NP biosynthesis and excluding contamination. X-ray diffraction (XRD) analysis was performed to characterise the crystalline structure; however, due to the very small particle size (5–25 nm), no clear diffraction patterns could be obtained, as nanocrystals below ~20–30 nm typically produce signals below the detection limit of standard XRD instrumentation. The novelty of this research is the cost-effective, rapid biosynthesis of quasi-spherical AuNPs and AgNPs with diverse sizes and enhanced properties, making them more eco-friendly, less toxic, and suitable for antibacterial and anticancer studies.

The nano size as well as physical and chemical properties of Au and Ag nanoparticles (NPs) allow them to be used in medicine or plant protection, but chemical solvents used during synthesis makes them toxic and pose a threat to the environment. Chemical NP synthesis can be replaced by in vivo synthesis in which independently growing plants such as alfalfa take up and then split the precursor in their cells down to nano size using synthesis-promoting solvent-biomolecules, which can break down materials without free radicals and have anti-inflammatory, antioxidant effects, making NPs environmentally benign. In this study, two-week-old seedlings of two Medicago sativa L. genotypes, ‘Kometa’ and ‘la Bella’, were exposed to two precursors (AgNO₃, HAuCl₄) for 24 and 48 h to determine whether in vivo synthesis is possible. Two-beam and certain wavelength spectrophotometry and confocal microscopy confirmed statistically significant (p < 0.05) changes in light absorption and light fluorescence compared to the control. Confocal microscopy showed both precursors visible in the roots of both genotypes. Currently, NP synthesis and visualisation methods require a complex, expensive, and time-consuming sequence of methods. It is important to find an effective, environmentally friendly, and as cheap and simple as possible method for the biosynthesis of NPs.

The nano size, physical and chemical properties of Au and Ag nanoparticles (NPs) allow them to be used in medicine or plant protection, but chemical solvents used during synthesis makes them toxic and pose a threat to the environment. Chemical NPs synthesis can be replaced by in vivo synthesis in which independently growing plants such as alfalfa take up and then split the precursor in their cells down to nano size using synthesis-promoting solvents–biomolecules, which can break down materials without free radicals and has anti-inflammatory, antioxidant effects, making NPs environmentally benign. In this study, two-week-old seedlings of two Medicago sativa L. genotypes, ‘Kometa’ and ‘la Bella’, were exposed to two precursors (AgNO3, HAuCl4) for 24 and 48 h to determine whether in vivo synthesis is possible. Double-blazed and certain wavelength spectrophotometry and confocal microscopy confirmed, statistically significant (P<0.05) changes in light absorption and light fluorescence compared to the control. Confocal microscopy showed both precursors visible in the roots of both genotypes. Currently, NPs synthesis and visualisation methods require a complex, expensive and time-consuming sequence of methods. It is important to find an effective, environmentally friendly, and as cheap and simple as possible method for the biosynthesis of NPs.