Introduction

Nanomaterials (NMs) are made up of nanoscale particles and have dimensions of 1 to 100 nm1. Because of their massive surface area to unit volume ratio, nanoparticles (NPs) showed enhanced catalytic reactivity, chemical stability, thermal conductivity, and nonlinear optical performance2,3,4. Metal nanoparticles have many optical features that make them interesting for use in biomedical applications. One such property is surface plasmon resonance (SPR), which allows the material to modulate the optical field. Since metal nanoparticles are tiny, they can more easily penetrate biological membranes, which are often impervious to other macromolecules5,6.

The straight wide gap (3.37 eV, 387 nm), deep violet/borderline ultraviolet (UV), and strong exciton-binding energy (60 meV) of ZnO make it a good n-type semiconductor7. Nanoscale ZnO is an important semiconductor that has garnered remarkable attention for its wide range of applications, including electronics, optics, optoelectronics, and biomedicine. They are commercially deployed in diverse industries, namely for producing various materials8, leather and rubber industry9, and as a protective agent from sunlight10. Because of the antimicrobial properties of ZnO, it has been used in the food industry and even in cement production as an additive11,12. Different types of physical and chemical approaches have been used to generate metal nanoparticles in bulk production, such as chemical precipitation13, microwave14, sol-gel15, pulsed laser deposition (PLD)16, and polyol17, among others.

However, conventional methods such as physical and chemical approaches typically involve using hazardous reducing agents and organic solvents, most of which are extremely reactive, expensive and toxic to the environment, which can impart various health risks18. A new approach known as ‘green synthesis’ uses extracts from plants and microbes to prepare nanoparticles with potential uses in biomedicine19. Numerous benefits of this approach include safety, biocompatibility, affordability, and environmental friendliness. Furthermore, many studies have demonstrated the potent antibacterial qualities of metal/metal oxide nanoparticles produced by green synthesis techniques20.

The synthesis of NPs via phytochemical route involves various plant parts, including roots, leaves, seeds, stems, and fruits, because their potent extracts have been shown to work as both reducing and stabilizing agents21,22. Plant-based polyphenols are bioactive and exhibit cytotoxic, antiproliferative, and strong antioxidant activity23,24. Various water-soluble phytoconstituents, such as proteins, reducing sugars, amino acids, quinones, flavonoids, catechins, and terpenoids, could play key roles in synthesising stable high-surface-area metal nanoparticles25,26,27. The factors influencing nanoparticle commercial production entail inexpensively expeditious production with low toxicity and minimal use of hazardous reagents.

Green nanotechnology has such distinctive and appealing attributes regarding material design that has become the most important factor in contemporary scientific studies. Greener synthesis of nanoparticles deploying plant extracts does not require complicated processes and is more appealing than NPs from microbes involving repeated filtration methods and preservation of cell cultures28. The Food and Drug Administration of the United States has acknowledged that ZnO is an antimicrobial metal oxide that is safe for the environment and biocompatible with human cells29,30. Consequently, deploying environmentally friendly methods of producing natural nanoparticles of the desired morphology and size is imperative. For this reason, these are regarded as environmentally friendly protocols for producing desired morphological natural nanoparticles.

The plant Eechinochloa colonais is an annual weed belonging to the family of Poaceae. Except in Greenland and Antarctica, the annual or perennial grass Echinochloa colona is found across the world's warm climates. It is typical in regions with a lot of rainfall and fluctuating temperatures. In India, Echinochloa colona, a terrestrial, tufted, upright grass, is frequently called "jungle rice". This weed is also an alternate host of diseases, insects, and nematodes31. It is rich in phytochemicals, like alkaloids, steroids, carbohydrates, glycosides, tannins, phenols, flavonoids, etc., which could be exploited for the bio-reduction process32. In this work, ZnO NPs prepared through a green route using an aqueous leaf extract of E. colona highlight the nanoparticle growth at high temperatures and are used as antibacterial and anti-biofilm agents.

Materials and methods

Zinc nitrate hexahydrate (Zn (NO3)2·6H2O) was received from Merck, Mumbai. The leaves of the E. colona plant were collected during flowering time. Dr. Madhava Chetty, a taxonomist at Sri Venkateswara University in Tirupathi, India, recognized and verified the plant. The first Author (Hussain Udayagiri) has permission to collect E. colona, and all the methods were carried out according to relevant guidelines and regulations. Double distilled water was used in all steps for the preparation of nanoparticles. The fresh and young healthy leaves of E. colona were cleaned with purified water to eliminate unwanted compounds on the surface of the leaves. 10 g of dry leaf powder was combined with 100 mL of distilled water and then heated the mixture to 80 °C for 30 min. Then, the extract was cooled to room temperature and filtered. Further, it was subjected to a centrifuge at a speed of 3000 rpm for 5 min to remove heavy molecules, and finally, the extract was collected and stored at 4 °C for future use. Because these compounds function as both reducing and protecting agents during the production of metal oxides, the various phytochemicals comprising the leaf extract were identified chemically.

Phenolic content

The quantitative analysis of phenol was performed using the method previously developed with minor modifications33. The leaf extract (140 µL) mixed with 600 µL of reagent (Folin-Ciocalteu) was allowed to stand for a few minutes. Afterwards, 460 µL of 7.5 w/v % sodium carbonate (Na2CO3) was added, and the entire apparatus was kept at 45 °C for 30 min before being incubated for one hour at room temperature. Results are presented in gallic acid equivalents per gm (GAE/gm) extract (gallic acid equivalents per gram) based on absorbance measured at 764 nm using standard gallic acid.

Flavonoids

Based on the report by Chang et al.34, the quantitative analysis of flavonoids was measured by the aluminium chloride method. The plant extract (25 µL) and alcohol (75 µL) were mixed well, and to this, AlCl3 (5 µL) and potassium acetate (CH3COOK) (5 µL) were added and made up the volume up to 260 µL using distilled water. The absorbance at 415 nm was measured after the solution was incubated for 40 min at room temperature. The standard used was Rutin, and results were reported as Rutin equivalents per gram (RE/gm) of extract.

Total sugars

Using the Anthrone method, the quantitative analysis of sugar content was measured35. In brief, 3 mL of anthrone reagent and 1 mL of leaf extract were mixed well and incubated for 10 min in the water bath. The absorbance was measured at 630 nm against a reagent blank in a spectrophotometer using glucose as a standard.

Protein content

Using the Biuret method, the quantitative analysis of proteins in plant extract was performed35. In brief, 3 mL of biuret reagent and 1 mL of extract were mixed perfectly and subjected to 30 min of incubation. Bovine serum albumin (BSA) was used as a standard for the absorbance measurement at 540 nm.

Preparation of ZnO NPs

For the preparation of ZnO NPs, an aqueous extract of E. colona (30 mL) was mixed with 3 g of zinc salt, and the solution was stirred at 70–80 °C for four hours to achieve a deep, yellow-colored paste. This product was dried at 70 °C for 6 h and subjected to calcination for 3 h at 300 °C. Finally, the ensuing nanoparticles were collected in powdered form.

Characterization

UV–visible spectrophotometer (Model 3092, Lab India, Mumbai, India) was used to characterize the optical features of biosynthesized ZnO NPs. The resultant nanopowder was suspended in sterile milli-Q water and observed at a wavelength range of 300–600 nm. The functional groups, including phytochemical components that are associated with the reduction and stabilization of ZnO NPs, were analyzed by Fourier transform infrared spectroscopy (FTIR), recorded with Perkin Elmer Frontier Spectrophotometer with a resolution of 4 cm−1 in 400–4000 cm−1 range by KBr pellet method. RIGAKU smart lab X-ray diffractometer with a 1.5406 Å (CuKα) irradiation wavelengths was used for X-ray diffraction spectroscopic (XRD) analysis of dried ZnO NPs to access the purity and the crystalline size of the synthesized nanopowder; scanning angle was analyzed at 0.02 ͦ step in 10◦ to 80◦ range. The morphology of the particles was examined by scanning electron microscope (SEM), JEOL JSM-6310LV, operating at 200 kV to study the surface structure of the synthesized ZnO NPs. Energy-dispersive X-ray (EDX) spectroscopy was employed to analyze the elemental composition of the sample and determine its purity. The morphology, size, and crystallinity of NPs were studied using transmission electron microscopy (TEM). After coating onto a copper grid followed by drying, the ZnO nanoparticle suspension was analyzed via TEM JEOL 3010 with an acceleration voltage of 200 kV.

Antimicrobial activity

The antimicrobial activity of green and biosynthesized ZnO NPs was measured against two different bacterial strains such as Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae)strains acquired from Chandigarh's Institute of Microbial Technology. The disc diffusion method was used to examine ZnO NP's antibacterial activity. Using the disc diffusion method, the antibacterial activity of ZnO NPs was assessed at various doses, including 20, 40, 60, and 80 µg of NPs, in conjunction with a standard antibiotic drug (ampicillin)36. The MHA plates were prepared with respective bacterial strains at 108 CFU. ZnO NPs filled discs in varying concentrations are positioned at the corners of the plates. After 36 h of incubation, the ZOI was determined. Five separate experiments were conducted, and the clear zone that developed around the discs was measured and reported in millimeters (mm).

SEM investigations were performed to verify the morphological alterations in microorganisms brought about by biosynthesized ZnO NPs. After 8 h of growth in standard broth at 37 °C, microbial suspensions were treated with 80 µg/mL ZnO NPs and incubated for 12 h at 37 °C. Assorted microbes were centrifuged at 5000 rpm for 5 min at 4 °C, washed with PBS (0.1 M, pH 7.4) three times for 10 min each, then fixed in 2.5% (v/v) glutaraldehyde in PBS (0.1 M, pH 7.4) for 2 h (4 °C). The microbial specimen was dehydrated with 50, 70, 80, 90, and 100% ethanol for 10 min each, followed by tertiary butyl alcohol treatment. Following CO2 drying, the microbial specimens were coated in an ion coater (2 min) with gold. Using a scanning electron microscope (JEOL, JSM-6310LV operating at 200 kV), changes in the morphology of the bacterial cells treated with biogenic ZnO NPs were observed.

Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), and Anti-biofilm activity determination

Minimum inhibitory concentration (MIC) estimation was performed as per the ASM (American Society for Microbiology) manual according to CLSI guidelines as described by Bauer et al.36 and Eloff et al.37. MIC and MBC of nanoparticles were determined as follows. To 1 mL of nutrient broth, different concentrations of nanoparticles were added, and various concentration-containing tubes were used for treatment. Bacterial culture in the log phase was taken and checked for absorbance in a spectrophotometer to get 0.6 to 0.8 OD values equivalent to 1.5 × 108 CFU/mL. The culture was diluted 20 times and added this diluted culture (100 μL) was placed directly into the tubes and incubated for 16 h. The tubes were then filled with 40 μL of iodonitrotetrazolium (INT) at a concentration of 0.2 mg/mL, and they were incubated for 30 min at 37 °C. Tubes were observed to change color from yellow to pink or white. A color change signifies the existence of bacteria, whereas a colorless area denotes the absence of microorganisms. The MIC of the nanoparticle was determined by serially arranging tubes containing varying concentrations and watching for color changes.

Nevertheless, after a 24-h incubation period, a portion (10 μL) of the aforementioned MIC experimental solution from the tube where no color change was detected was collected, and spread over the nutrient agar plate to measure the MBC observed for bacterial colonies. The MBC concentration was found using a plate to examine for no bacterial colonies. Nanoparticles (µg) containing MIC and MBC were administered. These attributes are significant as several such characteristics are important requirements in various industries, including paint, sunscreen, pharmaceuticals, and cosmetics.

The anti-biofilm activity of ZnO NP was evaluated through the previously described method with some modifications36,37. Starting with 10 mL nutrient broth, it was inoculated with a loopful of tested microorganisms from overnight culture on nutrient agar. Diluted the culture until it reached the OD value of 1.0 at 600 nm. Every individual well in the flat bottom 96 well microtiter plate was filled with 180 μL of diluted culture with inoculated sterile broth served as blank. Afterwards, 10 µL of ZnO NPs or positive control ampicillin was added and mixed thoroughly. The culture plates were incubated at 37 °C for 24 h. After incubation, all the contents were gently removed and floated, including non-adherent cells in wells. The wells were washed thrice with 200 μL of normal saline and air-dried for 30 min. Biofilms of bacteria that remained adherent to the walls were fixed with 2% sodium acetate and stained with 0.1% crystal violet for 10 min. The excess stain was incubated for 30 min, washed with saline, and air-dried. These plates were then de-stained with 200 μL of 95% ethanol for 10 min and measured absorbance at 620 nm using a Microplate Reader (Biorad 680, USA). The percentage of inhibition of biofilm formation was calculated using the following formula:

$$Percentage\, of\, biofilm\, inhibition= \left[1-\frac{\text{OD }620\text{ cells treated with nanoparticle}}{\text{OD }620\text{ cells treated with no treatment}}\right]*100$$

Statistical analysis

The data presented in tables and figures represents mean ± SE of five individual determinations. Data was evaluated using one-way ANOVA post-hoc multiple comparisons from the Duncan Multiple Range (DMR) Test at a significance level of p ≤ 0.05.

Results and discussion

The water leaf extract of E. colona was identified for polyphenols, flavonoids, and proteins, and the extract was found to contain 17.4 ± 1.6 GAE/gm, 5.8 ± 0.05 RE/gm, 18.53 ± 0.3 and 210.33 ± 3.3 mg/gm of polyphenols, flavonoids, proteins, and sugars, respectively. The UV–vis spectroscopy approach was used to describe the optical property and determine the generation of ZnO NPs. The distinctive ZnO absorption peak is located at 370 nm in ZnO NPs dispersion in the UV–vis absorption spectrum, as illustrated in Fig. 1a. This peak is indicative of a pure sample since it occurs at the same time as the ZnO undergoes an electrical band gap between its valence as well as conduction, states38. The functional groups in the E. colona extract that might serve as reducing agents during the production of ZnO NPs were found using FT-IR spectroscopy. The current study discovered that zinc nitrate was reduced into ZnO NPs by the secondary metabolites of E. colona. FT-IR spectrum is depicted in Fig. 1b. The broad peak at 3245 cm−1 could be attributed to hydroxyl groups (O–H) originating from the phenolic chemicals present in the plant extract, indicating the existence of hydrogen-bonded groups38. A peak at 1034.79 cm-1 observed can be ascribed to the presence of phenolic groups and alcohols. It was identified that the Zn–O bond possessed a significant absorption band at 450 cm−1. The absorption peak at 1626 cm−1 indicates the stretching bands of C=O of the amide group39. Narrow peaks at 2922 cm−1 and 2852 cm−1 are attributed to C–H stretching vibration, which depicts the presence of alkanes group39. Flavonoids and polyphenols consist of many –OH groups of Zn-flavonoid complex, which resulted in the production of ZnO NPs by calcination. Previous studies have suggested that C–O, C–O–C, and C = C groups of heterocyclic compounds could have stabilizing properties. The aqueous plant extract could bind the zinc surface with phenols and flavonoids, causing zinc nitrate to synthesize and regulate ZnO NPs. It can be mentioned that functional groups of phenols and flavonoids in the extract could donate electrons that could reduce zinc ions (Zn2+) to ZnO.

Figure 1
figure 1

(a) UV–visible absorption spectrum of biosynthesized ZnO NPs and (b) FT-IR spectrum of biosynthesized ZnO NPs using E. colona extract.

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Moreover, the negative functional groups present in the extract could have a stabilizing effect29. Sanaz et al. reported that negatively charged biomolecules (proteins and carboxylic acids) are possibly involved in stabilizing nanoparticles40. Therefore, our investigation explained the importance of plant metabolites such as proteins, terpenoids, and phenolic compounds in the production and stability of ZnO NPs. Proteins have the ability to cover NPs in a protective shell that increases their dispersibility and keeps them from clumping in water. Furthermore, ZnO NPs can form and be more stable due to the interaction of free amino and carboxylic groups with the zinc surface40.

The XRD pattern of ZnO NPs that were biosynthesized using E. colona extract is shown in Fig. 2. In XRD pattern, at two theta degrees 31.85 (100), 34.47 (002), 36.37 (101), 47.57 (102), 56.64 (110), 63.03 (103), 66.53 (200), 68.05 (112), and 77.21° (202) confirms that ZnO NPs have a hexagonal wurtzite structure which match those of (JCPDS card No. 36–1451). The biosynthesized ZnO NPs of 14 nm size at the peak associated with the (101) planes employing Deby-Scherrer's formula40. The XRD pattern only displayed the expected ZnO peaks, further demonstrating the purity of the synthesized ZnO NPs, and the results matched the previous results40. The morphology of biosynthesized ZnO NPs was examined using the SEM (Fig. 3a–b), as well as their chemical composition was determined using EDX. The SEM images finalized the ZnO NPs, which had a regular distribution of both spherical and hexagonal shapes morphologically. The EDX spectrum of the nanoparticles of zinc oxide produced is depicted in Fig. 3c. EDX spectrum shows that zinc oxide nanoparticles have 50.21 Zn % and 22.08% by weight. This confirmed the existence of O and Zn in the prepared material. The formation of the ZnO NPs has been verified by employing a resolution transmission electron microscopy examination (Fig. 3d and e), and it is observed that neat ZnO NPs are spherical and hexagonal shaped. The high degree of crystallinity of the ZnO NPs is further demonstrated by the fact that the lattice fringes are presented clearly and without distortion. The selected area electron diffraction (SAED) pattern (Fig. 3f) demonstrates that ZnO NPs are made up of a sequence of rings interspersed with bright spots, which may be interpreted as evidence of crystallinity. Diffraction patterns in the SAED picture, as well as XRD spectral peaks, provide additional evidence that ZnO NPs have a hexagonal wurtzite crystalline structure40.

Figure 2
figure 2

XRD pattern of biosynthesized ZnO NPs using E.colona plant extract.

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Figure 3
figure 3

Scanning electron microscopic images of ZnO NPs (a) and (b), (c) energy-dispersive X-ray spectroscopy spectrum of ZnO NPs, (d) and (e) transmission electron microscopic images of ZnO NPs, and (f) SAED pattern of ZnO NPs.

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The antibacterial activity of ZnO NP was measured qualitatively and quantitatively using zone of inhibition (ZOI), minimum inhibitory concentration (MIC), and minimum bacteriocidal concentration (MBC). The results are presented in Table 1. The synthesized ZnO NPs are subjected to antibacterial activity through the disc diffusion method. ZnO NPs exhibited significant antibacterial activity by inhibiting growth in terms of ZOI and multiplication of bacteria E. coli, and K. pneumonia at lower concentrations, and inhibition concentration increased with a higher concentration of nanoparticles. These results are compared with a standard positive control drug (ampicillin) (Fig. 4 and Table 1). Teichoic acid and lipoteichoic acid are typical components of the cell walls of Gram-positive bacteria, which contain more layers of peptidoglycan polymer and are thicker (20–80 nm). These two acids act as chelating agents, allowing zinc ions to be transported into the cell from ZnO NPs. The outer layer of gram-negative bacteria cells has a thin coating of peptidoglycan (7–8 nm) and porins, thus allowing ZnO NPs to passively enter the cells41,42.

Table 1 MIC and MBC of ZnO nanoparticles against E. coli and Klebsiella pneumoniae bacteria.
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Figure 4
figure 4

Antibacterial activities of ZnO NPs in the zone of inhibition at different concentrations against E. coli and K. pneumoniae bacterial strains along with positive control (Ampicillin).

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ZnO NPs and the intracellular components they release, as well as the chelated zinc they contain, can trigger cell death by compromising the phospholipid bilayer due to the presence of ZnO NPs. Alkaline phosphatase, polymerases, and carboxy peptidases are only a few of the enzymes that might be inhibited by Zn ions. Strong interactions may be formed between zinc ions and the cysteine, histidine, and aspartate side chains of proteins at nanomolar concentrations, as demonstrated by Chulhun and Herbert43. The breakdown of bacterial cell walls causes a decrease in osmotic pressure and ionic strength in pathogenic species. Cellular functions, including growth, metabolism, and reproduction, are stifled by this drop in osmotic pressure. Smaller ZnO NPs may have an easier time breaking through bacterial membranes because of their larger interfacial area. As a result, their antimicrobial properties would become much stronger. The most potent bactericidal and fungicidal response was significantly influenced by NP size; smaller ZnO NPs displayed the highest levels of antibacterial activity44. SEM results (\* MERGEFORMAT Fig. 5a–d) clearly show that ZnO NPs treatment reduced the colony counts of the studied microbes and distorted cell wall shape and size, respectively ( \* MERGEFORMAT Fig. 5c, d) in comparison to untreated microbes (\* MERGEFORMAT Fig. 5a, b). Despite the thickness of bacterial cell walls, intracellular leakage is observed in these results, which corroborates previous reports that ZnO NPs can be used to prevent pathogenic microbial infections in living cells. The possible mechanism of the antibacterial activity of ZnO NPs is presented in \* MERGEFORMAT Fig. 6.

Figure 5
figure 5

Scanning electron microscopic images of (a) E. coli, (b) E. coli treated with ZnO NPs, (c) Klebsiella pneumonia, and (d) Klebsiella pneumonia treated with ZnO NPs.

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Figure 6
figure 6

Possible mechanism of antibacterial activity of Echinocloa colona extract mediated synthesized ZnO NPs.

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Biosynthesized NPs are bactericidal because their antibacterial effect is directed at the respiratory chain and cell division, both of which ultimately result in cell death. One of the most crucial roles that bacterial cell walls and membranes play is protecting against medicinal chemicals like NPs45.There is a great deal of diversity in the classification of bacteria based on the components of their cell walls. The cell wall of a Gram-negative bacterium, also known as the cell envelope, is composed of two layers of lipopolysaccharides. On the other hand, the thicker cell walls of gram-positive bacteria are almost entirely made up of peptidoglycans, a single family of chemicals. The presence of ZnO NPs suspensions significantly increases the generation of reactive oxygen species (ROS)46,47. Ahmed M. et al. investigated the enhanced antibacterial activity of bio-ZnO NPs, and the results were expressed in ZOI, particularly with a 22 mm ZOI against S. aureus and a 17 mm ZOI against E. coli. The study results demonstrate that ZnO nanoparticles are more effective against gram-positive bacteria due to structural variations in their cell walls48. Thana et al. studied the antibacterial activity against S. typhi, E. coli, S. pneumoniae, and S. aureus, which were found to be 21.4 mm, 15.8 mm, and 15 mm, respectively, in antibacterial activity. The amount of zinc oxide affected the antibacterial activity of the ZnO NPs in their prepared state49.

According to our results, ZnO NPs have a high degree of biofilm destruction capability against both bacteria (Fig. 7). The schematic representation of the anti-biofilm activity of ZnO NPs is presented in Fig. 8. This is comparable to ZnO NPs that have been shown in the past to stop the synthesis of exo-polysaccharides and prevent the formation of biofilms, which in turn stopped the growth of bacteria. According to another study, biologically generated metal oxides inhibited the biofilm growth before it reached the irreversible adhesion stage. It's interesting to note that first-stage biofilm activity was shown to be suppressed at the MIC values50. The investigation by Kaweeteerawat et al. suggests that metal oxide nanoparticles may interact with bacterial cell membranes to induce oxidative stress, which is the mechanism through which NPs reduce the biofilms50. Microscopy images that showed bacterial cell deformation, external cell roughness, and cell wall shrinkage have been deployed in an earlier investigation to interpret the anti-biofilm action.

Figure 7
figure 7

Antibiofilm activity of synthesized ZnO NPs using Echinocloacolona plant extract.

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Figure 8
figure 8

Schematic mechanism of anti-biofilm activity of ZnO NPs.

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Furthermore, less biofilm was developed, and fewer live cells were seen. Reactive oxygen species (ROS) generated by ZnO NPs and surface ions inhibited biofilm formation. Many variables, such as the size and dispersibility of the nanoparticles, influence the extent of growth inhibition. Similar to our results, Zahra et al. reported that a significant inhibition of biofilm formation was found at 85% and 97% against S. aureus ATCC 25,923 and P. aeruginosa ATCC 27,853 biofilm, respectively51. This finding demonstrated that the synthesised ZnO NPs could quickly and efficiently separate biofilm and suggest their usage as agents to disrupt the biofilms52. According to a prior explanation, the extracellular ROS production caused by biogenic synthesized ZnO NPs may be the origin of the bio mechanism of anti-biofilm activity, which destroys microorganisms' biofilm exo-polysaccharides52.

The MIC data suggest the significantly improved antibacterial activity of ZnO NPs is due to, in part, the greater impact on the surface along with the surface area of these particles. One study that examined the antibacterial properties of ZnO NPs found that smaller particles showed more antibacterial activity than larger ones. These nanoparticles may have enhanced antibacterial activity due to their high liposolubility index. Overtone postulated that the lipid barrier surrounding cells would only allow chemicals that are also soluble in lipids to enter through. Therefore, lipophilicity could be a significant feature of antibiotics53. Diminutive, synthesized nanoparticles can penetrate and rupture the cell membrane, leading to the death of the cell as a secondary mechanism of antibacterial activity. ZnO NPs cause the release of H2O2 molecules from the cell surface, which aids in the killing of bacteria.

Hsueh et al. have reported that ZnO NPs weakened the structural properties of the (epoxy polysaccharides) EPS that omprised the biofilm, leading to its dissolution. A. faecalis and P. gingivalis biofilm production decreased by 92.27 1.22% and 95.27 1.28%, respectively, when biosynthesized ZnO NPs were utilized54. The outcomes of this research were consistent with those of others that looked at S. aureus, E. coli, and Pseudomonas aeruginosa biofilms. Ankush et al. synthesized ZnO NPs using the leaf extract of the Saracaasoca plant, and the antibacterial and anti-biofilm activity of NPs was measured against the biofilm-producing bacteria Bacillus subtilis. The results showed that biofilm growth was suppressed by approximately 45%, 64%, and 83% at 0.5 × MIC, 0.75 × MIC, and 1 × MIC value, respectively. The concentration-dependent biofilm biomass produced or matured biofilms by ZnO NPs was assessed to be 68%, 50%, and 33% at concentrations of 0.5 Η MIC, 0.75 × MIC, and 1 × MIC, respectively 55.

Conclusions

This reports the synthesis of ZnO NPs using the bio-reduction method. The Eechinochloacolona plant leaf extract comprises a significant number of polyphenols, flavonoids, sugars, and proteins, which act as reducing as well as stabilizing agents in the production of ZnO NPs. The UV absorption peak confirmed the formation of ZnO NPs at 370 nm, and the hexagonal wurtzite structure was affirmed by XRD and TEM investigations, with a size range of  17 nm. Anti-biofilm assay results suggested that the synthesized ZnO NPs demonstrated a high degree of biofilm detachment property over the range of concentrations examined. Both Gram-positive and Gram-negative bacteria were unable to proliferate in the presence of nanoparticles, confirming the strong antibacterial activity of the synthesized ZnO NPs. The nanoparticle's ability to efficiently destroy particular diseases or preservation of food products can be enhanced by functionalizing them with specific chemicals or ligands. The impact of these nanoparticles on the environment and untargeted creatures should be the main focus of research. Additional research could be looked into how well they treat various medical conditions, control patient infections, and healing of wounds.