Highly Efficient Industrial Dye Degradation, Bactericidal Properties, and In Silico Molecular Docking Analysis of Ag/Cellulose-Doped CuO Nanostructures.

In this research, CuO nanostructures doped with Ag and cellulose nanocrystals (CNC) were synthesized using a facile coprecipitation technique. In this work, we doped Ag into fixed quantities of CNC and CuO to improve the photocatalytic, catalytic, and antibacterial activity. It was noted that catalytic activity increased upon doping, which was attributed to the formation of nanorods and a pH effect, while the reverse trend was observed in photocatalytic activity. The addition of Ag and CNC dopants into CuO improved the bactericidal efficacy for S. aureus and E. coli. In addition, to obtain insight into the possible mechanism behind their biocidal effects, molecular docking studies were conducted against specific enzyme targets: namely, dihydrofolate reductase from E. coli and DNA gyrase from S. aureus. This study suggested that codoped CuO could be highly efficient in the cleaning of polluted water and antibacterial applications.

Introduction

Water is an essential nutrient for life, but merely 2.5% of water is appropriate for human consumption, and the remaining 97.5% is salty water. With rampant population growth, potable water resources are being continuously depleted, posing severe challenges to the survival of living species.[1,2] By 2050, the earth’s population is expected to reach 9.0 billion, and by 2075, 75% of humankind may face water scarcity, according to the United Nations Water Agency report.[3] Aquatic pollution triggered by human waste causes adverse conditions.[4−6] Every year, industries produce around 7 x 105 tons dyes. Among them, 10–15% of methylene blue (MB) is discharged in water bodies annually, which can cause harmful diseases, including cancer, kidney malfunction, skin irritation, and hepatitis.[7,8] Moreover, ciprofloxacin (CF), detected in wastewater discharged from hospitals and medical industries and employed to treat infectious diseases, is a threat to the aquatic environment with concentrations of up to 150 μg/L and 31–50 mg/L, respectively.[9,10] In a nutshell, living resources are seriously endangered due to the phototoxicity, bioavailability, and aquatic toxicity of synthetic dyes and medicines.[11]

Due to these hazardous effects, toxic pollutants in water need to be controlled to preserve freshwater resources.[12] Intense studies have been undertaken to develop techniques to prevent domestic and industrial pollutants from affecting the environment.[13,14] The advanced oxidation processes include supercritical water oxidation, electrochemical oxidation, Fenton reactions, wet air oxidation, catalysis, and photocatalysis.[15] Among these techniques, catalysis and photocatalysis are effective and environmentally friendly techniques that have been utilized to degrade dyes for many years.[7,16]

Metal oxide nanoparticles (MONPs) are potential candidates for pollutant removal. In recent years, many MONPs (ZnO, CaO, TiO2, SnO2, and CuO) have been utilized as active catalysts.[17] Among the multiple MONPs, copper oxide (CuO) nanoparticles (NPs) are used because of their natural abundance, nontoxic nature, low-cost production, high thermal stability, and better electrical and optical characteristics.[18] As a narrow-band-gap p-type semiconductor, CuO has various applications that include solar energy conversion, the water-gas shift reaction, field emission, superconducting materials, sensing materials, glass, and ceramics.[19] Narrow-band-gap semiconductors exhibit superior antimicrobial properties and are powerful heterogeneous catalysts when they are integrated with coatings.[14] For this purpose, unique structures can provide a larger surface area and increase active sites for photocatalytic dye degradation. In this respect, many researchers have utilized a biopolymer (cellulose) for the enhancement of MONP properties.[20]

Currently, biopolymers, in terms of their efficient, sustainable, and environmentally friendly nature, are favorable building blocks for developing high-performance hybrid materials.[21,22] Cellulose is an innovative material and an abundantly available polysaccharide on earth, and its low-cost availability, biocompatibility, chemical stability, and ease of biodegradation offer a potential material for a variety of applications.[23−26] Cellulose nanocrystals (CNCs) also offer versatile surface chemistry that promotes the growth of various NPs, such as metal–organic frameworks (MOFs) and MONPs.[21,27] Cellulose-nanostructure-based characteristics lead to the strong binding of inorganic semiconductors on the surface, supporting the high stability of nanomaterials.[28−30]

The introduction of inorganic metal nanoparticles such as Ag, Au, Cu, and Zn NPs into cellulose has been a widely used approach to enhance antibacterial activity throughout the years.[23] Specifically, Ag has been given significant attention because of its potent antimicrobial and dye degradation activity due to its high surface to volume ratio.[23,24,31] Furthermore, a photocatalytic control sample (CuO) is boosted by coupling with transition metals, limiting photoinduced electron–hole recombination and increasing the band-gap energies.[14,32,33] It is reported that silver doping remarkedly improves the photocatalytic activity of semiconductor NPs.[14,34]

This study focuses on developing a facile approach for the eco-friendly degradation of industrial effluents and providing a strategy to control microbes. Ag- and cellulose-doped CuO nanostructures (Ag/CNC-CuO) were fabricated via a coprecipitation method for the photocatalytic and catalytic degradation of MB:CF and generating antimicrobial activity against Gram (positive and negative) bacteria. To understand how CNC-CuO NPs and Ag/CNC-CuO NPs kill bacteria, molecular docking experiments were performed on E. coli dihydrofolate reductase (DHFR) and S. aureus DNA gyrase enzymes.

Materials and Methods

Details of the materials used coupled with their suppliers, experimental protocols used in this study for determining the catalytic potential, photocatalysis, antimicrobial activity against identified strains of E. coli and S. aureus, and molecular docking analyses of the prepared samples are presented in the Supporting Information. Moreover, various techniques used for the extensive characterization of synthesized samples, including XRD, FTIR, ultraviolet–visible spectrophotometry, PL analysis, and HR-TEM, are also described in theSupporting Information.

Synthesis of Cellulose Nanocrystals (CNCs)

First, Avicel (10 g) added to a 50% solution of concentrated H2SO4 and DI water (200 mL) was stirred at 45 °C for 30 min to synthesize CNCs (Figure a). Subsequently, 5 L of DI water was incorporated to dilute H2SO4, and the supernatant was collected. To control the pH of the collected solution from acidic to neutral, an NaOH (0.5 M) solution was used. This neutral solution was centrifuged three times at 7100 rpm for 9 min.[35] The centrifuged CNC solution with neutral pH was dried for 7 h at 100 °C for further study. The obtained CNC in powder form had a concentration of 117 mg/mL.

Figure 1

(A) CNC synthesis from cellulose microfibrils, having crystalline and amorphous regions, by sulfuric acid hydrolysis. The synthesized CNC surface contained sulfate ester groups formed as a side reaction. (B) Schematic of the preparation and structure of Ag/CNC-CuO nanostructures.

Synthesis of Ag/Cellulose-Doped CuO

The CuO nanomaterial was synthesized via a coprecipitation method (Figure b). Initially, the Cu source was 0.1 M of Cu(NO3)2·3H2O was prepared with constant stirring. After that, an NaOH (0.5 M) solution was incorporated drop by drop into the colloidal solution to fix the pH to 12 with vigorous stirring at 90 °C for 30 min.[36] DI water (150 mL) was added, and the mixture was centrifuged three times to extract nitrate from the solution. A 2.5 wt % portion of CNC was added to the prepared CuO solution, and the mixture was heated at 95 °C for 30 min. Later, 150 mL of water was poured into the doped solution and the mixture was centrifuged three times and calcinated at 120 °C. Finally, 2% Ag was doped into the CNC-CuO solution by adding AgNO3 as a precursor and the mixture was stirred at around 90 °C and centrifuged two times. The obtained precipitates were dried at 120 °C for 7 h and ground well with a mortar and pestle.

Results and Discussion

The crystal structures, sizes, and phase compositions of CNC, CuO, CNC-CuO, and Ag/CNC-CuO were determined using X-ray diffraction (Figure a). The observed diffraction pattern for CNC revealed peaks positioned at 12, 19.5, 22.4, and 33.9° assigned to (101), (101), (002), and (112) crystal planes, respectively, and exhibited a monoclinic structure consistent with JCPDS card 46-0905.[37,38] Peaks found at 32.2, 35.3, 38.2, 48.3, 53.2, 58.1, 61.2, 66.04, 67.9, and 75.1° indexed as (110), (002), (111), (−202), (020), (202), (−113), (022), (113,) and (004) planes, respectively, correspond to the monoclinic phase of CuO and correlated with JCPDS card 48-1548.[39−41] Upon doping, the peaks were identical, attributed to a small amount of dopants being incorporated into the host material. The average crystallite sizes for CuO (13–15 nm) and CNC (10–11 nm) were calculated using the Scherrer equation. Furthermore, the interplanar spacing calculated with the Bragg equation was 0.35 nm for CNC and 0.27, 0.34, and 0.27 nm for undoped and CuO-doped samples. Figure b–e shows SAED patterns with ring characteristics formed by bright spots, corresponding to XRD data.

Figure 2

(a) XRD analysis of Ag/CNC-CuO. (a′) Reference code of CuO. (b–e) SAED patternd of CNC, CuO, CuO–CNC, and Ag/CNC-CuO, respectively. (f) FTIR spectra of the samples.

FTIR was employed to determine the presence of different functional groups in the 4000–450 cm–1 range (Figure f). The observed spectra for CuO and CNC exhibited transmittance peaks in the region 3000–3500 cm–1 corresponding to O–H stretching vibrations. Peaks recorded at around 1635 and 1435 cm–1 are correspondingly related to C=O and C–H2 stretching vibrations that could be attributed to the crystalline nature of CNC.[42−44] The observed peak in the range of 1019–1142 cm–1 illustrates the presence of sulfate ester bonds (C–O=S), which are induced by the hydrolysis of H2SO4 during CNC preparation.[44] For CuO and doped CuO, peaks at 1640 and 1502 cm–1 may indicate carbonyl C=O stretching, while the peak at 1371 cm–1 corresponds to C–O stretching of a carboxylate ion bonded to CuO as a bidentate ligand.[45,46] The band at around 1102 cm–1 was ascribed to a OH bending vibration due to excess hydroxyl groups.[17] The bands observed at 518 and 620 cm–1 are ascribed to the characteristic stretching vibrations of Cu–O bond formation, which confirmed the presence of a nanosized monoclinic phase of CuO.[45,46] Upon the addition of binary dopants, a minor shift in the transmittance peak toward a low wavenumber can be attributed to an alteration in Cu–O bond strength.[34]

To determine the optical properties of synthesized Ag-doped CNC-CuO nanomaterials, UV–vis spectroscopy was utilized (Figure a). The acquired spectra displayed characteristic absorption bands of 310–400 and 350–600 nm ranging from the UV to the visible region for CNC and CuO, respectively (Figure a). High-intensity peaks at 350 nm (CNC) and 360 nm (CuO) were recorded and attributed to the electronic transition from n to π* molecular orbitals of CuO.[37,47] In addition, a slight bathochromic shift (toward longer wavelength) was observed in the absorption spectra upon doping, corresponding to a decrease in band-gap energy (Eg) and an increase in the crystallite size of CuO. The Eg values of pristine and doped CNC:CuO were obtained via a Tauc plot between (αhν)2 vs hν, as presented in Figure b. Eg values for CNC (3.15 eV) and CuO (2.5 eV) were measured, which matched well with the reported values.[37,48,49] Upon doping, a reduction in Eg to 2.45 eV for CNC-CuO and 2.4 eV for Ag/CNC-CuO was observed. The red shift is responsible for the decrease in band gap, most probably due to lattice distortions, electron–phonon coupling, and charge carrier localization.[14]

Figure 3

(a) Absorption spectra, (b) band-gap energy plot, and (c) PL spectra.

To analyze the exciton migration phenomenon and the presence of the inherent defects of reference and codoped CuO, PL was employed at room temperature with 280 nm excitation and 325–525 nm emission ranges (Figure c). CNC exhibited an intense PL emission band located in the 325–550 nm range under excitation at 300 nm, as delineated in Figure c.[50] The UV emission peak recorded at ∼360 nm is ascribed to e––h+ recombination in free excitons, and visible emission peaks at 400 and 440 nm in the violet and blue regions, respectively, are ascribed to the near-band-edge emission (NBE) of the CuO nanostructure due to defects present in CuO.[51,52] A tiny luminescence peak at 486 nm is caused by the transition vacancy of interstitial oxygen.[51] The luminescence characteristics of CuO are strongly dependent upon the morphology of CuO, and surface contaminants may be formed during the transition of a mixed-phase crystal structure to a CuO crystalline structure.[51] An increase in luminescence intensity observed for binary-doped CuO is attributed to increasing intrinsic defect formation in the sample.[53]

The morphological features and crystal structures of doped and undoped CuO were characterized via HR-TEM, and the corresponding images at different scales are shown in Figure a–d,a′–d′). Figure a,a′ represents the formation of CNC NPs, and Figure b,b′ shows the formation of CuO nanorods (NRs), while Figure c,c′,d,d′ demonstrates an increase in length and diameter of the NRs with the incorporation of Ag/CNC. It seemed that Ag/CNC was connected with CuO, and agglomeration occurred in the doped materials, which eventually influenced the size of NRs. This increase in size offers an increased number of active sites for reactants, thus enhancing the antimicrobial activity. The corresponding SEM micrographs are also shown in Figure S3.

Figure 4

(a–d) HR-TEM images of CNC, CuO, CNC-CuO, and Ag/CNC-CuO, respectively on a 500 nm scale and (a′–d′) corresponding HR-TEM images on a 10 nm scale.

XPS was used to study the Ag and doped CuO surface elemental compositions, surface conditions, and binding energy shifts, see Figure . The high-resolution spectra of O 1s and Cu 2p are shown in Figure a,b. The O 1s spectrum revealed 529.18 and 531.08 eV binding energies, respectively, which relate to CuO (Figure a).[54] Primarily, Figure b specified the Cu 2p spectra of doped CuO containing peaks at binding energies of 933.3 and 953.3 eV ascribed to Cu 2p3/2 and Cu 2p1/2 spin orbitals, respectively, indicating the samples’ divalent oxidation state. The other two peaks at 942.2 and 962 eV are ascribed to Cu 2p3/2 and Cu 2p1/2 satellite peaks, respectively, which appeared primarily in a divalent oxidation state of partly filled 3d9 orbitals.[55] The O 1s spectrum’s greater peak at 530.8 eV is attributed to chemisorbed oxygen at the silver base.[56] The greater binding energy of O 1s in Ag is attributed to exposure to the air, although this binding energy is quite similar to that of a species identified as subsurface O in silver with a binding energy of 531.2 eV.[57] The XPS measurements specifically demonstrate the existence of metallic silver in the fresh sample, with binding energies of 368.3 and 374.1 eV for Ag 3d5/2 and Ag 3d3/2, respectively.[58]

Figure 5

XPS spectra of binary doped CuO: (a) CuO O 1s; (b) Cu 2p; (c) Ag O 1s; (d) Ag 2p.

To determine the catalytic activity of prepared samples in the presence of NaBH4 (reducing agent) MB:CF was used as a targeted contaminant (Figures S1, S7, and S8). The degradation performance of samples was assessed between 200 and 900 nm via UV–vis spectroscopy at room temperature in different media (acidic, basic, neutral) by varying the pH. MB:CF exhibited an absorption peak at ∼665 nm in an aqueous solution. In the absence of nanocatalysts, MB:CF reduction with NaBH4 showed only 0.1% degradation in 40 min, while the addition of nanocatalysts manifested a significant decrease in the concentration of MB:CF (Figure S1a–d. Bare and doped CNC and CuO nanocatalysts demonstrated efficient catalytic activity at pH ∼7 in the presence of NaBH4 and degraded about 16% (8 min) 90% (1 min), 96% (2 min), and 97% (3 min) of the dye, respectively. Almost 100% degradation was observed in an acidic medium within 1, 1, and 3 min, respectively, for pristine and codoped CuO, while CNC manifested an 18% degradation efficiency (8 min). However, poor catalytic reduction was observed in a basic medium for all samples, showing only 7%, 7%, 5%, and 10% dye degradation.

The degradation mechanism of MB:CF to Leuco MB:CF involves NRs acting as electron relay to initiate electrons shifting from BH4– ions (donor) to dye molecules (acceptor). A large surface area of NRs enhances adsorption by offering abundant active sites for BH4– ions and dye molecules to simultaneously react with each other.[59,60] The degradation performance of nanocatalysts is also dependent on the pH of targeted dye.[61] Upon adding H2SO4 to create an acidic medium, more H+ ions are available to be adsorbed on the surface of NRs to enhance catalytic activity. An increase in solution pH by adding NaOH increases the number of hydroxyl group,s resulting in oxidation of LMB:CF, hence decreasing the catalytic activity. Also, an electrostatic attraction between highly reactive OH– ions and H atoms supplied by the reducing agent results in the formation of H2O molecules, leaving the dye intact.[61,62] Consequently, the results demonstrated that the catalytic activity of nanocatalysts in acidic environments is significantly greater than that under alkaline conditions. Moreover, an increase in the catalytic activity of CuO was observed upon Ag-CNC doping in all mediums caused by an increase in active site number with doping. In conclusion, experimental results undoped and doped CuO NRs appear to show them to be suitable nanocatalysts for degrading dyes in industrial discharges. A literature comparison of the synthesized CuO NRs with other nanocatalysts under various conditions is also demonstrated in Table S1.

The photocatalytic potential of the metal oxide nanocomposite for reduction of MB:CF was evaluated under visible light irradiation in different media (acidic, neutral, basic) for 8, 120, and 40 min, respectively (Figures S9 and S10). In the absence of nanomaterials, the negligible reduction of MB:CF indicated that the dye gains stability with time and is hardly reduced. However, the addition of CNC, CuO, CNC-CuO, and Ag/CNC-CuO to an acidic medium displayed 4%, 9%, 9%, and 3% reduction in MB:CF concentration, respectively (Figure b). In neutral solution, only 2%, 7%, 6%, and 5% degradation efficiency was recorded for doped and undoped nanocatalysts, as demonstrated in Figure c. However, the dye degradation under alkaline conditions was 12%, 84%, 81%, and 57% for bare and codoped samples, respectively (Figure d)

Figure 6

(a) Schematic illustration of photocatalytic activity. Photodegradation (%) in (b) acidic, (c) neutral, and (d) basic media. (e) Rate constants (basic) of Ag/CNC-CuO nanorods.

In comparison, maximum dye degradation with nanocatalysts is achieved in a basic medium. The rate constant (pseudo-first-order kinetics) in basic medium for CNC, CuO, CNC-CuO, and Ag/CNC-CuO samples was 0.002, 0.044, 0.041, and 0.020 min–1, respectively (Figure e).

The photocatalytic dye degradation mechanism occurs in several steps: (i) adsorption of dye molecules on nanorod surfaces, (ii) photogeneration of electron–hole pairs in the catalyst, (iii) redox reactions occurring at the surface to produce reactive radical species, (iv) reaction of dye molecules with radical species to produce degraded products, and (v) desorption of products from the catalyst surface. The generated hydroxyl radicals and superoxide anions reduce MB:CF into nontoxic substances.[63] The basic photocatalytic mechanism of the Ag/CNC-CuO nanocatalyst (Figure a), is shown in reactions –5.

The photocatalytic activity of nanocatalyst is influenced by the catalyst amount, dye concentration, contact time, temperature, and pH of the dye solution.[64,65]

In an acidic medium, the surface of NRs will be positively charged due to the surplus number of H+ atoms, while in an alkaline medium, abundant OH– ions will induce a negative charge on the surface of the catalyst. MB:CF, being cationic, will offer more absorption on the negatively charged surface and hence more degradation will occur in a basic medium.[63]

As a result of our findings, we believe nanocatalysts in a basic medium are robust during reactions that rapidly remove organic dyes from water. According to the above analysis, the greater degradation efficiency of CuO is ascribed to the formation of intermediate energy levels, causing a decrease in electron–hole pair recombination. At the same time, a reduction in activity was observed upon Ag-CNC doping. On addition of codopants on the CuO surface, sunlight utilization decreases and faster e––h+ pair recombination occurs.[66]Table S2 compares various dyes with varying catalyst amounts and times.

The in vitro microbiocidal properties of the control and doped samples were investigated against S. aureus and E. coli with a well diffusion assay (Table S3). The extracted data indicated that each sample had antimicrobial activity toward both bacteria. A synergistic response was revealed among the prepared samples and measured inhibition zones. Significant inhibition areas (P < 0.05) at minimum and maximum concentrations for E. coli (3.30 mm and 4.45 mm) and S. aureus (0.95 mm and 1.65 mm) were accomplished in the case of CNC in comparison with the positive control (7.10 and 9 mm, respectively). Moreover, for bare and codoped CuO, inhibition zones against E. coli in the ranges 1.35–2.40 and 2.25–3.45 mm and against S. aureus in the ranges 4.25–5.65 and 4.40–7.85 mm were recorded for both concentrations, respectively (Figure S11). Accordingly, all findings were compared to those obtained with ciprofloxacin (5.10 and 9 mm) and DI water (0 mm). Undoped and Co-doped CuO revealed superior microbicidal potential against G+ ve in comparison to G– bacteria while CNC manifested an intensified bactericidal response for G– compared with G+ bacteria. Co-doped CuO NRs efficiently supported bacteria-killing activity and exhibited significant antimicrobial potential, as depicted in Table S1.

Oxidative stress is determined by the form, size, and concentration of NRs in the prepared products. A reduction in the size of NRs correlates negatively with antibacterial effectiveness. Following the ejection of cytoplasmic contents, reactive oxygen species (ROS) created by nanosized rods encapsulate the microbial cell membrane, causing the bacteria to explode (see Figure S6).[67,68] Another reason for the response of binary doped CuO with bacteria strains is the important contact of cations with negatively charged regions of the bacterial membranes, resulting in the collapse of microorganisms. Cations included in the codoped material affect bacterial metabolic processes and degrade DNA cross-links. Additionally, cations impair bacterial ribosome action and cause enzymatic breakdown, culminating in the death of pathogens.[69]

In silico molecular docking studies have been reported as an attractive approach to unveil the mechanism behind the antibacterial activities of nanoparticles. Cellulose/TiO2 NPs were previously reported to be potential antibacterial agents having inhibitory activity against DHFR and DHPS enzymes of the folate biosynthetic pathway.[37] The exact mechanism behind the antibacterial activity of NPs still needs to be explored, and the use of in silico approaches for the prediction of possible targets is important. Here, dihydrofolate reductase (DHFR) and DNA gyrase, being well-known targets for antibiotics discovery, were selected as shown in Figure S2. Molecular docking predictions revealed the binding tendency and mechanism behind the inhibition potential of CNC-CuO and Ag/CNC-CuO NRs against selected enzymes.

In the case of DNA gyrase from S. aureus, the best-docked conformation for CNC-CuO NRs showed an H-bonding interaction with Asp81 (bond distances 2.1 and 2.5 Å), Thr173 (bond distances 1.9 and 2.7 Å), and Gly85 (bond distance 2.3 Å) with an overall binding score of −13.769 kcal/mol. Similarly, Ag/CNC-CuO NRs also showed good binding interaction patterns (binding score −14.591 kcal/mol) inside the active site of DNA gyrase enzyme for H-bonding with Glu58 (bond distance 3.2 Å), Thr173 (bond distances 1.6 and 2.8 Å), Ser55 (bond distance 3.1 Å), Arg85 (bond distance 2.5 Å), and Asp81 (bond distances 2.4 and 2.0 Å) (Figure a,b).

Figure 7

Binding interaction patterns of (a) CNC-CuO NRs, (b). Ag/CNC-CuO NRs with active site residues of DNA gyrase from S. aureus, (c) CNC-CuO NRs, and (d). Ag/CNC-CuO NRs with active site residues of DHFR from E. coli.

The best docking score for dihydrofolate reductase (DHFR) enzyme from E. coli was −9.718 kcal/mol, showing H-bonding interactions, i.e., Gly95 (bond distance 2.2 Å), Ile14 (bond distance 2.3 Å), Ala7 (bond distance 2.0 Å), and Asp27 (bond distance 2.7 Å) as the main contributors to the inhibition potential of CNC-CuO NRs. Similar interactions were observed for the binding of Ag/CNC-CuO NRs inside the active site of DHFR with a binding score of −7.993 kcal/mol having H-bonding interactions with Asp27 (bond distance 2.7 Å), Ala7 (bond distance 2.4 Å), and Ile94 (bond distance 2.5 Å), as depicted in Figure c,d.

In silico molecular docking studies predicted CNC-CuO NRs and Ag/CNC-CuO NRs to be potential inhibitors of DHFR and DNA gyrase enzyme and suggested inhibition of these enzymes as a possible mechanism behind the in vitro antibacterial activity.

Conclusion

Ag/CNC-CuO NRs were successfully synthesized in this study via a coprecipitation procedure with a target of increasing their antimicrobial, catalytic, and photocatalytic efficiency. An XRD analysis confirmed that no phase transformation in the monoclinic phase of CuO occurs upon codoping, and its interlayer d spacing (0.27 nm) is in agreement with the HR-TEM results. FTIR spectra showed Cu–O molecular bonding with diverse functional groups, with transmittance peaks of about 518 and 620 cm–1 in the fingerprint region. A red shift in the absorption band was observed in the range of 350–600 nm upon doping. An increase in PL intensity was attributed to fast electron–hole recombination and defect formation in the sample with codopants. Doping increased the formation of rods, which enhanced the antibacterial and catalytic activity, as shown by HR-TEM. An EDS analysis confirmed the effective doping of Ag-CNC into CuO with appropriate portions. On the basis of this study, the synthesized NRs showed outstanding antimicrobial efficacy against G+ and G– bacteria with codopants and unique catalytic (under acidic and neutral conditions) and photocatalytic (under basic conditions) response for use in contaminated water treatment and biomedical applications. Molecular docking studies predicted the inhibition of DHFR and DNA gyrase enzyme from E. coli and S. aureus, respectively, as a possible mechanism behind the in vitro bactericidal activity of CNC-CuO NRs and Ag/CNC-CuO NRs. NRs as possible antibiotics will be expanded if enzyme inhibition investigations prove their efficacy as antibacterial agents.