Enhanced bactericidal, antibiofilm and antioxidative response of Lawsonia inermis leaf extract synthesized ZnO NPs loaded with commercial antibiotic

Globally, antibiotic resistance is a challenging issue in healthcare sector. The emergence of multiple drug-resistant bacteria has forced us to modify existing medicines and or formulate newer medicines that are effective and inexpensive. In this perspective, this study involves the formation of zinc oxide nanoparticles (ZnO NPs) by utilizing the Lawsonia inermis (Li) leaf extract. The prepared L. inermis leaf extract mediated ZnO NPs (Li-ZnO NPs) were bio-physically characterized. The antibacterial and radical scavenging effects of Li-ZnO NPs were evaluated. In addition, ZnO NPs were conjugated with standard antibiotic (ciprofloxacin) and its drug loading efficiency, drug release and antibacterial efficacy were tested and compared with non-drug loaded ZnO NPs. An absorbance peak at 340 nm was noted for Li-ZnO NPs. After conjugation with the drug, two absorbance peaks- one at 242 nm characteristic of ciprofloxacin and the other at 350 nm characteristics of ZnO NPs were observed. The crystallite size was 18.7 nm as determined by XRD. The antibacterial effect was higher on Gram-positive (S. aureus and S. pyogenes) than the Gram-negative pathogens (E. coli and K. pneumoniae). Inhibition of S. aureus and S. pyogenes biofilm at 100 μg mL-1were, respectively, 97.5 and 92.6%. H2O2 free radicals was inhibited to 90% compared to the standard ascorbic acid at 100 μg mL-1. After drug loading, the FTIR spectrum confirmed the existence of ciprofloxacin peaks at 965 cm-1 and Zn-O bond at 492 cm-1. The drug loading capacity of 15 nm sized ZnO NPs was higher (58, 75, 90 and 95% at 1, 2.5, 5 and 10% drug concentrations, respectively) compared to 20 nm. Similarly, the percentage of drug (ciprofloxacin) released from 15 nm ZnO NPs were increased to 90% at 10% drug-loaded samples, respectively. Also, the antibiotic loaded ZnO NPs had significant antibacterial effects against tested bacteria compared to Li-ZnO NPs and ciprofloxacin alone. This revealed that the antibiotic loaded ZnO NPs offer a sustainable route to treat multi-drug-resistant bacterial infections.

Solvent-assisted synthesis of Ag2Se and Ag2S nanoparticles on carbon fabric for enhanced thermoelectric performance

The challenge of developing low-cost, highly flexible, and high-performance thermoelectric (TE) materials persists due to the low thermoelectric efficiency of conducting polymers and the inflexibility of inorganic materials. In this study, we successfully integrated Ag2Se and Ag2S with highly conductive carbon fabric (CF) to produce a flexible thermoelectric material. A facile one-step solvothermal method was employed to synthesize the Ag2Se-CF and Ag2S-CF, which were then subjected to X-ray analysis to confine the phase formation of Ag2Se and Ag2S on the carbon fabric. The analysis revealed that Ag2Se and Ag2S nanoparticles were tightly packed on the surface of carbon fabric, and compositional analysis confirmed the interaction between the material and carbon fabric. The thermoelectric properties of Ag2Se-CF and Ag2S-CF were significantly altered due to carrier concentration and mobility variations, resulting in a low power factor of 6.7 μW/mK2 for Ag2Se-CF and a high-power factor of 24 μW/mK2 at 373 K for Ag2S-CF. The growth of Ag2Se-CF and Ag2S-CF on carbon fabric led to an enhancement in their thermoelectric properties. Further, TE legs were fabricated using the Ag2Se-CF (p-type) and Ag2S-CF (n-type), and the fabricated legs exhibited an output voltage of ∼20 mV to ∼86.65 mV at a temperature gradient (ΔT) of 3-8 K. This work represents a cutting-edge approach to the fabrication of high-performance, wearable thermoelectric devices.

Engineering resistance against Cucumber mosaic virus in Nicotiana tabacum through virus derived transgene expressing hairpin RNA

Cucumber mosaic virus (CMV) is the one of notorious virus known for its ubiquitous nature and causes substantial yield loss worldwide. The resistance against the Cucumber mosaic virus (CMV) was envisaged in Nicotiana tabacum transgenic lines by introducing viral gene fragments. The chimeric hairpin RNA constructs incorporating 401 bp of coat protein, 411 bp of replicase protein and 361 bp of 2b gene were developed respectively and transformed into N. tabacum. The regenerated transgenic lines introduced with inverted repeats of CMV gene fragments exhibited enhanced resistance against CMV. The preliminary molecular screening and qPCR confirmed the integration of transgene in the transgenic lines. The spectrum of resistance in transgenic lines was evaluated by challenge inoculation with CMV and the resistance was determined through DAC-ELISA. The complete resistance was achieved in the hpRNA-CP transformant with a very low titre (0.029) of CMV followed by hpRNA-REP (0.099) with no symptoms.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03576-1.

Co-existence of chlorosis inducing strain of Cucumber mosaic virus with tospoviruses on hot pepper (Capsicum annuum) in India

Cucumo- and tospoviruses are the most destructive viruses infecting hot pepper (chilli). A diagnostic survey was conducted to assess the prevalence of cucumo and tospoviruses in chilli growing tracts of Tamil Nadu. Infected plants showing mosaic with chlorotic and necrotic rings, veinal necrosis, mosaic mottling, leaf filiformity and malformation were collected. Molecular indexing carried out through reverse transcription polymerase chain reaction (RT-PCR) with coat protein gene specific primer of Cucumber mosaic virus (CMV) and tospovirus degenerate primer corresponding to the L segment (RdRp). Ostensibly, amplifications were observed for both CMV and tospoviruses as sole as well for mixed infections. The sequence analysis indicated that the Capsicum chlorosis virus (CaCV) and Groundnut bud necrosis virus (GBNV) to be involved with CMV in causing combined infections. The co-infection of CMV with CaCV was detected in 10.41% of the symptomatic plant samples and combined infection of CMV with GBNV was recorded in around 6.25% of the symptomatic plants surveyed. The amino acid substitution of Ser¹²⁹ over conserved Pro¹²⁹ in coat protein of CMV implies that CMV strain involved in mixed infection as chlorosis inducing strain. Further, the electron microscopy of symptomatic plant samples explicated the presence of isometric particles of CMV and quasi spherical particles of tospoviruses. This is the first molecular evidence for the natural co-existence of chlorosis inducing CMV strain with CaCV and GBNV on hot pepper in India.

High synergistic antibacterial, antibiofilm, antidiabetic and antimetabolic activity of Withania somnifera leaf extract-assisted zinc oxide nanoparticle

Nanotechnology is currently gaining immense attention to combat food borne bacteria, and biofilm. Diabetes is a common metabolic disease affecting majority of people. A better therapy relies on phytomediated nanoparticle synthesis. In this study, W. somnifera leaf extract-assisted ZnO NPs (Ws-ZnO NPs) was synthesized and characterized. From HR-TEM analysis, it has been found that the hexagonal wurtzite particle is 15.6 nm in size and - 12.14 mV of zeta potential. A greater antibacterial effect of Ws-ZnO NPs was noticed against E. faecalis and S. aureus at 100 µg mL^-1. Also, the biofilm of E. faecalis and S. aureus was greatly inhibited at 100 µg mL^-1 compared to E. coli and P. aeruginosa. The activity of α-amylase and α-glucosidase enzyme was inhibited at 100 µg mL^-1 demonstrating its antidiabetic potential. The larval and pupal development was delayed at 25 µg mL^-1 of Ws-ZnO NPs. A complete mortality (100%) was recorded at 25 µg mL^-1. Ws-ZnO NPs showed least LC₅₀ value (9.65 µg mL^-1) compared to the uncoated ZnO NPs (38.8 µg mL^-1) and leaf extract (13.06 µg mL^-1). Therefore, it is concluded that Ws-ZnO NPs are promising to be used as effective antimicrobials, antidiabetic and insecticides to combat storage pests.

High synergistic antibacterial, antibiofilm, antidiabetic and antimetabolic activity of Withania somnifera leaf extract-assisted zinc oxide nanoparticle

Nanotechnology is currently gaining immense attention to combat food borne bacteria, and biofilm. Diabetes is a common metabolic disease affecting majority of people. A better therapy relies on phytomediated nanoparticle synthesis. In this study, W. somnifera leaf extract-assisted ZnO NPs (Ws-ZnO NPs) was synthesized and characterized. From HR-TEM analysis, it has been found that the hexagonal wurtzite particle is 15.6 nm in size and - 12.14 mV of zeta potential. A greater antibacterial effect of Ws-ZnO NPs was noticed against E. faecalis and S. aureus at 100 µg mL^-1. Also, the biofilm of E. faecalis and S. aureus was greatly inhibited at 100 µg mL^-1 compared to E. coli and P. aeruginosa. The activity of α-amylase and α-glucosidase enzyme was inhibited at 100 µg mL^-1 demonstrating its antidiabetic potential. The larval and pupal development was delayed at 25 µg mL^-1 of Ws-ZnO NPs. A complete mortality (100%) was recorded at 25 µg mL^-1. Ws-ZnO NPs showed least LC₅₀ value (9.65 µg mL^-1) compared to the uncoated ZnO NPs (38.8 µg mL^-1) and leaf extract (13.06 µg mL^-1). Therefore, it is concluded that Ws-ZnO NPs are promising to be used as effective antimicrobials, antidiabetic and insecticides to combat storage pests.