One-step synthesis of eco-friendly boiled rice starch blended polyvinyl alcohol bionanocomposite films decorated with in situ generated silver nanoparticles for food packaging purpose.

The study reports a one-step preparation of polyvinyl alcohol/boiled rice starch blend film fabricated with in situ generated silver nanoparticles (PVA/BRS/sAgNPs) formed in the presence of sunlight irradiation. The bionanocomposite appeared to have dark brown color with a characteristic surface plasmon resonance peak at 439 nm. Further characterization has confirmed the presence of physical interactions among the components PVA, BRS and sAgNPs. Compared to the control PVA, the nanocomposites showed improved mechanical and optical properties with decreased water sensitivity. Presence of boiled rice starch and sAgNPs were also found to influence the light transmittance of composite film. Moreover, PVA/BRS/sAgNPs film was found to have superior barrier property against environmental microorganisms. Biodegradation of the composite films was studied by indoor soil burial test and was assessed by visual appearance, weight loss and FTIR analysis. Interestingly, both the PVA/BRS and PVA/BRS/sAgNPs films proved to be biodegradable and hence have promising application as cost effective food packaging material with the latter having marked antimicrobial property.

Starch-PVA composite films with zinc-oxide nanoparticles and phytochemicals as intelligent pH sensing wraps for food packaging application.

The increasing acceptance of ready to eat food generates demand on development of active and intelligent food packaging material. Even though many polymers have been used for the packaging, they have limitations for broad applications. Among the various polymers, Poly Vinyl Alcohol is a promising film forming polymer with highly flexible, emulsifying and adhesive properties. A variety of nano-fabrication techniques have already been reported to improve the mechanical and antimicrobial properties of PVA to exploit its wider applications. In the present study, starch-PVA based composite films incorporated with zinc oxide nanoparticles and phytochemicals were prepared by solvent casting technique. The films were characterized by XRD, FT-IR, UV-Vis spectrometry and SEM. The developed nanocomposite films were demonstrated to have enhanced water barrier, mechanical and antimicrobial properties. The unique features of the nanocomposite with its pH indication property demonstrated in the study indicate its potential usage in food packaging applications.

Antibacterial Effectiveness of Rice Water (Starch)-Capped Silver Nanoparticles Fabricated Rapidly in the Presence of Sunlight.

Green synthesized silver nanoparticles (AgNPs) have enormous applications. Hence, there is an increasing demand to explore diverse bioresources for AgNP fabrication to make the process more cost-effective and rapid as possible. Due to the abundantly present hydroxyl groups of rice starch, it provides ideal sites for metal ion complexation and thereby synthesis of nanoparticles with promising activity. So the study was designed to develop rapid, eco-friendly and cost-effective method for green AgNP synthesis using boiled rice water starch in the presence of sunlight irradiation. The starch-capped nanoparticles (sAgNPs) formed in the study were found to have the surface plasmon absorbance at 439 nm. The study showed optimum yield of sAgNPs when 25% rice starch was treated with aqueous 1 mM AgNO3 for 15 min in the presence of sunlight. Fourier transform infrared spectroscopy analysis provided mechanistic insight into the role of -OH groups of starch in the reduction of AgNO3 to sAgNPs. On further characterization by X-ray diffraction analysis, the sAgNPs were identified to have FCC crystal structure. At the same time, high-resolution transmission electron microscopic analysis showed majority of sAgNPs to have spherical morphology, and dynamic light scattering study revealed the average particle size as 36.3 nm. Further confirmation on presence of AgNPs was carried out by energy-dispersive X-ray spectroscopy. Moreover, the sAgNPs exhibited promising antibacterial activity against foodborne pathogens, Salmonella Typhimurium and Staphylococcus aureus.

Microbially and phytofabricated AgNPs with different mode of bactericidal action were identified to have comparable potential for surface fabrication of central venous catheters to combat Staphylococcus aureus biofilm.

In spite of newer innovations and process improvements, catheter related infections still pose serious threat to hospitalized patients. Silver nanoparticles (AgNPs) are well demonstrated to have antibacterial properties and also have been implemented for surface fabrication of many indwelling medical devices. So, herein we sought to compare the performance of AgNPs generated through biogenic routes using bacteria and plant extract for their antibacterial and antibiofilm potential against biofilm forming Staphylococcus aureus. The biosynthesized AgNPs were characterized by UV- Visible spectroscopy, HR-TEM and EDS analysis. The antibacterial efficiency of the nanoparticles was detected by Disc diffusion assay, MIC and MBC analysis. The antibiofilm properties of the nanoparticles were also investigated. The antibacterial mode of interaction of both nanoparticles on the bacterium was analyzed by HR-TEM. Insight into mode of interaction and mechanism of antibacterial activity of both AgNPs showed them to have promises for surface fabrication of central venous catheters. No study has been conducted so far to compare the efficiency of two different biogenic AgNPs and this highlights the novelty of the current work. Though both AgNPs were observed to exhibit comparable activity in terms of bactericidal and antibiofilm, the mode of bacterial interaction and degree of damage caused was entirely different.

Studies on prevalence of biofilm associated genes and primary observation on sasX gene in clinical isolates of coagulase negative staphylococci (CoNS).

Coagulase negative staphylococci (CoNS) are nosocomial pathogens that cause indwelling medical device associated infections due to its biofilm forming potential and multiple antibiotic resistance. The current study focused on species identification, antibiotic resistance profile and molecular basis of biofilm formation and attachment of CoNS isolated from clinical samples. Along with this, molecular screening for mecA and newly identified surface colonization protein encoded by sasX gene was also conducted. S. epidermidis (n = 19, 47%) was identified as the most prevalent CoNS species and very interestingly two biofilm forming, mecA positive S. epidermidis isolates were found to carry all the biofilm associated genes screened in this study, which indicates its potential to form the strong biofilm. Another novel observation of the study is the detection of sasX gene in one biofilm positive S. epidermidis isolate. The study also identified one doxycycline resistant mecA positive, multidrug resistant S. haemolyticus isolate. In conclusion, the study signifies the existence of multiple biofilm related genes, multidrug resistance and the presence of sasX gene among clinical isolates of CoNS.

Antimicrobial, antibiofilm, and microbial barrier properties of poly (ε-caprolactone)/cloisite 30B thin films.

Development of antibacterial and antibiofilm surfaces is in high demand. In this study, nanocomposite of Poly (ε-caprolactone)/Cloisite 30B was prepared by the solvent casting method. The membranes were characterised by SEM, AFM, and FTIR. Evaluation of water uptake, antimicrobial, antibiofilm, and microbial barrier properties demonstrated a significant antimicrobial and antibiofilm activity against MTCC strain of Staphylococcus haemolyticus and strong biofilm positive Staphylococcus epidermidis of clinical origin at low clay concentrations. These membranes acted as an excellent barrier to the penetration of microorganism. These nanocomposites can have promising applications in various fields including packaging.