Nejra Omerović

Bio: Nejra Omerović is an academic researcher from University of Novi Sad. The author has contributed to research in topics: Field-effect transistor & Graphene. The author has an hindex of 2, co-authored 5 publications receiving 25 citations.

Antimicrobial nanoparticles and biodegradable polymer composites for active food packaging applications.

Abstract: The food industry faces numerous challenges to assure provision of tasty and convenient food that possesses extended shelf life and shows long-term high-quality preservation. Research and development of antimicrobial materials for food applications have provided active antibacterial packaging technologies that are able to meet these challenges. Furthermore, consumers expect and demand sustainable packaging materials that would reduce environmental problems associated with plastic waste. In this review, we discuss antimicrobial composite materials for active food packaging applications that combine highly efficient antibacterial nanoparticles (i.e., metal, metal oxide, mesoporous silica and graphene-based nanomaterials) with biodegradable and environmentally friendly green polymers (i.e., gelatin, alginate, cellulose, and chitosan) obtained from plants, bacteria, and animals. In addition, innovative syntheses and processing techniques used to obtain active and safe packaging are showcased. Implementation of such green active packaging can significantly reduce the risk of foodborne pathogen outbreaks, improve food safety and quality, and minimize product losses, while reducing waste and maintaining sustainability.

Photo-Induced Doping in a Graphene Field-Effect Transistor with Inkjet-Printed Organic Semiconducting Molecules

Abstract: In this work, we report a novel method of maskless doping of a graphene channel in a field-effect transistor configuration by local inkjet printing of organic semiconducting molecules. The graphene-based transistor was fabricated via large-scale technology, allowing for upscaling electronic device fabrication and lowering the device's cost. The altering of the functionalization of graphene was performed through local inkjet printing of N,N'-Dihexyl-3,4,9,10-perylenedicarboximide (PDI-C6) semiconducting molecules' ink. We demonstrated the high resolution (about 50 µm) and accurate printing of organic ink on bare chemical vapor deposited (CVD) graphene. PDI-C6 forms nanocrystals onto the graphene's surface and transfers charges via π-π stacking to graphene. While the doping from organic molecules was compensated by oxygen molecules under normal conditions, we demonstrated the photoinduced current generation at the PDI-C6/graphene junction with ambient light, a 470 nm diode, and 532 nm laser sources. The local (in the scale of 1 µm) photoresponse of 0.5 A/W was demonstrated at a low laser power density. The methods we developed open the way for local functionalization of an on-chip array of graphene by inkjet printing of different semiconducting organic molecules for photonics and electronics.

Photosensitive junctions based on UV-modified graphene and inkjet-printed organic molecules

Abstract: In this work, we report a novel method of mask-less doping of graphene channel in field-effect transistor configuration by local inkjet printing of organic semiconducting molecules. Graphene-based transistor was fabricated via large-scale technology, allowing for upscaling electronic device fabrication and lowering the device cost. The altering of functionalization of graphene was performed through local inkjet printing of semiconducting molecules: N,N′-Dihexyl- 3,4,9,10-perylenedicarboximide (PDI-C6), 5,5′′′-Dihexyl-2,2′:5′,2′′:5′′,2′′′-quaterthiophene (HEX-4T-HEX) and polyalanine (PANI). We found the effect of UV treatment on fabrication of graphene/organic junctions because of change in graphene hydrophobic properties. We demonstrated the high resolution (about 50 μm) and accurate printing of organic ink on UV treated chemical vapor deposited (CVD) graphene. The PANI/graphene junction demonstrate more stable photoresponse characteristic for 470 nm diode illumination. The characteristics of PDI/graphene junction demonstrate the saturation for high diode power because of organic crystals degradation. The photoresponse of 1 mA/W was demonstrated for PANI/graphene junction at 0.3 V bias voltage. The developed method opens the way for local functionalization of on-chip array of graphene by inkjet printing of different semiconducting organic molecules for photonics and electronics application.

Fabrication of BaTiO3-based thin film heterostructures with ring electrodes by low cost deposition techniques

Abstract: In this paper the fabrication of BaTiO3-based thin film heterostructures with ring silver electrodes by low cost deposition techniques was investigated. BaTiO3, Ba1−xSrxTiO3 (x = 0.1, 0.2, 0.3, 0.4) and BaTi1−xZrxO3 (x = 0.1, 0.2) thin films for potential application in microwave technologies were prepared by chemical solution deposition method on Pt-coated silicon substrates and sintered at different temperatures. The prepared films were examined by SEM, AFM, XRD and Raman spectroscopy in order to study the influence of dopants on microstructure and phase changes. Dielectric and ferroelectric properties of the doped BaTiO3 thin films were also investigated to find the optimal composition and structure for tunable application. Complex shaped silver electrodes suitable for measurements of tunability at GHz frequencies were prepared by inkjet printing method. The electrodes with circular shape were printed on the surface of BaTiO3 based thin films by Dimatix inkjet printer. Precision limits of the method and the influence of printing conditions on electrode size and quality were also investigated.

Plant protein-based food packaging films; recent advances in fabrication, characterization, and applications

Abstract: Plant-based proteins as an alternative to synthetic polymers have attracted the interest of the global packaging industry in the last decade due to their biodegradability, sustainability, environmental, and beneficial health claims. This review covers the recent developments in biodegradable packaging such as edible films/coatings and innovative packaging materials based on plant protein sources. The importance, sources, and techno-functional properties of plant-derived proteins for food packaging are discussed. The impact of different additives on the functionality of plant protein-based biodegradable materials is also investigated. In addition, plant protein-based packaging characteristics and their application in food are also introduced. The sustainability, biodegradability, renewability, and appropriate mechanical and techno-functional properties of proteins from plant origin make them an emerging substitute to the conventional synthetic polymers currently used as food packaging. The functional performance of plant protein-based biodegradable materials can be extended or enhanced by incorporating other additives or biopolymers. Bio-packaging materials made from plant-based proteins provide great potential for enhancing food quality and safety, reducing the environmental pollution. Schematic representation of major plant sources with protein components as the origin of biopolymeric packaging materials for applications in food packaging. • Plant-based protein films/coatings provide great potential for enhancing food quality. • Plant-based protein films/coatings are delivery systems for various bioactives. • Blending plant-based protein with nanoparticles improves functionality of coatings/films. • Plant-based protein packaging characteristics and their application in foods are summarized.

Metal oxide nanoparticles for safe active and intelligent food packaging

Abstract: Background Food safety and food security remain the major concern of consumers and the food industry. Bacterial contamination continues to be a crucial food safety issue. Smart packaging incorporates both active and intelligent components. Intrinsic antibacterial activity, oxygen and ethylene scavenging (active) and the sensing (intelligent) properties of metal oxide nanoparticles are in research focus for application in smart food packaging, especially bio-nanocomposite films. Scope and approach Metal oxide nanoparticle properties are closely linked to their morphology resulting from the synthesis process. In this review, we cover current innovative synthesis methods for obtaining metal oxide nanoparticles and current incorporation techniques used to obtain smart (active and/or intelligent) packaging, focusing on bio-nanocomposites, commonly used metal oxides and future mixed metal or doped metal oxides. Taking into account safety, we focus on current legislation, and methods for risk assessment due to particle release from the packaging material and a summary of cytotoxic studies of metal oxide nanoparticles on human cells and the gut microbiota. Key findings and conclusions Antimicrobial effectiveness of metal oxide nanoparticles is highly dependent on morphology as a result of the synthesis method. Solution casting and electrospinning are innovative methods applied to synthesize metal oxide incorporated biopolymer films for active packaging with improved mechanical and barrier properties combined with active components (antimicrobial, ethylene scavenging). Metal oxides show sensitivity and selectivity to most gases produced during food spoilage. In selection of metal oxide for smart packaging, particle migration and cytotoxic activity are key issues requiring careful and detailed characterization.