Gum Arabic (GA) collected from Acacia senegal trees was used with polyvinyl alcohol (PVA) to prepare of a series of biodegradable membranes doped and non-doped with potassium dichromate (K 2 Cr 2 O 7 ). Adding the K 2 Cr 2 O 7 to the GA/PVA blends slightly decreased their crystallinity index (CI) by about 2 %. Increasing the PVA concentration in the chromated GA/PVA blends was responsible for increasing the CI. Adding the K 2 Cr 2 O 7 to the pure GA solution modified its differential thermal behavior whereby the exothermic reactions occurred between 321°C and 433°C were disappeared. The K 2 Cr 2 O 7 increased the heat change drastically for all the bioplastic blends with the highest increase for the pure GA. Adding K 2 Cr 2 O 7 to the pure PVA increased the nanometric particle size (NPS) significantly. Increasing the PVA concentration in a blend had a greater effect than did the K 2 Cr 2 O 7 on the NPS. The buried bioplastic membranes in the control soil had different count and species of microbial communities. The numbers of bacteria and fungi in the initial soil sample were lower than those for chromated GA membranes and were greater than those for the chromated PVA. All bacterial and fungi species had growth ability and are expected to be detoxification tools of chromium ion-doped blends of GA and PVA leading to a green environment.

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Passivated-carbon quantum dots (P-CQDs) have been attracting great interest as an antimicrobial therapy tool due to their bright fluorescence, lack of toxicity, eco-friendly nature, simple synthetic schemes, and possession of photocatalytic functions comparable to those present in traditional nanometric semiconductors. Besides synthetic precursors, CQDs can be synthesized from a plethora of natural resources including microcrystalline cellulose (MCC) and nanocrystalline cellulose (NCC). Converting MCC into NCC is performed chemically via the top-down route, while synthesizing CODs from NCC can be performed via the bottom-up route. Due to the good surface charge status with the NCC precursor, we focused in this review on synthesizing CQDs from nanocelluloses (MCC and NCC) since they could become a potential source for fabricating carbon quantum dots that are affected by pyrolysis temperature. There are several P-CQDs synthesized with a wide spectrum of featured properties, namely functionalized carbon quantum dots (F-CQDs) and passivated carbon quantum dots (P-CQDs). There are two different important P-CQDs, namely 2,2′-ethylenedioxy-bis-ethylamine (EDA-CQDs) and 3-ethoxypropylamine (EPA-CQDs), that have achieved desirable results in the antiviral therapy field. Since NoV is the most common dangerous cause of nonbacterial, acute gastroenteritis outbreaks worldwide, this review deals with NoV in detail. The surficial charge status (SCS) of the P-CQDs plays an important role in their interactions with NoVs. The EDA-CQDs were found to be more effective than EPA-CQDs in inhibiting the NoV binding. This difference may be attributed to their SCS as well as the virus surface. EDA-CQDs with surficial terminal amino (-NH2) groups are positively charged at physiological pH (-NH3+), whereas EPA-CQDs with surficial terminal methyl groups (-CH3) are not charged. Since the NoV particles are negatively charged, they are attracted to the positively charged EDA-CQDs, resulting in enhancing the P-CQDs concentration around the virus particles. The carbon nanotubes (CNTs) were found to be comparable to the P-CQDs in the non-specific binding with NoV capsid proteins, through complementary charges, π-π stacking, and/or hydrophobic interactions.

Poly β- hydroxyl butrate (PHB) is a polymer produced by bacteria and can be used safely in different modern application to replace biobased plastic which has adverse effects on the environments. This study is aimed to isolate some fungi for PHB degradation and optimise the growth conditions for maximum degradation. Contaminated soil samples were collected from the industrial area of Jeddah and used for fungal isolations. All fungal isolates were screened for PHB biodegradation on solid agar medium. Out of 20 isolates, 2 isolates were the most active in PHB degradation. They were identified as Trichoderma asperellum NM 6, and Aspergillus fumigates NM10 using morphological and molecular methods. The effects of some growth factors on growth and PHB degradation by the two isolated fungi were determined. Growth was measured by either CPV (ml) or dry weight (g/l) while PHB degradation was detected by depolymerase assay (U/ml). Presence of yeast extract (2.5 g/l) and glucose (1 g/l) enhanced both growth and PHB degradation by the two isolates. Similarly, adjusting medium pH at 7-7.5 and incubation at 25°C after for five days led to maximum growth and PHB degradation. The presence of PHB in growth medium enhanced both growth and PHB degradation and the maximum growth (CPV ml or dry weight (g/l) were in medium containing 0.5 g/l of PHB for both tested fungi. The maximum growth, measured by either CPV (ml) or dry weight (g/l), was in the medium that was inoculated with 10x106 spore/ml for the two tested fungi. In conclusion, PHB degradation by the two tested fungi was similar. It was affected by the same physical and biochemical factors and optimisation of these conditions enhanced both growth and degradation process by the two tested fungi.

NDBs were fabricated from gum arabic (GA) and polyvinyl alcohol (PVA) in different ratios using novel techniques (casting, dehydration, and peeling). The GA/PVA blends were cast with a novel vibration-free horizontal flow (VFHF) technique, producing membranes free of air bubble defects with a homogenous texture, smooth surface, and constant thickness. The casting process was achieved on a self-electrostatic template (SET) made of poly-(methyl methacrylate), which made peeling the final product membranes easy due to its non-stick behavior. After settling of the cast membranous blind, sheets were dried using nanometric dehydration under a mild vacuum stream using a novel stratified nanodehydrator (SND) loaded with P2O5. After drying the TBM, the dry, smooth membranes were peeled easily without scratching defects. The physicochemical properties of the NDBs were investigated using FTIR, XRD, TGA, DTA, and AFM to ensure that the novel techniques did not distort the product quality. The NDBs retained their virgin characteristics, namely, their chemical functional groups (FTIR results), crystallinity index (XRD data), thermal stability (TGA and DTA), and ultrastructural features (surface roughness and permeability), as well as their microbial biodegradation ability. Comparing the two TBM’ s precursors, PVA had a higher crystallinity index (CI), more mass loss at higher temperatures, greater thermal stability due to higher heat resistance, and a higher clearance of surface roughness due to its large particle size (PS), as well as its higher permeability parameters, namely pore diameter (PD) and void volume (VV), than those for GA. Accordingly, increasing the PVA allocation in the bioplastic blends can enhance their properties except for mass loss, whereby increasing the GA allocation in the TBM blend reduces its mass loss at an elevated temperature. In addition, there is no statistical difference between the NDBs and ordinary air-dried NDBs in PS, PD, and VV, indicating that the novel procedures used did not distort their parent properties examined, as well as their ability for biodegradation. In comparison to control samples, the separated bacteria and fungus destroyed the NDBs. Pseudomonas spp. and Bacillus spp. were the two main strains of isolated bacteria, and Rhizobus spp. was the main fungus. The nanodehydration method gave the best solution for the prompt drying of water-based biopolymers free of manufacturing defects, with simple and easily acquired machinery required for the casting and peeling tasks, in addition to its wonderful biodegradation behavior when buried in wetted soil.