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•Polyhydroxyalkanoates a potential biopolymer substitute for conventional plastics.•Critically reviewed various waste streams for sustainable and inexpensive PHA production.•Recent ...advances on fermentation strategies & synthetic biology for higher PHA production.•Discussed PHA- nanocomposites and their application in various sectors.•Future perspectives & technical challenges for efficient waste-bioplastic production addressed.
Polyhydroxyalkanoates (PHA) are appealing as an important alternative to replace synthetic plastics owing to its comparable physicochemical properties to that of synthetic plastics, and biodegradable and biocompatible nature. This review gives an inclusive overview of the current research activities dealing with PHA production by utilizing different waste fluxes generated from food, milk and sugar processing industries. Valorization of these waste fluxes makes the process cost effective and practically applicable. Recent advances in the approaches adopted for waste treatment, fermentation strategies, and genetic engineering can give insights to the researchers for future direction of waste to bioplastics production. Lastly, synthesis and application of PHA-nanocomposites, research and development challenges, future perspectives for sustainable and cost-effective PHB production are also discussed. In addition, the review addresses the useful information about the opportunities and confines associated with the sustainable PHA production using different waste streams and their evaluation for commercial implementation within a biorefinery.
Halloysite nanotubes (HNTs) were tuned with supermagnetic Fe3O4 (M-HNTs) and functionalized with γ-aminopropyltriethoxysilane (APTES) (A-M-HNTs). Gluteraldehyde (GTA) was linked to A-M-HNTs ...(A-M-HNTs-GTA) and explored for covalent laccase immobilization. The structural characterization of M-HNTs, A-M-HNTs, and A-M-HNTs-GTA-immobilized laccase (A-M-HNTs-GTA-Lac) was determined by X-ray photoelectron spectroscopy, field-emission high-resolution transmission electron microscopy, a magnetic property measurement system, and thermogavimetric analyses. A-M-HNTs-GTA-Lac gave 90.20% activity recovery and a loading capability of 84.26 mg/g, with highly improved temperature and storage stabilities. Repeated usage of A-M-HNTs-GTA-Lac revealed a remarkably consistent relative activity of 80.49% until the ninth cycle. The A-M-HNTs-GTA-Lac gave consistent redox-mediated sulfamethoxazole (SMX) degradation up to the eighth cycle. In the presence of guaiacol, A-M-HNTs-GTA-Lac gave elevated SMX degradation compared with 2,2′-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) and syrinialdehyde. Therefore, the A-M-HNTs can serve as supermagnetic amino-functionalized nanoreactors for biomacromolecule immobilization. The obtained A-M-HNTs-GTA-Lac is an environmentally friendly biocatalyst for effective degradation of micropollutants, such as SMX, and can be easily retrieved from an aqueous solution by a magnet after decontamination of pollutants in water and wastewater.
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•PSMGPB nanocomposites were synthesized by low cost facile method for cesium removal.•The PSMGPB nanocomposites were characterized by XPS, XRD, MPMS, TEM, and SEM.•Pectin-stabilized ...separation of graphene oxide sheets enhanced the cesium adsorption.•Based on nonlinear regression, Langmuir model gave the best fit to experimental data.•Thermodynamic study indicated the spontaneous and exothermic nature of adsorption.
This work focused on the development of pectin-stabilized magnetic graphene oxide Prussian blue (PSMGPB) nanocomposites for removal of cesium from wastewater. The PSMGPB nanocomposite showed an improved adsorption capacity of 1.609mmol/g for cesium, compared with magnetic graphene oxide Prussian blue, magnetic pectin Prussian blue, and magnetic Prussian blue nanocomposites, which exhibited adsorption capacities of 1.230, 0.901, and 0.330mmol/g, respectively. Increased adsorption capacity of PSMGPB nanocomposites was attributed to the pectin-stabilized separation of graphene oxide sheets and enhanced distribution of magnetites on the graphene oxide surface. Scanning electron microscopy images showed the effective separation of graphene oxide sheets due to the incorporation of pectin. The optimum temperature and pH for adsorption were 30°C and 7.0, respectively. A thermodynamic study indicated the spontaneous and the exothermic nature of cesium adsorption. Based on non-linear regression, the Langmuir isotherm fitted the experimental data better than the Freundlich and Tempkin models.
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•MCNCs were synthesized by an inexpensive reduction precipitation method.•Adsorptive removal of pure textile dye Acid Red 2 was achieved.•The Redlich–Peterson isotherm gave the best ...fit to experimental adsorption data.•MCNCs were successfully applied for dye removal from real textile wastewater.•Recovery efficiency of 100%, makes MCNCs attractive for further real application.
Magnetic chitosan nanocomposites (MCNCs) were synthesized by an inexpensive reduction precipitation technique using a glutaraldehyde cross-linking agent at room temperature. Successful chitosan coating of iron oxide nanoparticles was confirmed by X-ray photoemission spectroscopy. X-ray diffraction data revealed crystalline particle sizes for the iron oxide and MCNCs to be around 6–7 and 8–9nm, respectively. In addition, the MCNCs exhibited supermagnetic properties having magnetic saturation of 17.5emu/g. The synthesized MCNCs showed 91.60% absorption of Acid Red 2, while iron oxide 16.40% absorption; enhanced performance in MCNCs was resulted from presence of free amino and hydroxyl groups. Furthermore, the optimum pH and adsorbent concentration were 3 and 1.0g/L, respectively. The Redlich–Peterson isotherm fit experimental data better than Langmuir and Freundlich models, based on non-linear regression. Finally, MCNCs showed 96% American Dye Manufacturing Institute (ADMI) value removal and gave recovery efficiency of 100%, making them attractive for further practical applications.
Highly stable gas sensors for high temperatures <400 °C with ultra-fast detection of hydrogen (H2) gas are immediately needed especially for the H2 synthesizing industries that require ...high-temperatures. The Fe3O4-HNTs-APTES-Palladium (M-HNTs-A-Pd) nanocomposite possess exceptional physicochemical characteristics and possible to be ideal candidates for high-temperature H2 gas sensor. In the present work, M-HNTs-A-Pd nanocomposite was successfully synthesized and applied for high-temperature gas sensing. The obtained H2 gas sensing results present that the as-prepared gas sensor has the best gas response towards H2 gas at 300 °C. Also, low sensor response to the interfering gases (nitrogen dioxide (NO2), ethanol (EtOH), hydrogen sulfide (H2S), benzene (C6H6), carbon monoxide (CO), and methane (CH4)) showed the improved selectivity towards hydrogen. The as-prepared sensor also presents stability as shown by its repeatable property after exposed at a different concentration of H2 (250 ppb–100 ppm). The H2-sensing response was systematically described in terms of the adsorption-desorption mechanism. In conclusion, M-HNTs-A-Pd nanocomposites system proves to be an ideal material for the highly-stable H2 gas sensor at higher temperatures.
•M-HNTs-A-Pd nanocomposites were successfully synthesized and applied for high-temperature gas sensing.•The gas sensing results present high selectivity, high stability, and high gas response.•The enhanced gas response is described in terms of the adsorption-desorption mechanism.•M-HNTs-A-Pd nanocomposites proves to be an ideal material for the highly-stable hydrogen gas detection.
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•Chitosan (CTA)-functionalized supermagnetic HNTs (M-HNTs) were synthesized.•Laccase (Lac) was covalently immobilized on M-HNTs–CTA.•M-HNTs–CTA–Lac exhibited better biocatalysis than ...free laccase.•M-HNTs–CTA–Lac exhibited excellent degradation of Direct Red 80 (DR80).•Repeated cycles of DR80 degradation confirmed sustainable and greener biocatalysis.
Halloysite nanotubes (HNTs) were modified with supermagnetic Fe3O4 (M-HNTs) and functionalized with chitosan (CTA) (termed as M-HNTs–CTA). Furthermore, M-HNTs–CTA were cross-linked using glutaraldehyde and applied for covalent laccase immobilization (M-HNTs–CTA–Lac). Facile-synthesized modified HNTs were structurally characterized by scanning electron microscopy, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analyses. M-HNTs–CTA–Lac exhibited 92.74 mg/g of laccase immobilization capacity and 92% of activity recovery. Biochemical properties of M-HNTs–CTA–Lac exhibited higher pH and temperature stabilities, with exceptional reusability capabilities until the 11th cycle. Moreover, M-HNTs–CTA–Lac exhibited 87% of 2,2′-azinobis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS)-mediated Direct Red 80 (DR80) decolorization. By the 11th cycle, M-HNTs–CTA–Lac exhibited 33% DR80 decolorization. Therefore, M-HNTs–CTA can function as CTA-modified supermagnetic nonreactors for immobilization of biomacromolecules. The investigated M-HNTs–CTA–Lac are thus biocompatible and environment-friendly biocatalysts for degradation of textile waste, such as DR80, and can be rapidly retrieved from aqueous solution by a magnet after decontamination of environmental pollutants.
In this study, a defined consortium-AP of Aspergillus ochraceus NCIM-1146 fungi and Pseudomonas sp. SUK1 bacterium was studied to assess its potential for enhanced decolorization and detoxification ...of azo dye Rubine GFL and textile effluent. Developed consortium-AP showed enhanced decolorization of dye (95% in 30 h) and effluent (98% ADMI removal in 35 h) without formation of aromatic amines under microaerophilic conditions. Individual A. ochraceus NCIM-1146 showed only 46% and 5% decolorization of the dye and effluent. However, Pseudomonas sp. SUK1 showed 63% and 44% decolorization of the dye and effluent respectively with the production of aromatic amines. Induction of laccase, veratryl alcohol oxidase, azo reductase and NADH-DCIP reductase in the consortium-AP suggests synergetic reactions of fungal and bacterial cultures for enhanced decolorization process. Differential fate of metabolism of Rubine GFL by an individual and consortium-AP cultures were proposed on the basis of enzymatic status, FTIR and GC-MS analysis. Furthermore, consortium-AP also achieved a significant reduction in COD (96%), BOD (82%) and TOC (48%) of textile effluent. The results of toxicity studies suggest that this consortium may effectively be used for complete detoxification of dye and effluent and has potential environmental implication in cleaning up azo dyes containing effluents.
► Defined consortium-AP showed an enhanced degradation than monocultures. ► Induced oxidoreductive enzymes pattern was found in the consortium. ► Mechanism involved in consortium and individual degradation of dye is discussed. ► COD and TOC reduction gives additional insight into the effluent mineralization. ► Toxicological study confirms the detoxification of dye and effluent.
This study fabricated a nano-biomaterial of supermagnetized α-cellulose (αCS@Fe
3
O
4
) for enhanced osteoconduction of hADSCs (human adipose-derived stem cells). First, the reduction precipitation ...method was successfully employed to synthesize αCS@Fe
3
O
4
. The synthesized material αCS@Fe
3
O
4
was structurally and morphologically characterized by SEM, TEM, XRD, TGA, and XPS analyses. The characterizations confirmed a nanostructural modification of αCS using Fe
3
O
4
nanoparticles. Next, the fabricated material αCS@Fe
3
O
4
was assessed for biocompatibility. The obtained data confirmed the biocompatible nature of the αCS@Fe
3
O
4
. Then, the αCS@Fe
3
O
4
was applied for the osteoconductive differentiation of the hADSCs. The hADSCs osteoconduction was enhanced significantly (11.325 fold increase) in the presence of the αCS@Fe
3
O
4
compared to the control hADSCs. The Alizarin Red S (ARS) staining microscopic images corroborated the osteoconduction enhancement. Furthermore, the relative gene expression of the important osteogenic markers ALP, OCN, and RUNX2 was analyzed. The expression levels were significantly enhanced in the presence of the target material αCS@Fe
3
O
4
. Finally, the immunofluorescent staining of ALP, OCN, and RUNX2 corroborated the enhanced osteoconduction. Thus, in conclusion, αCS@Fe
3
O
4
is a low-cost, economical, biocompatible nano-biomaterial with significant osteoconduction enhancement potential that can be applied in bone defect treatments in the future.
Owing to the ubiquitous availability and simple biocatalysis, the anti-proliferative laccase holds enormous opportunities for anti-cancer applications. However, accessing efficient and specific ...(super-magnetically targetable) new delivery system for anti-proliferative laccase is vital step towards laccase based anti-cancer approach. Therefore, in this investigation, super-magnetized (Fe3O4) and chitosan (CS) functionalized halloysite nanotubes (HNTs) (termed as Fe3O4-HNTs-CS) was facile synthesized. Further, laccase from Trametes versicolor was immobilized on Fe3O4-HNTs-CS (termed as Fe3O4-HNTs-CS-Lac). Then free laccase and Fe3O4-HNTs-CS-Lac were evaluated for anti-proliferative properties against cancer cell lines of liver (HepG2), lung (H460), cervix (Hela) and stomach (AGS). Laccase and Fe3O4-HNTs-CS-Lac gave significant cytotoxicity against all studied cancer cell lines. Moreover, the apoptosis analysis and FE-SEM morphology observations of cells support the anti-proliferative potential of laccase immobilized on Fe3O4-HNTs-CS. Therefore, investigated Fe3O4-HNTs-CS-Lac is natural and super-magnetic nano-biocatalyst, having the significant anti-proliferative potential and furthermore, Fe3O4-HNTs-CS can be used as efficient and specific delivery system for other anti-cancer enzymes.
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•Trametes versicolor laccase gave significant anti-proliferative properties.•Laccase was immobilized on iron oxide-chitosan modified halloysite-nanotubes.•Immobilized laccase retained the significant anti-proliferative potential.•Laccase was anti-proliferative to cells with or without the estrogen-receptors.•Immobilized laccase can be further developed as potential anti-cancer drug.
Removal of biofilms is extremely pivotal in environmental and medicinal fields. Therefore, reporting the new-enzymes and their combinations for dispersal of infectious biofilms can be extremely ...critical. Herein, for the first time, we accessed the enzyme "protease from bovine pancreas type-I (PtI)" for anti-biofilm properties. We further investigated the anti-biofilm potential of PtI in combination with α-amylase from
. (αA). PtI showed a very significant biofilm inhibition effect (86.5%, 88.4%, and 67%) and biofilm prevention effect (66%, 64%, and 70%), against the
,
, and MRSA, respectively. However, the new enzyme combination (
-PtI+αA) exhibited biofilm inhibition effect (78%, 90%, and 93%) and a biofilm prevention effect (44%, 51%, and 77%) against
,
, and MRSA, respectively. The studied enzymes were found not to be anti-bacterial against the
,
, and MRSA. In summary, the PtI exhibited significant anti-biofilm effects against
, MRSA, and
.
-PtI+αA exhibited enhancement of the anti-biofilm effects against
and MRSA biofilms. Therefore, this study revealed that this
-PtI+αA enzymatic system can be extremely vital for the treatment of biofilm complications resulting from
,
, and MRSA.
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