Poly(Lactic Acid)/Poly(Butylene Succinate) Dual-Layer Membranes With Cellulose Nanowhisker for Heavy Metal Ion Separation

In this study, poly(lactic acid) (PLA)/poly(butylene succinate) (PBS) dual-layer membranes filled with cellulose nanowhisker (CNWs), were fabricated by employing an integrated method combining water vapor-induced and crystallization-induced phase inversions. Four membranes (denoted as C-neat, C-I, C-II, and C-III) loaded with CNWs in the range of 0-3 wt% were prepared and characterized using various materials research aspects. The use of CNWs fillers was found to synergize the precipitation of the polymer layers in the integrated water vapor-induced and crystallization-induced method. With morphological examination, the C-III membrane showed prominent and well-laminated two layers structure, evidencing the great precipitating effect of 3 wt% CNWs on the crystallization the polymeric layers. The increase in CNWs loadings was found to improve the membrane porosity with, which was accompanied by a decrease in the pore size. The heat resistance of C-neat membrane was enhanced by CNWs loading of 1 wt% (C-I) whereas it decreased with loadings of 2 and 3 wt% (C-II and C-III) due to flaming behaviour of sulphated nanocellulose. Furthermore, The C-III membrane displayed the best mechanical properties in with respect to tensile strength, elongation at break and Young’s modulus compared to other membrane samples. For wastewater filtration performance, the continuous operation test showed that C-III membrane exhibited the highest removal efficiency for both Co2+ and Ni2+ metal ions reaching 83 and 84%, respectively. Thus, it can be concluded that CNWs filled dual-layer membranes have a strong potential for future development for the removal of heavy metal ions from wastewater streams.

Different Approaches to the Synthesis and Applications of Biomedical and Pharmaceutical Smart Biomaterials

In this study, two strategies were used to functionalize cellulose nanowhiskers. Firstly, by grafting its surface with β-cyclodextrin (βCD) for developing drug-nanocarrier. Secondly, by conjugating short polymer segments to its surface for reinforcing Poly(Ɛ-Caprolactone) (PCL), in order to develop nanocomposites with promoted properties suitable for regenerative medicine. In addition, the production and recovery of biodegradable bioplastics poly(3-hydroxybutyrate) (P(3HB)) from agro-industrial residues of hemp hurd biomass was also examined. In the first part, a drug-nanocarrier system based on βCD-grafted bacterial cellulose nanowhisker (BCNC-g-βCD) was developed as a prolonged drug release nanocarrier. Antibiotic Ciprofloxacin (CIP) and anticancer drugs; Doxorubicin (DOX) and Paclitaxel (PTX) were conjugated to BCNC-g-βCD as model drugs to form the drug-nanocarrier (BCNC-g-βCD-drug). Compared with un-grafted BCNC, the developed drug-nanocarrier showed significant increase in drug payloads from 495 ±4 to 810 ±7 µg/mg along with radical improvement in the drug release profiles. Initial burst releases was reduced significantly and prolonged and sustained release for (74.5–90%) of drug payload over 4–5.5 days were observed. In addition, an improved drug release performances were pragmatic in acidic pH of 6.4 that mimicked extracellular tumor cells. In vitro drug release data pointed to zero-order kinetic model with estimated zero-order release constants (K0) of 0.68, 0.74, and 0.79 µg drug/h (at pH 6.4, 37°C) for BCNC-g-βCD-CIP, BCNC-g-βCD-DOX and BCNC-g-βCD-PTX nanosystems, respectively. In the second part, the functionalized bacterial cellulose nanowhisker (BCNW-g-βCD-PCL2000) was synthesized. Reinforcing PCL matrix with 4 wt% of the functionalized nanowhisker resulted in bionanocomposite with promoted bulk properties. Compared to neat PCL, the obtained bionanocomposite showed 115% and 51% improvements in tensile strength and Young’s modulus, respectively; 20% increase in hydrophilicity; 7% increase in degradation rate; and 6% decrease in crystallinity. Gas foaming/combined particulate leaching technique is used to develop highly porous strutures having porosity of 86-95% and interconnected macropores with mean pore diameters of 250-420 µm. Porous scaffolds showed compression moduli values of 5.3-9.1 MPa in the range of cancellous bones. In the third part a dual-function PCL scaffold was fabricated. The envisioned drug-laden scaffold would provide adequate structural and mechanical supports for the newly regenerated tissues and simultaneously serve as localized drug delivery system. In this context, reinforced PCL with 4 wt% of BCNW-g-βCD-PCL2000 and 25 wt% of doxorubicin anticancer drug resulted in drugladen bionanocomposite of combined promoted bulk properties. Improvements of 165% and 107% in tensile strength and Young’s modulus, respectively; 31% in hydrophilicity; 10% in degradation rate; and 8°C increases in thermal stability. The obtained drug-laden porous scaffolds showed compressive moduli in the range of 7.2-12.3 MPa. In vitro drug releases fit the first-order release mechanism and occurred in a diffusion-controlled and sustained manner 60 days without obvious burst releases. The scaffolds will ultimately minimize systemic toxicities of drugs, lessen the number of dosing, and diminish the need for removal procedure. The forth study described prospective trials for greener production and extraction of the biodegradable bioplastics poly(3-hydroxybutyrate) P(3HB) from agro-industrial residues of hemp hurd biomass. Results showed that maximum hydrolysis yield of 72.4% was achieved by alkali pretreatment with 2% NaOH at 135°C for 60 min along with two-step enzymatic hydrolysis and ultrasonication. Total hydrolysate sugar concentration of 53.0 g/L was obtained. Under optimum conditions, total P(3HB) production of 13.4 g/L was achieved within 80 h of fermentation. Ultrasonic-assisted sodium dodecyl sulfate (SDS) has showed effectiveness as economic recovery method. It recovered bioplastics directly from the broth cell concentrate with P(3HB) content of 92%. Number average molecular weights (Mn) of recovered bioplastics were in the range of 150–270 kDa with polydispersity index (Mw/Mn) of 2.1–2.4.

Different Approaches to the Synthesis and Applications of Biomedical and Pharmaceutical Smart Biomaterials

In this study, two strategies were used to functionalize cellulose nanowhiskers. Firstly, by grafting its surface with β-cyclodextrin (βCD) for developing drug-nanocarrier. Secondly, by conjugating short polymer segments to its surface for reinforcing Poly(Ɛ-Caprolactone) (PCL), in order to develop nanocomposites with promoted properties suitable for regenerative medicine. In addition, the production and recovery of biodegradable bioplastics poly(3-hydroxybutyrate) (P(3HB)) from agro-industrial residues of hemp hurd biomass was also examined. In the first part, a drug-nanocarrier system based on βCD-grafted bacterial cellulose nanowhisker (BCNC-g-βCD) was developed as a prolonged drug release nanocarrier. Antibiotic Ciprofloxacin (CIP) and anticancer drugs; Doxorubicin (DOX) and Paclitaxel (PTX) were conjugated to BCNC-g-βCD as model drugs to form the drug-nanocarrier (BCNC-g-βCD-drug). Compared with un-grafted BCNC, the developed drug-nanocarrier showed significant increase in drug payloads from 495 ±4 to 810 ±7 µg/mg along with radical improvement in the drug release profiles. Initial burst releases was reduced significantly and prolonged and sustained release for (74.5–90%) of drug payload over 4–5.5 days were observed. In addition, an improved drug release performances were pragmatic in acidic pH of 6.4 that mimicked extracellular tumor cells. In vitro drug release data pointed to zero-order kinetic model with estimated zero-order release constants (K0) of 0.68, 0.74, and 0.79 µg drug/h (at pH 6.4, 37°C) for BCNC-g-βCD-CIP, BCNC-g-βCD-DOX and BCNC-g-βCD-PTX nanosystems, respectively. In the second part, the functionalized bacterial cellulose nanowhisker (BCNW-g-βCD-PCL2000) was synthesized. Reinforcing PCL matrix with 4 wt% of the functionalized nanowhisker resulted in bionanocomposite with promoted bulk properties. Compared to neat PCL, the obtained bionanocomposite showed 115% and 51% improvements in tensile strength and Young’s modulus, respectively; 20% increase in hydrophilicity; 7% increase in degradation rate; and 6% decrease in crystallinity. Gas foaming/combined particulate leaching technique is used to develop highly porous strutures having porosity of 86-95% and interconnected macropores with mean pore diameters of 250-420 µm. Porous scaffolds showed compression moduli values of 5.3-9.1 MPa in the range of cancellous bones. In the third part a dual-function PCL scaffold was fabricated. The envisioned drug-laden scaffold would provide adequate structural and mechanical supports for the newly regenerated tissues and simultaneously serve as localized drug delivery system. In this context, reinforced PCL with 4 wt% of BCNW-g-βCD-PCL2000 and 25 wt% of doxorubicin anticancer drug resulted in drugladen bionanocomposite of combined promoted bulk properties. Improvements of 165% and 107% in tensile strength and Young’s modulus, respectively; 31% in hydrophilicity; 10% in degradation rate; and 8°C increases in thermal stability. The obtained drug-laden porous scaffolds showed compressive moduli in the range of 7.2-12.3 MPa. In vitro drug releases fit the first-order release mechanism and occurred in a diffusion-controlled and sustained manner 60 days without obvious burst releases. The scaffolds will ultimately minimize systemic toxicities of drugs, lessen the number of dosing, and diminish the need for removal procedure. The forth study described prospective trials for greener production and extraction of the biodegradable bioplastics poly(3-hydroxybutyrate) P(3HB) from agro-industrial residues of hemp hurd biomass. Results showed that maximum hydrolysis yield of 72.4% was achieved by alkali pretreatment with 2% NaOH at 135°C for 60 min along with two-step enzymatic hydrolysis and ultrasonication. Total hydrolysate sugar concentration of 53.0 g/L was obtained. Under optimum conditions, total P(3HB) production of 13.4 g/L was achieved within 80 h of fermentation. Ultrasonic-assisted sodium dodecyl sulfate (SDS) has showed effectiveness as economic recovery method. It recovered bioplastics directly from the broth cell concentrate with P(3HB) content of 92%. Number average molecular weights (Mn) of recovered bioplastics were in the range of 150–270 kDa with polydispersity index (Mw/Mn) of 2.1–2.4.

Fabrication and Characterization of Novel Poly(d-Lactic Acid) Nanocomposite Membrane for Water Filtration Purpose

The development of membrane technology from biopolymer for water filtration has received a great deal of attention from researchers and scientists, owing to the growing awareness of environmental protection. The present investigation is aimed at producing poly(D-lactic acid) (PDLA) membranes, incorporated with nanocrystalline cellulose (NCC) and cellulose nanowhisker (CNW) at different loadings of 1 wt.% (PDNC-I, PDNW-I) and 2 wt.% (PDNC-II PDNW-II). From morphological characterization, it was evident that the nanocellulose particles induced pore formation within structure of the membrane. Furthermore, the greater surface reactivity of CNW particles facilitates in enhancing the surface wettability of membranes due to increased hydrophilicity. In addition, both thermal and mechanical properties for all nanocellulose filled membranes under investigation demonstrated significant improvement, particularly for PDNW-I-based membranes, which showed improvement in both aspects. The membrane of PDNW-I presented water permeability of 41.92 L/m2h, when applied under a pressure range of 0.1–0.5 MPa. The investigation clearly demonstrates that CNWs-filled PDLA membranes fabricated for this investigation have a very high potential to be utilized for water filtration purpose in the future.