ABSTRACT
Bacterial cellulose nanocrystals (BCNCs) obtained by enzymatic hydrolysis have been loaded in pullulan biopolymer for use as nanoparticles in the generation of high-oxygen barrier coatings intended for food packaging applications. Bacterial cellulose (BC) produced by Komagataeibacter sucrofermentans was hydrolyzed by two different enzymatic treatments, i.e., using endo-1,4-ß-glucanases (EGs) from Thermobifida halotolerans and cellulase from Trichoderma reesei. The hydrolytic activity was compared by means of turbidity experiments over a period of 145 h, whereas BCNCs in their final state were compared, in terms of size and morphology, by atomic force microscopy (AFM) and dynamic light scattering (DLS). Though both treatments led to particles of similar size, a greater amount of nano-sized particles (≈250 nm) were observed in the system that also included cellulase enzymes. Unexpectedly, transmission electron microscopy (TEM) revealed that cellulose nanoparticles were round-shaped and made of 4-5 short (150-180 nm) piled whiskers. Pullulan/BCNCs nanocomposite coatings allowed an increase in the overall oxygen barrier performance, of more than two and one orders of magnitude (≈0.7 mL·m-2·24 h-1), of pure polyethylene terephthalate (PET) (≈120 mL·m-2·24 h-1) as well as pullulan/coated PET (≈6 mL·m-2·24 h-1), with no significant difference between treatments (hydrolysis mediated by EGs or with the addition of cellulase). BCNCs obtained by enzymatic hydrolysis have the potential to generate high oxygen barrier coatings for the food packaging industry.
ABSTRACT
BACKGROUND: Total knee arthroplasty (TKA) can result in major postoperative blood loss which can impact on the recovery and rehabilitation of patients. It also requires expensive transfusions. The purpose of the study was to investigate whether a hemostatic matrix, composed of cross-linked gelatin and a thrombin solution, would reduce blood loss in patients following TKA. MATERIALS AND METHODS: THIS WAS A PROSPECTIVE, RANDOMIZED, CONTROLLED STUDY (TRIAL REGISTRATION: Hospital S. Salvatore L'Aquila ADJ00843) conducted in 93 patients. Criteria for participation were unilateral TKA for osteoarthritis, and a preoperative hemoglobin level >13 g/dL. The outcomes measured were postoperative hemoglobin and hematocrit levels measured at 24h, 72 h, and 7 days. The mean total postoperative blood loss was calculated from drainage volume, patient blood volume, hematocrit, and red blood cell volume. In addition, the drain output within 24 h following surgery and any transfusion requirements were determined. RESULTS: Hemostatic matrix-treated patients (n = 51) showed significant reductions in calculated postoperative blood loss of 32.3% and 28.7% versus control in men and women, respectively (P < 0.01). Postoperative blood loss after 24 h in drain was significantly less with the hemostatic matrix versus control, as were decreases in hemoglobin levels 7 days post-surgery (each P < 0.01). Three patients in the control group required blood transfusion, whereas no blood transfusions were necessary in the hemostatic matrix group. CONCLUSION: The use of a hemostatic matrix provides a safe and effective means to reduce blood loss and blood transfusion requirements in TKA.