Analysis of process parameters on the characteristics of liposomes prepared by ethanol injection with a view to process scale-up: Effect of temperature and batch volume

Liposomes have been extensively used as carriers of several compounds, due to their structural versatility in terms of size, composition, surface charge, lamellarity, and facility to incorporate hydrophilic and hydrophobic substances. Among the methodologies for liposomes production, the ethanol injection technique is probably the most suitable for implementation at industrial scale, mainly due to its simplicity. The effects of the aqueous phase temperature and preparation volume on the characteristics of liposomes produced by this technique were evaluated, seeking to attain criteria for its implementation in large scale. The aqueous phase temperature significantly affects the final characteristics of liposomes obtained by this methodology. By varying this parameter, it is possible to control size distribution and polydispersity of the lipid vesicles. Subsequently, process scale-up was carried out using a 10-fold scale ratio. The adapted power per unit of volume (P/V) scale-up criterion showed to be appropriate to reproduce in larger scale the final characteristics of liposomes produced in smaller scale. The results demonstrate that using the ethanol injection technique, it is possible to obtain a relatively narrow distribution of small unilamellar vesicles, appropriately modulating the experimental conditions. Therefore, the preparation of vesicles with the desired diameter and size distribution was essentially fulfilled.     

Clarification of red raspberry juice using microfiltration with gas backwashing: A viable strategy to maximize permeate flux and minimize a loss of anthocyanins

Red raspberry (Rubus idaeus) juice was produced by maceration of raspberry pulp at 50 °C for 2 h using 400 mg kg^?1 Klerzyme^®150 enzymatic pectolitic preparation followed by raw juice clarification with gelatin and bentonite or cross-flow membrane filtration. A minimal loss of anthocyanins from 630 to 540 mg l^?1 was obtained when the juice was clarified using a ceramic multichannel microfilter (MF) with a pore size of 0.2 μm. A light transmission at 625 nm in MF permeate was above 85% and the residual pectin (900 mg l^?1) was completely removed. During ultrafiltration through ceramic or polysulfone membranes with a molecular weight cut-off of 30–300 kDa, the content of anthocyanins was reduced to 220–370 mg l^?1, but a light transmission at 625 nm was as high as 96%. The permeate flux in MF was maintained at high values above 170 l m^?2 h^?1 at 3 bar for more than 2 h by backwashing the membrane with a compressed air every 6 min for 1 min. The cake compression at high pressures was avoided by short filtration times between backwashing.     

Surface-grafted silica linked with l-lactic acid oligomer: A novel nanofiller to improve the performance of biodegradable poly(l-lactide)

A new surface modification method by grafting l-lactic acid oligomer onto the surface silanol groups of silica nanoparticles has been developed. The surface-grafting reaction is confirmed by IR and ²⁹Si MAS NMR analyses. TEM and SEM results show that grafted SiO₂ (g-SiO₂) nanoparticles can be comparatively uniformly dispersed in chloroform or PLLA matrix, while the unmodified SiO₂ nanoparticles tend to aggregate. The loading of g-SiO₂ nanoparticles in poly(l-lactide) (PLLA) matrix greatly improves the toughness and tensile strength of this material. In contrast, the incorporation of un-grafted SiO₂ nanoparticles into PLLA leads to the deterioration of its mechanical properties. DSC analysis shows that g-SiO₂ nanoparticles can serve as a nucleating agent for the crystallization of PLLA in the composites. SEM characterization shows the tough characteristics and great interfacial combination strength for g-SiO₂ (5 wt%)/PLLA nanocomposites.