Emma Piacentini

Polycaprolactone multicore-matrix particle for the simultaneous encapsulation of hydrophilic and hydrophobic compounds produced by membrane emulsification and solvent diffusion processes

Co-encapsulation of drugs in the same carrier, as well as the development of microencapsulation processes for biomolecules using mild operating conditions, and the production of particles with tailored size and uniformity are major challenges for encapsulation technologies. In the present work, a suitable method consisting of the combination of membrane emulsification with solvent diffusion is reported for the production of multi-core matrix particles with tailored size and potential application in multi-therapies. In the emulsification step, the production of a W/O/W emulsion was carried out using a batch Dispersion Cell for formulation testing and subsequently a continuous azimuthally oscillating membrane emulsification system for the scaling-up of the process to higher capacities. In both cases precise and gentle control of droplet size and uniformity of the W/O/W emulsion was achieved, preserving the encapsulation of the drug model within the droplet. Multi-core matrix particles were produced in a post emulsification step using solvent diffusion. The compartmentalized structure of the multicore-matrix particle combined with the different chemical properties of polycaprolactone (matrix material) and fish gelatin (core material) was tested for the simultaneous encapsulation of hydrophilic (copper ions) and hydrophobic (α-tocopherol) test components. The best operating conditions for the solidification of the particles to achieve the highest encapsulation efficiency of copper ions and α-tocopherol of 99 (± 4)% and 93(± 6)% respectively were found. The multi-core matrix particle produced in this work demonstrates good potential as a co-loaded delivery system.

Influence of protein bulk properties on membrane surface coverage during immobilization

Biomolecules immobilization is a key factor for many biotechnological applications. For this purpose, the covalent immobilization of bovine serum albumin (BSA), lipase from Candida rugosa and protein G on differently functionalized regenerated cellulose membranes was investigated. Dynamic light scattering and electrophoresis measurements carried out on biomolecules in solution indicated the presence of monomers, dimers and trimers for both BSA and protein G, while large aggregates were observed for lipase. The immobilization rate and the surface coverage on functionalized regenerated cellulose membranes were studied as a function of biomolecule concentration. Results indicated that the saturation coverage of BSA and protein G was concentration independent (immobilized protein amount of 2.40±0.03mg/g and 2.65±0.07mg/g, respectively). Otherwise, a different immobilization kinetics trend was obtained for lipase, for which the immobilized amount increases as a function of time without reaching a saturation value. Atomic force microscopy (AFM) micrographs showed the formation of monolayers for both BSA and protein G on the membrane surface, while a multilayer structure is found for lipase, in agreement with the trends observed in the related immobilization kinetics. As a result, the morphology of the proteins layer on the membrane surface seems to be strictly dependent on the proteins behavior in solution. Besides, the surface coverage has been described for BSA and protein G by the pseudo second order models, the results indicating the surface reaction as the controlling step of immobilization kinetics. Finally, enzyme activity and binding capacity studies indicated the preservation of the biomolecule functional properties.

Preparation of stimulus responsive multiple emulsions by membrane emulsification using con a as biochemical sensor

In this work, a novel strategy for the controlled fabrication of biomolecular stimulus responsive water‐in‐oil‐in‐water (W/O/W) multiple emulsion using the membrane emulsification process was investigated. The emulsions interface was functionalized with a biomolecule able to function as a receptor for a target compound. The interaction between the biomolecular receptor and target stimulus activated the release of bioactive molecules contained within the structured emulsion. A glucose sensitive emulsion was investigated as a model study case. Concanavalin A (Con A) was used as the biomolecular glucose sensor. Various physicochemical strategies for stimulus responsive materials formulation are available in literature, but the preparation of biomolecule‐responsive emulsions has been explored for the first time in this paper. The development of novel drug delivery systems requires advanced and highly precise techniques to obtain their particular properties and targeting requirements. The present study has proven the flexibility and suitability of membrane emulsification for the preparation of stable and functional multiple emulsions containing Con A as interfacial biomolecular receptor able to activate the release of a bioactive molecule as a consequence of interaction with the glucose target molecule. The influence of emulsion interfacial composition and membrane emulsification operating conditions on droplets stability and functional properties have been investigated. The release of the bioactive molecule as a function of glucose stimulus and its concentration has been demonstrated. Biotechnol. Bioeng. 2011; 108:913–923.

1.4 Basic Aspects in Polymeric Membrane Preparation

In this chapter, the methods for the preparation of various types of membranes are described. The chapter begins with the preparation of porous (symmetric and asymmetric) membranes made from polymeric and inorganic material. In particular, for the preparation of polymeric membranes, the phase-inversion method is discussed. The preparation of composite membranes is discussed as well. The chapter is based on a series of lectures Prof. Strathmann has given at ITM-CNR during advanced courses for Ph.D Students and published in the book “An introduction to membrane science and technology”, Strathmann H., Giorno L., Drioli E., CNR, Rome, 2006.

Micro and nano polycaprolactone particles preparation by pulsed back-and-forward cross-flow batch membrane emulsification for parenteral administration.

In the pharmaceutical field, manufacturing processes which are able to make products with tailored size at suitable shear stress conditions and high productivity are important requirements for their industrial application. Cross-flow and premix membrane emulsification are the membrane-based processes generally used for particles preparation at large scale, however some disadvantages still limit their applicability for the production of fragile products. In this work, we investigated, for the first time, the preparation of micro and nano polymeric particles in a size range between 2.35 (±0.14)μm and 210 (±10)nm by using pulsed back-and-forward membrane emulsification for the application in pharmaceutical field. The suitability of the method to produce tailored particles by applying mild shear conditions has been demonstrated. The optimized fluid-dynamic conditions studied allowed the production of particles with target size by selecting the appropriate pore size of the membrane (1 μm and 0.1 μm). The uniformity of the particles could be obtained with an axial velocity of 0.5 ms(-1) (corresponding to a shear stress of 4.1 Pa) that is 9 times lower than the maximum cross flow velocity reported in literature (4.5 ms(-1)).

Pharmaceutical Particles Design by Membrane Emulsification: Preparation Methods and Applications in Drug Delivery

Nowadays, the rational design of particles is an important issue in the development of pharmaceutical medicaments. Advances in manufacturing methods are required to design new pharmaceutical particles with target properties in terms of particle size, particle size distribution, structure and functional activity. Membrane emulsification is emerging as a promising tool for the production of emulsions and solidified particles with tailored properties in many fields. In this review, the current use of membrane emulsification in the production of pharmaceutical particles is highlighted. Membrane emulsification devices designed for small-scale testing as well as membrane-based methods suitable for large-scale production are discussed. A special emphasis is put on the important factors that contribute to the encapsulation efficiency and drug loading. The most recent studies about the utilization of the membrane emulsification for preparing particles as drug delivery systems for anticancer, proteins/peptide, lipophilic and hydrophilic bioactive drugs are reviewed.

1.1 From Biological Membranes to Artificial Biomimetic Membranes and Systems

This chapter aims at describing the biological membrane structure and composition with related functions and properties as a model for development of biohybrid membrane systems as well as synthetic membranes able to mimic the specificity and selectivity of the biomembrane. Besides, intriguing properties such as self-cleaning and self-healing will be discussed.

3.13 Membrane Emulsification Advances and Perspectives

Fundamentals of membrane emulsification processes and their application in emulsions and particles production are discussed. A brief comparison with traditional emulsification methods is reported. Parameters governing emulsion micromanufacturing by membrane emulsification in dynamic and static conditions are illustrated. Advances promoted and technological development still needed to fully exploit the technology is pointed out as well. The use of membrane emulsification for the preparation of simple, double emulsions and particles as well as their use in various fields including food, pharmaceutical, and chemical manufacturing is reported. Highlights on the use of membranes to assist nanoprecipitation for the production of micro- and nanosuspensions are also included.

Microencapsulation by Membrane Emulsification of Biophenols Recovered from Olive Mill Wastewaters

Biophenols are highly prized for their free radical scavenging and antioxidant activities. Olive mill wastewaters (OMWWs) are rich in biophenols. For this reason, there is a growing interest in the recovery and valorization of these compounds. Applications for the encapsulation have increased in the food industry as well as the pharmaceutical and cosmetic fields, among others. Advancements in micro-fabrication methods are needed to design new functional particles with target properties in terms of size, size distribution, and functional activity. This paper describes the use of the membrane emulsification method for the fine-tuning of microparticle production with biofunctional activity. In particular, in this pioneering work, membrane emulsification has been used as an advanced method for biophenols encapsulation. Catechol has been used as a biophenol model, while a biophenols mixture recovered from OMWWs were used as a real matrix. Water-in-oil emulsions with droplet sizes approximately 2.3 times the membrane pore diameter, a distribution span of 0.33, and high encapsulation efficiency (98% ± 1% and 92% ± 3%, for catechol and biophenols, respectively) were produced. The release of biophenols was also investigated.