title: Facts and evidences on the lyophilization of polymeric nanoparticles for drug delivery.
abstract: Lyophilization has been used to improve the long-term stability of polymeric nanoparticles for drug delivery applications, avoiding their instability in suspension. However, this dehydration process may induce stresses to nanoparticles, mitigated by the use of some excipients such as cryo- and lyoprotectants. Still, the lyophilization of polymeric nanoparticles is frequently based in empirical principles, without considering the physical-chemical properties of formulations and the engineering principles of lyophilization. Therefore, the optimization of formulations and the lyophilization cycle is crucial to obtain a good lyophilizate, and guarantee the preservation of nanoparticle stability. The proper characterization of the lyophilizate and nanoparticles has a great importance in achieving these purposes. This review updates the fundaments involved in the optimization procedures for lyophilization of polymeric nanoparticles, with the aim of obtaining the maximum stability of formulations. Different characterization methods to obtain and guarantee a good lyophilized product are also discussed. A special focus is given to encapsulated therapeutic proteins. Overall, this review is a contribution for the understanding of the parameters involved in the lyophilization of polymeric nanoparticles. This may definitely help future works to obtain lyophilized nanoparticles with good quality and with improved therapeutic benefits.
authors.affiliation: UCIBIO, REQUIMTE, Department of Chemical Sciences - Applied Chemistry Lab, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira 228, 4050-113 Porto, Portugal; CESPU, Instituto de Investigação e Formação Avançada em Ciências e Tecnologias da Saúde and Instituto Universitário de Ciências da Saúde, Rua Central de Gandra 1317, 4585-116 Gandra-Prd, Portugal. Electronic address: pedrofonte86@gmail.com.
authors.forename: Pedro
authors.initials: P
authors.lastname: Fonte
authors.affiliation: UCIBIO, REQUIMTE, Department of Chemical Sciences - Applied Chemistry Lab, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira 228, 4050-113 Porto, Portugal.
authors.forename: Salette
authors.initials: S
authors.lastname: Reis
authors.affiliation: CESPU, Instituto de Investigação e Formação Avançada em Ciências e Tecnologias da Saúde and Instituto Universitário de Ciências da Saúde, Rua Central de Gandra 1317, 4585-116 Gandra-Prd, Portugal; i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal; INEB - Instituto de Engenharia Biomédica, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal. Electronic address: bruno.sarmento@ineb.up.pt.
authors.forename: Bruno
authors.initials: B
authors.lastname: Sarmento
mesh_terms: D000818:Animals; D016503:Drug Delivery Systems; D005612:Freeze Drying; D053758:Nanoparticles / Q000008:administration & dosage / Q000737:chemistry*; D011108:Polymers / Q000008:administration & dosage / Q000737:chemistry*; D011506:Proteins / Q000008:administration & dosage / Q000737:chemistry
chemical_list: D011108:Polymers; D011506:Proteins
keywords: Cryoprotectant; Lyophilization; Lyoprotectant; Nanoparticles; Polymer; Protein stability