Silver nanoparticles (Ag-NPs) have been among the most commonly used nano-materials in our health care system, widely used in a range of biomedical applications, including diagnosis, treatment, drug delivery, medical device coating and for personal health care. Ag-NPs present unique physicochemical properties such as antibacterial, antifungal, antiviral and anti-inflammatory activity. In this matter, bionanocomposites materials, formed by the combination of natural polymers and inorganic components, like hybrid Ag-NPs, represents an important stake in scientific research offering the combined properties inherent to the natural biopolymers and inorganic nanoparticles. Meanwhile, hyaluronic acid (HA), an immunoneutral polysaccharide ubiquitously present in the human body, is an attractive starting materials since can be chemically modified through its reactive functional groups and transformed into many physical forms (viscoelastic solutions, soft or stiff hydrogels or even nanoparticulate fluids) as a biocompatible platform for a wide range of biomedical applications.
Multifunctional hydrogels were enzymatically generated by the crosslinking reaction between silver lignin nanoparticles (Ag-Lig NPs) and thiolated hyaluronic acid (HA-SH). First, Ag-lig NPs were synthesized using a green, eco-friendly procedure from aqueous AgNO3 solution with lignin, one of the most abundant biopolymers in nature, serving as a dual reducing and capping agent. Afterwards, the multiple functional groups present in lignin, mainly phenolic hydroxyls, serve as reactive groups to crosslink with thiol groups from HA by the action of the enzyme laccase. The morphology, swelling properties, and rheological characteristics of the performed HA hydrogels with embedded Ag-lig NPs together with their stability, control over MMP and MPO and cellularROS scavenging were investigated. Finally, the potential toxicology, the silver release from the hydrogel matrix, the anti-inflammatory effect and the antibacterial activity in front of different bacterial stains were addressed to explore their potential biomedical applications.
The occurrence of drug resistance is global healthcare concern, and although new drugs are constantly being sought, the pace of development is slow compared to the evolution and spread of multidrug resistant bacteria. The high persistence of bacteria in the form of both planktonic cells and biofilms on living tissues and medical surfaces calls for novel antibacterial strategies for the prevention and treatment of bacterial infections. In this study, enzymatic disruption of bacterial quorum sensing by acylase and ultrasound assisted nanospherization were innovatively combined to enhance the bactericidal e ffi cacy of the conventional antibiotic gentamicin, lowering the drug dosage. The generated hybrid nanoantibacterials were stable, with zeta potential – 40 ± 0.23 mV and size of 200 ± 1nm. They possessed membrane disrupting capacity and killed the medically relevant Gram-negative Pseudomonas aeruginosa bacteria after 45 min. The synergistic combination demonstrated improved antibiofilm activity compared to the individual counterparts and reduced the resistant P. aeruginosa biofilm up to 6 logs. Moreover, the bactericidal e ffi caicy of the hybrids was not drastically a ff ected in “protein corona” conditions, demonstrating their real application scenario. Further in situ ultrasound assisted synthesis and deposition of the acylase enzyme and gentamicin onto the surface of urinary catheters increased the life span of the medical devices and decreased the occurrence of bacterial biofilms. The obtained hybrid nanoantibacterials with complimentary modes of action were not found innocuous towards human fibroblasts (BJ-5ta cells) and as a such might be valuable alternative to control bacterial diseases at reduced antibiotic dosages.
Osteoarthritis (OA) is a degenerative disease characterised with pain, stiffness and loss of function in the weight-bearing joints, caused by the inflammatory biological molecules that disturb the balance between the tissue synthesis and degradation. Maintaining the composition of the physiological lubricant, named synovial fluid, by restoration of homeostasis is thus a necessary step to retard the OA progression and provide a suitable environment for tissue remodelling.
Thiolated hyaluronic acid (HA-SH) was enzymatically crosslinked with gallic acid (GA) by the action of laccase as a method to prepare multifunctional hydrogels, designed as delivery systems that enable long-term efficiency of biological entities in cell-based therapies. Owing to its characteristics and mild conditions employed, the encapsulation of very unstable and sensitive cargoes is possible, highlighting its potential as a platform for a variety of biomedical applications. A cytokine cocktail (ACC) and chondrocytes cells were encapsulated together as therapy to delay the disease progression and boost the anabolic pathways for recovery of the damaged cartilage. The morphology, swelling ratio, rheological properties and stability of the hydrogels were characterised and optimised in order to fit the requirements of the therapy. The efficiency of the developed platforms was evaluated in vitro against the major factors governing the OA disease, namely the anti-inflammatory effect, cellular ROS scavenging and the inhibitory capacity of the hydrogels towardsdeleterious enzymes as MMPs, MPO and hyalurodinase. Finally, experiments to determine the ability of the cells to survive, growth and differentiate in the multifunctional hydrogels were assessed in order to explore their potential in a cell-based therapies and regenerative medicine.
Perez, S.; Pashkuleva, I.; Gedanken, A.; Vidal, F.; Wey, M.; Sousa, R.A.; Tzanov, T. European & Global Summit for Clinical Nanomedicine and Targeted Medicine p. 200-201 Data de presentació: 2017-05-08 Presentació treball a congrés