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EP-4593765-B1 - METHOD OF MANUFACTURING A SILVER DENDRITE PLATFORM FOR BIOMEDICAL APPLICATIONS

EP4593765B1EP 4593765 B1EP4593765 B1EP 4593765B1EP-4593765-B1

Inventors

  • CONOCI, SABRINA
  • IRRERA, Alessia
  • CALABRESE, Giovanna
  • SCIUTO, Emanuele Luigi
  • LEONARDI, Antonio Alessio
  • SPINELLA, CORRADO ROSARIO
  • FRANCO, Domenico
  • GUGLIELMINO, Salvatore
  • RIZZO, Maria Giovanna

Dates

Publication Date
20260513
Application Date
20231002

Claims (9)

  1. Method of manufacturing a silver dendrite platform (30), comprising the steps of: - providing a silicon wafer stripped of its native surface silicon oxide layer, - immersing said silicon wafer (10) in a solution of silver nitrate and hydrofluoric acid, wherein, in said step of immersing the silicon wafer in the solution of silver nitrate and hydrofluoric acid, the silver nitrate dissociates into NO 3 − anions and Ag + cations, and said Ag + cations then precipitate on the silicon wafer, thus resulting in the formation of multiple silver dentrites (25), characterized in that the silver dendrite platform is for biomedical applications, and in that the method further comprises: - separating the silver dendrites from the silicon wafer thus obtaining the silver dentrite platform comprising a layer of isolated silver dendrites.
  2. Method according to claim 1, wherein the obtained silver dendrites have a fractal-like structure.
  3. Method according to claim 1 or 2, wherein in said step of immersing the silicon wafer in the solution of silver nitrate and hydrofluoric acid, a matrix of silicon nanowires (12) forms on the surface of the silicon wafer by the process of metal-assisted chemical etching, wherein the silver formed on the surface of the wafer acts as catalyst for said chemical etching.
  4. Method according to any one of the preceding claims, wherein said step of immersing the silicon wafer in the solution of silver nitrate and hydrofluoric acid is carried out substantially at room temperature.
  5. Method according to any one of the preceding claims, wherein said step of immersing the silicon wafer in the solution of silver nitrate and hydrofluoric acid is carried out for essentially 30 minutes.
  6. Method according to any one of the preceding claims, wherein the obtained silver dendrites have a length between 50 nm and 20 µm and a thickness between 10 µm and 30 µm.
  7. Method according to any one of claims 2 to 5, wherein the obtained silicon nanowires have a length of about 2 µm.
  8. Prosthetic device (40) comprising at least one silver dendrite platform (30) obtained by the method according to any one of claims 1 to 7.
  9. Prosthetic device according to claim 8, said device being a femoral prosthesis (40) comprising an acetabular cup (41), an acetabular insert (42), a femoral head (43) and a femoral stem (44), wherein the silver dendrite platform is applied between the acetabular cup and the acetabular insert and/or between the acetabular insert and the femoral head and/or between the femoral head and the femoral stem.

Description

Technical Field The present invention relates to a method of manufacturing a silver dendrite platform for biomedical applications. The invention further relates to a prosthetic device comprising said silver dendrite platform. Background Art One of the most dreaded complications following the implantation of a prosthetic device is periprosthetic infection, as the metal surface of the implant is an ideal breeding ground for bacteria and the formation of a biofilm. In Italy the rate of prosthetic infection is 2-5% and the cost for a revision of an infected prosthesis is 4.8 times that of a primary implant. In addition, periprosthetic infection causes bone-destroying processes that lead not only to the loosening of the prosthesis but also to the progressive destruction of the joint as a whole. Among the most widely used systems to reduce biofilm formation in orthopaedic implants is the use of metals, including silver, copper, gold, titanium and zinc, in the preparation of implantable devices. At the nanoparticle scale, however, the most interesting metals seem to be copper and, above all, silver. In fact, silver nanoparticles have been widely studied in recent years because of their ability to reduce the adhesion of fungi and bacteria. However, although silver nanoparticles have shown exceptional antibacterial and anti-biofilm properties, they present cytotoxicity problems that severely limit their use, especially in the biomedical field. Researchers are still trying to determine the optimal amount and size of silver nanoparticles to be used in implantable materials or for doping implantable materials in order to avoid possible adverse effects. Unfortunately, this is one of the most important limitations for the use of silver nanostructures in the manufacture of implantable orthopaedic devices to date. Manel Abouda-Lachiheb et al., "The dual role of silver during silicon etching in HF solution", Nanoscale Research Letters 2012 report that during silicon etching, silver was subjected to have a controversial role. Some researchers debate that silver protects silicon, and, at the same time, other ones confirm that silver catalyzes silicon underneath. The authors give experimental results arguing the dual role that silver has during the formation of silicon nanostructures, and they give a proof that the role of silver depends on the experimental details and the intrinsic properties of silver during its deposition on the silicon wafer. The object of the invention is to overcome the problems and limitations of current prosthetic devices by providing a platform for biomedical applications in the orthopaedic field that exhibits exceptional antimicrobial capabilities while having good compatibility with eukaryotic cells. This and other objects are achieved with the platform for biomedical applications obtained by the method as claimed in the appended claims. Summary of Invention The method of manufacturing a silver dendrite platform according to the invention is defined in claim 1 and comprises the steps of: providing a silicon wafer stripped of its native surface silicon oxide layer,immersing said silicon wafer in a solution of silver nitrate and hydrofluoric acid. In said step of immersing the silicon wafer in the solution of silver nitrate and hydrofluoric acid, the silver nitrate dissociates into NO3− anions and Ag+ cations, and said Ag+ cations then precipitate on the silicon wafer, thus resulting in the formation of multiple silver dendrites. Preferably, said step of immersing the silicon wafer in the solution of silver nitrate and hydrofluoric acid is carried out at room temperature and for essentially 30 minutes. The method further comprises the step of separating the silver dendrites from the silicon wafer thus obtaining a layer of isolated silver dendrites, i.e., the silver dendrite platform. According to the invention, in the step of immersing the silicon wafer in the solution of silver nitrate and hydrofluoric acid, a matrix of silicon nanowires forms on the surface of the silicon wafer by the process of metal-assisted chemical etching, wherein the silver formed on the surface of the wafer acts as catalyst for said chemical etching. Advantageously, the silver dendrites of the platform obtained by the method according to the invention have a fractal-like structure. The method makes it possible to obtain silver dendrites having a length between 50 nm and 20 µm and a thickness between 10 µm and 30 µm. Advantageously, the silver dendrite platform obtained by the method according to the invention exhibits excellent antimicrobial capabilities and has shown good compatibility with eukaryotic cells, therefore being particularly suitable for biomedical applications, especially for prosthetic devices such as orthopaedic or dental implants. The pronounced antimicrobial activity of the silver dendrites of the platform is also due to their enormous surface-to-volume ratio, due to their fractal-like structure, which allow