Laser‑Based Biofabrication of Biomaterials and Medical Devices

Theodore Maiman demonstrated the first device capable of light amplification by stimulated emission of radiation fifty years ago. Since that time, lasers have found many uses in medicine and surgery because of their ability to direct high energy radiation with a single wavelength to a focused location on the body. Many current medical applications of lasers involve use as an “optical scalpel” in minimally invasive techniques, which are associated with little blood loss, no laser-tissue contact, and accurate removal of unwanted tissue. Lasers are also finding greater use in processing biomaterials, which are defined as materials that are used in medical devices. One advantage of laser-based methods for processing biomaterials is that devices with complex interior geometries can be fabricated in order to precisely meet the requirements of a given application. For example, patient-specific medical devices and prostheses may be prepared based on computed tomography data, magnetic resonance imaging data, or other medical imaging data.

Several recent advances in laser-based processing of biomaterials have involved use of two-photon polymerization. This process utilizes excitation of photoinitiator molecules to initiate chemical reactions involving monomers within a transparent resin. Polymerization and hardening of material occurs in locations where energies exceed the excitation threshold of the photoinitiator. The nonlinear nature of two photon absorption enables excitation of photoinitiator molecules and solidification of material to occur within the diffraction limit; fabrication of sub-micrometer structures out of biocompatible materials has been demonstrated. A variety of three-dimensional small-scale medical devices, including microneedles, small prostheses, and scaffolds for tissue engineering, have been created using two-photon polymerization. For example, microneedles for transdermal drug delivery have been fabricated out of organically-modified ceramic materials and acrylate-based polymers using two-photon polymerization. In recent work, polymer microneedles created using two photon polymerization were shown to enable more rapid distribution of quantum dot solution to the deep epidermis and dermis layers of porcine skin than topical administration.

Inpatient and outpatient medical care will involve increasing use of advanced medical devices, including drug delivery devices, patient-specific prostheses, and artificial tissues. Laser technologies such as two photon polymerization may be used to create novel biomaterials for these complex applications.