Joachim Kohn

The International Union of Societies for Biomaterials Science and Engineering (IUSBSE) is a global organization in the field of biomaterials that brings together national and international biomaterials societies. It is dedicated to the advancement of not only biomaterials but also surgical implants, prosthetics, artificial organs, tissue engineering, drug delivery, and regenerative medicine. IUSBSE and the World Biomaterials Congress were established in 1996. This article highlights the efforts and contributions of IUSBSE’s past and current presidents from 1980 to 2024 in both academia and industry. The history of IUSBSE acknowledges its background, its role, and the lifetime contributions of its presidents in fostering international networks among students, researchers, and societies in biomaterials science, as well as advancing academic and industrial progress in support of human health.

The skin’s uppermost layer, the stratum corneum is a very effective barrier against the penetration of compounds including pharmaceuticals and cosmetic actives. To deliver higher amounts of drugs into the skin layers or to deliver drugs deeper into the skin (e.g., into the dermis), several enhancement techniques have been established. These techniques include chemical penetration enhancers as well as physical techniques such as iontophoresis and microneedles. In addition, one of the newer approaches includes the use of nano-based carriers such as metallic nanoparticles and polymeric self-assembling nanospheres. This mini-review explores this new approach of using nano-based drug carriers for skin penetration enhancement. In particular we will explore the use of gold nanoparticles as well as biocompatible tyrosine-derived polymeric nanoparticles known as Tyrospheres. The most investigated carriers in the class of metallic carriers are gold nanoparticles that can be used for both medical as well as diagnostic uses. Many investigators have reported that gold nanoparticles are able to enhance the skin transport and delivery of macromolecular and hydrophilic drugs. Meanwhile, for challenging highly lipophilic and/or unstable compounds such as adapalene and Vitamin D3 packaging them into polymeric nanocarriers such as Tyrospheres enables drug delivery to hair follicles, significantly increased aqueous solubility and resulted in elevated amounts of drug in targeted skin layers. The relatively new approach of using nanotechnological approaches as a way of enhancement of drug delivery to skin shows significant promise over some other established techniques such as the addition of chemical penetration enhancers to formulations used for topical/transdermal uses.

Much of the priorities in drug delivery research are focused on targeted drug delivery for cancer therapies and a wide range of controlled drug release systems for commonly used active pharmaceutical ingredients (APIs). In this “thousand words article” we highlight some of the emerging health threats and future opportunities for drug delivery research. Important emerging health threats include viral pandemics beyond COVID, antibiotic-resistant pathogens, the need for new antifungal therapies, and emerging diseases caused by increasing pollution and climate change. Fundamentally new drugs may be needed. For example, one little known research effort focuses on the development of new antibiotics based on metal-organic frameworks. Finally, new delivery approaches will be needed. This is illustrated by the development of a topical peptide delivery system as a wound dressing for burn patients, combining biotechnology (a new peptide) with polymer science (a new topical delivery system) to address a medical need (burn injury) for which there is currently no effective treatment. Another important trend is the shift in our collective understanding of impact, moving away from “counting papers” to considering the societal benefit of the research including its potential for commercialization. To remain relevant in the coming decade, we need to anticipate and embrace future challenges. This is particularly important for younger scientists.

We report the development of a peptide-polyester block copolymer where protease-mediated resorption is tuned through the chemistry of the polymer backbone and protease specificity is imparted through incorporation of specific peptide sequences.

Here, we describe the characterization of tooth-germ organoids, three-dimensional (3D) constructs cultured in vitro with the potential to develop into living teeth. To date, the methods used to successfully create tooth organoids capable of forming functional teeth have been quite limited. Recently, hydrogel microparticles (HMP) have demonstrated utility in tissue repair and regeneration based on their useful characteristics, including their scaffolding ability, effective cell and drug delivery, their ability to mimic the natural tissue extracellular matrix, and their injectability. These outstanding properties led us to investigate the utility of using HMPs (average diameter: 158 ± 32 µm) derived from methacrylated gelatin (GelMA) (degree of substitution: 100%) to create tooth organoids. The tooth organoids were created by seeding human dental pulp stem cells (hDPSCs) and porcine dental epithelial cells (pDE) onto the HMPs, which provided an extensive surface area for the cells to effectively attach and proliferate. Interestingly, the cell-seeded HMPs cultured on low-attachment tissue culture plates with gentle rocking self-assembled into organoids, within which the cells maintained their viability and morphology throughout the incubation period. The self-assembled organoids reached a volume of ~50 mm³ within two weeks of the in vitro tissue culture. The co-cultured hDPSC-HMP and pDE-HMP structures effectively attached to each other without any externally applied forces. The presence of polarized, differentiated dental cells in these composite tooth-bud organoids demonstrated the potential of self-assembled dental cell HMPs to form tooth-bud organoid-like structures for potential applications in tooth regeneration strategies.

Three-dimensional (3D) printing has emerged as a valuable tool in medicine over the past few decades. With a growing number of applications using this advanced processing technique, new polymer libraries with varied properties are required. Herein, we investigate tyrosol-based poly(ester-arylate)s as biodegradable inks in fused deposition modeling (FDM). Tyrosol-based polycarbonates and polyesters have proven to be useful biomaterials due to their excellent tunability, nonacidic degradation components, and the ability to be functionalized. Polymers are synthesized by polycondensation between a custom diphenol and commercially available diacids. Thermal properties, degradation rates, and mechanical properties are all tunable based on the diphenol and diacid chosen. Evaluation of material print as it relates to chemical structure, molecular weight, and thermal properties was explored. Higher-molecular-weight polymers greater than 50 kDa exhibit thermal degradation during printing and at some points are too viscous to print. It was determined that polymers with lower processing temperatures and molecular weights were printable regardless of the structure. An exception to this was pHTy6 that was printed at 65 kDa with minimal degradation. This is most likely due to its low melting temperature and, as a result, lower printing temperatures. Additionally, chemical improvements were made to incorporate thiol–alkene click chemistry as a means for postprint curing. Low-molecular-weight pHTy6 was end-capped with alkene functionality. This material was then formulated with either a dithiol for chain extension or tetrathiol for cross-linking. Scaffolds were cured after printing for 5, 15, 30 and 60 min intervals where longer cure times resulted in a tougher material. This design builds on the library of biologically active materials previously explored and aims to bring new biomaterials to the field of 3D-printed personal medicine.

New biodegradable polymers are needed for use in drug delivery systems to overcome the high burst release, lack of sustained drug release, and acidic degradation products frequently observed in current formulations. Commercially available poly(lactide-co-glycolide) (PLGA) is often used for particle drug release formulations; however, it is often limited by its large burst release and acidic degradation products. Therefore, a biocompatible and biodegradable tyrosol-derived poly(ester-arylate) library has been used to prepare a microparticle drug delivery system which shows sustained delivery of hydrophobic drugs. Studies were performed using polymers with varying hydrophilicity and thermal properties and compared to PLGA. Various drug solubilizing cosolvents were used to load model drugs curcumin, dexamethasone, nicotinamide, and acyclovir. Hydrophobic drugs curcumin and dexamethasone were successfully loaded up to 50 weight percent (wt %), and a linear correlation between drug wt % loaded and the particle glass transition temperature (T_g) was observed. Both curcumin and dexamethasone were visible on the particle surface at 20 wt % loading and higher. By adjusting the polymer concentration during particle formation, release rates were able to be controlled. Release studies of dexamethasone loaded particles with a lower polymer concentration showed a biphasic release profile and complete release after 47 days. Particles prepared using a higher polymer concentration showed sustained release for up to 77 days. Comparably, PLGA showed a traditional triphasic release profile and complete release after 63 days. This novel tyrosol-derived poly(ester-arylate) library can be used to develop injectable, long-term release formulations capable of providing sustained drug delivery.