Polymeric Carriers for Delivery Systems in Biomedical Applications—In Memory of Professor Andrzej Dworak

Since the appearance of the first civilizations, various substances have been used to improve human health [...].

Since the appearance of the first civilizations, various substances have been used to improve human health. Although nature is undoubtedly the source of many medicinal substances, since the early 19th century there has been an enormous development of pharmaceutical products aimed at treating or improving human health. Over time, the emergence of new generations of therapeutic agents has been observed, including not only small molecules, but also proteins and peptides, monoclonal antibodies, nucleic acids, and living cells. This progress has opened up new possibilities for the use of these therapeutic agents in the treatment of specific diseases, while at the same time causing enormous challenges in delivering them into the body while maintaining their therapeutic usefulness. For the effective action of these agents, it is necessary, among other things, for them to have proper solubility, stability, target location, off-target non-toxicity, controlled pharmacokinetics, possibility of bypassing biological barriers (cell membranes, nucleus) or, in the case of cells, maintaining cell viability and phenotypes [1]. These challenges have compelled scientists to develop a variety of advanced drug delivery systems (DDSs). DDSs are formulations or devices used to transport and release (preferably in a controlled manner) therapeutic agents to their destinations in the body, and to minimize off-target drug accumulation. Thanks to such control of the rate, time, and localization of release of these drugs in the body, the DDSs enable us to achieve maximum therapeutic efficacy. The developed systems for delivering the bioactive agents include various forms, from the conventional (e.g., tablets, capsules, drops, sprays, injections, or creams) to controlled ones (smart, modulated, and targeted delivery systems in the form of micro-and nanoparticles, micelles, liposomes, polymersomes, conjugates, gels, or implants) [2,3].
Polymers, along with metals and ceramics, constitute the most common platform used for DDSs [4,5]. They have many advantages over the other classes, and many of them are well tolerated during contact with a living system without producing any adverse effects. They are non-toxic and biologically inert. Both natural and synthetic polymers can be applied for controlled drug delivery, although the use of synthetic ones is preferable. This is due to the fact that, thanks to the controlled processes of polymerization, it is possible to obtain materials with a highly reproducible structure-function relationship. Some of the polymers are biodegradable, so the problem of their accumulation within the body is eliminated, providing that their degradation by-products are non-toxic, that they do not produce any immune response, or lie below the renal threshold level. Moreover, polymers can be fabricated into complex structures and shapes (e.g., homo-and copolymers, star polymers, dendrimers, branched polymers, micelles, nanoparticles, vesicles, gels, surfaces) leading to a wide range of physicochemical properties. Last but not least, polymers have tunable chemistries, including controllable and responsive properties (e.g., stimuli responsive) and countless possibilities for modifications to achieve desired properties and mimic biological systems. All these beneficial properties of polymers have enabled huge progress in the development of drug delivery technologies, allowing for transportation of not only small drugs, both hydrophilic and hydrophobic, but also proteins and nucleic acids ( Figure 1). This achievement, by improving drug safety and efficacy, may unquestionably facilitate better patient comfort and quality of life.
Polymers 2023, 15, x FOR PEER REVIEW 2 of 5 have tunable chemistries, including controllable and responsive properties (e.g., stimuli responsive) and countless possibilities for modifications to achieve desired properties and mimic biological systems. All these beneficial properties of polymers have enabled huge progress in the development of drug delivery technologies, allowing for transportation of not only small drugs, both hydrophilic and hydrophobic, but also proteins and nucleic acids ( Figure 1). This achievement, by improving drug safety and efficacy, may unquestionably facilitate better patient comfort and quality of life. Over the past 70 years, DDS polymer materials and their designs have progressed from external devices and simple off-the-shelf macroscopic supplies through to microscopic particles and ultimately to complex and rationally designed nanocarriers. The application of DDSs has improved the clinical usefulness of many drugs and enabled new therapeutics, such as anti-cancer and siRNA therapies. However, there are still remaining challenges that drug delivery systems have to overcome to be clinically viable. The next generation of DDSs will need to be able to overcome the biological barriers which limit the delivery of complex therapeutic molecules, and utilize less invasive systems which secrete biomolecules into specific tissues, at specific times and concentrations, sometimes for a prolonged period of time. Therefore, the innovations in the field of polymer materials will be the driving force in overcoming existing boundaries, while the polymer DDSs will still be considered the most active field of biomedical research in pharmaceutical industries and academic laboratories.
This book comprises articles concerning recent advances in natural and synthetic polymeric materials with the desired physical, chemical, biological, and biomechanical properties to match the various requirements of controlled delivery of various therapeutic agents. The book contains reviews and original articles of eminent scientists and friends of Professor Dworak, each of which was published previously as original contributions to the Polymers Special Issue dedicated to the memory of late Professor Andrzej Dworak Over the past 70 years, DDS polymer materials and their designs have progressed from external devices and simple off-the-shelf macroscopic supplies through to microscopic particles and ultimately to complex and rationally designed nanocarriers. The application of DDSs has improved the clinical usefulness of many drugs and enabled new therapeutics, such as anti-cancer and siRNA therapies. However, there are still remaining challenges that drug delivery systems have to overcome to be clinically viable. The next generation of DDSs will need to be able to overcome the biological barriers which limit the delivery of complex therapeutic molecules, and utilize less invasive systems which secrete biomolecules into specific tissues, at specific times and concentrations, sometimes for a prolonged period of time. Therefore, the innovations in the field of polymer materials will be the driving force in overcoming existing boundaries, while the polymer DDSs will still be considered the most active field of biomedical research in pharmaceutical industries and academic laboratories.
This book comprises articles concerning recent advances in natural and synthetic polymeric materials with the desired physical, chemical, biological, and biomechanical properties to match the various requirements of controlled delivery of various therapeutic agents. The book contains reviews and original articles of eminent scientists and friends of Professor Dworak, each of which was published previously as original contributions to the Polymers Special Issue dedicated to the memory of late Professor Andrzej Dworak https://www.mdpi.com/journal/polymers/special_issues/polym_carr_deliv_ biomed_appli_mem_prof_Dworak (accessed on 23 February 2021) Prof. Dworak was an outstanding specialist with experience in the studies of the mechanisms of oxirane and cyclic imines polymerization and controlled radical polymerization of various types of monomers in order to obtain macromolecules with carefully planned structures and properties, including polymers sensitive to stimuli. In his research, he successfully translated knowledge in the field of polymer chemistry and polymer materials into their potential use in medicine and pharmacy. Prof. Dworak initiated many national and European projects in which he carried out studies in the field of basic research, including the preparation and therapeutic use of various types of nanoparticles and polymer nanocontainers carrying different types of active substances. He also managed projects related to the development of polymer supports for the culture and transfer of cell sheets, which significantly accelerated the healing process of burn wounds. The results of Prof. Dworak's research has been published in nearly 150 articles in international journals, and he was the co-author of several patents.
On https://www.mdpi.com/journal/polymers/special_issues/polym_carr_deliv_biomed_ap-pli_mem_prof_Dworak (accessed on 23 February 2021) Prof. Dworak was an outstanding specialist with experience in the studies of the mechanisms of oxirane and cyclic imines polymerization and controlled radical polymerization of various types of monomers in order to obtain macromolecules with carefully planned structures and properties, including polymers sensitive to stimuli. In his research, he successfully translated knowledge in the field of polymer chemistry and polymer materials into their potential use in medicine and pharmacy. Prof. Dworak initiated many national and European projects in which he carried out studies in the field of basic research, including the preparation and therapeutic use of various types of nanoparticles and polymer nanocontainers carrying different types of active substances. He also managed projects related to the development of polymer supports for the culture and transfer of cell sheets, which significantly accelerated the healing process of burn wounds. The results of Prof. Dworak's research has been published in nearly 150 articles in international journals, and he was the co-author of several patents. On