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Magnetically Controlled Targeted Chemotherapy
Published in Neville Willmott, John Daly, Microspheres and Regional Cancer Therapy, 2020
Yet another way to classify drug targeting is based on the transport of carrier across the target tissue microvasculature.27,28 Hence, according to classification V, biochemical targeting refers to extravascular transport due to specific interaction between target cell ligands and drug carrier, e.g., antigen-antibody binding. Biomechanical targeting refers to extravascular drug delivery due to transient, regional opening of endothelial junctions as a result of osmotic imbalance or anoxia following embolization. However, biophysical targeting refers to magnetic drag of responsive drug carrier through endothelium or use of temperature-sensitive drug carrier with concomitant regional hyperthermia. Bioadhesive targeting refers to a combination of biochemical and biophysical effects, e.g., a process in which specific binding of drug carrier to the endothelium is followed by transient alteration in the microvascular barrier, and it ultimately leads to the extravascular transfer of drug carrier.27,28
Drug Targeting to the Lung: Chemical and Biochemical Considerations
Published in Anthony J. Hickey, Sandro R.P. da Rocha, Pharmaceutical Inhalation Aerosol Technology, 2019
Peter A. Crooks, Narsimha R. Penthala, Abeer M. Al-Ghananeem
The use of bioadhesive targeting as a means for specific delivery of drugs has gained some impetus since the late 1980s (Gu et al. 1988). The term bioadhesion refers to interactions involving multiple molecular and usually non-covalent bonds. However, a bioadhesive agent, to be effective as a drug carrier, must initially be trapped or sequestered by endothelial or epithelial cells, followed by multiligand binding of the surface material of the carrier particle to cell surface determinants, which then induces the rapid (10-minute to 15-minute) envelopment of the carrier by the cell either by transcytosis or migrational overgrowth mechanisms, followed by transfer to the proximal tissues. Bioadhesion targeting is, therefore, a combination of biophysical trapping and biochemical adherence. The carrier is usually a hydrophilic macromolecule or microparticulate, and, for systemic delivery, a particle size between 3 μm and 5 μm (non-embolizing) is preferable for pulmonary trapping, whereas larger particle sizes between 5 μm and 250 μm (embolizing) are also usable. Multivalent binding agents may comprise substance such as heparins, lectins, and antibodies to endothelial antigens, epithelial antigens, and glycosylated albumin.
Marine Adhesive Proteins for Novel Applications
Published in Se-Kwon Kim, Marine Biochemistry, 2023
Smit P. Bhavsar, Maushmi S. Kumar, Vandana B. Patravale
Bioadhesives are natural polymeric materials that act as adhesives and studies have proved the possibility of their usage for biomedical and other applications (Zhao et al., 2017; Zhu et al., 2017). The requirements for medical adhesives are crucial; for instance, they should be biocompatible, strongly adhere to numerous surfaces being elastic, and show results in wet conditions as well. Most adhesives comprise one or more of these criteria (Vinters et al., 1985; Li et al., 2017). Synthetic adhesives might be toxic, carcinogenic, allergenic, and fail to exist in severe environmental conditions and/or comply with legislative restrictions. To the contrary, adhesives that are present in nature are biocompatible, nontoxic and capable of sticking to numerous surfaces that are dry, wet, or underwater. This can be temporary or permanent and might not instill an exothermic reaction. Hence, there has been an increase in research focusing on the characterization and biomimetic utilization of biological adhesive systems. Biological attachment is an extremely common feature among several species (Peled-Bianco and Davidovich Pinhas, 2015; Smith et al., 2016). Since conditions for adhesion in aquatic and terrestrial environments are severely different (Ditsche and Summers, 2014), we discuss underwater adhesion. Many attachment devices have evolved uniquely and consist of many biological functions. For example, interstitial meiofauna (organisms living between sand granules of marine or freshwater beaches) have to secure themselves to a substrate to avoid displacement from their environment. Meanwhile, many species show a highly mobile lifestyle. In recent times, research on adhesive secretions has primarily focused on marine invertebrates and permanently attached animals, such as mussels and barnacles (Maier and Butler, 2017; Waite et al., 2017). We have summarized the protein structures and arrangements of various marine adhesives along with their relevant features, in comparison to a unique model system, known as the competitive model of adhesion. Byssus formed by mussels is a prominent adhesive and is widely studied to elucidate its mechanism of adhesion. An outlook for biotechnological production of mussel-inspired materials is being discussed with some unique applications involving the role of the catecholic amino acid 1–3,4-dihydroxyphenylalanine (Dopa) along with specific industries of relevance.
Mucoadhesive drug delivery systems: a promising non-invasive approach to bioavailability enhancement. Part I: biophysical considerations
Published in Expert Opinion on Drug Delivery, 2023
Radha Kulkarni, Suraj Fanse, Diane J. Burgess
Adhesion is defined as a state in which two surfaces are held together by interfacial forces, which may consist of physical and chemical interactions including van der Waals forces, hydrogen bonds, and molecular interlocking. Bioadhesion, a specialized form of adhesion, is the ability of a material (synthetic or biological) to adhere to a biological tissue for an extended period of time by means of interfacial forces [1]. In the context of drug therapy and medicine, not all forms of bioadhesion are found to be desirable. For example, minimal adhesion is desirable to prevent complications such as unwanted thrombus formation and plaque buildup in cardiovascular devices and dental prosthetics, respectively. On the other hand, maximum adhesion and immobility is required for orthopedic implants and drug delivery devices, such as a buccal patch to ensure their safety and efficacy. Mucoadhesion is a subset of bioadhesion, which specifically describes the adhesion of a formulation to the mucus layer that covers certain epithelial tissues [2,3]. This phenomenon has been explored over the past four decades to design specialized mucoadhesive drug delivery systems (MDDS) that increase the contact time of the dosage forms to the tissues.
Treatment challenges and delivery systems in immunomodulation and probiotic therapies for periodontitis
Published in Expert Opinion on Drug Delivery, 2021
Anže Zidar, Julijana Kristl, Petra Kocbek, Špela Zupančič
Nanofibers represent a very promising nanodelivery system for the incorporation of immunomodulatory drugs, or even nanoparticles. Their structure and composition are based on bioadhesive polymers. This defines their potential for high bioadhesivity, which is vital for their prolonged retention in the periodontal pocket, where the drug can be released over a prolonged period [1,150–154]. There have been several review articles already published on nanofibers in general [128,155–157], and on their dental applications in particular [158,159]. For example, the antimicrobial ciprofloxacin that also shows immunomodulatory activity [160–162] was successfully incorporated into a double-layer nanofiber mat, which enabled its controlled release over 3 weeks [163]. Also, chronic wounds represent a pathological condition that is similar to periodontitis, for which nanofibers have been widely investigated. The results from these studies can thus be transferred to the area of periodontitis treatment. Further, nanofibers that include collagen and hyaluronic acid (MW >15 kDa) have been shown to accelerate wound healing, due to their effects on inflammatory cells and their binding to pro-inflammatory mediators, to thus suppress the inflammatory process. The same therapeutic activities can be exploited in periodontitis, along with the incorporation of other immunomodulatory drugs [164,165].
Thiolated okra chitosan nanoparticles: preparation and optimisation as intranasal drug delivery agents
Published in Journal of Microencapsulation, 2020
Bioadhesion is the ability of a polymer material to adhere to a biological tissue for a prolonged period of time (Longer and Robinson 1986, Ugwoke et al. 2001). The bioadhesive polymer can penetrate into the tissue cervices and as a result interpenetration between mucoadhesive polymer chains and mucus occurs. Although natural polysaccharides possess inherent bioadhesive strength, attempts have been made to enhance the bioadhesive strength by introduction of functional groups. Thiomers/Thiolated polymers are second generation mucoadhesive polymers which can form stable covalent bonds with the cysteine rich subdomains of mucin glycoproteins (Gum et al. 1992). The thiol (–SH) side chains of thiolated polymers can form bond with cysteine rich subdomains of mucus glycoprotein resulting in disulphide bonds (-S-S-) between the polymer and the mucus layer (Bernkop-Schnürch 2005) leading to increased residence time and improved bioavailability (Albrecht et al. 2006). Furthermore, thiolated polymers have permeation enhancing, enzyme inhibiting and efflux pump inhibitory properties (Borchard et al.1996). The enhanced mucoadhesive properties of thiolated polymers have been previously reported in thiolated hyaluronic acid (Kafedjiiski et al.2007), thiolated pectin (Sharma and Ahuja 2011), thiolated tamarind seed polysaccharide (Kaur et al. 2012) and thiolated xyloglucan (Mahajan et al. 2013).