Aptamer-modified M cell targeting liposomes for oral delivery of macromolecules

The stomach, small intestine, and colon-specific gastrointestinal tract delivery systems for bioactive nutrients

Oral administration is a convenient way to deliver bioactive nutrients. However, the complex and dynamic environment of the gastrointestinal (GI) tract poses distinct challenges. These include the acidic environment of the stomach, limited transport across the GI mucosa, and the risk of enzymatic degradation, all of which can compromise the nutritional effectiveness of orally delivered nutrients. In response to these challenges, various GI tract delivery systems have been developed to target specific regions, such as the stomach, small intestine, or colon, to precisely control the release of bioactive nutrients and enhance their health-promoting benefits. This review critically examines the principles underlying stomach-, small intestine-, and colon-targeted delivery systems, highlighting the selection of appropriate wall materials and the interactions between delivery systems and the mucosal epithelial barrier. Moreover, we describe relevant biological models and quantitative analyses to measure these interactions. In particular, we emphasize the significant advantages offered by colon-targeted delivery systems in maintaining a healthy colonic microenvironment. This review aims to inspire novel concepts and stimulate further research into GI tract delivery systems, offering promising avenues for maximizing the therapeutic effects of bioactive nutrients in practical applications.

Recent advances in functional lipid-based nanomedicines as drug carriers for organ-specific delivery

Lipid-based nanoparticles have emerged as promising drug delivery systems for a wide range of therapeutic agents, including plasmids, mRNA, and proteins. However, these nanoparticles still encounter various challenges in drug delivery, including drug leakage, poor solubility, and inadequate target specificity. In this comprehensive review, we present an in-depth investigation of four distinct drug delivery methods: liposomes, lipid nanoparticle formulations, solid lipid nanoparticles, and nanoemulsions. Moreover, we explore recent advances in lipid-based nanomedicines (LBNs) for organ-specific delivery, employing ligand-functionalized particles that specifically target receptors in desired organs. Through this strategy, LBNs enable direct and efficient drug delivery to the intended organs, leading to superior DNA or mRNA expression outcomes compared to conventional approaches. Importantly, the development of novel ligands and their judicious combination holds promise for minimizing the side effects associated with nonspecific drug delivery. By leveraging the unique properties of lipid-based nanoparticles and optimizing their design, researchers can overcome the limitations associated with current drug delivery systems. In this review, we aim to provide valuable insights into the advancements, challenges, and future directions of lipid-based nanoparticles in the field of drug delivery, paving the way for enhanced therapeutic strategies with improved efficacy and reduced adverse effects.

Advances in Oral Biomacromolecule Therapies for Metabolic Diseases

Metabolic diseases like obesity and diabetes are on the rise, and therapies with biomacromolecules (such as proteins, peptides, antibodies, and oligonucleotides) play a crucial role in their treatment. However, these drugs are traditionally injected. For patients with chronic diseases (e.g., metabolic diseases), long-term injections are accompanied by inconvenience and low compliance. Oral administration is preferred, but the delivery of biomacromolecules is challenging due to gastrointestinal barriers. In this article, we introduce the available biomacromolecule drugs for the treatment of metabolic diseases. The gastrointestinal barriers to oral drug delivery and strategies to overcome these barriers are also explored. We then discuss strategies for alleviating metabolic defects, including glucose metabolism, lipid metabolism, and energy metabolism, with oral biomacromolecules such as insulin, glucagon-like peptide-1 receptor agonists, proprotein convertase subtilisin/kexin type 9 inhibitors, fibroblast growth factor 21 analogues, and peptide YY analogues.

Intestinal nanoparticle delivery and cellular response: a review of the bidirectional nanoparticle-cell interplay in mucosa based on physiochemical properties

Orally administered nanocarriers play an important role in improving druggability, promoting intestinal absorption, and enhancing therapeutic applications for the treatment of local and systemic diseases. However, the delivering efficiency and cell response in mucosa to orally administered nanocarriers is affected by the physiological environment and barriers in the gastrointestinal tract, the physicochemical properties of the nanocarriers, and their bidirectional interactions. Goblet cells secrete and form extracellular mucus, which hinders the movement of nanoparticles. Meanwhile, intestinal epithelial cells may absorb the NPs, allowing for their transcytosis or degradation. Conversely, nanoparticle-induced toxicity may occur as a biological response to the nanoparticle exposure. Additionally, immune response and cell functions in secretions such as mucin, peptide, and cytokines may also be altered. In this review, we discuss the bidirectional interactions between nanoparticles and cells focusing on enterocytes and goblet cells, M cells, and immune cells in the mucosa according to the essential role of intestinal epithelial cells and their crosstalk with immune cells. Furthermore, we discuss the recent advances of how the physiochemical properties of nanoparticles influence their interplay, delivery, and fate in intestinal mucosa. Understanding the fate of nanoparticles with different physiochemical properties from the perspective of their interaction with cells in mucosa provides essential support for the development, rational design, potency maximation, and application of advanced oral nanocarrier delivery systems.

Research Progress on Peptide Drugs for Type 2 Diabetes and the Possibility of Oral Administration

Diabetes is a global disease that can lead to a range of complications. Currently, the treatment of type 2 diabetes focuses on oral hypoglycemic drugs and insulin analogues. Studies have shown that drugs such as oral metformin are useful in the treatment of diabetes but can limit the liver's ability to release sugar. The development of glucose-lowering peptides has provided new options for the treatment of type 2 diabetes. Peptide drugs have low oral utilization due to their easy degradation, short half-life, and difficulty passing through the intestinal mucosa. Therefore, improving the oral utilization of peptide drugs remains an urgent problem. This paper reviews the research progress of peptide drugs in the treatment of diabetes mellitus and proposes that different types of nano-formulation carriers, such as liposomes, self-emulsifying drug delivery systems, and polymer particles, should be combined with peptide drugs for oral administration to improve their absorption in the gastrointestinal tract.

Transepithelial transport of nanoparticles in oral drug delivery: From the perspective of surface and holistic property modulation

Despite the promising prospects of nanoparticles in oral drug delivery, the process of oral administration involves a complex transportation pathway that includes cellular uptake, intracellular trafficking, and exocytosis by intestinal epithelial cells, which are necessary steps for nanoparticles to enter the bloodstream and exert therapeutic effects. Current researchers have identified several crucial factors that regulate the interaction between nanoparticles and intestinal epithelial cells, including surface properties such as ligand modification, surface charge, hydrophilicity/hydrophobicity, intestinal protein corona formation, as well as holistic properties like particle size, shape, and rigidity. Understanding these properties is essential for enhancing transepithelial transport efficiency and designing effective oral drug delivery systems. Therefore, this review provides a comprehensive overview of the surface and holistic properties that influence the transepithelial transport of nanoparticles, elucidating the underlying principles governing their impact on transepithelial transport. The review also outlines the chosen of parameters to be considered for the subsequent design of oral drug delivery systems.

Current developments of SELEX technologies and prospects in the aptamer selection with clinical applications

Aptamers are single-stranded oligonucleotide sequences capable of binding to specific ligands with high affinity. In this manner, they are like antibodies but have advantages such as lower manufacturing costs, lower immunogenicity, fewer batch-to-batch differences, a longer shelf life, high tolerance to different molecular milieus, and a greater number of potential targets. Due to their special features, they have been used in drug delivery, biosensor technology, therapy, and diagnostics. The methodology that allowed its production was the "Systematic Evolution of Ligands by Exponential enrichment" (SELEX). Unfortunately, the traditional protocol is time-consuming and laborious. Therefore, numerous variants with considerable optimization steps have been developed, nonetheless, there are still challenges to achieving real applications in the clinical field. Among them, are control of in vivo activities, fast renal filtration, degradation by nucleases and toxicity testing. This review focuses on current technologies based on SELEX, the critical factors for successful aptamer selection, and its upcoming biomedical and biotechnological applications.

Aptamer-functionalized liposomes for drug delivery

Among the various targeting ligands for drug delivery, aptamers have attracted much interest in recent years because of their smaller size compared to antibodies, ease of modification, and better batch-to-batch consistency. In addition, aptamers can be selected to target both known and even unknown cell surface biomarkers. For drug loading, liposomes are the most successful vehicle and many FDA-approved formulations are based on liposomes. In this paper, aptamer-functionalized liposomes for targeted drug delivery are reviewed. We begin with the description of related aptamers selection, followed by methods to conjugate aptamers to liposomes and the fate of such conjugates in vivo. Then a few examples of applications are reviewed. In addition to intravenous injection for systemic delivery and hoping to achieve accumulation at target sites, for certain applications, it is also possible to have aptamer/liposome conjugates applied directly at the target tissue such as intratumor injection and dropping on the surface of the eye by adhering to the cornea. While previous reviews have focused on cancer therapy, the current review mainly covers other applications in the last four years. Finally, this article discusses potential issues of aptamer targeting and some future research opportunities.

Nanoparticle delivery systems of functional substances for precision nutrition

Foodborne functional substances have received much attention for their functional benefits in health and disease. However, these substances are easily affected by the adverse environment during production, transportation, or storage. They will also be damaged by the gastric environment and limited by the mucosal barrier after entering the human body, thus affecting the bioavailability of functional substances in the body. The construction of nanoparticle delivery systems is helpful to protect the biological activity of functional substances and improve their solubility, stability, and absorption of substances. Responsive delivery systems help control the release of functional substances in specific environments and targeted sites to achieve nutritional intervention, disease prevention, and treatment. In this chapter, the main types of foodborne functional substances and their commonly used delivery systems were reviewed, and the application of delivery systems in precision nutrition was described from the aspects of environmental stimuli-responsive delivery systems, site-specific delivery systems, and disease-targeted delivery systems.

Biological activity, limitations and steady-state delivery of functional substances for precision nutrition

Food-related functional substances with biological activity serve as a crucial material foundation for achieving precision nutrition, which has gained increasing attraction in regulating physiological functions, preventing chronic diseases, and maintaining human health. Nutritional substances typically include bioactive proteins, peptides, polysaccharides, polyphenols, functional lipids, carotenoids, probiotics, vitamins, saponins, and terpenes. These functional substances play an essential role in precise nutrition. This chapter introduces and summarizes typical functional substances to demonstrate the challenges in precision nutrition for their stability, solubility, and bioavailability. The current status of delivery systems of functional substances is described to give an insight into the development of desirable characteristics, such as food grade status, high loading capacity, site targeting, and controlled release capacity. Finally, the applications of food-borne delivery systems of functional substances for precision nutrition are emphasized to meet the requirement for precision nutrition during nutritional intervention for chronic diseases.

Construction Strategy of Functionalized Liposomes and Multidimensional Application

Liposomes are widely used in the biological field due to their good biocompatibility and surface modification properties. With the development of biochemistry and material science, many liposome structures and their surface functional components have been modified and optimized one by one, pushing the liposome platform from traditional to functionalized and intelligent, which will better satisfy and expand the needs of scientific research. However, a main limiting factor effecting the efficiency of liposomes is the complicated environmental conditions in the living body. Currently, in order to overcome the above problem, functionalized liposomes have become a very promising strategy. In this paper, binding strategies of liposomes with four main functional elements, namely nucleic acids, antibodies, peptides, and stimuli-responsive motif have been summarized for the first time. In addition, based on the construction characteristics of functionalized liposomes, such as drug-carrying, targeting, long-circulating, and stimulus-responsive properties, a comprehensive overview of their features and respective research progress are presented. Finally, the paper critically presents the limitations of these functionalized liposomes in the current applications and also prospectively suggests the future development directions, aiming to accelerate realization of their industrialization.

Targeted Liposomal Drug Delivery: Overview of the Current Applications and Challenges

In drug development, it is not uncommon that an active substance exhibits efficacy in vitro but lacks the ability to specifically reach its target in vivo. As a result, targeted drug delivery has become a primary focus in the pharmaceutical sciences. Since the approval of Doxil® in 1995, liposomes have emerged as a leading nanoparticle in targeted drug delivery. Their low immunogenicity, high versatility, and well-documented efficacy have led to their clinical use against a wide variety of diseases. That being said, every disease is accompanied by a unique set of physiological conditions, and each liposomal product must be formulated with this consideration. There are a multitude of different targeting techniques for liposomes that can be employed depending on the application. Passive techniques such as PEGylation or the enhanced permeation and retention effect can improve general pharmacokinetics, while active techniques such as conjugating targeting molecules to the liposome surface may bring even further specificity. This review aims to summarize the current strategies for targeted liposomes in the treatment of diseases.

A Colorimetric/Fluorescent Dual-Mode Aptasensor for Salmonella Based on the Magnetic Separation of Aptamers and a DNA-Nanotriangle Programmed Multivalent Aptamer

Salmonella infection has emerged as a global health threat, causing death, disability, and socioeconomic disruption worldwide. The rapid and sensitive detection of Salmonella is of great significance in guaranteeing food safety. Herein, we developed a colorimetric/fluorescent dual-mode method based on a DNA-nanotriangle programmed multivalent aptamer for the sensitive detection of Salmonella. In this system, aptamers are precisely controlled and assembled on a DNA nanotriangle structure to fabricate a multivalent aptamer (NTri-Multi-Apt) with enhanced binding affinity and specificity toward Salmonella. The NTri-Multi-Apt was designed to carry many streptavidin-HRPs for colorimetric read-outs and a large load of Sybr green I in the dsDNA scaffold for the output of a fluorescent signal. Therefore, combined with the magnetic separation of aptamers and the prefabricated NTri-Multi-Apt, the dual-mode approach achieved simple and sensitive detection, with LODs of 316 and 60 CFU/mL for colorimetric and fluorescent detection, respectively. Notably, the fluorescent mode provided a self-calibrated and fivefold-improved sensitivity over colorimetric detection. Systematic results also revealed that the proposed dual-mode method exhibited high specificity and applicability for milk, egg white, and chicken meat samples, serving as a promising tool for real bacterial sample testing. As a result, the innovative dual-mode detection method showed new insights for the detection of other pathogens.

Oral delivery of biomacromolecules by overcoming biological barriers in the gastrointestinal tract: an update

INTRODUCTION

Biomacromolecules have proven to be an attractive choice for treating diseases due to their properties of strong specificity, high efficiency, and low toxicity. Besides greatly improving the patient's complaint, oral delivery of macromolecules also complies with hormone physiological secretion, which has become one of the most innovative fields of research in recent years.

AREAS COVERED

Oral delivery biological barriers for biomacromolecule, transport mechanisms, and various administration strategies were discussed in this review, including absorption enhancers, targeting nanoparticles, mucoadhesion nanoparticles, mucus penetration nanoparticles, and intelligent bionic drug delivery systems.

EXPERT OPINION

The oral delivery of biomacromolecules has important clinical implications; however, these are still facing the challenges of low bioavailability due to certain barriers. Various promising technologies have been developed to overcome the barriers and improve the therapeutic effect of oral biomacromolecules. By considering safety and efficacy comprehensively, the development of intelligent nanoparticles based on the GIT environment has demonstrated some promise in overcoming these barriers; however, a more comprehensive understanding of the oral fate of oral biomacromolecules is still required.