Polymeric Nanoparticles Amenable to Simultaneous Installation of Exterior Targeting and Interior Therapeutic Proteins

Ursodeoxycholic Acid-Decorated Zwitterionic Nanoparticles for Orally Liver-Targeted Close-Looped Insulin Delivery

Oral insulin therapies targeting the liver and further simulating close-looped secretion face significant challenges due to multiple trans-epithelial barriers. Herein, ursodeoxycholic acid (UDCA)-decorated zwitterionic nanoparticles (NPs) (UC-CMs@ins) are designed to overcome these barriers, target the liver, and respond to glycemia, thereby achieving oral one-time-per-day therapy. UC-CMs@ins show excellent mucus permeability through the introduction of zwitterion (carboxy betaine, CB). Furthermore, UC-CMs@ins possess superior cellular internalization via proton-assisted amino acid transporter 1 (PAT1, CB-receptor) and apical sodium-dependent bile acid transporter (ASBT, UDCA-receptor) pathways. Moreover, UC-CMs@ins exhibit excellent endolysosomal escape ability and improve the basolateral release of insulin into the bloodstream via the ileal bile acid-binding protein and the heteromeric organic solute transporter (OSTα- OSTβ) routes compared with non-UDCA-decorated C-CMs@ins. Therefore, CB and UDCA jointly overcome mucus and intestinal barriers. Additionally, UC-CMs@ins prevent insulin degradation in the gastrointestinal tract for crosslinked structure, improve insulin accumulation in the liver for UDCA introduction, and effectively regulate glycemia for "closed-loop" glucose control. Surprisingly, oral ingestion of UC-CMs@ins shows a superior effect on glycemia (≈22 h, normoglycemia) and improves postprandial glycemic levels in diabetic mice, illustrating the enormous potential of the prepared NPs as a platform for oral insulin administration in diabetes treatment.

Recent Advances of Engineered Cell Membrane-Based Nanotherapeutics to Combat Inflammatory Diseases

An immune reaction known as inflammation serves as a shield from external danger signals, but an overactive immune system may additionally lead to tissue damage and even a variety of inflammatory disorders. By inheriting biological functionalities and serving as both a therapeutic medication and a drug carrier, cell membrane-based nanotherapeutics offer the potential to treat inflammatory disorders. To further strengthen the anti-inflammatory benefits of natural cell membranes, researchers alter and optimize the membranes using engineering methods. This review focuses on engineered cell membrane-based nanotherapeutics (ECMNs) and their application in treating inflammation-related diseases. Specifically, this article discusses the methods of engineering cell membranes for inflammatory diseases and examines the progress of ECMNs in inflammation-targeted therapy, inflammation-neutralizing therapy, and inflammation-immunomodulatory therapy. Additionally, the article looks into the perspectives and challenges of ECMNs in inflammatory treatment and offers suggestions as well as guidance to encourage further investigations and implementations in this area.

Oral Nanomedicine: Challenges and Opportunities

Compared to injection administration, oral administration is free of discomfort, wound infection, and complications and has a higher compliance rate for patients with diverse diseases. However, oral administration reduces the bioavailability of medicines, especially biologics (e.g., peptides, proteins, and antibodies), due to harsh gastrointestinal biological barriers. In this context, the development and prosperity of nanotechnology have helped improve the bioactivity and oral availability of oral medicines. On this basis, first, the biological barriers to oral administration are discussed, and then oral nanomedicine based on organic and inorganic nanomaterials and their biomedical applications in diverse diseases are reviewed. Finally, the challenges and potential opportunities in the future development of oral nanomedicine, which may provide a vital reference for the eventual clinical transformation and standardized production of oral nanomedicine, are put forward.

Nanotechnology-based delivery systems to overcome drug resistance in cancer

Cancer nanomedicine is defined as the application of nanotechnology and nanomaterials for the formulation of cancer therapeutics that can overcome the impediments and restrictions of traditional chemotherapeutics. Multidrug resistance (MDR) in cancer cells can be defined as a decrease or abrogation in the efficacy of anticancer drugs that have different molecular structures and mechanisms of action and is one of the primary causes of therapeutic failure. There have been successes in the development of cancer nanomedicine to overcome MDR; however, relatively few of these formulations have been approved by the United States Food and Drug Administration for the treatment of cancer. This is primarily due to the paucity of knowledge about nanotechnology and the fundamental biology of cancer cells. Here, we discuss the advances, types of nanomedicines, and the challenges regarding the translation of in vitro to in vivo results and their relevance to effective therapies.

Polymeric nanoparticles (PNPs) for oral delivery of insulin

Successful oral insulin administration can considerably enhance the quality of life (QOL) of diabetes patients who must frequently take insulin injections. Oral insulin administration, on the other hand, is seriously hampered by gastrointestinal enzymes, wide pH range, mucus and mucosal layers, which limit insulin oral bioavailability to ≤ 2%. Therefore, a large number of technological solutions have been proposed to increase the oral bioavailability of insulin, in which polymeric nanoparticles (PNPs) are highly promising for oral insulin delivery. The recently published research articles chosen for this review are based on applications of PNPs with strong future potential in oral insulin delivery, and do not cover all related work. In this review, we will summarize the controlled release mechanisms of oral insulin delivery, latest oral insulin delivery applications of PNPs nanocarrier, challenges and prospect. This review will serve as a guide to the future investigators who wish to engineer and study PNPs as oral insulin delivery systems.

Folic acid-modified reverse micelle-lipid nanocapsules overcome intestinal barriers and improve the oral delivery of peptides

The oral absorption of exenatide, a type 2 diabetes medication, can be increased by employing lipid nanocapsules (LNC). To increase mucus permeability and exenatide intestinal absorption, reverse micelle lipid nanocapsules (RM-LNC) were prepared and their surface was modified with DSPE-PEG-FA. The RM-LNC with surface modification of DSPE-PEG-FA (FA-RM-LNC) were able to target enterocytes and reduce mucus aggregation in the intestine. Furthermore, in vitro absorption at different intestinal sites and flip-flop intestinal loop experiments revealed that LNCs with surface modification significantly increased their absorption efficiency in the small intestine. FA-RM-LNC delivers more drugs into Caco-2 cells via caveolin-, macrophagocytosis-, and lipid raft-mediated endocytosis. Additionally, the enhanced transport capacity of FA-RM-LNC was observed in a study of monolayer transport in Caco-2 cells. The oral administration of exenatide FA-RM-LNC resulted in a prolonged duration of hypoglycemia in diabetic mice and a relative bioavailability (BR) of up to 7.5% in rats. In conclusion, FA-RM-LNC can target enterocytes and has promising potential as a nanocarrier for the oral delivery of peptides.

Efficient oral delivery of resveratrol-loaded cyclodextrin-metal organic framework for alleviation of ulcerative colitis

Developing innovative strategies for the oral administration of phytochemicals presents a promising approach to addressing intestinal diseases. However, numerous challenges persist, including limited therapeutic efficacy, poor bioavailability, and inadequate biocompatibility. In this study, we employed a cross-linked cyclodextrin-metal organic framework (CDF) to encapsulate resveratrol (Res), generating Res-CDF, which was subsequently incorporated into natural polysaccharide hydrogel microspheres (Res-CDF in MPs) for targeted oral delivery to alleviate ulcerative colitis (UC). The underlying adsorption mechanism of Res by γ-CD elucidated by molecular dynamics simulations. Importantly, the Res-CDF in MPs formulation protected against gastric acid degradation while preserving the bioactivity of Res. Moreover, the design enabled specific release of Res-CDF in response to the mildly alkaline environment of the intestinal tract, followed by sustained Res release. In UC mice model, Res-CDF in MPs demonstrated potent anti-inflammatory effects by attenuating pro-inflammatory cytokine production and exhibited antioxidant properties. Additionally, Res-CDF in MPs enhanced the expression of tight junction proteins ZO-1, Occludin, and mucin-2 (Muc-2), thereby maintaining normal intestinal barrier function. This innovative oral delivery strategy capitalizes on the advantageous properties of polysaccharide hydrogel and CDF to augment bioavailability of phytochemicals, laying the groundwork for developing novel oral interventions employing natural phytochemicals to address intestinal-related diseases.

Oral Delivery of Protein Drugs via Lysine Polymer-Based Nanoparticle Platforms

Oral delivery of proteins has opened a new perspective for the treatment of different diseases. However, advances of oral protein formulation are usually hindered by protein susceptibility and suboptimal absorption in the gastrointestinal tract (GIT). Polymeric nano drug delivery systems are considered revolutionary candidates to solve these issues, which can be preferably tunable against specific delivery challenges. Herein, a tailored family of lysine-based poly(ester amide)s (Lys-aaPEAs) is designed as a general oral protein delivery platform for efficient protein loading and protection from degradation. Insulin, as a model protein, can achieve effective internalization by epithelial cells and efficient transport across the intestinal epithelium layer into the systemic circulation, followed by controlled release in physiological environments. After the oral administration of insulin carried by Lys-aaPEAs with ornamental hyaluronic acid (HA), mice with type 1 diabetes mellitus showed an acceptable hypoglycemic effect with alleviated complications. A successful oral insulin delivery is associated with patient comfort and convenience and simultaneously avoids the risk of hypoglycemia compared with injections, which is of great feasibility for daily diabetes therapy. More importantly, this versatile Lys-aaPEAs polymeric library can be recognized as a universal vehicle for oral biomacromolecule delivery, providing more possibilities for treating various diseases.

Material design for oral insulin delivery

Frequent insulin injections remain the primary method for controlling the blood glucose level of individuals with diabetes mellitus but are associated with low compliance. Accordingly, oral administration has been identified as a highly desirable alternative due to its non-invasive nature. However, the harsh gastrointestinal environment and physical intestinal barriers pose significant challenges to achieving optimal pharmacological bioavailability of insulin. As a result, researchers have developed a range of materials to improve the efficiency of oral insulin delivery over the past few decades. In this review, we summarize the latest advances in material design that aim to enhance insulin protection, permeability, and glucose-responsive release. We also explore the opportunities and challenges of using these materials for oral insulin delivery.

Mechanisms of Nanoparticle Transport across Intestinal Tissue: An Oral Delivery Perspective

Oral drug administration has been a popular choice due to patient compliance and limited clinical resources. Orally delivered drugs must circumvent the harsh gastrointestinal (GI) environment to effectively enter the systemic circulation. The GI tract has a number of structural and physiological barriers that limit drug bioavailability including mucus, the tightly regulated epithelial layer, immune cells, and associated vasculature. Nanoparticles have been used to enhance oral bioavailability of drugs, as they can act as a shield to the harsh GI environment and prevent early degradation while also increasing uptake and transport of drugs across the intestinal epithelium. Evidence suggests that different nanoparticle formulations may be transported via different intracellular mechanisms to cross the intestinal epithelium. Despite the existence of a significant body of work on intestinal transport of nanoparticles, many key questions remain: What causes the poor bioavailability of the oral drugs? What factors contribute to the ability of a nanoparticle to cross different intestinal barriers? Do nanoparticle properties such as size and charge influence the type of endocytic pathways taken? In this Review, we summarize the different components of intestinal barriers and the types of nanoparticles developed for oral delivery. In particular, we focus on the various intracellular pathways used in nanoparticle internalization and nanoparticle or cargo translocation across the epithelium. Understanding the gut barrier, nanoparticle characteristics, and transport pathways may lead to the development of more therapeutically useful nanoparticles as drug carriers.

Palmitic acid- and cysteine-functionalized nanoparticles overcome mucus and epithelial barrier for oral delivery of drug

Nanoparticles (NPs) used for oral administration have greatly improved drug bioavailability and therapeutic efficacy. Nevertheless, NPs are limited by biological barriers, such as gastrointestinal degradation, mucus barrier, and epithelial barrier. To solve these problems, we developed the PA-N-2-HACC-Cys NPs loaded with anti-inflammatory hydrophobic drug curcumin (CUR) (CUR@PA-N-2-HACC-Cys NPs) by self-assembled amphiphilic polymer, composed of the N-2-Hydroxypropyl trimethyl ammonium chloride chitosan (N-2-HACC), hydrophobic palmitic acid (PA), and cysteine (Cys). After oral administration, the CUR@PA-N-2-HACC-Cys NPs had good stability and sustained release under gastrointestinal conditions, followed by adhering to the intestine to achieve drug mucosal delivery. Additionally, the NPs could penetrate mucus and epithelial barriers to promote cellular uptake. The CUR@PA-N-2-HACC-Cys NPs could open tight junctions between cells for transepithelial transport while striking a balance between mucus interaction and diffusion through mucus. Notably, the CUR@PA-N-2-HACC-Cys NPs improved the oral bioavailability of CUR, which remarkably relieved colitis symptoms and promoted mucosal epithelial repair. Our findings proved that the CUR@PA-N-2-HACC-Cys NPs had excellent biocompatibility, could overcome mucus and epithelial barriers, and had significant application prospects for oral delivery of the hydrophobic drugs.

Specific ion effects on the aggregation of polysaccharide-based polyelectrolyte complex particles induced by monovalent ions within Hofmeister series

Polysaccharide-based polyelectrolyte complex (PEC) particles have been utilized as carriers for drug delivery systems (DDS) and as building components for material development. Despite their versatility, the aggregation mechanism of PEC particles in the presence of salts remains unclear. To clarify the aggregation mechanism, the specific ion effects of monovalent salts within the Hofmeister series on the aggregation behavior of PEC particles composed of chitosan and chondroitin sulfate C, which are often used as DDS carriers and materials, were studied. Here, we found that weakly hydrated chaotropic anions promoted the aggregation of positively charged PEC particles. The hydrophobicity of the PEC particles was increased by these ions. Strongly hydrated ions such as Cl^- are less likely to accumulate in these particles, whereas weakly hydrated chaotropic ions such as SCN^- are more likely to accumulate. Molecular dynamics simulations suggested that the hydrophobicity of PECs might be strengthened by ions due to changes in intrinsic and extrinsic ion pairs and hydrophobic interactions. Based on our results, it is expected that the control of surface hydrophilicity or hydrophobicity is an effective approach for controlling the stability of PEC particles in the presence of ions.

Engineering fucoxanthin-loaded probiotics' membrane vesicles for the dietary intervention of colitis

Extracellular vesicles (EVs) are very attractive as carriers of active components due to their good immunological and their ability to penetrate the physiological barrier that synthetic delivery carriers cannot penetrate. However, the low secretion capacity of EVs limited its widespread adoption, let alone the lower yield of EVs loaded with active components. Here, we report a large-scale engineering preparation strategy of synthetic probiotic membrane vesicles for encapsulating fucoxanthin (FX-MVs), an intervention for colitis. Compared with the EVs naturally secreted by probiotics, the engineering membrane vesicles showed a 150-fold yield and richer protein. Moreover, FX-MVs improved the gastrointestinal stability of fucoxanthin and inhibited H₂O₂-induced oxidative damage by scavenging free radicals effectively (p < 0.05). The in vivo results showed that FX-MVs could promote the polarization of macrophages to M2 type, prevent the injury and shortening of colon tissue (p < 0.05), and improve the colonic inflammatory response. Consistently, proinflammatory cytokines were effectively suppressed after FX-MVs treatment (p < 0.05). Unexpectedly, such engineering FX-MVs could also reshape the gut microbiota communities and improve the abundance of short-chain fatty acids in the colon. This study lays a foundation for developing dietary interventions using natural foods to treat intestinal-related diseases.

Recent Advances in Oral and Transdermal Protein Delivery Systems

Protein and peptide drugs are predominantly administered by injection to achieve high bioavailability, but this greatly compromises patient compliance. Oral and transdermal drug delivery with minimal invasiveness and high adherence represent attractive alternatives to injection administration. However, oral and transdermal administration of bioactive proteins must overcome biological barriers, namely the gastrointestinal and skin barriers, respectively. The rapid development of new materials and technologies promises to address these physiological obstacles. This review provides an overview of the latest advances in oral and transdermal protein delivery, including chemical strategies, synthetic nanoparticles, medical microdevices, and biomimetic systems for oral administration, as well as chemical enhancers, physical approaches, and microneedles in transdermal delivery. We also discuss challenges and future perspectives of the field with a focus on innovation and translation.

In Situ Polymerization of Zwitterions on Therapeutic Proteins to Enable Their Effective Oral Delivery

Oral administration of protein drugs has always been challenging owing to various intestinal barriers. Herein, we developed an efficient oral protein delivery strategy by using in situ polymerization of zwitterions to encapsulate proteins, which were then loaded into enteric coated capsules for oral feeding. After oral administration of such capsules, the enteric coating would be degraded once the capsule enters the intestine, releasing polyzwitterion/protein nanocomplexes. With the help of polyzwitterion modification, such nanocomplexes were able to pass through the mucus and cellular barriers, likely by the proton-assisted amino acid transporter 1 (PAT1) pathway. Such a polyzwitterion-based protein encapsulation strategy could allow for effective oral delivery of different proteins, including bovine serum albumin (BSA), insulin, and antibodies. Using this strategy, the oral bioavailabilities of insulin and immunoglobin G (IgG) were measured to be as high as 16.9% and 12.5%, respectively. Notably, oral feeding of polyzwitterion/insulin capsules could effectively lower the blood glucose level of diabetic animals (mice, rats, and pigs). Moreover, polyzwitterion/antiprogramed death-1 (αPD-1) capsules were able to induce efficient antitumor immune responses, showing significant tumor inhibition effects toward B16F10- and 4T1-tumor bearing mouse models after oral administration. No significant toxic effect was observed for such oral protein formulations in the treated animals. Our work presents a strategy for the efficient oral delivery of protein drugs, including those with large molecular weights (e.g., antibodies) that can hardly be orally delivered using existing technologies.

Progress in oral insulin delivery by PLGA nanoparticles for the management of diabetes

Currently, the only practical way to treat type 1 and advanced insulin-dependent type 2 diabetes mellitus (T1/2DM) is the frequent subcutaneous injection of insulin, which is significantly different physiologically from endogenous insulin secretion from pancreatic islets and can lead to hyperinsulinemia, pain, and infection in patients with poor compliance. Hence, oral insulin delivery has been actively pursued to revolutionize the treatment of insulin-dependent diabetes. In this review, we provide an overview of recent progress in developing poly(lactic co-glycolic acid) (PLGA) nanoparticles (NPs) for oral insulin delivery. Different strategies for insulin-loaded PLGA NPs to achieve normoglycemic effects are discussed. Finally, challenges and future perspectives of PLGA NPs for oral insulin delivery are put forward.

Development of a Lysine-Based Poly(ester amide) Library with High Biosafety and a Finely Tunable Structure for Spatiotemporal-Controlled Protein Delivery

With the fast growth of protein therapeutics, efficient, precise, and universal delivery platforms are highly required. However, very few reports have discussed the progress of precisely spatiotemporal-controlled protein delivery. Therefore, a mini library of well-designed amino acid-based poly(ester amide)s derived from lysine (Lys-aaPEAs) has been developed. Lys-aaPEAs can interact with and encapsulate proteins into nanocomplexes via electrostatic interactions. The chemical structure of Lys-aaPEAs can be finely tuned by changing the type and molar ratio of the monomers. Studies of structure-function relationships reveal that the carbon chain length of diacid/diol segments, hydrophilicity, and electrical properties affect the polymer-protein interaction, cell-material interaction, and, therefore, the outcome of protein delivery. By modulating the structures of Lys-aaPEAs, the delivery systems could present customized physiochemical and biological properties and perform time- and space-specific protein release and delivery without causing any systematic toxicity. The screened systems exhibited prolonged hypoglycemic activity and superior biosafety in vivo, using insulin as a model protein and a mouse model bearing type 1 diabetes mellitus (T1DM). This work establishes a novel lysine-based polymer platform for spatiotemporal-controlled protein delivery and offers a paradigm of precise structure-function controllability for designing the next generation of polymers.

Exploring Intestinal Surface Receptors in Oral Nanoinsulin Delivery

Subcutaneous and inhaled insulins are associated with needle phobia, lipohypertrophy, lipodystrophy, and cough in diabetes treatment. Oral nanoinsulin has been developed, reaping the physiologic benefits of peroral administration. This review profiles intestinal receptors exploitable in targeted delivery of oral nanoinsulin. Intestinal receptor targeting improves oral insulin bioavailability and sustains blood glucose-lowering response. Nonetheless, these studies are conducted in small animal models with no optimization of insulin dose, targeting ligand type and content, and physicochemical and molecular biologic characteristics of nanoparticles against the in vivo/clinical diabetes responses as a function of the intestinal receptor population characteristics with diabetes progression. The interactive effects between nanoinsulin and antidiabetic drugs on intestinal receptors, including their up-/downregulation, are uncertain. Sweet taste receptors upregulate SGLT-1, and both have an undefined role as new intestinal targets of nanoinsulin. Receptor targeting of oral nanoinsulin represents a viable approach that is relatively green, requiring an in-depth development of the relationship between receptors and their pathophysiological profiles with physicochemical attributes of the oral nanoinsulin. SIGNIFICANCE STATEMENT: Intestinal receptor targeting of oral nanoinsulin improves its bioavailability with sustained blood glucose-lowering response. Exploring new intestinal receptor and tailoring the design of oral nanoinsulin to the pathophysiological state of diabetic patients is imperative to raise the insulin performance to a comparable level as the injection products.

Atropine-functionalized gold nanoparticles binding to muscarinic receptors after passage across the intestinal epithelium

Gold nanoparticles have a high potential to be a treatment of diseases by their specific drug delivery properties and multivalent receptor stimulation. For the present project, spherical gold nanoparticles were synthesized and functionalized with the muscarinic receptor antagonist atropine (Au-MUDA-AT NPs). The diameter of the gold core could precisely be controlled by using different synthetic methods and reducing agents resulting in functionalized gold nanoparticles with diameters ranging from 8 to 16 nm. The ability to interact with intestinal muscarinic receptors is size-dependent. When using intestinal chloride secretion induced by the stable acetylcholine derivative, carbachol, as read-out, the strongest inhibition, i.e. the most efficient blockade of muscarinic receptors, was observed with 13 nm sized Au-MUDA-AT NPs. Functional experiments indicate that Au-MUDA-AT NPs with a diameter of 14 nm are able to pass the intestinal mucosa in a time-dependent manner after administration to the intestinal lumen. For example, luminally administered Au-MUDA-AT NPs inhibited contractions of the small intestinal longitudinal muscle layer induced by electrical stimulation of myenteric neurons. A similar inhibition of basolateral epithelial receptors was observed after luminal administration of Au-MUDA-AT NPs when using carbachol-induced chloride secretion across the intestinal epithelium as a test system. Thus, Au-MUDA-AT NPs might be a therapeutic tool for the modulation of intestinal secretion and motility after oral application in the future.

Safer plant-based nanoparticles for combating antibiotic resistance in bacteria: A comprehensive review on its potential applications, recent advances, and future perspective

BACKGROUND

Antibiotic resistance is one of the current threats to human health, forcing the use of drugs that are more noxious, costlier, and with low efficiency. There are several causes behind antibiotic resistance, including over-prescription of antibiotics in both humans and livestock. In this scenario, researchers are shifting to new alternatives to fight back this concerning situation.

SCOPE AND APPROACH

Nanoparticles have emerged as new tools that can be used to combat deadly bacterial infections directly or indirectly to overcome antibiotic resistance. Although nanoparticles are being used in the pharmaceutical industry, there is a constant concern about their toxicity toward human health because of the involvement of well-known toxic chemicals (i.e., sodium/potassium borohydride) making their use very risky for eukaryotic cells.

KEY FINDINGS AND CONCLUSIONS

Multiple nanoparticle-based approaches to counter bacterial infections, providing crucial insight into the design of elements that play critical roles in the creation of antimicrobial nanotherapeutic drugs, are currently underway. In this context, plant-based nanoparticles will be less toxic than many other forms, which constitute promising candidates to avoid widespread damage to the microbiome associated with current practices. This article aims to review the actual knowledge on plant-based nanoparticle products for antibiotic resistance and the possible replacement of antibiotics to treat multidrug-resistant bacterial infections.

Recent Advances of Poly(ester amide)s-Based Biomaterials

Biodegradable and biocompatible biomaterials have offered much more opportunities from an engineering standpoint for treating diseases and maintaining health. Poly(ester amide)s (PEAs), as an outstanding family among such biomaterials, have risen overwhelmingly in the past decades. These synthetic polymers have easily and widely available raw materials and a diversity of synthetic approaches, which have attracted considerable attention. More importantly, combining the superiorities of polyamides and polyesters, PEAs have emerged with better functions. They could have improved biodegradability, biocompatibility, and cell-material interactions. The PEAs derived from α-amino acids even allow the introduction of pendant sites for further modification or functionalization. Meanwhile, it is gradually recognized that the chemical structures are closely related to the physiochemical and biological properties of PEAs so that their properties can be precisely controlled. PEAs therefore become significant materials in the biomedical fields. This review will attempt to summarize the recent progress in the development of PEAs with respect to the preparation materials and methods, structure-property relationships along with their latest biomedical accomplishments, especially for drug delivery and tissue engineering.

Immuno-Engineered Nanodecoys for the Multi-Target Anti-Inflammatory Treatment of Autoimmune Diseases

Overactivated T cells and overproduced pro-inflammatory cytokines form a self-amplified signaling loop to continuously exacerbate the dysregulated inflammatory response and propel the progression of autoimmune diseases (AIDs). Herein, immuno-engineered nanodecoys (NDs) based on poly(lactic-co-glycolic acid) nanoparticles coated with programmed death-ligand 1 (PD-L1)-expressing macrophage membrane (PRM) are developed to mediate multi-target interruption of the self-promoted inflammatory cascade in AIDs. The PRM collected from IFN-γ-treated RAW 264.7 cells possesses elevated surface levels of adhesion molecule receptors and pro-inflammatory cytokine receptors, and, thus, systemically administered PRM NDs afford higher accumulation level in inflamed tissues and stronger scavenging efficiency toward multiple pro-inflammatory cytokines. More importantly, IFN-γ treatment induces remarkable PD-L1 expression on PRM, thereby allowing PRM NDs to bind membrane-bound programmed death-1 (PD-1) on CD4⁺ T cell surfaces or neutralize free soluble PD-1, which reconstructs the PD-1/PD-L1 inhibitory axis to suppress CD4⁺ T cell activation and restore immune tolerance. As such, PRM NDs provoke potent and cooperative anti-inflammatory and immune-suppressive efficacies to alleviate autoimmune damages in Zymosan A-induced arthritis mice and dextran sulfate sodium-induced ulcerative colitis mice. This study provides an enlightened example for the immuno-engineering of cell-membrane-based NDs, rendering promising implications into the treatment of AIDs via multi-target immune-modulation.

Efficient oral insulin delivery enabled by transferrin-coated acid-resistant metal-organic framework nanoparticles

Oral protein delivery is considered a cutting-edge technology to improve patients' quality of life, offering superior patient compliance and convenience compared with injections. However, oral protein formulation has stagnated because of the instability and inefficient penetration of protein in the gastrointestinal tract. Here, we used acid-resistant metal-organic framework nanoparticles (UiO-68-NH₂) to encapsulate sufficient insulin and decorated the exterior with targeting proteins (transferrin) to realize highly efficient oral insulin delivery. The UiO-68-NH₂ nanocarrier with proper pore size achieved high insulin loading while protecting insulin from acid and enzymatic degradation. Through receptor-mediated transcellular pathway, the transferrin-coated nanoparticles realized efficient transport across the intestinal epithelium and controlled insulin release under physiological conditions, leading to a notable hypoglycemic effect and a high oral bioavailability of 29.6%. Our work demonstrates that functional metal-organic framework nanoparticles can protect proteins from the gastric environment and overcome the intestinal barrier, thus providing the possibility for oral biomacromolecule delivery.

Combatting Helicobacter pylori with oral nanomedicines

Helicobacter pylori (H. pylori) infection is considered to be the main cause of most digestive diseases,such as chronic active gastritis, gastroduodenal ulcers, or even gastric cancer. Oral medication is a transformative approach to treat H. pylori-induced infections. However, unlike intravenous administration, orally administrated drugs have to overcome various barriers before reaching the infected sites, which significantly limits the therapeutic efficacy. These challenges may be addressed by emerging nanomedicine that is equipped with nanotechnology approaches to enable efficient and effective targeted delivery of drugs. Herein, in this review, we first discuss the conventional therapy for the eradication of H. pylori. Through the introduction of the critical barriers of oral administration, the benefits of nanomedicine are highlighted. Recently-published examples of nanocarriers for combating H. pylori in terms of design, preparation, and antimicrobial mechanisms are then presented, followed by our perspective on potential future research directions of oral nanomedicines.

Poly(disulfide)s: From Synthesis to Drug Delivery

Bioresponsive polymers have been widely used in drug delivery because of their degradability. For example, poly(disulfide)s with repeating disulfide bonds in the main chain have attracted considerable research attention. The characteristics of the disulfide bonds, including their dynamic and reversible properties and their responsiveness to stimuli such as reductants, light, heat, and mechanical force, make them ideal platforms for on-demand drug delivery. This review introduces the synthesis methods and applications of poly(disulfide)s. Furthermore, the synthesis methods of poly(disulfide)s are classified on the basis of the monomers used: oxidative step-growth polymerization with dithiols, ring-opening polymerization with cyclic disulfides, and polymerization with linear disulfides. In addition, recent advances in poly(disulfide)s for the delivery of small-molecule or biomacromolecular drugs are discussed. Quantum-dot-loaded poly(disulfide) delivery systems for imaging are also included. This review provides an overview of the various design strategies employed in the construction of poly(disulfide) platforms to inspire new applications in the field of drug delivery.

Enhancement of bioactivity, thermal stability and tumor retention by self-fused concatenation of green fluorescent protein

The widespread application of protein and peptide therapeutics is hampered by their poor stability, strong immunogenicity and short half-life. However, the existing protein modification technologies require the introduction of exogenous macromolecules, resulting in inevitable immunogenicity and decreased bioactivity. Herein, we reported an easy but universal protein modification approach, self-fused concatenation (SEC), to enhance the in vitro thermal stability and in vivo tumor retention of proteins. In this proof of concept study, we successfully obtained a set of green fluorescence protein (GFP) concatemers, monomer (GFP 1), dimer (GFP 2) and trimer (GFP 3) of GFP, and systematically studied the effects of SEC on the biological activity and stability of GFP. Notably, GFP concatemers displayed remarkable improvement in in vitro bioactivity and thermal stability over the monomeric GFP. In a murine tumor model, GFP 2 and GFP 3 exhibited significantly prolonged duration, with increases of 220- and 381-fold relative to GFP 1 in tumor retention 4 h after administration. Furthermore, the biological activity, thermal stability and tumor retention can be enhanced by the concatenated number of self-fused proteins. These findings demonstrate that SEC may be a promising alternative to design advanced protein and peptide therapeutics with enhanced pharmaceutic profiles.

Oral delivery of infliximab using nano-in-microparticles for the treatment of inflammatory bowel disease

The anti-tumor necrosis factor-α (anti-TNF-α) blocker, has shown great efficacy for the treatment of inflammatory bowel disease (IBD). However, systemic exposure to it can cause considerable safety problems due to reduced suppression of the systemic immune response and loss of response to the production of anti-drug antibodies. Thus, we try to devise a targeted vehicle system for oral administration of anti-TNF-α antibodies for the treatment of IBD. In the present study, we developed an oral Infliximab (IFX) loaded nano-in-microparticles, based on chitosan (CS)/carboxymethyl chitosan (CMC) and alginate (Alg), which could protect IFX from the harsh environment of the gastrointestinal tract and produce targeted drug delivery to the inflamed intestine. In vivo studies demonstrated that the IFX loaded nano-in-micro vehicle can alleviate colitis by ameliorating inflammation and maintaining the intestinal epithelial barrier.

Orally deliverable strategy based on microalgal biomass for intestinal disease treatment

Design of innovative strategies for oral drug delivery is particularly promising for intestinal disease treatment. However, many obstacles such as poor therapeutic efficacy and low bioavailability and biocompatibility remain to be addressed. Here, we report a versatile formulation based on a helical-shaped cyanobacterium, Spirulina platensis (SP), loaded with curcumin (SP@Curcumin) for the treatment of colon cancer and colitis, two types of intestinal diseases. In radiotherapy for colon cancer, SP@Curcumin could mediate combined chemo- and radiotherapy to inhibit tumor progression while acting as a radioprotector to scavenge reactive oxygen species induced by the high dose of x-ray radiation in healthy tissues. SP@Curcumin could also reduce the production of proinflammatory cytokines and thereby exerted anti-inflammatory effects against colitis. The oral drug delivery system not only leveraged the biological properties of microalgal carriers to improve the bioavailability of loaded drugs but also performed excellent antitumor and anti-inflammation efficacy for intestinal disease treatment.

Brij-functionalized chitosan nanocarrier system enhances the intestinal permeability of P-glycoprotein substrate-like drugs

The highly expressed P-glycoprotein (Pgp) in the intestine plays a key role in preventing drugs across the intestinal epithelium, which linked by tight junctions (TJs). Thus increasing the oral bioavailability of Pgp substrate-like drugs (PSLDs) remains a great challenge. Herein, we construct a nanocarrier system derived from Brij-grafted-chitosan (BC) to enhance the oral bioavailability and therapeutic effect of berberine (BBR, a typical PLSD) against diabetic kidney disease. The developed BC nanoparticles (BC-NPs) are demonstrated to improve the intestinal permeability of BBR via transiently and reversibly modulating the intercellular TJs (paracellular pathway) and Pgp-mediated drug efflux (transcellular pathway). As compared to free BBR and chitosan nanoparticles, the BC-NPs enhanced the relative oral bioavailability of BBR in rats (4.4- and 2.7-fold, respectively), and the therapeutic potency of BBR in renal function and histopathology. In summary, such strategy may provide an effective nanocarrier system for oral delivery of BBR and PSLDs.

A pH-Triggered Self-Unpacking Capsule Containing Zwitterionic Hydrogel-Coated MOF Nanoparticles for Efficient Oral Exendin-4 Delivery

Oral peptide or protein delivery is considered a revolutionary alternative to daily subcutaneous injection; however, major challenges remain in terms of impediments of the gastrointestinal environment and the intestinal epithelium consisting of mucus and the epithelial cell layer, leading to low bioavailability. To protect against gastrointestinal degradation and promote penetration across the intestinal mucosa, a pH-triggered self-unpacking capsule encapsulating zwitterionic hydrogel-coated metal-organic framework (MOF) nanoparticles is engineered. The MOF nanoparticles possess a high exendin-4 loading capacity, and the zwitterionic hydrogel layer imparts unique capability of permeation across the mucus layer and effective internalization by epithelial cells to the nano-vehicles. In addition to the gastro-resistant feature, the pH-responsive capsules are dissociated drastically in the intestinal environment due to the rapid generation of abundant CO₂ bubbles, which triggers a sudden release of the nanoparticles. After oral administration of the capsules containing exendin-4-loaded nanoparticles into a diabetes rat model, markedly enhanced plasma exendin-4 levels are achieved for over 8 h, leading to significantly increased endogenous insulin secretion and a remarkable hypoglycemic effect with a relative pharmacological availability of 17.3%. Owing to the low risk of hypoglycemia, this oral exendin-4 strategy will provide a vast potential for daily and facile diabetes treatment.

[Construction of Oral Insulin-Loaded Solid Lipid Nanoparticles and Their Intestinal Epithelial Cell Transcytosis Study]

OBJECTIVE

To construct solid lipid nanoparticle (SNPs) drug delivery system loaded with peptide and protein drugs by using mixedsolvents, to study the transcytosis mechanisms of SNPs across intestinal epithelial cells, and to improve the endocytosis and transcytosis efficiency of peptide and protein drugs.

METHODS

The formulation of insulin-loaded water-in-oil-in-water solid lipid nanoparticles (INS-SNPs) was prepared by using a methanol-chloroform mixed solvent. The formulation was optimized with the single factor screening method. The optimized INS-SNPs were then characterized in terms of their morphology, stability and drug release properties. The cytotoxicity, cellular uptake and endocytosis mechanisms of INS-SNPs were then assessed on Caco-2 cells. The transcytosis efficiency of INS-SNPs was finally evaluated by using cellular monolayer in Transwell ® insert.

RESULTS

The size, zeta potentials and drug loading efficiency of the optimized INS-SNPs were observed to be (145.4±0.5) nm, (-12.9±0.2) mV and (7.93±0.02)%, respectively. INS-SNPs were then shown to maintain desirable colloidal stability and sustained release of insulin in the simulated intestinal fluid. It was revealed that the cellular uptake of INS-SNPs reached its maximum after cellular incubation for 2 hours and was 1.53-fold higher than that of free insulin. Investigation of the endocytic mechanism revealed that INS-SNPs enter intestinal epithelial cells mainly through the clathrin-mediated and caveolae-mediated endocytosis pathways. Further investigation revealed that the amount of INS-SNPs permeating the cell monolayers was 1.54-fold higher than that of free insulin, which was comparable to the increase in their cellular uptake efficiency, indicating that INS-SNPs displayed enhanced absorption across the intestinal epithelium.

CONCLUSION

The INS-SNPs prepared with mixed solvents in this study could significantly enhance the transcytosis efficiency of peptide and protein drugs, displaying great potentials in the application of oral drug delivery. This study may provide information and reference for the designing of efficient oral nano-drug delivery system in the future.

A Microstirring Pill Enhances Bioavailability of Orally Administered Drugs

Majority of drugs are administered orally, yet their efficient absorption is often difficult to achieve, with a low dose fraction reaching the blood compartment. Here, a microstirring pill technology is reported with built-in mixing capability for oral drug delivery that greatly enhances bioavailability of its therapeutic payload. Embedding microscopic stirrers into a pill matrix enables faster disintegration and dissolution, leading to improved release profiles of three widely used model drugs, aspirin, levodopa, and acetaminophen, without compromising their loading. Unlike recently developed drug-carrying nanomotors, drug molecules are not associated with the microstirrers, and hence there is no limitation on the loading capacity. These embedded microstirrers are fabricated through the asymmetric coating of titanium dioxide thin film onto magnesium microparticles. In vitro tests illustrate that the embedded microstirrers lead to substantial enhancement of local fluid transport. In vivo studies using murine and porcine models demonstrate that the localized stirring capability of microstirrers leads to enhanced bioavailability of drug payloads. Such improvements are of considerable importance in clinical scenarios where fast absorption and high bioavailability of therapeutics are critical. The encouraging results obtained in porcine model suggest that the microstirring pill technology has translational potential and can be developed toward practical biomedical applications.

Sustained Release Systems for Delivery of Therapeutic Peptide/Protein

Peptide/protein therapeutics have been significantly applied in the clinical treatment of various diseases such as cancer, diabetes, etc. owing to their high biocompatibility, specificity, and therapeutic efficacy. However, due to their immunogenicity, instability stemming from its complex tertiary and quaternary structure, vulnerability to enzyme degradation, and rapid renal clearance, the clinical application of protein/peptide therapeutics is significantly confined. Though nanotechnology has been demonstrated to prevent enzyme degradation of the protein therapeutics and thus enhance the half-life, issues such as initial burst release and uncontrollable release kinetics are still unsolved. Moreover, the traditional administration method results in poor patient compliance, limiting the clinical application of protein/peptide therapeutics. Exploiting the sustained-release formulations for more controllable delivery of protein/peptide therapeutics to decrease the frequency of injection and enhance patient compliance is thus greatly meaningful. In this review, we comprehensively summarize the substantial advancements of protein/peptide sustained-release systems in the past decades. In addition, the advantages and disadvantages of all these sustained-release systems in clinical application together with their future challenges are also discussed in this review.

Angiopep-2-functionalized nanoparticles enhance transport of protein drugs across intestinal epithelia by self-regulation of targeted receptors

Ligand-modified nanoparticles (NPs) have been widely used in oral drug delivery systems to promote endocytosis on intestinal epithelia. However, their transcytosis across the intestinal epithelia is still limited. Except for complex intracellular trafficking, recycling again from the apical sides into the intestinal lumen of the endocytosed NPs cannot be ignored. In this study, we modified NP surfaces with angiopep-2 (ANG) that targeted the low-density lipoprotein receptor-related protein 1 (LRP-1) expressed on the intestine to increase both the apical endocytosis and basolateral transcytosis of NPs. Notably, our finding revealed that ANG NPs could increase the apical expression and further basolateral redistribution of LRP-1 on Caco-2 cells, thus generating an apical-to-basolateral absorption pattern. Because of the enhanced transcytosis, insulin loaded ANG NPs possessed much stronger absorption efficiency and induced maximal blood glucose reduction to 61.46% in diabetic rats. Self-regulating the distribution of receptors on polarized intestine cells to promote basolateral transcytosis will provide promising insights for the rational design of oral delivery systems of protein/peptide drugs.

Complying with the physiological functions of Golgi apparatus for secretory exocytosis facilitated oral absorption of protein drugs

Intestinal epithelial cells are the primary biological barriers for orally administrated nano-formulations and the delivered protein drugs. Thereinto, besides the cellular uptake, intracellular trafficking pathway and the related exocytosis are of great importance to the trans-epithelial transport of drug-loaded NPs. Herein, inspired by the physiological functions of Golgi apparatus for secreting proteins out of cells, Golgi localization-related amino acid l-cysteine (Cys) was modified on the surface of NPs to see whether and how this modification could guide the Golgi pathway-related transport and facilitate the exocytosis of drug-loaded NPs. Meanwhile, cell-penetrating peptide octa-arginine (R8) was co-modified to increase the cellular uptake. The proportion of R8 and Cys modification was explored to get the best effect of endocytosis and exocytosis of NPs. As a result, 25%R8 + 75%Cys NPs with most Cys modification showed efficient transcytosis with the highest transcytosis/endocytosis ratio (0.87). Interestingly, exocytosis mechanism studies indicated that they trafficked through the Golgi secretory pathway and bypassed lysosomes due to Cys modification. The detailed Golgi position mechanism studies further suggested that the thiol group from Cys was important for mediating Golgi transport. In particular, competitive inhibition studies demonstrated that Cys-modified NPs were more conducive to their exocytosis after being transported through the Golgi secretory pathway. We proved that cargos transported via Golgi apparatus tended to be trafficked out of the cells and avoid degradation, which contributed to the transcytosis of 25%R8 + 75%Cys NPs in vitro. Inspiringly, compared with unmodified NPs, 25%R8 + 75%Cys NPs also exhibited promoted intestinal penetration and oral absorption in vivo. Oral delivery of insulin-loaded 25%R8 + 75%Cys NPs showed stronger hypoglycemic effects in diabetic rats. In summary, this work provides a strategy for complying with the physiological functions of Golgi apparatus for secreting to facilitate the exocytosis of NPs, thus further improving the oral absorption of loaded protein drugs.

Acoustofluidic centrifuge for nanoparticle enrichment and separation

Liquid droplets have been studied for decades and have recently experienced renewed attention as a simplified model for numerous fascinating physical phenomena occurring on size scales from the cell nucleus to stellar black holes. Here, we present an acoustofluidic centrifugation technique that leverages an entanglement of acoustic wave actuation and the spin of a fluidic droplet to enable nanoparticle enrichment and separation. By combining acoustic streaming and droplet spinning, rapid (<1 min) nanoparticle concentration and size-based separation are achieved with a resolution sufficient to identify and isolate exosome subpopulations. The underlying physical mechanisms have been characterized both numerically and experimentally, and the ability to process biological samples (including DNA segments and exosome subpopulations) has been successfully demonstrated. Together, this acoustofluidic centrifuge overcomes existing limitations in the manipulation of nanoscale (<100 nm) bioparticles and can be valuable for various applications in the fields of biology, chemistry, engineering, material science, and medicine.

Nano and microscale delivery platforms for enhanced oral peptide/protein bioavailability

In recent years, peptide/protein drugs have attracted considerable attention owing to their superior targeting and therapeutic effect and fewer side effects compared with chemical drugs. Oral administration modality with enhanced patient compliance is increasingly being recognized as an ideal route for peptide/protein delivery. However, the limited permeation efficiency and low oral bioavailability of peptide/protein drugs significantly hinder therapeutic advances. To address these problems, various nano and microscale delivery platforms have been developed, which offer significant advantages in oral peptide/protein delivery. In this review, we briefly introduce the transport mechanisms of oral peptide/protein delivery and the primary barriers to this delivery process. We also highlight the recent advances in various nano and microscale delivery platforms designed for oral peptide/protein delivery. We then summarize the existing strategies used in these delivery platforms to improve the oral bioavailability and permeation efficiency of peptide/protein therapeutics. Finally, we discuss the major challenges faced when nano and microscale systems are used for oral peptide/protein delivery. This review is expected to provide critical insight into the design and development of oral peptide/protein delivery systems with significant therapeutic advances.

Nasal absorption enhancement of protein drugs independent to their chemical properties in the presence of hyaluronic acid modified with tetraglycine-L-octaarginine

Our previous mouse studies demonstrated that mean bioavailability of exendin-4, which is an injectable glucagon-like peptide-1 (GLP-1) analogue whose molecular weight (Mw) and isoelectric point (pI) are ca. 4.2 kDa and 4.5, respectively, administered nasally with poly(N-vinylacetamide-co-acrylic acid) (PNVA-co-AA) bearing D-octaarginine, which is a typical cell-penetrating peptide, was 20% relative to subcutaneous administration even though it was less than 1% when exendin-4 alone was given nasally. The studies also revealed that the absorption-enhancing ability of D-octaarginine-linked PNVA-co-AA for exendin-4 was statistically equivalent to that of sodium salcaprozate (SNAC), which is an absorption enhancer formulated in tablets of semaglutide approved recently as an orally available GLP-1 analogue. From a perspective of clinical application of our technology, we have separately developed hyaluronic acid modified with L-octaarginine via a tetraglycine spacer which would be degraded in biological conditions. The present study revealed that tetraglycine-L-octaarginine-linked hyaluronic acid enhanced nasal absorption of exendin-4 in mice, as did D-octaarginine-linked PNVA-co-AA. There was no significant difference in absorption-enhancing abilities between the hyaluronic acid derivative and SNAC when octreotide (Mw: ca. 1.0 kDa, pI: 8.3) and lixisenatide (Mw: ca. 4.9 kDa, pI: 9.5) were used as a model protein drug. On the other hand, SNAC did not significantly enhance nasal absorption of somatropin (Mw: ca. 22.1 kDa, pI: 5.3) when compared with absorption enhancer-free conditions. Substitution of SNAC with tetraglycine-L-octaarginine-linked hyaluronic acid resulted in a 5-fold increase in absolute bioavailability of somatropin with statistical significance. It appeared that pI hardly ever influenced absorption-enhancing abilities of both enhancers. Results indicated that our polysaccharide derivative would be a promising absorption enhancer which delivers biologics applied on the nasal mucosa into systemic circulation and was of greater advantage than SNAC for enhancing nasal absorption of protein drugs with a larger Mw.

Polydimethylsiloxane-customized nanoplatform for delivery of antidiabetic drugs

Aim: To develop a new self-emulsified silicon-grafted-alginate platform for pharmaceutical delivery. The produced biocompatible polymeric blend would be used to encapsulate metformin by a vibrational jet-flow ionotropic gelation process. Materials & methods: Polydimethylsiloxane was homogenized with alginate to prepare a stable polymeric mixture to which metformin was added. A metformin-loaded polymeric vehicle was then pumped through Buchi B-390 into CaCl2 to produce microcapsules. Results & conclusion: The platform showed a powerful, pseudoplastic thixotropic and demonstrated strong, efficient and wide applications of polydimethylsiloxane-customized technology in drug delivery and stability. A substantial improvement in drug loading, encapsulation efficiency and flow properties were noticed in siliconized microcapsules compared with the control.

A Nanocomposite Vehicle Based on Metal-Organic Framework Nanoparticle Incorporated Biodegradable Microspheres for Enhanced Oral Insulin Delivery

Oral insulin delivery has revolutionized diabetes treatment, but challenges including degradation in the gastrointestinal environment and low permeation across the intestinal epithelium remain. Herein, to overcome these barriers, we developed a novel biodegradable nanocomposite microsphere embedded with metal-organic framework (MOF) nanoparticles. An iron-based MOF nanoparticle (NP) (MIL-100) was first synthesized as a carrier with an insulin loading capacity of 35%. The insulin-loaded MIL-100 nanoparticles modified with sodium dodecyl sulfate (Ins@MIL100/SDS) promoted insulin permeation across Caco-2 monolayer models in vitro. To improve resistance to the gastric acid environment, Ins@MIL100/SDS nanoparticles were embedded into a biodegradable microsphere to construct the nanocomposite delivery system (Ins@MIL100/SDS@MS). The microspheres effectively protected the MOF NPs from rapid degradation under acidic conditions and could release insulin-loaded MOF NPs in the simulated intestinal fluid. After the oral administration of Ins@MIL100/SDS@MS into BALB/c nude mice, increased intestinal absorption of the insulin was detected compared to the oral administration of free insulin or Ins@MIL100/SDS. Furthermore, significantly enhanced plasma insulin levels were obtained for over 6 h after oral administration of Ins@MIL100/SDS@MS into diabetic rats, leading to a remarkably enhanced effect in lowering blood glucose level with a relative pharmacological availability of 7.8%. Thus, the MOF-nanoparticle-incorporated microsphere may provide a new strategy for effective oral protein delivery.