Glucagon-Like Peptide-1 Receptor Agonists and Strategies To Improve Their Efficiency

Expanded ribosomal synthesis of non-standard cyclic backbones in vitro

The ribosome polymerizes L-α-amino acids into polypeptides, catalyzing peptide bond formation through aminolysis. This process is facilitated by entropy trapping within its peptidyl transferase center (PTC). In this research, we harness this capability to synthesize polymers containing cyclic motifs in the backbone. We design 26 non-canonical monomers (ncMs) with two distinct substrates: dicarboxylic esters and hydrazinoesters, each containing bifunctional moieties that undergo ring-closing reactions through multiple aminolysis reactions. Using a cell-free system that enables the consecutive incorporation of these ncMs into a growing peptide, we discover that the ribosome can produce 5- and 6-membered cyclic backbones, which have never been reported. We also demonstrate that the formation of such cyclic backbones within the ribosome is tunable by altering the substituents of dicarboxylic esters. This discovery expands the range of non-standard backbones that can be synthesized by the ribosome and motivates future research towards expanding ribosome-mediated chemistries for biopolymer synthesis.

Biased agonism in peptide-GPCRs: A structural perspective

G protein-coupled receptors (GPCRs) are dynamic membrane receptors that transduce extracellular signals to the cell interior by forming a ligand-receptor-effector (ternary) complex that functions via allosterism. Peptides constitute an important class of ligands that interact with their cognate GPCRs (peptide-GPCRs) to form the ternary complex. "Biased agonism", a therapeutically relevant phenomenon exhibited by GPCRs owing to their allosteric nature, has also been observed in peptide-GPCRs, leading to the development of selective therapeutics with fewer side effects. In this review, we have focused on the structural basis of signalling bias at peptide-GPCRs of classes A and B, and reviewed the therapeutic relevance of bias at peptide-GPCRs, with the hope of contributing to the discovery of novel biased peptide drugs.

Activation of GLP-1R modulates the spontaneous discharge of nigral dopaminergic neurons and motor behavior in mice with chronic MPTP Parkinson's disease

The gradual decline of nigral dopaminergic neurons is the main cause of Parkinson's disease (PD), yet as of now, there exists no conclusive therapeutic intervention. Glucagon-like peptide-1 (GLP-1) is an incretin, which is also a key substance regulating neuronal activity and synaptic transmission. GLP-1 receptors (GLP-1Rs) are widely expressed in the central nervous system. Chronic administration of low doses of 1-methyl-4-phenyl, 1,2,3,6-tetrahydropiridine (MPTP) mitigates mortality in mice during the modeling phase, thereby more closely mirroring the progression of PD. This study aims to observe the effects of GLP-1 receptor agonists (GLP-1RAs) on the firing activity of nigral dopaminergic neurons and motor behaviors in MPTP-induced chronic PD mice. Our findings revealed that peripheral administration of GLP-1RAs exendin-4 significantly alleviated motor impairments in MPTP-induced chronic PD mice. Concurrently, peripheral administration of exendin-4 increased the number of active dopaminergic neurons, improved the spontaneous firing activity, as well as alleviated MPTP-induced dopaminergic neuron loss in MPTP-induced PD mice. Furthermore, local administration of exendin-4 directly increased the firing rate of nigral dopaminergic neurons via GLP-1Rs, suggesting that peripheral administration of exendin-4 may exert neuroprotection through its mild excitation on dopaminergic neurons. These findings collectively imply that peripheral administration of GLP-1RAs may hold potential in the treatment of PD.

Innovative PEGylated chitosan nanocarriers for co-delivery of doxorubicin and CpG in breast cancer therapy: Preparation, characterization, and immunotherapeutic potential

This study aimed to design polyethylene glycol (PEG)ylated chitosan (CS, PEG-CS) nanoparticles for the co-delivery of doxorubicin (DOX), cytosine-phosphate-guanine oligodeoxynucleotide (CpG), and ovalbumin (OVA) to enhance breast cancer therapy. PEG-CS nanoparticles were synthesized using the ionotropic gelation method and characterized for size, zeta potential (ZP), entrapment efficiency, and drug release. In vitro and in vivo studies were conducted to assess cytotoxicity, immune activation, and antitumor efficacy. The optimized nanoparticles had a mean diameter of 156.4 ± 8.9 nm, a ZP of +18 mV, and demonstrated 75.3% DOX and 68.3% CpG release over 72 h. PEG-CS-DOX/CpG/OVA enhanced tumor reduction by 2.6-fold in vivo, with no significant toxicity. PEG-CS-DOX/CpG/OVA nanoparticles showed promise as a co-delivery platform for cancer therapy, combining cytotoxic and immune-stimulating effects with minimal toxicity.

Advance in peptide-based drug development: delivery platforms, therapeutics and vaccines

The successful approval of peptide-based drugs can be attributed to a collaborative effort across multiple disciplines. The integration of novel drug design and synthesis techniques, display library technology, delivery systems, bioengineering advancements, and artificial intelligence have significantly expedited the development of groundbreaking peptide-based drugs, effectively addressing the obstacles associated with their character, such as the rapid clearance and degradation, necessitating subcutaneous injection leading to increasing patient discomfort, and ultimately advancing translational research efforts. Peptides are presently employed in the management and diagnosis of a diverse array of medical conditions, such as diabetes mellitus, weight loss, oncology, and rare diseases, and are additionally garnering interest in facilitating targeted drug delivery platforms and the advancement of peptide-based vaccines. This paper provides an overview of the present market and clinical trial progress of peptide-based therapeutics, delivery platforms, and vaccines. It examines the key areas of research in peptide-based drug development through a literature analysis and emphasizes the structural modification principles of peptide-based drugs, as well as the recent advancements in screening, design, and delivery technologies. The accelerated advancement in the development of novel peptide-based therapeutics, including peptide-drug complexes, new peptide-based vaccines, and innovative peptide-based diagnostic reagents, has the potential to promote the era of precise customization of disease therapeutic schedule.

Enhanced antitumor efficacy of nanostructured lipid carrier co-loaded with docetaxel and 5-fluorouracil for targeted gastric cancer therapy

This study presents nanostructured lipid carrier (NLC) co-loaded with Docetaxel (DCT) and 5-Fluorouracil (5-FU) as a targeted therapeutic approach for gastric cancer (GC). Using nanoprecipitation, NLC-DCT/5-FU were synthesized and exhibited an average particle size of 215.3 ± 10.4 nm, a polydispersity index (PDI) of 0.29, and a zeta potential of - 17.1 mV. Encapsulation efficiency reached 95.9% for DCT and 5-FU, with a loading efficiency of 11.2%. In vitro release studies demonstrated a biphasic release profile, with an initial burst and sustained release, achieving 85.6% DCT and 75.8% 5-FU release over 72 h. Cytotoxicity assays in MKN45 cells showed a significantly lower half-maximal inhibitory concentration (IC50) for NLC-DCT/5-FU (0.3 µM) compared to free DCT (3.9 µM) and free 5-FU (19.5 µM), indicating enhanced efficacy. In vivo evaluation in a GC mouse model confirmed substantial tumor volume reduction to 213 mm3 with NLC-DCT/5-FU treatment, compared to 432 mm3 with the free-drug combination. Systemic safety assessment showed minimal adverse effects, suggesting the nanoparticles' enhanced therapeutic index. These results demonstrate that NLC-based co-delivery systems could substantially improve the clinical outcomes of GC therapy.

Exploring the Antitumor Efficacy of PEGylated Liposomes Loaded with Licorice Extract for Cancer Therapy

BACKGROUND

Glycyrrhizic Acid (GA), a compound derived from licorice, has exhibited promising anticancer properties against several cancer types, including Prostate Cancer (PCa) and Gastric Cancer (GCa).

OBJECTIVE

This study has introduced a novel approach involving the encapsulation of GA and Licorice extract (Lic) into Polyethylene Glycol Liposomes (PEG-Lip) and assessed their efficacy against AGS (human gastric cancer) and PC-3 (human prostate cancer) cells, marking the first report of this endeavor.

METHODS

We synthesized GA-loaded PEG-Lip (GA PEG-Lip) and Lic-loaded PEG-Lip (Lic PEG-Lip) through the reverse-phase evaporation method.

RESULTS

Characterization of these liposomal formulations revealed their size, drug encapsulation, and loading efficiencies to be 110 ± 2.05 nm, 117 ± 1.24 nm; 61 ± 0.81%, 34 ± 0.47%; and 8 ± 0.41% and 4.6 ± 0.21%, respectively. Importantly, the process has retained the chemical structure of both GA and Lic. Furthermore, GA and Lic have been released from the PEG-Lip formulations in a controlled manner. In our experiments, both nanoformulations exhibited enhanced cytotoxic effects against AGS and PC-3 cells. Notably, GA PEG-Lip outperformed Lic PEG-Lip, reducing the viability of PC-3 and AGS cells by 12.5% and 15.9%, respectively.

CONCLUSION

These results have been corroborated by apoptosis assays, which have demonstrated GA PEG-Lip and Lic PEG-Lip to induce stronger apoptotic effects compared to free GA and Lic on both PC-3 and AGS cells. This study has underscored the potential of encapsulating GA and Lic in PEG-Lip as a promising strategy to augment their anticancer efficacy against prostate and gastric cancers.

Synthesis, radiolabeling, and biodistribution of 99 m-technetium-labeled zif-8 nanoparticles for targeted imaging applications

This study investigates the synthesis and radiolabeling of zeolitic imidazolate frameworks (ZIF-8) with the radioisotope technetium-99 m (99mTc) using a solvothermal method in methanol. The methanolic medium facilitated the formation of nanoparticles with favorable characteristics, including a smaller particle size (198 ± 9.8 nm) and a low polydispersity index (PDI = 0.219 ± 0.011). Radiolabeling efficiency (RE%) and radiochemical purity (RCP%) were optimized by employing SnCl2 as a reducing agent, resulting in an RE% of 95.2 ± 1.9% and an RCP% of 96.1 ± 1.7% in triplicate (n = 3) at 65 °C. The nanoparticles exhibited high serum stability, retaining 99.05% of RCP% after 24 h, and demonstrated hemocompatibility, with hemolysis rates below 5% across all tested concentrations. In vitro biocompatibility assessments using NIH-3T3 cells indicated cell viability above 70% at concentrations up to 40 μg/mL. Biodistribution studies in rabbits (n = 6) revealed predominant accumulation in the bladder, with radiotracer uptake in the bladder being 6.3, 7.2, and 36.2 times higher than in the liver, kidneys, and heart (p < 0.0001), respectively, suggesting renal clearance. These results underscore the potential of 99mTc-(ZIF-8) nanoparticles for biomedical applications, particularly in targeted imaging and drug delivery. Future research will focus on improving targeting specificity and enhancing therapeutic efficacy in disease models.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-024-04145-w.

Surface-functionalized UIO-66-NH2 for dual-drug delivery of vancomycin and amikacin against vancomycin-resistant Staphylococcus aureus

BACKGROUND

Conventional antibacterial compounds can inhibit the growth of microorganisms, but their adverse effects and the development of drug limit their widespread use. The current study aimed to synthesize PEG-coated UIO-66-NH2 nanoparticles loaded with vancomycin and amikacin (VAN/AMK-UIO-66-NH2@PEG) and evaluate their antibacterial and anti-biofilm activities against vancomycin-resistant Staphylococcus aureus (VRSA) clinical isolates.

METHODS

The VAN/AMK-UIO-66-NH2@PEG were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS) to determine their size, polydispersity index (PDI), encapsulation efficiency (EE%), zeta-potential, drug release profile, and physical stability. Antibacterial activity was evaluated using minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and time-kill assays. Biofilm formation by VRSA was assessed using the crystal violet (CV) and minimum biofilm eradication concentration (MBEC) assays. The effect of sub-MIC concentrations of the formulations on the expression of biofilm-related genes (icaA, icaD) and resistance-related genes (mecA, vanA) was investigated using quantitative real-time polymerase chain reaction (RT-qPCR).

RESULTS

As demonstrated by MIC, MBC and time-kill assay, the VAN/AMK-UIO-66-NH2@PEG nanoparticles exhibited enhanced antibacterial activity against VRSA isolates compared to free drugs and prepared formulations. Furthermore, CV and MBEC tests indicated that the VAN/AMK-UIO-66@NH2/PEG can reduce biofilm formation dramatically compared to VAN/AMK and VAN/AMK-UIO-66@NH2, due to its great drug release properties. This study also found that the expression level of the mecA, vanA, icaA, and icaD genes in VAN/AMK-UIO-66@NH2/PEG treated VRSA isolates was substantially decreased compared to other groups.

CONCLUSIONS

These findings highlighted the efficiency of VAN/AMK-UIO-66@NH2/PEG in combating antimicrobial resistance and biofilm formation in VRSA isolates. Future studies, particularly in vivo models, are necessary to evaluate the safety, efficacy, and clinical applicability of these nanoparticles for the treatment of bacterial infections.

Bioengineered Nanomedicines Targeting the Intestinal Fc Receptor Achieve the Improved Glucoregulatory Effect of Semaglutide in a Type 2 Diabetic Mice Model

The oral administration of the glucagon-like peptide-1 analogue, semaglutide, remains a hurdle due to its limited bioavailability. Herein, neonatal Fc receptor (FcRn)-targeted nanoparticles (NPs) were designed to enhance the oral delivery of semaglutide. The nanocarriers were covalently linked to the FcRn-binding peptide FcBP or the affibody molecule ZFcRn that specifically binds to the human FcRn (hFcRn) in a pH-dependent manner. These FcRn-targeted ligands were selected over the endogenous ligands of the receptor (albumin and IgG) due to their smaller size and simpler structure, which could facilitate the transport of functionalized NPs through the tissues. The capacity of FcRn-targeted semaglutide-NPs in controlling the blood glucose levels was evaluated in an hFcRn transgenic mice model, where type 2 diabetes mellitus (T2DM) was induced via intraperitoneal injection of nicotinamide followed by streptozotocin. The encapsulation of semaglutide into FcRn-targeted NPs was translated in an improved glucoregulatory effect in T2DM-induced mice when compared to the oral free semaglutide or nontargeted NP groups, after daily oral administrations for 7 days. Notably, a similar glucose-lowering response was observed between both FcRn-targeted NPs and the subcutaneous semaglutide groups. An increase in insulin pancreatic content and a recovery in β cell mass were visualized in the mice treated with FcRn-targeted semaglutide-NPs. The biodistribution of fluorescently labeled NPs through the gastrointestinal tract demonstrated that the nanosystems targeting the hFcRn are retained longer in the ileum and colorectum, where the expression of FcRn is more prevalent, than nontargeted NPs. Therefore, FcRn-targeted nanocarriers proved to be an effective platform for improving the pharmacological effect of semaglutide in a T2DM-induced mice model.

Binding sites and design strategies for small molecule GLP-1R agonists

Glucagon-like peptide-1 receptor (GLP-1R) is a pivotal receptor involved in blood glucose regulation and influencing feeding behavior. It has received significant attention in the treatment of obesity and diabetes due to its potent incretin effect. Peptide GLP-1 receptor agonists (GLP-1RAs) have achieved tremendous success in the market, driving the vigorous development of small molecule GLP-1RAs. Currently, several small molecules have entered the clinical research stage. Additionally, recent discoveries of GLP-1R positive allosteric modulators (PAMs) are also unveiling new regulatory patterns and treatment methods. This article reviews the structure and functional mechanisms of GLP-1R, recent reports on small molecule GLP-1RAs and PAMs, as well as the optimization process. Furthermore, it combines computer simulations to analyze structure-activity relationships (SAR) studies, providing a foundation for exploring new strategies for designing small molecule GLP-1RAs.

Optimizing expression, purification, structural and functional assessments of a novel dimeric incretin (GLP-1cpGLP-1)

Glucagon-like peptide-1 (GLP-1) is an incretin hormone that reduces postprandial glycemic excursions by enhancing insulin secretion. In this study, a new dimeric GLP-1 analogue (GLP-1cpGLP-1) was designed by inserting human insulin C-peptide (CP) in the middle of a dimer of [Gly8] GLP-1 (7-36). Then, the dimeric incretin (GLP-1cpGLP-1) was ligated to human αB-crystallin (αB-Cry) to create a hybrid protein, abbreviated as αB-GLP-1cpGLP-1. The constructed gene was well expressed in the bacterial host system. After specific chemical release from the hybrid protein, the dimeric incretin was purified by size exclusion chromatography (SEC). Finally, the RP-HPLC analysis indicated a purity of >99 % for the dimeric incretin. The secondary structure assessments by various spectroscopic methods, and in silico analysis suggested that the dimeric incretin has α-helical rich structure. The dynamic light scattering (DLS) analysis indicates that our dimeric incretin forms large oligomeric structures. This incretin analogue significantly reduced blood glucose levels in both healthy and diabetic mice while effectively triggering insulin release. The size exclusion HPLC also indicates the interaction of the new incretin analogue with human serum albumin, the main carrier protein in the bloodstream. Consistent with the results obtained from the biological activity assessments, this significant interaction indicates its potential as a viable therapeutic agent with a long-lasting effect. The results of our research represent a significant breakthrough in the successful design of an active incretin dimer capable of effectively controlling blood sugar levels and inducing insulin secretion in the realm of diabetes treatment.

Microsponges: Development, Characterization, and Key Physicochemical Properties

Microsponges are promising drug delivery carriers with versatile characteristics and controlled release properties for the delivery of a wide range of drugs. The microsponges will provide an optimized therapeutic effect, when delivered at the site of action without rupturing, then releasing the cargo at the predetermined time and area. The ability of the microsponges to effectively deliver the drug in a controlled manner depends on the material composition. This comprehensive review entails knowledge on the design parameters of an optimized microsponge drug delivery system and the controlled release properties of microsponges that reduces the side effects of drugs. Furthermore, the review delves into the fabrication techniques of microsponges, the mechanism of drug release from the microsponges, and the regulatory requirements of the U.S. Food and Drug Administration (FDA) for the successful marketing of microsponge formulation. The review also examines the patented formulations of microsponges. The prospects of these sophisticated drug delivery systems for improved clinical outcomes are highlighted.

Developing Engineered Nano-Immunopotentiators for the Stimulation of Dendritic Cells and Inhibition and Prevention of Melanoma

OBJECTIVE

This study aims to utilize PEGylated poly (lactic-co-glycolic acid) (PLGA) nanoparticles as a delivery system for simultaneous administration of the BRAFV600E peptide, a tumor-specific antigen, and imiquimod (IMQ). The objective is to stimulate dendritic cell (DC) maturation, activate macrophages, and facilitate antigen presentation in C57BL6 mice.

METHODS

PEG-PLGA-IMQ-BRAFV600E nanoparticles were synthesized using a PLGA-PEG-PLGA tri-block copolymer, BRAFV600E, and IMQ. Characterization included size measurement and drug release profiling. Efficacy was assessed in inhibiting BPD6 melanoma cell growth and activating immature bone marrow DCs, T cells, macrophages, and splenocyte cells through MTT and ELISA assays. In vivo, therapeutic and immunogenic effects potential was evaluated, comparing it to IMQ + BRAFV600E and PLGA-IMQ-BRAFV600E nanoparticles in inhibiting subcutaneous BPD6 tumor growth.

RESULTS

The results highlight the successful synthesis of PEG-PLGA-IMQ-BRAFV600E nanoparticles (203 ± 11.1 nm), releasing 73.4% and 63.2% of IMQ and BARFV600E, respectively, within the initial 48 h. In vitro, these nanoparticles demonstrated a 1.3-fold increase in potency against BPD6 cells, achieving ~ 2.8-fold enhanced cytotoxicity compared to PLGA-IMQ-BRAFV600E. Moreover, PEG-PLGA-IMQ-BRAFV600E exhibited a 1.3-fold increase in potency for enhancing IMQ cytotoxic effects and a 1.1- to ~ 2.4-fold increase in activating DCs, T cells, macrophages, and splenocyte cells compared to IMQ-BRAFV600E and PLGA-IMQ-BRAFV600E. In vivo, PEG-PLGA-IMQ-BRAFV600E displayed a 1.3- to 7.5-fold increase in potency for inhibiting subcutaneous BPD6 tumor growth compared to the other formulations.

CONCLUSIONS

The findings suggest that PEG-PLGA nanoparticles effectively promote DC maturation, T cell activation, and potentially macrophage activation. The study highlights the promising role of this nanocomposite in vaccine development.

Customizable Click Biochemistry Strategy for the Design and Preparation of Glucagon-like Peptide-1 Conjugates and Coagonists

The development of oligomeric glucagon-like peptide-1 (GLP-1) and GLP-1-containing coagonists holds promise for enhancing the therapeutic potential of the GLP-1-based drugs for treating type 2 diabetes mellitus (T2DM). Here, we report a facile, efficient, and customizable strategy based on genetically encoded SpyCatcher-SpyTag chemistry and an inducible, cleavable self-aggregating tag (icSAT) scheme. icSAT-tagged SpyTag-fused GLP-1 and the dimeric or trimeric SpyCatcher scaffold were designed for dimeric or trimeric GLP-1, while icSAT-tagged SpyCatcher-fused GLP-1 and the icSAT-tagged SpyTag-fused GIP were designed for dual GLP-1/GIP (glucose-dependent insulinotropic polypeptide) receptor agonist. These SpyCatcher- and SpyTag-fused protein pairs were spontaneously ligated directly from the cell lysates. The subsequent icSAT scheme, coupled with a two-step standard column purification, resulted in target proteins with authentic N-termini, with yields ranging from 35 to 65 mg/L and purities exceeding 99%. In vitro assays revealed 3.0- to 4.1-fold increased activities for dimeric and trimeric GLP-1 compared to mono-GLP-1. The dual GLP-1/GIP receptor agonist exhibited balanced activity toward the GLP-1 receptor or the GIP receptor. All the proteins exhibited 1.8- to 3.0-fold prolonged half-lives in human serum compared to mono-GLP-1 or GIP. This study provides a generally applicable click biochemistry strategy for developing oligomeric or dual peptide/protein-based drug candidates.

Oral peptide therapeutics for diabetes treatment: State-of-the-art and future perspectives

Diabetes, characterized by hyperglycemia, is a major cause of death and disability worldwide. Peptides, such as insulin and glucagon-like peptide-1 (GLP-1) analogs, have shown promise as treatments for diabetes due to their ability to mimic or enhance insulin's actions in the body. Compared to subcutaneous injection, oral administration of anti-diabetic peptides is a preferred approach. However, biological barriers significantly reduce the efficacy of oral peptide therapeutics. Recent advancements in drug delivery systems and formulation techniques have greatly improved the oral delivery of peptide therapeutics and their efficacy in treating diabetes. This review will highlight (1) the benefits of oral anti-diabetic peptide therapeutics; (2) the biological barriers for oral peptide delivery, including pH and enzyme degradation, intestinal mucosa barrier, and biodistribution barrier; (3) the delivery platforms to overcome these biological barriers. Additionally, the review will discuss the prospects in this field. The information provided in this review will serve as a valuable guide for future developments in oral anti-diabetic peptide therapeutics.

Glucagon-like peptide-1 analogs: Miracle drugs are blooming?

Glucagon-like peptide-1 (GLP-1), secreted by L cells in the small intestine, assumes a central role in managing type 2 diabetes mellitus (T2DM) and obesity. Its influence on insulin secretion and gastric emptying positions it as a therapeutic linchpin. However, the limited applicability of native GLP-1 stems from its short half-life, primarily due to glomerular filtration and the inactivating effect of dipeptidyl peptidase-IV (DPP-IV). To address this, various structural modification strategies have been developed to extend GLP-1's half-life. Despite the commendable efficacy displayed by current GLP-1 receptor agonists, inherent limitations persist. A paradigm shift emerges with the advent of unimolecular multi-agonists, such as the recently introduced tirzepatide, wherein GLP-1 is ingeniously combined with other gastrointestinal hormones. This novel approach has captured the spotlight within the diabetes and obesity research community. This review summarizes the physiological functions of GLP-1, systematically explores diverse structural modifications, delves into the realm of unimolecular multi-agonists, and provides a nuanced portrayal of the developmental prospects that lie ahead for GLP-1 analogs.

Microfluidics for personalized drug delivery

This review highlights the transformative impact of microfluidic technology on personalized drug delivery. Microfluidics addresses issues in traditional drug synthesis, providing precise control and scalability in nanoparticle fabrication, and microfluidic platforms show high potential for versatility, offering patient-specific dosing and real-time monitoring capabilities, all integrated into wearable technology. Covalent conjugation of antibodies to nanoparticles improves bioactivity, driving innovations in drug targeting. The integration of microfluidics with sensor technologies and artificial intelligence facilitates real-time feedback and autonomous adaptation in drug delivery systems. Key challenges, such as droplet polydispersity and fluidic handling, along with future directions focusing on scalability and reliability, are essential considerations in advancing microfluidics for personalized drug delivery.

Revolutionizing Wound Healing: Exploring Scarless Solutions through Drug Delivery Innovations

Human skin is the largest organ and outermost surface of the human body, and due to the continuous exposure to various challenges, it is prone to develop injuries, customarily known as wounds. Although various tissue engineering strategies and bioactive wound matrices have been employed to speed up wound healing, scarring remains a significant challenge. The wound environment is harsh due to the presence of degradative enzymes and elevated pH levels, and the physiological processes involved in tissue regeneration operate on distinct time scales. Therefore, there is a need for effective drug delivery systems (DDSs) to address these issues. The objective of this review is to provide a comprehensive exposition of the mechanisms underlying the skin healing process, the factors and materials used in engineering DDSs, and the different DDSs used in wound care. Furthermore, this investigation will delve into the examination of emergent technologies and potential avenues for enhancing the efficacy of wound care devices.

New insights into nanomedicines for oral delivery of glucagon-like peptide-1 analogs

Type 2 diabetes mellitus (T2DM) is a metabolic disorder that arises when the body cannot respond fully to insulin, leading to impaired glucose tolerance. Currently, the treatment embraces non-pharmacological actions (e.g., diet and exercise) co-associated with the administration of antidiabetic drugs. Metformin is the first-line treatment for T2DM; nevertheless, alternative therapeutic strategies involving glucagon-like peptide-1 (GLP-1) analogs have been explored for managing the disease. GLP-1 analogs trigger insulin secretion and suppress glucagon release in a glucose-dependent manner thereby, reducing the risk of hyperglycemia. Additionally, GLP-1 analogs have an extended plasma half-life compared to the endogenous peptide due to their high resistance to degradation by dipeptidyl peptidase-4. However, GLP-1 analogs are mainly administered via subcutaneous route, which can be inconvenient for the patients. Even considering an oral delivery approach, GLP-1 analogs are exposed to the harsh conditions of the gastrointestinal tract (GIT) and the intestinal barriers (mucus and epithelium). Hereupon, there is an unmet need to develop non-invasive oral transmucosal drug delivery strategies, such as the incorporation of GLP-1 analogs into nanoplatforms, to overcome the GIT barriers. Nanotechnology has the potential to shield antidiabetic peptides against the acidic pH and enzymatic activity of the stomach. In addition, the nanoparticles can be coated and/or surface-conjugated with mucodiffusive polymers and target intestinal ligands to improve their transport through the intestinal mucus and epithelium. This review focuses on the main hurdles associated with the oral administration of GLP-1 and GLP-1 analogs, and the nanosystems developed to improve the oral bioavailability of the antidiabetic peptides. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Assessing the performance of new chromatographic technologies for the separation of peptide epimeric impurities: the case of Icatibant

The biopharmaceutical industry faces the challenge of efficiently characterising impurity profiles of therapeutical peptides, also due to their complex polar and ionisable attributes. This research explores the potential of advanced chromatographic techniques to address this challenge. The study compares dynamic electrostatic repulsion reversed phase (d-ERRP) to its counterparts (static ERRP and ion pair reversed phase IP-RP) in analysing Icatibant and its elusive epimeric impurity, [L-Arg]1-Icatibant and highlights its exceptional capabilities in generating symmetric peaks, mitigating the common tailing phenomenon, and serving as a steadfast guardian of column longevity. The result highlights d-ERRP as a pioneering tool in the domain of liquid chromatography, fostering its role as a reference technique for the analysis of therapeutic peptides.

Nanoparticles targeting the intestinal Fc receptor enhance intestinal cellular trafficking of semaglutide

Semaglutide is the first oral glucagon-like peptide-1 (GLP-1) analog commercially available for the treatment of type 2 diabetes. In this work, semaglutide was incorporated into poly(lactic-co-glycolic acid)-poly(ethylene glycol) (PLGA-PEG) nanoparticles (NPs) to improve its delivery across the intestinal barrier. The nanocarriers were surface-decorated with either a peptide or an affibody that target the human neonatal Fc receptor (hFcRn), located on the luminal cell surface of the enterocytes. Both ligands were successfully conjugated with the PLGA-PEG via maleimide-thiol chemistry and thereafter, the functionalized polymers were used to produce semaglutide-loaded NPs. Monodisperse NPs with an average size of 170 nm, neutral surface charge and 3% of semaglutide loading were obtained. Both FcRn-targeted NPs exhibited improved interaction and association with Caco-2 cells (cells that endogenously express the hFcRn), compared to non-targeted NPs. Additionally, the uptake of FcRn-targeted NPs was also observed to occur in human intestinal organoids (HIOs) expressing hFcRn through microinjection into the lumen of HIOs, resulting in potential increase of semaglutide permeability for both ligand-functionalized nanocarriers. Herein, our study demonstrates valuable data and insights that the FcRn-targeted NPs has the capacity to promote intestinal absorption of therapeutic peptides.

Bioresponsive drug delivery systems

In this review, we highlight the potential of stimuli-responsive drug delivery systems (DDSs) to revolutionize healthcare. Through examining pH, temperature, enzyme, and redox responsiveness, the presented case studies highlight the precision and enhanced therapeutic outcomes achievable with these innovative systems. Challenges, such as complex design and bio-based material optimization, underscore the complete journey from bench to bedside. Clinical strides in magnetically and temperature-responsive systems hint at a promising future for healthcare. However, overcoming issues of stability, durability, penetration depth, sensitivity, and active targeting is crucial. The future envisions theranostic systems, amalgamating targeted therapy and diagnosis, for personalized healthcare. Bio-based materials emerge as pivotal, offering a nuanced approach to complex diseases, such as cancer and diabetes, reshaping the healthcare landscape.

Resorbable GBR Scaffolds in Oral and Maxillofacial Tissue Engineering: Design, Fabrication, and Applications

Guided bone regeneration (GBR) is a promising technique in bone tissue engineering that aims to replace lost or injured bone using resorbable scaffolds. The promotion of osteoblast adhesion, migration, and proliferation is greatly aided by GBR materials, and surface changes are critical in imitating the natural bone structure to improve cellular responses. Moreover, the interactions between bioresponsive scaffolds, growth factors (GFs), immune cells, and stromal progenitor cells are essential in promoting bone regeneration. This literature review comprehensively discusses various aspects of resorbable scaffolds in bone tissue engineering, encompassing scaffold design, materials, fabrication techniques, and advanced manufacturing methods, including three-dimensional printing. In addition, this review explores surface modifications to replicate native bone structures and their impact on cellular responses. Moreover, the mechanisms of bone regeneration are described, providing information on how immune cells, GFs, and bioresponsive scaffolds orchestrate tissue healing. Practical applications in clinical settings are presented to underscore the importance of these principles in promoting tissue integration, healing, and regeneration. Furthermore, this literature review delves into emerging areas of metamaterials and artificial intelligence applications in tissue engineering and regenerative medicine. These interdisciplinary approaches hold immense promise for furthering bone tissue engineering and improving therapeutic outcomes, leading to enhanced patient well-being. The potential of combining material science, advanced manufacturing, and cellular biology is showcased as a pathway to advance bone tissue engineering, addressing a variety of clinical needs and challenges. By providing this comprehensive narrative, a detailed, up-to-date account of resorbable scaffolds' role in bone tissue engineering and their transformative potential is offered.

Biocomposite-based strategies for dental bone regeneration

OBJECTIVE

Because of the anatomical complexity of the oral and maxillofacial sites, repairing bone defects in these regions is very difficult. This review article aims to consider the application of biocomposites-based strategies for dental bone regeneration.

STUDY DESIGN

Research papers related to the topic, published over the last 20 years, were selected using the Web of Science, Pubmed, Scopus, and Google Scholar databases.

RESULTS

The strategies of monophasic, biphasic/multiphasic scaffolds, and biopolymer-based nanocomposite scaffolds containing nanomaterials compared with traditional methods used for bone regeneration, such as autografts, allografts, xenografts, and alloplasts are found to be superior because of their ability to overcome the issues (e.g., limited bone sources, pain, immune responses, high cost) related to the applications of the traditional methods.

CONCLUSIONS

In addition, additive manufacturing technologies were found to be highly advantageous for improving the efficacy of biocomposite scaffolds for treating dental bone defects.

Lipophosphonoxins-A Novel Group of Broad Spectrum Antibacterial Compounds

Lipophosphonoxins (LPPOs) represent a new group of membrane-targeting antibiotics. Three generations of LPPOs have been described: First-generation LPPOs, second-generation LPPOs, and LEGO-LPPOs. All three generations have a similar mode of bactericidal action of targeting and disrupting the bacterial cytoplasmic membrane of prokaryotic cells, with limited effect on eukaryotic cells. First-generation LPPOs showed excellent bactericidal activity against Gram-positive species, including multiresistant strains. Second-generation LPPOs broaden the antibiotic effect also against Gram-negative bacteria. However, both first- and second-generation LPPOs lose their antibacterial activity in the presence of serum albumin. LEGO-LPPOs were found to be active against both Gram-positive and Gram-negative bacteria, have better selectivity as compared to first- and second-generation resistance to LEGO-LPPOs was also not observed, and are active even in the presence of serum albumin. Second-generation LPPOs have been studied as antimicrobial additives in bone cement and as nanofiber dressing components in the treatment of wound infections in mice. Second-generation LPPOs and LEGO-LPPOs were also tested to treat ex vivo simulated endodontic infections in dental root canals. The results of all these studies were encouraging and suggested further investigation of LPPOs in these indications. This paper aims to review and compile published data on LPPOs.

An updated patent review of GLP-1 receptor agonists (2020-present)

INTRODUCTION

Type 2 diabetes (T2DM) and obesity present significant global health issues, requiring the development of long-lasting and highly effective pharmacotherapies. Although glucagon-like peptide-1 receptor agonists (GLP-1RAs) are commonly used for diabetes treatment, their potential for addressing obesity is still being explored.

AREAS COVERED

This review offers a comprehensive overview of recently published patents from January 2020 to July 2023, focusing on modified GLP-1RAs, small molecule GLP-1RAs, GLP-1 R-based multi-agonists, GLP-1RA-based fusion proteins, and combination therapies. The patents discussed pertain to the treatment and prevention of diabetes and obesity. Patent searches were conducted using the PATENTSCOPE database of the World Intellectual Property Organization, using the keywords GLP-1, GLP-1/GIP, GLP-1/GCG, and GLP-1/GCG/GIP.

EXPERT OPINION

In recent years, patents have emphasized two main goals for developing GLP-1RAs drugs: oral delivery and improved weight reduction effects. To address the growing demand for improved treatments, researchers have focused their efforts on developing GLP-1 R-based multi-agonists, orally administered GLP-1RAs, and combination therapies utilizing GLP-1RAs. These new approaches offer promising benefits, such as improved effectiveness by targeting multiple pathways and reduced side effects. Additionally, the development of new uses, oral forms, and long-lasting preparations will be crucial in shaping the future market potential of GLP-1 drugs.

Emerging roles of oxyntomodulin-based glucagon-like peptide-1/glucagon co-agonist analogs in diabetes and obesity

Oxyntomodulin (OXM) is an endogenous peptide hormone secreted from the intestines following nutrient ingestion that activates both glucagon-like peptide-1 (GLP-1) and glucagon receptors. OXM is known to exert various effects, including improvement in glucose tolerance, promotion of energy expenditure, acceleration of liver lipolysis, inhibition of food intake, delay of gastric emptying, neuroprotection, and pain relief. The antidiabetic and antiobesity properties have led to the development of biologically active and enzymatically stable OXM-based analogs with proposed therapeutic promise for metabolic diseases. Structural modification of OXM was ongoing to enhance its potency and prolong half-life, and several GLP-1/glucagon dual receptor agonist-based therapies are being explored in clinical trials for the treatment of type 2 diabetes mellitus and its complications. In the present article, we provide a brief overview of the physiology of OXM, focusing on its structural-activity relationship and ongoing clinical development.

Eptifibatide, an Older Therapeutic Peptide with New Indications: From Clinical Pharmacology to Everyday Clinical Practice

Therapeutic peptides are oligomers or short polymers of amino acids used for various medical purposes. Peptide-based treatments have evolved considerably due to new technologies, stimulating new research interests. They have been shown to be beneficial in a variety of therapeutic applications, notably in the treatment of cardiovascular disorders such as acute coronary syndrome (ACS). ACS is characterized by coronary artery wall damage and consequent formation of an intraluminal thrombus obstructing one or more coronary arteries, leading to unstable angina, non-ST elevated myocardial infarction, and ST-elevated myocardial infarction. One of the promising peptide drugs in the treatment of these pathologies is eptifibatide, a synthetic heptapeptide derived from rattlesnake venom. Eptifibatide is a glycoprotein IIb/IIIa inhibitor that blocks different pathways in platelet activation and aggregation. In this narrative review, we summarized the current evidence on the mechanism of action, clinical pharmacology, and applications of eptifibatide in cardiology. Additionally, we illustrated its possible broader usage with new indications, including ischemic stroke, carotid stenting, intracranial aneurysm stenting, and septic shock. Further research is, however, required to fully evaluate the role of eptifibatide in these pathologies, independently and in comparison to other medications.

Carboplatin Niosomal Nanoplatform for Potentiated Chemotherapy

This study aimed to characterize a stable nano-niosome formulation, which could reduce the adverse effects of carboplatin (CB) and improve its therapeutic efficacy in the treatment of breast cancer. For this purpose, CB-loaded polyethylene glycol (PEG)ylated niosome nanoparticles (PEG-NS-CB) were synthesized using the reverse-phase evaporation method. PEG-NS-CB (226.0 ± 10.6 nm) could release CB in a controlled manner and, compared to CB and CB-loaded non-PEGylated niosome (NS-CB), caused higher cytotoxicity effects against mouse breast cancer 4T1 cells (IC₅₀: 83.4, 26.6, and 22.5 µM for CB, NS-CB, and PEG-NS-CB, respectively). Also, PEG-NS-CB demonstrated higher stability, in which its profile of drug release, cytotoxicity, and LE% did not change significantly three months after preparation compared to those at the production time. In addition, the in vivo results demonstrated that PEG-NS-CB caused higher therapeutic (the number of alive mice: 12, 15, and 17 out of 20 in CB, NS-CB, and PEG-NS-CB receiver groups, respectively) and less toxicity effects (weight loss of 17, 12.5, and 10% in CB, NS-CB, and PEG-NS-CB receiver groups, respectively), compared to NS-CB and CB in breast cancer-bearing mice. Overall, the results of this study suggest that PEG-NS-CB could be a promising formulation for the treatment of breast cancer.

Advanced Drug Delivery Platforms for the Treatment of Oral Pathogens

The oral cavity is a complex ecosystem accommodating various microorganisms (e.g., bacteria and fungi). Various factors, such as diet change and poor oral hygiene, can change the composition of oral microbiota, resulting in the dysbiosis of the oral micro-environment and the emergence of pathogenic microorganisms, and consequently, oral infectious diseases. Systemic administration is frequently used for drug delivery in the treatment of diseases and is associated with the problems, such as drug resistance and dysbiosis. To overcome these challenges, oral drug delivery systems (DDS) have received considerable attention. In this literature review, the related articles are identified, and their findings, in terms of current therapeutic challenges and the applications of DDSs, especially nanoscopic DDSs, for the treatment of oral infectious diseases are highlighted. DDSs are also discussed in terms of structures and therapeutic agents (e.g., antibiotics, antifungals, antiviral, and ions) that they deliver. In addition, strategies (e.g., theranostics, hydrogel, microparticle, strips/fibers, and pH-sensitive nanoparticles), which can improve the treatment outcome of these diseases, are highlighted.

Design, Preparation, and Evaluation of Osthol Poly-Butyl-Cyanoacrylate Nanoparticles with Improved In Vitro Anticancer Activity in Neuroblastoma Treatment

Osthol (osthole), known as a neuroprotective drug, has shown potent anticancer activity. However, the potential clinical application of osthol is limited due to its low water solubility and low bioavailability. Polybutyl cyanoacrylate (PBCA) has been widely used to improve the solubility of drugs with poor water solubility. In this study, an orthogonal experimental design (OED) was applied to design the preparation process of PBCA nanoparticles (NPs). Then, nanoparticles were prepared and evaluated in terms of physicochemical properties, in vitro release, and cellular uptake, etc. Further, the anti-cancer activity of osthol-PBCA NPs was demonstrated in SH-SY5Y cells. The pharmacokinetics and area under the curve (AUC) were investigated. The obtained osthol-NPs presented a spherical shape with a particle size of 110 ± 6.7 nm, a polydispersity index (PDI) of 0.126, and a zeta potential of −13 ± 0.32 mV. Compared with the free osthol, the drugs in osthol-NPs presented better stability and sustained release pattern activity. In vitro analysis using SH-SY5Y neuroblastoma cells showed that osthol-loaded nanoparticles displayed a significantly enhanced intracellular absorption process (three times) and cytotoxicity compared with free osthol (p < 0.05, increased 10−20%). The in vivo pharmacokinetic study revealed that the AUC of osthol-NPs was 3.3-fold higher than that of free osthol. In conclusion, osthol-PBCA NPs can enhance the bioactivity of osthol, being proposed as a novel, promising vehicle for drug delivery.

Impact of PEGylated Liposomal Doxorubicin and Carboplatin Combination on Glioblastoma

Glioblastoma is an incurable cancer with a 5-year survival chance of less than 5%. Chemotherapy is a therapeutic approach to treating the disease; however, due to the presence of the blood–brain barrier (BBB), the probability of success is low. To overcome this issue, nanoparticles are promising carriers for crossing the BBB and delivering drugs to the tumor. In this study, the anticancer efficacy of doxorubicin (DOX) and carboplatin (CB) loaded into polyethylene glycol (PEG)ylated liposome nanoparticles (PEG-Lip) and in treating brain cancer was evaluated in vitro and in vivo. The results demonstrated that PEG-Lip-DOX/CB with a size of 212 ± 10 nm was synthesized that could release the loaded drugs in a controlled manner, from which 56.3% of the loaded drugs were released after 52 h. In addition, PEG-Lip-DOX/CB could significantly increase the cytotoxicity effects of the drugs against rat glioma C6 cells (IC₅₀: 8.7 and 12.9 µM for the drugs-loaded nanoparticles and DOX + CB, respectively). The in vivo results also demonstrated that PEGylated liposomes, compared to non-PEGylated liposomes (Lip) and DOX + CB, were more efficient in increasing the therapeutic effects and decreasing the side effects of the drugs, in which the survival times of the glioblastoma-bearing rats were 39, 35, and 30 days in the PEG-Lip-DOX/CB, Lip-DOX/CB, and DOX + CB receiver groups, respectively. In addition, the weight loss was found to be 8.7, 10.5, and 13%, respectively, in the groups. The results of the toxicity evaluation were also confirmed by histopathological studies. Overall, the results of this study demonstrated that the encapsulation of DOX and CB into PEG-Lip is a promising approach to improving the properties of DOX and CB in terms of their therapeutic effects and drug side effects for the treatment of glioblastoma.

A PEGylated Nanostructured Lipid Carrier for Enhanced Oral Delivery of Antibiotics

Antimicrobial resistance is a major concern for public health throughout the world that severely restricts available treatments. In this context, methicillin-resistant Staphylococcus aureus (MRSA) is responsible for a high percentage of S. aureus infections and mortality. To overcome this challenge, nanoparticles are appropriate tools as drug carriers to improve the therapeutic efficacy and decrease the toxicity of drugs. In this study, a polyethylene glycol (PEG)ylated nanostructured lipid carrier (PEG-NLC) was synthesized to improve the oral delivery of trimethoprim/sulfamethoxazole (TMP/SMZ) for the treatment of MRSA skin infection in vitro and in vivo. The nanoformulation (PEG-TMP/SMZ-NLC) was synthesized with size and drug encapsulation efficiencies of 187 ± 9 nm and 93.3%, respectively, which could release the drugs in a controlled manner at intestinal pH. PEG-TMP/SMZ-NLC was found efficient in decreasing the drugs’ toxicity by 2.4-fold in vitro. In addition, the intestinal permeability of TMP/SMZ was enhanced by 54%, and the antibacterial effects of the drugs were enhanced by 8-fold in vitro. The results of the stability study demonstrated that PEG-TMP/SMZ-NLC was stable for three months. In addition, the results demonstrated that PEG-TMP/SMZ-NLC after oral administration could decrease the drugs’ side-effects such as renal and hepatic toxicity by ~5-fold in MRSA skin infection in Balb/c mice, while it could improve the antibacterial effects of TMP/SMZ by 3 orders of magnitude. Overall, the results of this study suggest that the application of PEGylated NLC nanoparticles is a promising approach to improving the oral delivery of TMP/SMZ for the treatment of MRSA skin infection.

Application of Mesoporous Silica Nanoparticles in Cancer Therapy and Delivery of Repurposed Anthelmintics for Cancer Therapy

This review focuses on the biomedical application of mesoporous silica nanoparticles (MSNs), mainly focusing on the therapeutic application of MSNs for cancer treatment and specifically on overcoming the challenges of currently available anthelmintics (e.g., low water solubility) as repurposed drugs for cancer treatment. MSNs, due to their promising features, such as tunable pore size and volume, ability to control the drug release, and ability to convert the crystalline state of drugs to an amorphous state, are appropriate carriers for drug delivery with the improved solubility of hydrophobic drugs. The biomedical applications of MSNs can be further improved by the development of MSN-based multimodal anticancer therapeutics (e.g., photosensitizer-, photothermal-, and chemotherapeutics-modified MSNs) and chemical modifications, such as poly ethyleneglycol (PEG)ylation. In this review, various applications of MSNs (photodynamic and sonodynamic therapies, chemotherapy, radiation therapy, gene therapy, immunotherapy) and, in particular, as the carrier of anthelmintics for cancer therapy have been discussed. Additionally, the issues related to the safety of these nanoparticles have been deeply discussed. According to the findings of this literature review, the applications of MSN nanosystems for cancer therapy are a promising approach to improving the efficacy of the diagnostic and chemotherapeutic agents. Moreover, the MSN systems seem to be an efficient strategy to further help to decrease treatment costs by reducing the drug dose.

Discovery of once-weekly, peptide-based selective GLP-1 and cholecystokinin 2 receptors co-agonizts

A group of long-acting, peptide-based, and selective GLP-1R/CCK-2R dual agonizts were identified by rational design. Guided by sequence analysis, structural elements of the CCK-2R agonist moiety were engineered into the GLP-1R agonist Xenopus GLP-1, resulting in hybrid peptides with potent GLP-1R/CCK-2R dual activity. Further modifications with fatty acids resulted in novel metabolically stable peptides, among which 3d and 3 h showed potent GLP-1R and CCK-2R activation potencies and comparable stability to semaglutide. In food intake tests, 3d and 3 h also showed a potent reduction in food intake, superior to that of semaglutide. Moreover, the acute hypoglycemic and insulinotropic activities of 3d and 3 h were better than that of semaglutide and ZP3022. Importantly, the limited pica response following 3d and 3 h administration in SD rats preliminarily indicated that the food intake reduction effects of 3d and 3 h are independent of nausea/vomiting. In a 35-day study in db/db mice, every two days administration of 3d and 3 h increased islet areas and numbers, insulin contents, β-cell area, β-cell proliferation, as well as improved glucose tolerance, and decreased HbA1c, to a greater extent than ZP3022 and semaglutide. In a 21-day study in DIO mice, once-weekly administration of 3d and 3 h significantly induced body weight loss, improved glucose tolerance, and normalized lipid metabolism, to a greater extent than semaglutide. The current study showed the antidiabetic and antiobesity potentials of GLP-1R/CCK-2R dual agonizts that warrant further investigation.

Multivalent γ-PGA-Exendin-4 conjugates to target pancreatic β-cells

Targeting of glucagon‐like peptide 1 receptor (GLP‐1R), expressed on the surface of pancreatic β‐cells, is of great interest for the development of advanced therapies for diabetes and diagnostics for insulinoma. We report the conjugation of exendin‐4 (Ex‐4), an approved drug to treat type 2 diabetes, to poly‐γ‐glutamic acid (γ‐PGA) to obtain more stable and effective GLP‐1R ligands. Exendin‐4 modified at Lysine‐27 with PEG4‐maleimide was conjugated to γ‐PGA functionalized with furan, in different molar ratios, exploiting a chemoselective Diels‐Alder cycloaddition. The γ‐PGA presenting the highest number of conjugated Ex‐4 molecules (average 120 per polymeric chain) showed a double affinity towards GLP‐1R with respect to exendin per se, paving the way to improved therapeutic and diagnostic applications.

Advances in oral peptide drug nanoparticles for diabetes mellitus treatment

Peptide drugs play an important role in diabetes mellitus treatment. Oral administration of peptide drugs is a promising strategy for diabetes mellitus because of its convenience and high patient compliance compared to parenteral administration routes. However, there are a series of formidable unfavorable conditions present in the gastrointestinal (GI) tract after oral administration, which result in the low oral bioavailability of these peptide drugs. To overcome these challenges, various nanoparticles (NPs) have been developed to improve the oral absorption of peptide drugs due to their unique in vivo properties and high design flexibility. This review discusses the unfavorable conditions present in the GI tract and provides the corresponding strategies to overcome these challenges. The review provides a comprehensive overview on the NPs that have been constructed for oral peptide drug delivery in diabetes mellitus treatment. Finally, we will discuss the rational application and give some suggestions that can be utilized for the development of oral peptide drug NPs. Our aim is to provide a systemic and comprehensive review of oral peptide drug NPs that can overcome the challenges in GI tract for efficient treatment of diabetes mellitus.

•Oral administration of peptide drugs is a promising strategy for diabetes mellitus treatment

•A series of formidable unfavorable conditions in gastrointestinal tract result in the low oral bioavailability of peptide drugs

•Nanoparticles can improve the oral bioavailability of peptide drugs

Therapeutic peptides: current applications and future directions

Peptide drug development has made great progress in the last decade thanks to new production, modification, and analytic technologies. Peptides have been produced and modified using both chemical and biological methods, together with novel design and delivery strategies, which have helped to overcome the inherent drawbacks of peptides and have allowed the continued advancement of this field. A wide variety of natural and modified peptides have been obtained and studied, covering multiple therapeutic areas. This review summarizes the efforts and achievements in peptide drug discovery, production, and modification, and their current applications. We also discuss the value and challenges associated with future developments in therapeutic peptides.

Anti-Diabetic Drugs GLP-1 Agonists and DPP-4 Inhibitors may Represent Potential Therapeutic Approaches for COVID-19

The fast spread of coronavirus 2019 (COVID-19) calls for immediate action to counter the associated significant loss of human life and deep economic impact. Certain patient populations like those with obesity and diabetes are at higher risk for acquiring severe COVID-19 disease and have a higher risk of COVID-19 associated mortality. In the absence of an effective and safe vaccine, the only immediate promising approach is to repurpose an existing approved drug. Several drugs have been proposed and tested as adjunctive therapy for COVID-19. Among these drugs are the glucagon-like peptide-1 (GLP-1) 2 agonists and the dipeptidylpeptidase-4 (DPP-4) inhibitors. Beyond their glucose-lowering effects, these drugs have several pleiotropic protective properties, which include cardioprotective effects, anti-inflammatory and immunomodulatory activities, antifibrotic effects, antithrombotic effects, and vascular endothelial protective properties. This narrative review discusses these protective properties and addresses their scientific plausibility for their potential use as adjunctive therapy for COVID-19 disease.

PEG-grafted liposomes for enhanced antibacterial and antibiotic activities: An in vivo study

Staphylococcus aureus (S. aureus) biofilm-associated infections are a primary concern for public health worldwide. Current therapeutics cannot penetrate the biofilms efficiently, resulting in low drug concentrations at the infected sites and increasing the frequency of drug usage. To solve this issue, nanotechnology platforms seem to be a promising approach. In this study, the potential therapeutic effects of (PEG)ylated liposome (PEG-Lip) for the delivery of nafcillin (NF) antibiotic were assessed. The results demonstrated that NF-loaded liposome (Lip-NF) and NF-loaded PEG-Lip (PEG-Lip-NF) released 76.4 and 62% of the loaded NF, respectively, in a controlled manner after 50 h. Also, it was found that PEG-Lip-NF, compared to Lip-NF and NF, was more effective against a methicillin-susceptible S. aureus (MSSA; minimum inhibitory concentration (MIC): 1.0 ± 0.03, 0.5 ± 0.02, and 0.25 ± 0.01 μg/mL; and minimum biofilm inhibitory concentration (MBIC₅₀): 4.0 ± 0.18, 1.0 ± 0.04, and 0.5 ± 0.02 μg/mL for NF, Lip-NF, and PEG-Lip-NF, respectively). PEG-Lip-NF, compared to NF and Lip-NF, could also more efficiently decrease the side effects of NF through improving human MG-63 osteoblast cell viability (cell viability at 100 μM of NF: 76, 68, and 38% for PEG-Lip-NF, Lip-NF, and NF, respectively). PEG-Lip-NF, compared to control, NF, and Lip-NF groups, was more efficacious by 45, 25, and 10%, respectively, to decrease the virulence of MSSA bacteremia through inhibiting the weight loss of the infected mice. Also, PEG-Lip-NF and Lip-NF, compared to control and NF groups, caused a considerable decrease in the mortality rate in a murine model of bacteremia (number of dead mice: 0, 0, 2, and 8 out of 15 for PEG-Lip-NF, Lip-NF, NF, and control groups, respectively). Overall, the results of this study demonstrated that the loading of NF into PEG-Lip is a promising strategy to decrease the side effects of NF with improved antibacterial effects for the treatment of MSSA biofilm-associated infections.

PEGylated Mesoporous Silica Nanoparticles (MCM-41): A Promising Carrier for the Targeted Delivery of Fenbendazole into Prostrate Cancer Cells

Low water solubility and thus low bioavailability limit the clinical application of fenbendazole (FBZ) as a potential anticancer drug. Solubilizing agents, such as Mobil Composition of Matter Number 41 (MCM) as a drug carrier, can improve the water solubility of drugs. In this study, PEGylated MCM (PEG-MCM) nanoparticles (NPs) were synthesized and loaded with FBZ (PEG-MCM-FBZ) to improve its solubility and, as a result, its cytotoxicity effect against human prostate cancer PC-3 cells. The loading efficiency of FBZ onto PEG-MCM NPs was 17.2%. The size and zeta potential of PEG-MCM-FBZ NPs were 366.3 ± 6.9 nm and 24.7 ± 0.4 mV, respectively. They had a spherical shape and released the drug in a controlled manner at pH 1.2 and pH 6.2. PEG-MCM-FBZ were found to inhibit the migration of PC-3 cells, increase the cytotoxicity effects of FBZ against PC-3 cells by 3.8-fold, and were more potent by 1.4-fold, when compared to the non-PEGylated NPs. In addition, PEG-MCM-FBZ promoted the production of reactive oxygen species by 1.3- and 1.2-fold, respectively, when compared to FBZ and MCM-FBZ. Overall, the results demonstrate that PEG-MCM-FBZ NPs enhanced FBZ delivery to PC-3 cells; therefore, they have the potential to treat prostate cancer after a comprehensive in vivo study.

Stapled, Long-Acting Xenopus GLP-1-Based Dual GLP-1/Glucagon Receptor Agonists with Potent Therapeutic Efficacy for Metabolic Disease

Novel peptidic glucagon receptor (GCGR) and glucagon-like peptide 1 receptor (GLP-1R) dual agonists are reported to have increased efficacy over GLP-1R monoagonists for the treatment of diabetes and obesity. We identified a novel Xenopus GLP-1-based dual GLP-1R/GCGR agonist (xGLP/GCG-13) designed with a proper activity ratio favoring the GLP-1R versus the GCGR. However, the clinical utility of xGLP/GCG-13 is limited by its short in vivo half-life. Starting from xGLP/GCG-13, dual Cys mutation was performed, followed by covalent side-chain stapling and serum albumin binder incorporation, resulting in a stabilized secondary structure, enhanced agonist potency at GLP-1R and GCGR, and improved stability. The lead peptide 2c (stapled xGLP/GCG-13 analogue with a palmitic acid albumin binder) exhibits balanced GLP-1R and GCGR activations and potent, long-lasting effects on in vivo glucose control. 2c was further explored pharmacologically in diet-induced obesity and db/db rodent models. Chronic administration of 2c potently induced body weight loss and hypoglycemic effects, improved glucose tolerance, increased energy expenditure, and normalized lipid metabolism and adiposity in relevant animal models. These results indicated that 2c has potential for development as a novel antidiabetic and/or antiobesity drug. Furthermore, we propose that the incorporation of a proper serum protein-binding motif into a di-Cys staple is an effective method for improving the stabilities and bioactivities of peptides. This approach is likely applicable to other therapeutic peptides, such as glucose-dependent insulin-tropic peptide receptor (GIPR) and GLP-1R dual agonists or GLP-1R/GCGR/GIPR triagonists.

Recent advances in proteolytic stability for peptide, protein, and antibody drug discovery

Introduction: To discover and develop a peptide, protein, or antibody into a drug requires overcoming multiple challenges to obtain desired properties. Proteolytic stability is one of the challenges and deserves a focused investigation.Areas covered: This review concentrates on improving proteolytic stability by engineering the amino acids around the cleavage sites of a liable peptide, protein, or antibody. Peptidases are discussed on three levels including all peptidases in databases, mixtures based on organ and tissue types, and individual peptidases. The technique to identify cleavage sites is spotlighted on mass spectrometry-based approaches such as MALDI-TOF and LC-MS. For sequence engineering, the replacements that have been commonly applied with a higher chance of success are highlighted at the beginning, while the rarely used and more complicated replacements are discussed later. Although a one-size-fits-all approach does not exist to apply to different projects, this review provides a 3-step strategy for effectively and efficiently conducting the proteolytic stability experiments to achieve the eventual goal of improving the stability by engineering the molecule itself.Expert opinion: Improving the proteolytic stability is a spiraling up process sequenced by testing and engineering. There are many ways to engineer amino acids, but the choice must consider the cost and properties affected by the changes of the amino acids.

Developing GLP-1 Conjugated Self-Assembling Nanofibers Using Copper-Catalyzed Alkyne-Azide Cycloaddition and Evaluation of Their Biological Activity

Glucagon-like peptide-1 GLP-1 is a gut-derived peptide secreted from pancreatic β-cells that reduces blood glucose levels and body weight; however, native GLP-1 (GLP-1(7-36)-NH₂ and GLP-1(7-37)) have short in vivo circulation half-lives (∼2 min) due to proteolytic degradation and rapid renal clearance due to its low molecular weight (MW; 3297.7 Da). This study aimed to improve the proteolytic stability and delivery properties of glucagon-like peptide-1 (GLP-1) through modifications that form nanostructures. For this purpose, N- (NtG) and C-terminal (CtG), and Lys26 side chain (K26G) alkyne-modified GLP-1 analogues were conjugated to an azide-modified lipidic peptide (L) to give N-L, C-L, and K-26-L, respectively; or CtG was conjugated with a fibrilizing self-assembling peptide (SAP) (AEAEAKAK)₃ to yield C-S, using copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). N-L demonstrated the best serum stability (t_1/2 > 48 h) compared to K-26-L (44 h), C-L (20 h), C-S (27 h), and the parental GLP-1(7-36;A8G)-NH₂ (A8G) (19 h) peptides. Each conjugate demonstrated subnanomolar hGLP-1RA potency, and none demonstrated toxicity toward PC-3 cells at concentrations up to 1 μM. Each analogue was observed by transmission electron microscopy to form fibrils in solution. K-26-L demonstrated among the best human serum stability (t_1/2 = 44 h) and similar hGLP-1RA potency (EC₅₀ 48 pM) to C-S. In conclusion, this study provided an alternative to lipid modification, i.e., fibrillizing peptides, that could improve pharmacokinetic parameters of GLP-1.

GLP-1 peptide analogs for targeting pancreatic beta cells

Loss or dysfunction of the pancreatic beta cells or insulin receptors leads to diabetes mellitus (DM). This usually occurs over many years; therefore, the development of methods for the timely detection and clinical intervention are vital to prevent the development of this disease. Glucagon-like peptide-1 receptor (GLP-1R) is the receptor of GLP-1, an incretin hormone that causes insulin secretion in a glucose-dependent manner. GLP-1R is highly expressed on the surface of pancreatic beta cells, providing a potential target for bioimaging. In this review, we provide an overview of various strategies, such as the development of GLP-1R agonists (e.g., exendin-4), and GLP-1 sequence modifications for GLP-1R targeting for the diagnosis and treatment of pancreatic beta cell disorders. We also discuss the challenges of targeting pancreatic beta cells and strategies to address such challenges.

Poly(aspartic acid) in Biomedical Applications: From Polymerization, Modification, Properties, Degradation, and Biocompatibility to Applications

Poly(aspartic acid) (PASP) is an anionic polypeptide that is a highly versatile, biocompatible, and biodegradable polymer that fulfils key requirements for use in a wide variety of biomedical applications. The derivatives of PASP can be readily tailored via the amine-reactive precursor, poly(succinimide) (PSI), which opens up a large window of opportunity for the design and development of novel biomaterials. PASP also has a strong affinity with calcium ions, resulting in complexation, which has been exploited for bone targeting and biomineralization. In addition, recent studies have further verified the biocompatibility and biodegradability of PASP-based polymers, which is attributed to their protein-like structure. In light of growing interest in PASP and its derivatives, this paper presents a comprehensive review on their synthesis, characterization, modification, biodegradation, biocompatibility, and applications in biomedical areas.

Poly ethylene glycol (PEG)-Related controllable and sustainable antidiabetic drug delivery systems

Diabetes mellitus is one of the most challenging threats to global public health. To improve the therapy efficacy of antidiabetic drugs, numerous drug delivery systems have been developed. Polyethylene glycol (PEG) is a polymeric family sharing the same skeleton but with different molecular weights which is considered as a promising material for drug delivery. In the delivery of antidiabetic drugs, PEG captures much attention in the designing and preparation of sustainable and controllable release systems due to its unique features including hydrophilicity, biocompatibility and biodegradability. Due to the unique architecture, PEG molecules are also able to shelter delivery systems to decrease their immunogenicity and avoid undesirable enzymolysis. PEG has been applied in plenty of delivery systems such as micelles, vesicles, nanoparticles and hydrogels. In this review, we summarized several commonly used PEG-contained antidiabetic drug delivery systems and emphasized the advantages of stimuli-responsive function in these sustainable and controllable formations.

Role of lipid nanocarriers for enhancing oral absorption and bioavailability of insulin and GLP-1 receptor agonists

Growing demand for insulin and glucagon-like peptide-1 receptor agonists (GLP-1 RA) is observed, considering the progressive nature of diabetes and the potential therapeutic role of peptides in its treatment. However, chronic parenteral administration is responsible for pain and rashes at the site of injection. Oral delivery of insulin and GLP-1 RA promises better patient compliance owing to their ease of administration and reduction in chances of peripheral hypoglycaemia and weight gain. The review article discusses the potential of lipid carriers in combination with different strategies such as absorption enhancers, PEGylation, lipidisation, etc. The lipid nanocarriers improve the membrane permeability and oral bioavailability of high molecular weight peptides. Additionally, the clinical status of different nanocarriers for anti-diabetic peptides is discussed. Previous research on nanocarriers showed significant hypoglycaemic activity and safety in animal studies; however, extrapolation of the same in human subjects is not validated. With the rising global burden of diabetes, the lipid nanocarriers show the potential to revolutionise treatment with oral delivery of insulin and GLP-1 RA.