Long-Acting Release Formulation of Exendin-4 Based on Biomimetic Mineralization for Type 2 Diabetes Therapy

Nature-inspired protein mineralization strategies for nanoparticle construction: advancing effective cancer therapy

Recently, nanotechnology has shown great potential in the field of cancer therapy due to its ability to improve the stability and solubility and reduce side effects of drugs. The biomimetic mineralization strategy based on natural proteins and metal ions provides an innovative approach for the synthesis of nanoparticles. This strategy utilizes the unique properties of natural proteins and the mineralization ability of metal ions to combine nanoparticles through biomimetic mineralization processes, achieving the effective treatment of tumors. The precise control of the mineralization process between proteins and metal ions makes it possible to obtain nanoparticles with the ideal size, shape, and surface characteristics, thereby enhancing their stability and targeting ability in vivo. Herein, initially, we analyze the role of protein molecules in biomineralization and comprehensively review the functions, properties, and applications of various common proteins and metal particles. Subsequently, we systematically review and summarize the application directions of nanoparticles synthesized based on protein biomineralization in tumor treatment. Specifically, we discuss their use as efficient drug delivery carriers and role in mediating monotherapy and synergistic therapy using multiple modes. Also, we specifically review the application of nanomedicine constructed through biomimetic mineralization strategies using natural proteins and metal ions in improving the efficiency of tumor immunotherapy.

Enhancing the Therapeutic Efficacy of GLP-1 for Hyperglycemia Treatment: Overcoming Barriers of Oral Gene Therapy with Taurocholic Acid-Conjugated Protamine Sulfate and Calcium Phosphate

Activating the glucagon-like peptide-1 (GLP-1) receptor by oral nucleic acid delivery would be a promising treatment strategy against hyperglycemia due to its various therapeutic actions. However, GLP-1 receptor agonists are effective only in subcutaneous injections because they face multiple barriers due to harsh gastrointestinal tract (GIT) conditions before reaching the site of action. The apical sodium bile acid transporter (ASBT) pathway at the intestinal site could be an attractive target to overcome the problem. Herein, we used our previously established multimodal carrier system utilizing bile salt, protamine sulfate, and calcium phosphate as excipients (PTCA) and the GLP-1 gene as an active ingredient (GENE) to test the effects of different formulation doses against diabetes and obesity. The carrier system demonstrated the ability to protect the GLP-1 model gene encoded within the plasmid at the GIT and transport it via ASBT at the target site. A single oral dose, regardless of quantity, showed the generation of GLP-1 and insulin from the body and maintained the normoglycemic condition by improving insulin sensitivity and blood sugar tolerance for a prolonged period. This oral gene therapy approach shows significantly higher therapeutic efficacy in preclinical studies than currently available US Food and Drug Administration-approved GLP-1 receptor agonists such as semaglutide and liraglutide. Also, a single oral dose of GENE/PTCA is more effective than 20 insulin injections. Our study suggests that oral GENE/PTCA formulation could be a promising alternative to injection-based therapeutics for diabetics, which is effective in long-term treatment and has been found to be highly safe in all aspects of toxicology.

Unravelling the role of microneedles in drug delivery: Principle, perspectives, and practices

In recent year, the research of transdermal drug delivery systems has got substantial attention towards the development of microneedles (MNs). This shift has occurred due to multifaceted advantages of MNs as they can be utilized to deliver the drug deeper to the skin with minimal invasion, offer successful delivery of drugs and biomolecules that are susceptible to degradation in gastrointestinal tract (GIT), act as biosensors, and help in monitoring the level of biomarkers in the body. These can be fabricated into different types based on their applications as well as material for fabrication. Some of their types include solid MNs, hollow MNs, coated MNs, hydrogel forming MNs, and dissolving MNs. These MNs deliver the therapeutics via microchannels deeper into the skin. The coated and hollow MNs have been found successful. However, they suffer from poor drug loading and blocking of pores. In contrast, dissolving MNs offer high drug loading. These MNs have also been utilized to deliver vaccines and biologicals. They have also been used in cosmetics. The current review covers the different types of MNs, materials used in their fabrication, properties of MNs, and various case studies related to their role in delivering therapeutics, monitoring level of biomarkers/hormones in body such as insulin. Various patents and clinical trials related to MNs are also covered. Covered are the major bottlenecks associated with their clinical translation and potential future perspectives.

Hybrid biomineralized nanovesicles to enhance inflamed lung biodistribution and reduce side effect of glucocorticoid for ARDS therapy

Acute respiratory distress syndrome (ARDS) is a critical illness characterized by severe lung inflammation. Improving the delivery efficiency and achieving the controlled release of anti-inflammatory drugs at the lung inflammatory site are major challenges in ARDS therapy. Taking advantage of the increased pulmonary vascular permeability and a slightly acidic-inflammatory microenvironment, pH-responsive mineralized nanoparticles based on dexamethasone sodium phosphate (DSP) and Ca2+ were constructed. By further biomimetic modification with M2 macrophage membranes, hybrid mineralized nanovesicles (MM@LCaP) were designed to possess immunomodulatory ability from the membranes and preserve the pH-sensitivity from core nanoparticles for responsive drug release under acidic inflammatory conditions. Compared with healthy mice, the lung/liver accumulation of MM@LCaP in inflammatory mice was increased by around 5.5 times at 48 h after intravenous injection. MM@LCaP promoted the polarization of anti-inflammatory macrophages, calmed inflammatory cytokines, and exhibited a comprehensive therapeutic outcome. Moreover, MM@LCaP improved the safety profile of glucocorticoids. Taken together, the hybrid mineralized nanovesicles-based drug delivery strategy may offer promising ideas for enhancing the efficacy and reducing the toxicity of clinical drugs.

Glucose oxidase-instructed biomineralization of calcium-based biomaterials for biomedical applications

In recent years, glucose oxidase (GOx) has aroused great research interest in the treatment of diseases related to abnormal glucose metabolisms like cancer and diabetes. However, as a kind of endogenous oxido-reductase, GOx suffers from poor stability and system toxicity in vivo. In order to overcome this bottleneck, GOx is encapsulated in calcium-based biomaterials (CaXs) such as calcium phosphate (CaP) and calcium carbonate (CaCO3) by using it as a biotemplate to simulate the natural biomineralization process. The biomineralized GOx holds improved stability and reduced side effects, due to the excellent bioactivity, biocompatibitliy, and biodegradability of CaXs. In this review, the state-of-the-art studies on GOx-mineralized CaXs are introduced with an emphasis on their application in various biomedical fields including disease diagnosis, cancer treatment, and diabetes management. The current challenges and future perspectives of GOx-mineralized CaXs are discussed, which is expected to promote further studies on these smart GOx-mineralized CaXs biomaterials for practical applications.

pH-temperature Responsive Hydrogel-Mediated Delivery of Exendin-4 Encapsulated Chitosan Nanospheres for Sustained Therapeutic Efficacy in Type 2 Diabetes Mellitus

Type 2 Diabetes Mellitus (T2D) is a chronic, obesity-related, and inflammatory disorder characterize by insulin resistance, inadequate insulin secretion, hyperglycemia, and excessive glucagon secretion. Exendin-4 (EX), a clinically established antidiabetic medication that acts as a glucagon-like peptide-1 receptor agonist, is effective in lowering glucose levels and stimulating insulin secretion while significantly reducing hunger. However, the requirement for multiple daily injections due to EX's short half-life is a significant limitation in its clinical application, leading to high treatment costs and patient inconvenience. To address this issue, an injectable hydrogel system is developed that can provide sustained EX release at the injection site, reducing the need for daily injections. In this study, the electrospray technique is examine to form EX@CS nanospheres by electrostatic interaction between cationic chitosan (CS) and negatively charged EX. These nanospheres are uniformly dispersed in a pH-temperature responsive pentablock copolymer, which forms micelles and undergoes sol-to-gel transition at physiological conditions. Following injection, the hydrogel gradually degraded, exhibiting excellent biocompatibility. The EX@CS nanospheres are subsequently released, maintaining therapeutic levels for over 72 h compared to free EX solution. The findings demonstrate that the pH-temperature responsive hydrogel system containing EX@CS nanospheres can be a promising platform for the treatment of T2D.

Biomineralized Polydopamine Nanoparticle-Based Sodium Alginate Hydrogels for Delivery of Anti-serine/Threonine Protein Kinase B-Rapidly Accelerated Fibrosarcoma siRNA for Metastatic Melanoma Therapy

Malignant melanoma, as a highly aggressive skin cancer, is strongly associated with mutations in serine/threonine protein kinase B-RAF (BRAF, where RAF stands for rapidly accelerated fibrosarcoma). Targeted therapy with anti-BRAF small interfering RNA (siBRAF) represents a crucial aspect of metastatic melanoma treatment. In this study, an injectable hydrogel platform based on sodium alginate (SA), with multifunctions of photothermal and Ca2+-overload cell apoptosis, was explored as a siBRAF carrier for metastatic melanoma therapy. We employed polydopamine nanoparticles (PDAs) as a photothermal core and constructed a calcium phosphate (CaP) shell via biomineralization (PDA@CaP) to load siBRAF (PDA@siBRAF/CaP). The pH-sensitive CaP shell facilitated the release of Ca2+ under the weakly acidic tumor microenvironment, triggering the gelation of PDA@siBRAF/CaP-SA to localized release siBRAF at tumor sites with the interruption of the RAS-RAF-MEK-ERK (MAPK) pathway. Besides, the continuous release of Ca2+ could also lead to Ca2+-overload cell apoptosis. Moreover, the photothermal effect of PDA regulated the release kinetics, resulting in coordinated therapeutic abilities of individual components in the PDA@siBRAF/CaP-SA hydrogels. Consequently, the effective inhibition of tumor growth and metastasis was achieved in vitro and in vivo using a highly metastatic melanoma cell line B16F10 as the model, by combining photothermal ablation, Ca2+ overload, and BRAF silencing. Our work provides a proof-of-concept for an injectable hydrogel system that simultaneously targets multiple mechanisms involved in melanoma progression and has the potential to be translated into clinical use for the metastatic melanoma therapy.

Recent Advances in Formulations for Long-Acting Delivery of Therapeutic Peptides

Recent preclinical and clinical studies have focused on the active area of therapeutic peptides due to their high potency, selectivity, and specificity in treating a broad range of diseases. However, therapeutic peptides suffer from multiple disadvantages, such as limited oral bioavailability, short half-life, rapid clearance from the body, and susceptibility to physiological conditions (e.g., acidic pH and enzymolysis). Therefore, high peptide dosages and dose frequencies are required for effective patient treatment. Recent innovations in pharmaceutical formulations have substantially improved therapeutic peptide administration by providing the following advantages: long-acting delivery, precise dose administration, retention of biological activity, and improvement of patient compliance. This review discusses therapeutic peptides and challenges in their delivery and explores recent peptide delivery formulations, including micro/nanoparticles (based on lipids, polymers, porous silicon, silica, and stimuli-responsive materials), (stimuli-responsive) hydrogels, particle/hydrogel composites, and (natural or synthetic) scaffolds. This review further covers the applications of these formulations for prolonged delivery and sustained release of therapeutic peptides and their impact on peptide bioactivity, loading efficiency, and (in vitro/in vivo) release parameters.

Nanofiber matrix formulations for the delivery of Exendin-4 for tendon regeneration: In vitro and in vivo assessment

Tendon and ligament injuries are the most common musculoskeletal injuries, which not only impact the quality of life but result in a massive economic burden. Surgical interventions for tendon/ligament injuries utilize biological and/or engineered grafts to reconstruct damaged tissue, but these have limitations. Engineered matrices confer superior physicochemical properties over biological grafts but lack desirable bioactivity to promote tissue healing. While incorporating drugs can enhance bioactivity, large matrix surface areas and hydrophobicity can lead to uncontrolled burst release and/or incomplete release due to binding. To overcome these limitations, we evaluated the delivery of a peptide growth factor (exendin-4; Ex-4) using an enhanced nanofiber matrix in a tendon injury model. To overcome drug surface binding due to matrix hydrophobicity of poly(caprolactone) (PCL)-which would be expected to enhance cell-material interactions-we blended PCL and cellulose acetate (CA) and electrospun nanofiber matrices with fiber diameters ranging from 600 to 1000 nm. To avoid burst release and protect the drug, we encapsulated Ex-4 in the open lumen of halloysite nanotubes (HNTs), sealed the HNT tube endings with a polymer blend, and mixed Ex-4-loaded HNTs into the polymer mixture before electrospinning. This reduced burst release from ∼75% to ∼40%, but did not alter matrix morphology, fiber diameter, or tensile properties. We evaluated the bioactivity of the Ex-4 nanofiber formulation by culturing human mesenchymal stem cells (hMSCs) on matrix surfaces for 21 days and measuring tenogenic differentiation, compared with nanofiber matrices in basal media alone. Strikingly, we observed that Ex-4 nanofiber matrices accelerated the hMSC proliferation rate and elevated levels of sulfated glycosaminoglycan, tendon-related genes (Scx, Mkx, and Tnmd), and ECM-related genes (Col-I, Col-III, and Dcn), compared to control. We then assessed the safety and efficacy of Ex-4 nanofiber matrices in a full-thickness rat Achilles tendon defect with histology, marker expression, functional walking track analysis, and mechanical testing. Our analysis confirmed that Ex-4 nanofiber matrices enhanced tendon healing and reduced fibrocartilage formation versus nanofiber matrices alone. These findings implicate Ex-4 as a potentially valuable tool for tendon tissue engineering.

Monitoring Subtle Changes of Blood-Brain Barrier Permeability via Detection of MiRNA-155 in Brain Microvasculature

The changes of blood-brain barrier (BBB) permeability need to be sensitively reported when purposefully regulating the BBB or during some brain diseases. Currently available techniques for assessment of BBB integrity all suffer from limited sensitivity and only report serious BBB damage. Here, a targeted activatable nanoprobe is created to monitor subtle changes of BBB permeability by detecting the expression levels of BBB permeability-related miRNA (miRNA-155) in brain microvessel endothelial cells (BMECs). The probe is fabricated by coating the BMEC membrane on calcium phosphate (CaP)-mineralized metal-organic framework (MOF) nanoparticles loaded with hybridization chain reaction (HCR) probes. The coating of the BMEC membrane endows the nanoprobe with homologous targeting ability to BBB, and HCR probes released and escaped from lysosomes can be specifically lightened by miRNA-155. The activatable nanoprobe is able to monitor BBB permeability in inflammatory and AD mice. This work provides a new idea for highly sensitive evaluation of the BBB permeability, which has guiding significance in regulating BBB and formulating targeted therapeutic strategies.

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.

Formulation and characterization of insulin nanoclusters for a controlled release

The growing interest in biopharmaceuticals combined with the challenges regarding formulation and delivery continues to encourage the development of new and improved formulations of this class of therapeutics. Nanoclusters (NCs) represent a type of formulation strategy where the biopharmaceutical is clustered in a reversible manner to function as both the therapeutic and the vehicle. In this study, insulin NCs (INCs) were formulated by a new methodology of first crosslinking proteins followed by desolvation. Crosslinking of the protein with the reducible DTSSP crosslinker improved control of the INC synthesis process to give INCs with a mean size of 198 ± 7 nm and a mean zeta potential of -39 ± 1 mV. Crosslinking and clustering of insulin did not induce cytotoxicity or major differences in the biological activity compared to the free unmodified protein. The potency of the crosslinked insulin and the INCs appeared slightly lower than that of the unmodified protein, and significantly higher doses of the INCs compared to the free protein were applied to achieve similar blood sugar lowering effects in vivo. Interestingly, the INCs allowed for high doses to be subcutaneously delivered with prolonged efficacy without being lethal in rats.

Metallic Microneedles for Transdermal Drug Delivery: Applications, Fabrication Techniques and the Effect of Geometrical Characteristics

Current procedures for transdermal drug delivery (TDD) have associated limitations including poor administration of nucleic acid, small or large drug molecules, pain and stress for needle phobic people. A painless micro-sized device capable of delivering drugs easily and efficiently, eliminating the disadvantages of traditional systems, has yet to be developed. While polymeric-based microneedle (MN) arrays have been used successfully and clinically as TDD systems, these devices lack mechanical integrity, piercing capacity and the ability to achieve tailored drug release into the systemic circulation. Recent advances in micro/nano fabrication techniques using Additive Manufacturing (AM), also known as 3D printing, have enabled the fabrication of metallic MN arrays, which offer the potential to overcome the limitations of existing systems. This review summarizes the different types of MNs used in TDD and their mode of drug delivery. The application of MNs in the treatment of a range of diseases including diabetes and cancer is discussed. The potential role of solid metallic MNs in TDD, the various techniques used for their fabrication, and the influence of their geometrical characteristics (e.g., shape, size, base diameter, thickness, and tip sharpness) on effective TDD are explored. Finally, the potential and the future directions relating to the optimization of metallic MN arrays for TDD are highlighted.

On-demand therapeutic delivery of hydrogen sulfide aided by biomolecules

Hydrogen sulfide (H₂S), known as the third gasotransmitter, exerts various physiological functions including cardiac protection, angiogenesis, anti-inflammatory, and anti-cancer capability. Given its promising therapeutic potential as well as severe perniciousness if improper use, the sustained and tunable H₂S delivery systems are highly required for H₂S-based gas therapy with enhanced bioactivity and reduced side effects. To this end, a series of stimuli-responsive compounds capable of releasing H₂S (termed H₂S donors) have been designed over the past two decades to mimic the endogenous generation of H₂S and elucidate the biological functions. Further to improve the stability of H₂S donors and achieve the targeted delivery, various delivery systems have been constructed. In this review, we focus on the recent advances of an emerging subset, biomolecular-based H₂S delivery systems, which combine H₂S donors with biomolecular vectors including polysaccharide, peptide, and protein. We demonstrated their basic structures, building strategies, and therapeutic applications respectively to unfold their inherent merits endued by biomolecules including biocompatibility, biodegradability as well as expansibility. The varied development potentials of biomolecular-based H₂S delivery systems based on their specific properties are also discussed. At the end, brief future outlooks and upcoming challenges are presented as well.

Effects of immunoglobulin Y-loaded amorphous calcium phosphate on dentinal tubules occlusion and antibacterial activity

Aim: This study aimed to evaluate the effects of immunoglobulin Y (IgY)-loaded amorphous calcium phosphate (ACP) (IgY@ACP) on dentinal tubule occlusion and antibacterial activity.

Methodology: IgY@ACP was synthesized based on a biomimetic mineralization strategy. The structure was examined by transmission electron microscopy and Fourier transform infrared spectroscopy. The IgY release property was assessed in vitro. The cell biocompatibility of IgY@ACP was evaluated by CCK-8. The dentin disks were prepared using healthy human molars, and their dentinal tubules were exposed to EDTA. Subsequently, they were randomly selected and treated with or without IgY@ACP for 7 days. The tubule occlusion morphologies and newly formed layers were observed by scanning electron microscopy (SEM) and x-ray diffraction, respectively. To evaluate the acid resistance and abrasion resistance of IgY@ACP, dentin disks that were treated for 1 day were immersed in acid solution or subjected to a toothbrush. The antibacterial effects against Streptococcus mutans (S. mutans) were evaluated by colony-forming unit (CFU) counting, adhesion property assessment, and crystal violet and live/dead bacterial staining. Finally, the occlusion effect was evaluated in rat incisors in vivo. One-way analysis of variance (ANOVA) was performed for statistical analysis. The level of significance was set at 0.05.

Results: IgY@ACP presented an amorphous phase with a nanosize (60–80 nm) and sustained release of protein within 48 h. The CCK-8 results showed that IgY@ACP had good biocompatibility. After treatment with IgY@ACP for 1 day, the majority of dentinal tubules were occluded by a 0.3-μm-thick mineralized layer. Seven days later, all dentinal tubules were occluded by mineralization with a thickness of 1.4 μm and a depth of 16 μm. The newly mineralized layer showed hydroxyapatite-like diffraction peaks. In addition, IgY@ACP had good acid and abrasion resistance. After treatment with IgY@ACP, the CFU counting and adhesion rate of S. mutans were significantly reduced, the crystal violet staining was lighter, and the S. mutans staining revealed more dead cells. Most importantly, IgY@ACP had a certain occluding property in rat incisors in vivo.

Conclusion: IgY@ACP can effectively occlude dentinal tubules with acid-resistant stability and has prominent anti-S. mutans effects, rendering it a potentially suitable desensitization material in the clinic.

Mineralized Enzyme-Based Biomaterials with Superior Bioactivities for Bone Regeneration

The formation and metabolic balance of bone tissue is a controllable process of biomineralization, which is regulated by various cells, biomolecules, and ions. Enzyme molecules play an important role in this process, and alkaline phosphatase (ALP) is one of the most critical factors. In this study, inspired by the process of bone biomineralization, a biomimetic strategy is achieved for the preparation of mineralized ALP nanoparticles (MALPNs), by taking advantages of the unique reaction between ALP and calcium ions in Dulbecco's modified Eagle's medium. Benefiting from the mild biomineralization reaction, the MALPN system highly maintains the activity of ALP. Furthermore, the in vitro studies show that the MALPN system significantly enhances the proliferation of bone marrow mesenchymal stem cells and upregulates their osteogenic differentiation. When evaluated as synthetic graft materials for bone regeneration, the MALPN-incorporated gelatin methacryloyl graft shows excellent mechanical properties, a sustained release profile of ALP, and high biocompatibility and efficacy in guiding bone regeneration and vascularization for critical-sized rat calvarial defect. Moreover, we also demonstrate that the biomimetic mineralization strategy can be adopted for other proteins such as acid phosphatase, bovine serum albumin, fibrinogen, and gelatin, suggesting its universality for constructing mineralized protein-/enzyme-based bioactive materials for the application of tissue regeneration.

Hydrogel microcapsules containing engineered bacteria for sustained production and release of protein drugs

Subcutaneous administration of sustained-release formulations is a common strategy for protein drugs, which avoids first pass effect and has high bioavailability. However, conventional sustained-release strategies can only load a limited amount of drug, leading to insufficient durability. Herein, we developed microcapsules based on engineered bacteria for sustained release of protein drugs. Engineered bacteria were carried in microcapsules for subcutaneous administration, with a production-lysis circuit for sustained protein production and release. Administrated in diabetic rats, engineered bacteria microcapsules was observed to smoothly release Exendin-4 for 2 weeks and reduce blood glucose. In another example, by releasing subunit vaccines with bacterial microcomponents as vehicles, engineered bacterial microcapsules activated specific immunity in mice and achieved tumor prevention. The engineered bacteria microcapsules have potential to durably release protein drugs and show versatility on the size of drugs. It might be a promising design strategy for long-acting in situ drug factory.

Designer self-assembling peptide nanofibers induce biomineralization of lidocaine for slow-release and prolonged analgesia

The burst release of small molecular water-soluble drugs is a major problem when pursuing their long-acting formulations. Although various types of carrier materials have been developed for tackling this problem, it is still a big challenge to prevent water-soluble small molecules from fast release and diffusion. In this study, a biomineralization strategy based upon a self-assembling peptide is proposed for the slow release of lidocaine, a classic anesthetic with high solubility and a very small molecular weight. A bolaamphiphilic peptide was designed to self-assemble and produce negatively charged nanofibers, which were used as the template to absorb positively charged lidocaine molecules through an electrostatic interaction. The biomineralization of lidocaine was then induced by adjusting the pH, which lead to the formation of lidocaine microcrystals with a homogenous size. The microcrystals were incorporated into a hyaluronic acid hydrogel to form an injectable formulation. This formulation slowly released lidocaine and generate a prolonged anesthetic and analgesic effect in rodent models. Due to the constrained local and plasma lidocaine concentration, as well as the biocompatibility and biodegradability of the peptide materials, this formulation also showed considerable safety. These results suggest that nanofiber assisted biomineralization can provide a potential strategy for the fabrication of long-acting formulations for small molecular water-soluble drugs. STATEMENT OF SIGNIFICANCE: Long-acting formulations are highly pursued to achieve stronger therapeutic effect, or to avoid repeated administration of drugs, especially through painful injection. Using carrier materials to slow down the release of bioactive molecules is a common strategy to reach this goal. However, for many water-soluble small molecular drugs currently used in clinic, it is notoriously difficult to slow down their release and diffusion. This study proposes a novel strategy based on a controllable mineralization process using self-assembling peptide nanofibers as the template. Taking lidocaine as an example, we showed how peptide-drug microcrystals with well-controlled size and shape could be obtained, which exhibit significantly prolonged anesthetic and analgesic effect. As a proof-of-concept study, this work proposes a promising strategy to control the release of water-soluble small molecular drugs.

Manganese Phosphate-Doxorubicin-Based Nanomedicines Using Mimetic Mineralization for Cancer Chemotherapy

Inorganic nanomaterials showed great potential as drug carriers for chemotherapeutics molecules due to their biocompatible physical and chemical properties. A manganese-based inorganic nanomaterial manganese phosphate (MnP) had become a new drug carrier in cancer therapy. However, the approach for manganese phosphate preparation and drug integration is still confined in complex methods. Inspired by mimetic mineralization, we proposed a "one-step" method for the preparation of manganese phosphate-doxorubicin (DOX) nanomedicines (MnP-DOX) by manganese ion and DOX complexation. The structural characterization results revealed that the prepared MnP-DOX nanocomplexes were homogeneous with controlled sizes and shapes. More importantly, the MnP-DOX nanocomposites could significantly induce cancer inhibition in vitro and in vivo. The results indicated that the drug molecules were integrated into MnP nanocarriers by mimetic mineralization, which not only prevented the premature release of the drug but also reduced excessive modification. Moreover, the designed MnP-DOX complex showed high loading efficacy and pH-dependent degradation leading to drug release, achieving high efficiency for cancer chemotherapy in vitro and in vivo via a facile process. These achievements presented an approach to construct the manganese phosphate-based chemotherapy nanomedicines by mimetic mineralization for cancer therapy.

Biopharmaceutical nanoclusters: Towards the self-delivery of protein and peptide therapeutics

Protein and peptide biopharmaceuticals have had a major impact on the treatment of a number of diseases. There is a growing interest in overcoming some of the challenges associated with biopharmaceuticals, such as rapid degradation in physiological fluid, using nanocarrier delivery systems. Biopharmaceutical nanoclusters (BNCs) where the therapeutic protein or peptide is clustered together to form the main constituent of the nanocarrier system have the potential to mimic the benefits of more established nanocarriers (e.g., liposomal and polymeric systems) whilst eliminating the issue of low drug loading and potential side effects from additives. These benefits would include enhanced stability, improved absorption, and increased biopharmaceutical activity. However, the successful development of BNCs is challenged by the physicochemical complexity of the protein and peptide constituents as well as the dynamics of clustering. Here, we present and discuss common methodologies for the synthesis of therapeutic protein and peptide nanoclusters, as well as review the current status of this emerging field.

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

Auto-segmentation and time-dependent systematic analysis of mesoscale cellular structure in β-cells during insulin secretion

The mesoscale description of the subcellular organization informs about cellular mechanisms in disease state. However, applications of soft X-ray tomography (SXT), an important approach for characterizing organelle organization, are limited by labor-intensive manual segmentation. Here we report a pipeline for automated segmentation and systematic analysis of SXT tomograms. Our approach combines semantic and first-applied instance segmentation to produce separate organelle masks with high Dice and Recall indexes, followed by analysis of organelle localization based on the radial distribution function. We demonstrated this technique by investigating the organization of INS-1E pancreatic β-cell organization under different treatments at multiple time points. Consistent with a previous analysis of a similar dataset, our results revealed the impact of glucose stimulation on the localization and molecular density of insulin vesicles and mitochondria. This pipeline can be extended to SXT tomograms of any cell type to shed light on the subcellular rearrangements under different drug treatments.

Theranostic microneedle array patch for integrated glycemia sensing and self-regulated release of insulin

Diabetes can cause various complications and affect the normal functioning of the human body. A theranostic and diagnostic platform for real-time glycemia sensing and simultaneous self-regulated release of insulin is...

A pH-Responsive Nanoplatform Based on Fluorescent Conjugated Polymer Dots for Imaging-Guided Multitherapeutics Delivery and Combination Cancer Therapy

For cancer treatment, nanocarriers were designed with cationic lipids and polymers to improve the cytosolic delivery efficiency of siRNA. Though the positively charged nanocarriers showed great potential for RNA therapy, it was inevitable to generate the potential cytotoxicity. We constructed a pH-responsive nanoplatform, which co-carried siRNA and anticancer drug (hydroxycamptothecine, HCPT), to integrate gene therapy and chemotherapy for combination cancer therapy. The fluorescent conjugated polymer nanoparticles (CPNPs) modified with cell-penetrating peptides were employed as cores to carry siRNA molecules (siRNA-CPNPs) and track the biodistribution of nanotherapeutics by virtue of fluorescence. Calcium phosphate (CaP) nanocoatings were deposited on the surface of siRNA-CPNPs, followed by loading with HCPT and aptamers targeting cancer cells to obtain a targeted and tumor acid-responsive biocompatible nanoplatform. After the uptake of cancer cells, the CaP nanocoatings were decomposed in the acidic endo/lysosomes to release HCPT, and the siRNA-CPNPs were exposed to facilitate the siRNA endo/lysosome escape and cytoplasm delivery. Results obtained from both in vitro and in vivo studies in tumor inhibition expressed that the combined therapy exhibited a better therapeutic efficacy than any monotherapy.

Tumor Diagnosis and Therapy Mediated by Metal Phosphorus-Based Nanomaterials

Metal phosphorus-based nanomaterials (Metal-P NMs) including metal phosphate nanomaterials, metal phosphide nanomaterials, and metal-black phosphorus (Metal-BP) nanocomposite are widely used in the field of biomedicine owing to their excellent physical and chemical properties, biocompatibility, and biodegradability. In recent years, metal phosphate nanomaterials and Metal-BP nanocomposite acted as medicine delivery system have made breakthroughs in tumor diagnosis including magnetic resonance imaging, fluorescence imaging, photoacoustic imaging, nuclear imaging, and therapies including chemotherapy, gene therapy, photothermal therapy, photodynamic therapy, and radiation therapy. Metal phosphate nanomaterials have good biodegradability, especially calcium-based metal phosphate nanomaterials can be dissolved into nontoxic ions and participate in the metabolisms of normal organs. Compared with metal phosphate nanomaterials, metal phosphide nanomaterials have excellent optical, magnetic, and catalytic properties, which can be used as multifunctional diagnostic nanoplatforms and therapeutic agents for chemodynamic therapy, photothermal therapy, or immunotherapy. The latest developments in Metal-P NMs, covering the range of preparation methods and biological applications, such as serving as drug carriers, tumor diagnosis, and therapy, are focused. All in all, the current trends, key issues, future prospects and challenges of Metal-P NMs are concluded and discussed, which are important for the development of this research field and shining more lights on this direction.

Exendin-4 may improve type 2 diabetes by modulating the epigenetic modifications of pancreatic histone H3 in STZ-induced diabetic C57BL/6 J mice

Type 2 diabetes (T2D) is a complicated systemic disease that might be improved by exendin-4, although the epigenetic role remains unclear. In the current study, C57BL/6 J mice were used to generate a T2D model, followed by treatment with exendin-4 (10 μg/kg). Histone H3K9 and H3K23 acetylation, H3K4 mono-methylation, and H3K9 di-methylation were explored by western blot analysis of pancreatic histone extracts. Real-time polymerase chain reaction (PCR) was used to examine the expression levels of pancreatic beta cell development-related genes, and chromatin immunoprecipitation (ChIP) was applied to analyze H3 and H3K9 acetylation, H3K4 mono-methylation, and H3K9 di-methylation in the promoter region of the pancreatic and duodenal homeobox 1 (Pdx1) gene. The results showed that total H3K9 di-methylation and H3K9 and H3K23 acetylation increased in pancreatic tissues of diabetic mice, whereas H3K4 mono-methylation was reduced. All of these changes could be abrogated by treatment with exendin-4. Our data indicated that T2D progression might be improved by exendin-4 treatment through the reversal of global pancreatic histone H3K9 and H3K23 acetylation, H3K4 mono-methylation, and H3K9 di-methylation. A better understanding of these epigenetic alterations may, therefore, lead to novel therapeutic strategies for T2D.

A review of existing strategies for designing long-acting parenteral formulations: Focus on underlying mechanisms, and future perspectives

The need for long-term treatments of chronic diseases has motivated the widespread development of long-acting parenteral formulations (LAPFs) with the aim of improving drug pharmacokinetics and therapeutic efficacy. LAPFs have been proven to extend the half-life of therapeutics, as well as to improve patient adherence; consequently, this enhances the outcome of therapy positively. Over past decades, considerable progress has been made in designing effective LAPFs in both preclinical and clinical settings. Here we review the latest advances of LAPFs in preclinical and clinical stages, focusing on the strategies and underlying mechanisms for achieving long acting. Existing strategies are classified into manipulation of in vivo clearance and manipulation of drug release from delivery systems, respectively. And the current challenges and prospects of each strategy are discussed. In addition, we also briefly discuss the design principles of LAPFs and provide future perspectives of the rational design of more effective LAPFs for their further clinical translation.

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.

Glucose oxidase and Fe3O4/TiO2/Ag3PO4 co-embedded biomimetic mineralization hydrogels as controllable ROS generators for accelerating diabetic wound healing

The hyperglycemic environment and the presence of bacterial infections delay the healing of diabetic wounds. Herein, glucose oxidase (GOx) and Fe₃O₄/TiO₂/Ag₃PO₄ were embedded in a polyacrylic acid-calcium phosphate (PAA-CaPs@Nps@GOx) hydrogel through an in situ biomimetic mineralization approach. The GOx encapsulation efficiency was 96.75% and exhibited exceptional enzyme activity stability. Moreover, the co-immobilization of GOx and Fe₃O₄/TiO₂/Ag₃PO₄ nanoparticles generated a simple and multifunctional antibacterial platform with the advantages of decreasing blood glucose concentration and efficiently producing reactive oxygen species (ROS). In addition, the degradation rate of the hydrogel was controlled by regulating the concentration of phosphate thus controlling the release of Fe₃O₄/TiO₂/Ag₃PO₄ and GOx. As a result, both the potential toxicity and oxidative stress associated with the antimicrobial biomaterial can be controlled within the body therefore potentially preventing detriment. In vivo results indicated that the PAA-CaPs@Nps@GOx hydrogel effectively promoted diabetic wound healing and showed great potential for clinical applications of chronic wound management.

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.

Size controlled fabrication of enzyme encapsulated amorphous calcium phosphate nanoparticle and its intracellular biosensing application

Inorganic-enzyme composites have been widely used for applications in catalysis and analytical science. Amorphous calcium phosphate, as a biocompatible material, can form open hydrated structure to encapsulate and protect enzymes. So far, there have been few progress on size-adjustable amorphous calcium phosphate nanoparticles since the diameter controllability is limited by its natural aggregation characteristics. By co-precipitation and nano-channel extrusion, we developed enzyme-loaded amorphous calcium phosphate nanoparticles with adjustable diameters. These enzyme-loaded particles showed high thermal and chemical stability as well as biocompatibility. The nano-sized enzyme-loaded particles can further expand their application fields and be used as intracellular enzyme probes. Delivering glucose oxidase enzyme by amorphous calcium phosphate nanoparticles enables fluorescent monitoring of glucose levels in living cells, which can be used to study the metabolism rates of cancer cells and normal cells. The nano-channel extrusion method can also be used as a template to encapsulate different kinds of enzymes to expand catalysis and biosensing applications.

Biomineralized Bacterial Outer Membrane Vesicles Potentiate Safe and Efficient Tumor Microenvironment Reprogramming for Anticancer Therapy

The highly immunosuppressive tumor microenvironment (TME) in solid tumors often dampens the efficacy of immunotherapy. In this study, bacterial outer membrane vesicles (OMVs) are demonstrated as powerful immunostimulants for TME reprogramming. To overcome the obstacles of antibody-dependent clearance and high toxicity induced by OMVs upon intravenous injection (a classic clinically relevant delivery mode), calcium phosphate (CaP) shells are employed to cover the surface of OMVs, which enables potent OMV-based TME reprograming without side effects. Meanwhile, the pH-sensitive CaP shells facilitate the neutralization of acidic TME, leading to highly beneficial M2-to-M1 polarization of macrophages for improved antitumor effect. Moreover, the outer shells can be integrated with functional components like folic acid or photosensitizer agents, which facilitates the use of the OMV-based platform in combination therapies for a synergic therapeutic effect.

A Review on Experimental Methods for Diabetes Induction and Therapeutic Efficacy of Anti-diabetic Drug Loaded Nanoformulation

Background:

Different experimental methods have been used to induce diabetes in animals. There are a number of anti-diabetic drug loaded nano-formulations with high therapeutic value that are used to target diabetes with high therapeutic efficacy.

Methods:

From this review, various anti-hyperglycemic agents have been screened for their activity. The use of nano-formulation in diabetes treatment is considered due to the possibility of the incorporation of both hydrophilic and hydrophobic substances.

Results:

The clinical symptoms of diabetes are similar to those of hyperglycemia, glucosuria, polydipsia, polyphagia, and polyuria and these symptoms were produced in experimental animal models through various diabetogens. The treatment by using nano-formulation enhance the therapeutic efficacy due to an increase in high carrier capacity.

Conclusion:

The characteristic features of the disease and pathological changes during disease in small animals (rats or mice) are similar to that of human beings. The use of synthetic as well as herbal drugs have shown greater therapeutic efficacy by encapsulating into nano drug delivery system.

Liver-targeted delivery of TSG-6 by calcium phosphate nanoparticles for the management of liver fibrosis

Mesenchymal stem cells (MSCs) transplantation is a promising antifibrotic strategy but facing clinical controversies. Inspired by advances in nanomedicine, we aimed to bypass these clinical barriers of MSCs by identifying the key antifibrotic molecule of MSCs and developing a specific liver-targeting nanocarrier.

Methods: Cytokines secreted by MSCs were examined with serum stimulation of cirrhotic patients. Immunohistochemistry, microarray, immunoblotting, and quantitative real-time PCR (qRT-PCR) were applied to identify the critical antifibrotic cytokine and to discover its role in modulating antifibrotic effects. Biomineralization method was used to prepare calcium phosphate nanoparticles (NPs). The targeting and therapeutic efficiency of NPs were evaluated by in vivo imaging and biochemical studies on fibrotic mice induced by CCl₄.

Results: The stimulated MSCs exhibited high-level expression of Tumor necrosis factor (TNF)-stimulated gene 6 (TSG-6). On animal study, exogenous administration of TSG-6 alone can ameliorate liver fibrosis while TSG-6 knocked MSCs (Lv-TSG-6 MSCs) lost antifibrotic effects. Further studies verified the importance of TSG-6 and identified its antifibrotic mechanism by modulating M2 macrophages and increasing matrix metalloproteinase 12 (MMP12) expression. Additionally, we found a feedback loop between TSG-6, MMP12 and pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β), which may improve our understanding of the aggravating process of cirrhosis and antifibrotic mechanisms of TSG-6 and MSCs. Based on these findings, we developed calcium phosphate nanoparticles (CaP@BSA NPs) by biomineralization method using bovine serum albumin (BSA) as the biotemplate. Imaging tracking and drug loading studies showed specific liver targeting and high TSG-6 loading efficacy of as-prepared CaP@BSA NPs. In vivo therapeutic study further demonstrated the improved therapeutic effects of TSG-6 loaded CaP@BSA.

Conclusions: TSG-6 was a major antifibrotic cytokine of MSCs, TSG-6 loaded CaP@BSA NPs showed specific liver accumulation and improved therapeutic effects, which indicated translational potentials of CaP@BSA as a promising drug carrier for the liver disease management.

Bio-Inspired Strategies against Diabetes and Associated Complications: A Review

Bio-molecules are the most important target to be considered while designing any drug delivery system. The logic lies in using such bio-sensing or bio-mimicking systems in their formulations that can mimic the active site of those receptors to which the drug is going to bind. Polymers mimicking the active site of target enzymes are regarded as bio-inspired polymers and can be used to ameliorate many diseased conditions. Nowadays, this strategy is also being adopted against diabetes and its complications. Under hyperglycemic conditions, many pathways get activated which are responsible for the progression of diabetes-associated secondary complications viz. retinopathy, neuropathy, and nephropathy. The enzymes involved in the progression of these complications can be mimicked for their effective management. For an instance, Aldose Reductase (ALR2), a rate-limiting enzyme of the polyol pathway (downstream pathway) which gets over-activated under hyperglycemic condition is reported to be mimicked by using polymers which are having same functionalities in their structure. This review aims at critically appraising reports in which target mimicking bio-inspired formulations have been envisaged against diabetes and its complications. The information summarized in this review will provide an idea about the bio-sensing approaches utilized to manage blood glucose level and the utility of bio-inspired polymers for the management of diabetic complications (DC). Such type of information may be beneficial to pharmaceutical companies and academia for better development of targeted drug delivery systems with sustained-release property against these diseased conditions.

Biodegradable Manganese-Doped Calcium Phosphate Nanotheranostics for Traceable Cascade Reaction-Enhanced Anti-Tumor Therapy

Glucose oxidase (GOx) has been recognized as a "star" enzyme catalyst involved in cancer treatment in the past few years. Herein, GOx is mineralized with manganese-doped calcium phosphate (MnCaP) to form spherical nanoparticles (GOx-MnCaP NPs) by an in situ biomimetic mineralization method, followed by the loading of doxorubicin (DOX) to construct a biodegradable, biocompatible, and tumor acidity-responsive nanotheranostics for magnetic resonance imaging (MRI) and cascade reaction-enhanced cooperative cancer treatment. The GOx-driven oxidation reaction can effectively eliminate intratumoral glucose for starvation therapy, and the elevated H₂O₂ is then converted into highly toxic hydroxyl radicals via a Mn²⁺-mediated Fenton-like reaction for chemodynamic therapy (CDT). Moreover, the acidity amplification due to the gluconic acid generation will in turn accelerate the degradation of the nanoplatform and promote the Mn²⁺-H₂O₂ reaction for enhanced CDT. Meanwhile, the released Mn²⁺ ions can be used for MRI to monitor the treatment process. After carrying the anticancer drug, the DOX-loaded GOx-MnCaP can integrate starvation therapy, Mn²⁺-mediated CDT, and DOX-induced chemotherapy together, which showed greatly improved therapeutic efficacy than each monotherapy. Such an orchestrated cooperative cancer therapy demonstrated high-efficiency tumor suppression on 4T1 tumor-bearing mice with minimal side effects. Our findings suggested that the DOX-loaded GOx-MnCaP nanotheranostics with excellent biodegradability and biocompatibility hold clinical translation potential for cancer management.

Activatable Core-Shell Metallofullerene: An Efficient Nanoplatform for Bimodal Sensing of Glutathione

Metallofullerenes have attracted considerable attention as potential novel noninvasive high-relaxivity magnetic resonance contrast agents. However, the applications of metallofullerenes as stimuli-responsive biosensors to monitor biological processes are still scarce. Herein, manganese-fullerenes core-shell nanocomposites are prepared via a facile one-pot approach to achieve GSH-activatable magnetic resonance/fluorescence bimodal imaging functions. The nanocomposites initially have a FRET-induced quenched fluorescence, and water-resisting stimulated low T₁-MRI contrast. Upon exposure to GSH, collapse of the outer MnO₂ shell led to reconstruction of the nanoprobes and subsequently resulted in multicolor fluorescence recovery and longitudinal (T₁) relaxivity enhancement (r₁ value up to 29.8 mM^-1 s^-1 at 0.5 T based on Mn ion). Our work demonstrates feasibility of using fullerenes to fabricate activatable probes for molecular imaging of GSH, which may promote the development of new fullerene-based stimuli-responsive multimodal probes for the detection and regulation of particular biological processes in vivo.

Sustained Release Strategy Designed for Lixisenatide Delivery to Synchronously Treat Diabetes and Associated Complications

Diabetes and its complications have become a global challenge of public health. Herein, we aimed to develop a long-acting delivery system of lixisenatide (Lixi), a glucose-dependent antidiabetic peptide, based on an injectable hydrogel for the synchronous treatment of type 2 diabetes mellitus (T2DM) and associated complications. Two triblock copolymers, poly(ε-caprolactone-co-glycolic acid)-poly(ethylene glycol)-poly(ε-caprolactone-co-glycolic acid) and poly(d,l-lactic acid-co-glycolic acid)-poly(ethylene glycol)-poly(d,l-lactic acid-co-glycolic acid) possessing temperature-induced sol-gel transitions, were synthesized by us. Compared to the two single-component hydrogels, their 1/1 mixture hydrogel not only maintained the temperature-induced gelation but also exhibited a steadier degradation profile in vivo. Both in vitro and in vivo release studies demonstrated that the mixture hydrogel provided the sustained release of Lixi for up to 9 days, which was attributed to balanced electrostatic interactions between the positive charges in the peptide and the negative charges in the polymer carrier. The hypoglycemic efficacy of Lixi delivered from the mixture hydrogel after a single subcutaneous injection into diabetic db/db mice was comparable to that of twice-daily administrations of Lixi solution for up to 9 days. Furthermore, three successive administrations of the abovementioned gel system within a month significantly increased the plasma insulin level, lowered glycosylated hemoglobin, and improved the pancreatic function of the animals. These results were superior or equivalent to those of twice-daily injections of Lixi solution for 30 days, but the number of injections was markedly reduced from 60 to 3. Finally, an improvement in hyperlipidemia, augmentation of nerve fiber density, and enhancement of motor nerve conduction velocity in the gel formulation-treated db/db mice indicated that the sustained delivery of Lixi arrested and even ameliorated diabetic complications. These findings suggested that the Lixi-loaded mixture hydrogel has great potential for the treatment of T2DM with significant improvements in the health and quality of life of patients.

Near-Infrared-II Molecular Dyes for Cancer Imaging and Surgery

Fluorescence bioimaging affords a vital tool for both researchers and surgeons to molecularly target a variety of biological tissues and processes. This review focuses on summarizing organic dyes emitting at a biological transparency window termed the near-infrared-II (NIR-II) window, where minimal light interaction with the surrounding tissues allows photons to travel nearly unperturbed throughout the body. NIR-II fluorescence imaging overcomes the penetration/contrast bottleneck of imaging in the visible region, making it a remarkable modality for early diagnosis of cancer and highly sensitive tumor surgery. Due to their convenient bioconjugation with peptides/antibodies, NIR-II molecular dyes are desirable candidates for targeted cancer imaging, significantly overcoming the autofluorescence/scattering issues for deep tissue molecular imaging. To promote the clinical translation of NIR-II bioimaging, advancements in the high-performance small molecule-derived probes are critically important. Here, molecules with clinical potential for NIR-II imaging are discussed, summarizing the synthesis and chemical structures of NIR-II dyes, chemical and optical properties of NIR-II dyes, bioconjugation and biological behavior of NIR-II dyes, whole body imaging with NIR-II dyes for cancer detection and surgery, as well as NIR-II fluorescence microscopy imaging. A key perspective on the direction of NIR-II molecular dyes for cancer imaging and surgery is also discussed.

Biomolecule-assisted green synthesis of nanostructured calcium phosphates and their biomedical applications

Calcium phosphates (CaPs) are ubiquitous in nature and vertebrate bones and teeth, and have high biocompatibility and promising applications in various biomedical fields. Nanostructured calcium phosphates (NCaPs) are recognized as promising nanocarriers for drug/gene/protein delivery owing to their high specific surface area, pH-responsive degradability, high drug/gene/protein loading capacity and sustained release performance. In order to control the structure and surface properties of NCaPs, various biomolecules with high biocompatibility such as nucleic acids, proteins, peptides, liposomes and phosphorus-containing biomolecules are used in the synthesis of NCaPs. Moreover, biomolecules play important roles in the synthesis processes, resulting in the formation of various NCaPs with different sizes and morphologies. At room temperature, biomolecules can play the following roles: (1) acting as a biocompatible organic phase to form biomolecule/CaP hybrid nanostructured materials; (2) serving as a biotemplate for the biomimetic mineralization of NCaPs; (3) acting as a biocompatible modifier to coat the surface of NCaPs, preventing their aggregation and increasing their colloidal stability. Under heating conditions, biomolecules can (1) control the crystallization process of NCaPs by forming biomolecule/CaP nanocomposites before heating; (2) prevent the rapid and disordered growth of NCaPs by chelating with Ca2+ ions to form precursors; (3) provide the phosphorus source for the controlled synthesis of NCaPs by using phosphorus-containing biomolecules. This review focuses on the important roles of biomolecules in the synthesis of NCaPs, which are expected to guide the design and controlled synthesis of NCaPs. Moreover, we will also summarize the biomedical applications of NCaPs in nanomedicine and tissue engineering, and discuss their current research trends and future prospects.

Facile and Efficient Chemoenzymatic Semisynthesis of Fc-Fusion Compounds for Half-Life Extension of Pharmaceutical Components

The formation of Fc-fusions, in which biologically active molecules and the Fc fragment of antibodies are linked to each other, is one of the most efficient and successful half-life extension technologies to be developed and applied to peptide and protein pharmaceuticals thus far. Fc-fusion compounds are generally produced by recombinant methods. However, these cannot be applied to artificial middle molecules, such as peptides with non-natural amino acids, unnatural cyclic peptides, or pharmaceutical oligonucleotides. Here, we developed a simple, efficient, semisynthetic method for Fc-fusion production involving our previously developed enzymatic N-terminal extension reaction (i.e., NEXT-A reaction) and strain-promoted azide-alkyne cycloaddition, achieving quantitative conversion and high selectivity for the N-terminus of the Fc protein. An Fc-fusion compound prepared by this method showed comparable biological activity to that of the original peptide and a long-circulating plasma half-life. Thus, the proposed method is potentially applicable for the conjugation of a wide range of pharmaceutical components.

Long-Acting Release Microspheres Containing Novel GLP-1 Analog as an Antidiabetic System

Glucagon-like peptide 1 (GLP-1) has recently received significant attention as an efficacious way to treat diabetes mellitus. However, the short half-life of the peptide limits its clinical application in diabetes. In our previous study, a novel GLP-1 analog (PGLP-1) with a longer half-life was synthesized and evaluated. Herein, we prepared the PGLP-1-loaded poly(d,l-lactide- co-glycolide) microspheres to achieve long-term effects on blood glucose control. The incorporation of zinc ion into the formulation can effectively decrease the initial burst release, and a uniform drug distribution was obtained, in contrast to native PGLP-1 encapsulated microspheres. We demonstrated that the solubility of the drug encapsulated in microspheres played an important role in in vitro release behavior and drug distribution inside the microspheres. The Zn-PGLP-1 microspheres had a prominent acute glucose reduction effect in the healthy mice. A hypoglycemic effect was observed in the streptozotocin (STZ) induced diabetic mice through a 6-week treatment of Zn-PGLP-1-loaded microspheres. Meanwhile, the administration of Zn-PGLP-1 microspheres led to the β-cell protection and stimulation of insulin secretion. The novel GLP-1 analog-loaded sustained microspheres may greatly improve patient compliance along with a desirable safety feature.

Improving long-term subcutaneous drug delivery by regulating material-bioenvironment interaction

Subcutaneous long-acting release (LAR) formulations have been extensively developed in the clinic to increase patient compliance and reduce treatment cost. Despite preliminary success for some LAR systems, a major obstacle limiting the therapeutic effect remains on their interaction with surrounding tissues. In this review, we summarize how living bodies respond to injected or implanted materials, and highlight some typical strategies based on smart material design, which may significantly improve long-term subcutaneous drug delivery. Moreover, possible strategies to achieve ultra-long (months, years) subcutaneous drug delivery systems are proposed. Based on these discussions, we believe the well-designed subcutaneous long-acting formulations will hold great promise to improve patient quality of life in the clinic.

Multimodal Theranostic Nanoformulations Permit Magnetic Resonance Bioimaging of Antiretroviral Drug Particle Tissue-Cell Biodistribution

RATIONALE

Long-acting slow effective release antiretroviral therapy (LASER ART) was developed to improve patient regimen adherence, prevent new infections, and facilitate drug delivery to human immunodeficiency virus cell and tissue reservoirs. In an effort to facilitate LASER ART development, "multimodal imaging theranostic nanoprobes" were created. These allow combined bioimaging, drug pharmacokinetics and tissue biodistribution tests in animal models.

METHODS

Europium (Eu3+)- doped cobalt ferrite (CF) dolutegravir (DTG)- loaded (EuCF-DTG) nanoparticles were synthesized then fully characterized based on their size, shape and stability. These were then used as platforms for nanoformulated drug biodistribution.

RESULTS

Folic acid (FA) decoration of EuCF-DTG (FA-EuCF-DTG) nanoparticles facilitated macrophage targeting and sped drug entry across cell barriers. Macrophage uptake was higher for FA-EuCF-DTG than EuCF-DTG nanoparticles with relaxivities of r2 = 546 mM-1s-1 and r2 = 564 mM-1s-1 in saline, and r2 = 850 mM-1s-1 and r2 = 876 mM-1s-1 in cells, respectively. The values were ten or more times higher than what was observed for ultrasmall superparamagnetic iron oxide particles (r2 = 31.15 mM-1s-1 in saline) using identical iron concentrations. Drug particles were detected in macrophage Rab compartments by dual fluorescence labeling. Replicate particles elicited sustained antiretroviral responses. After parenteral injection of FA-EuCF-DTG and EuCF-DTG into rats and rhesus macaques, drug, iron and cobalt levels, measured by LC-MS/MS, magnetic resonance imaging, and ICP-MS were coordinate.

CONCLUSION

We posit that these theranostic nanoprobes can assess LASER ART drug delivery and be used as part of a precision nanomedicine therapeutic strategy.

Calcium-based biomaterials for diagnosis, treatment, and theranostics

Calcium-based biomaterials with good biosafety and bio-absorbability are promising for biomedical applications such as diagnosis, treatment, and theranostics.

Microneedle-array patches loaded with dual mineralized protein/peptide particles for type 2 diabetes therapy

The delivery of therapeutic peptides for diabetes therapy is compromised by short half-lives of drugs with the consequent need for multiple daily injections that reduce patient compliance and increase treatment cost. In this study, we demonstrate a smart exendin-4 (Ex4) delivery device based on microneedle (MN)-array patches integrated with dual mineralized particles separately containing Ex4 and glucose oxidase (GOx). The dual mineralized particle-based system can specifically release Ex4 while immobilizing GOx as a result of the differential response to the microenvironment induced by biological stimuli. In this manner, the system enables glucose-responsive and closed-loop release to significantly improve Ex4 therapeutic performance. Moreover, integration of mineralized particles can enhance the mechanical strength of alginate-based MN by crosslinking to facilitate skin penetration, thus supporting painless and non-invasive transdermal administration. We believe this smart glucose-responsive Ex4 delivery holds great promise for type 2 diabetes therapy by providing safe, long-term, and on-demand Ex4 therapy.

Diabetes treatments often rely on frequent and scheduled drug administration, which reduces patient compliance and increases treatment cost. Here, the authors develop a microneedle-array patch that separately loads drug-releasing module and glucose-sensing element for on-demand, long-term diabetes therapy.