Understanding Mucosal Physiology and Rationale of Formulation Design for Improved Mucosal Immunity.

The oral and nasal cavities serve as critical gateways for infectious pathogens, with microorganisms primarily gaining entry through these routes. Our first line of defense against these invaders is the mucosal membrane, a protective barrier that shields the body's internal systems from infection while also contributing to vital functions like air and nutrient intake. One of the key features of this mucosal barrier is its ability to protect the physiological system from pathogens. Additionally, mucosal tolerance plays a crucial role in maintaining homeostasis by regulating the pH and water balance within the body. Recognizing the importance of the mucosal barrier, researchers have developed various mucosal formulations to enhance the immune response. Mucosal vaccines, for example, deliver antigens directly to mucosal tissues, triggering local immune stimulation and ultimately inducing systemic immunity. Studies have shown that lipid-based formulations such as liposomes and virosomes can effectively elicit both local and systemic immune responses. Furthermore, mucoadhesive polymeric particles, with their prolonged delivery to target sites, have demonstrated an enhanced immune response. This Review delves into the critical role of material selection and delivery approaches in optimizing mucosal immunity.

ß-Glucan and Fatty Acid Based Mucoadhesive Carrier for Gastrointestinal Tract Specific Local and Sustained Drug Delivery.

The oral route is considered the most convenient route of drug administration for both systemic and local delivery. Besides stability and transportation, another unmet but important issue regarding oral medication is retention duration within the specific region of the gastrointestinal (GI) tract. We hypothesize that an oral vehicle that can adhere and maintain retention within the stomach for a longer duration can be more effective to treat stomach-related diseases. Therefore, in this project, we developed a carrier that is highly specific to the stomach and maintains its retention for a longer duration. We developed a vehicle composed of ß-Glucan And Docosahexaenoic Acid (GADA) to observe its affinity and specificity to the stomach. GADA forms a spherical-shaped particle with negative zeta potential values that vary based on the feed ratio of docosahexaenoic acid. Docosahexaenoic acid is an omega-3 fatty acid that has transporters and receptors throughout the GI tract, such as CD36, plasma membrane-associated fatty acid-binding protein (FABP (pm)), and a family of fatty acid transport proteins (FATP1-6). The in vitro studies and characterization data showed that GADA has the capability to carry a payload of hydrophobic molecules and specifically deliver the payload to the GI tract, exert its therapeutic effects, and help to maintain stability for more than 12 h in the gastric and intestinal fluid. The particle size and surface plasmon resonance (SPR) data showed that GADA has a strong binding affinity with mucin in the presence of simulated gastric fluids. We observed a comparatively higher drug release of lidocaine in gastric juice than that in intestinal fluids, demonstrating the influence of the pH values of the media on drug-release kinetics. In vivo and ex vivo imaging of mice demonstrated that GADA maintains its retention within the stomach for at least 4 hr. This stomach-specific oral vehicle holds strong promise to translate various injectable therapeutic drugs to oral form upon further optimizations.

A nanoparticle probe for the imaging of autophagic flux in live mice via magnetic resonance and near-infrared fluorescence.

Autophagy-the lysosomal degradation of cytoplasmic components via their sequestration into double-membraned autophagosomes-has not been detected non-invasively. Here we show that the flux of autophagosomes can be measured via magnetic resonance imaging or serial near-infrared fluorescence imaging of intravenously injected iron oxide nanoparticles decorated with cathepsin-cleavable arginine-rich peptides functionalized with the near-infrared fluorochrome Cy5.5 (the peptides facilitate the uptake of the nanoparticles by early autophagosomes, and are then cleaved by cathepsins in lysosomes). In the heart tissue of live mice, the nanoparticles enabled quantitative measurements of changes in autophagic flux, upregulated genetically, by ischaemia-reperfusion injury or via starvation, or inhibited via the administration of a chemotherapeutic or the antibiotic bafilomycin. In mice receiving doxorubicin, pre-starvation improved cardiac function and overall survival, suggesting that bursts of increased autophagic flux may have cardioprotective effects during chemotherapy. Autophagy-detecting nanoparticle probes may facilitate the further understanding of the roles of autophagy in disease.

Bile acid linked ß-glucan nanoparticles for liver specific oral delivery of biologics.

Oral delivery remains one of the most convenient routes for drug administration compared to intravenous, intramuscular, and via suppositories. However, due to the risk of degradation, and proteolysis of molecules in the acidic gastric medium, as well as the difficulty of transporting large molecules through the intestinal membrane, more than half of the therapeutic molecules are prohibited for oral administration. Moreover, most of the large molecules and biological therapeutics are not available in oral dosage form due to their instability in the stomach and inability of intestinal absorption. To achieve expected bioavailability, an orally administered therapeutic molecule must be protected within the stomach, and transportation facilitated via the small intestine. In this project, we have introduced a hybrid carrier, composed of Taurocholic Acid (TA) and ß-Glucan (TAG), that is shown to be effective for the simultaneous protection of the biologics in acidic buffer and simulated gastric juice as well as facilitate enhanced absorption and transportation via the small intestine. In this project, we have used an eGFP encoded plasmid as a model biologic to prepare particles mediated with TAG. TAG show the potential of enhancing transfection and expression of eGFP as we have observed two fold higher expression in the cell upon coincubation for 4 h. In vivo studies on orally dosed mice showed that eGFP expression in the liver was significantly higher in TAG containing particles compared to particles without TAG. The findings suggest that the TAG carrier is capable of not only preserving biologics but also transporting them more efficiently to the liver. As a result, this strategy can be employed for a variety of liver-targeted therapeutic delivery to treat a variety of liver diseases.

Lysyl oxidase regulation and protein aldehydes in the injured newborn lung.

During newborn lung injury, excessive activity of lysyl oxidases (LOXs) disrupts extracellular matrix (ECM) formation. Previous studies indicate that TGFß activation in the O2-injured mouse pup lung increases lysyl oxidase (LOX) expression. But how TGFß regulates this, and whether the LOXs generate excess pulmonary aldehydes are unknown. First, we determined that O2-mediated lung injury increases LOX protein expression in TGFß-stimulated pup lung interstitial fibroblasts. This regulation appeared to be direct; this is because TGFß treatment also increased LOX protein expression in isolated pup lung fibroblasts. Then using a fibroblast cell line, we determined that TGFß stimulates LOX expression at a transcriptional level via Smad2/3-dependent signaling. LOX is translated as a pro-protein that requires secretion and extracellular cleavage before assuming amine oxidase activity and, in some cells, reuptake with nuclear localization. We found that pro-LOX is processed in the newborn mouse pup lung. Also, O2-mediated injury was determined to increase pro-LOX secretion and nuclear LOX immunoreactivity particularly in areas populated with interstitial fibroblasts and exhibiting malformed ECM. Then, using molecular probes, we detected increased aldehyde levels in vivo in O2-injured pup lungs, which mapped to areas of increased pro-LOX secretion in lung sections. Increased activity of LOXs plays a critical role in the aldehyde generation; an inhibitor of LOXs prevented the elevation of aldehydes in the O2-injured pup lung. These results reveal new mechanisms of TGFß and LOX in newborn lung disease and suggest that aldehyde-reactive probes might have utility in sensing the activation of LOXs in vivo during lung injury.

Bioreducible Poly(ethylene glycol)-Triphenylphosphonium Conjugate as a Bioactivable Mitochondria-Targeting Nanocarrier.

Bioactivable nanocarrier systems have favorable characteristics such as high cellular uptake, target specificity, and an efficient intracellular release mechanism. In this study, we developed a bioreducible methoxy polyethylene glycol (mPEG)-triphenylphosphonium (TPP) conjugate (i.e., mPEG-(ss-TPP)2 conjugate) as a vehicle for mitochondrial drug delivery. A bioreducible linkage with two disulfide bond-containing end groups was used at one end of the hydrophilic mPEG for conjugation with lipophilic TPP molecules. The amphiphilic mPEG-(ss-TPP)2 self-assembled in aqueous media, which thereby formed core-shell structured nanoparticles (NPs) with good colloidal stability, and efficiently encapsulated the lipophilic anticancer drug doxorubicin (DOX). The DOX-loaded mPEG-(ss-TPP)2 NPs were characterized in terms of their physicochemical and morphological properties, drug-loading and release behaviors, in vitro anticancer effects, and mitochondria-targeting capacity. Our results suggest that bioreducible DOX-loaded mPEG-(ss-TPP)2 NPs can induce fast drug release with enhanced mitochondrial uptake and have a better therapeutic effect than nonbioreducible NPs.

Thermosensitive hexanoyl glycol chitosan-based ocular delivery system for glaucoma therapy.

UNLABELLED: Conventional eye drops quickly move away from the surface of the eye; as a result, ocular bioavailability is very limited. To overcome this issue, we developed a thermosensitive hexanoyl glycol chitosan (HGC) as a carrier for topical drug delivery to the eye. Here, we modulated the degree of N-hexanoylation to control the thermogelling behavior and prepared a new ocular formulation of HGC for glaucoma therapy. The viscosity of the aqueous formulation sharply and significantly increases at body temperature. The results from cytotoxicity evaluation showed that HGC is non-toxic at up to 1.25wt.%. In vivo experiments demonstrated that HGC is maintained on the preocular surface for a comparatively longer period of time due to its enhanced viscosity at body temperature. As a result, when brimonidine was loaded, the formulation exhibited attractive bioavailability properties as well as more prolonged period of lowered intra-ocular pressure (14h) compared with Alphagan P, the marketed medication for brimonidine treatment. STATEMENT OF SIGNIFICANCE: In this manuscript, hexanoyl glycol chitosan (HGC) was synthesized by the N-hexanoylation of glycol chitosan. We have observed that an aqueous solution of HGC exhibited a dramatic increase in viscosity as the temperature increased. The HGC-based formulation showed prolonged retention on the preocular surface and enhanced drug availability and efficacy.

A hyaluronic acid nanogel for photo-chemo theranostics of lung cancer with simultaneous light-responsive controlled release of doxorubicin.

The combined delivery of photo- and chemo-therapeutic agents is an emerging strategy to overcome drug resistance in treating cancer, and controlled light-responsive drug release is a proven tactic to produce a continuous therapeutic effect for a prolonged duration. Here, a combination of light-responsive graphene, chemo-agent doxorubicin and pH-sensitive disulfide-bond linked hyaluronic acid form a nanogel (called a graphene-doxorubicin conjugate in a hyaluronic acid nanogel) that exerts an activity with multiple effects: thermo and chemotherapeutic, real-time noninvasive imaging, and light-glutathione-responsive controlled drug release. The nanogel is mono-dispersed with an average diameter of 120 nm as observed by using TEM and a hydrodynamic size analyzer. It has excellent photo-luminescence properties and good stability in buffer and serum solutions. Graphene itself, being photoluminescent, can be considered an optical imaging contrast agent as well as a heat source when excited by laser irradiation. Thus the nanogel shows simultaneous thermo-chemotherapeutic effects on noninvasive optical imaging. We have also found that irradiation enhances the release of doxorubicin in a controlled manner. This release synergizes therapeutic activity of the nanogel in killing tumor cells. Our findings demonstrate that the graphene-doxorubicin conjugate in the hyaluronic acid nanogel is very effective in killing the human lung cancer cell line (A549) with limited toxicity in the non-cancerous cell line (MDCK).

Photoluminescent graphene nanoparticles for cancer phototherapy and imaging.

Graphene-based nanomaterials are of great interest in a wide range of applications in electronics, the environment, and energy as well as in biomedical and bioengineering. Their unique properties make them generally applicable as prognostic, diagnostic, and therapeutic agents in cancer. In this work, we focused on photodynamic and photothermal therapeutic properties of our previously synthesized carboxylated photoluminescent graphene nanodots (cGdots). The cGdots are ∼5 nm in diameter and excited at 655 nm. Our findings reveal that, upon laser irradiation by near-infrared (wavelength 670 nm) sensitizer, electrons of the cGdots starts to vibrate and form electron clouds, thereby generating sufficient heat (>50 °C) to kill the cancer cells by thermal ablation. The generation of singlet oxygen also occurs due to irradiation, thus acting similarly to pheophorbide-A, a well-known photodynamic therapeutic agent. The cGdots kills MDA-MB231 cancer cells (more than 70%) through both photodynamic and photothermal effects. The cGdots were equally effective in the in vivo model of MDA-MB231 xenografted tumor-bearing mice also as observed for 21 days. The cGdot was intravenously injected, and the tumor was irradiated by laser, resulting in final volume of tumor was ∼70% smaller than that of saline-treated tumor. It indicates that the growth rate of cGdot-treated tumor was slower compared to saline-treated tumor. The synthesized cGdots could enable visualization of tumor tissue in mice, thereby illustrating their use as optical imaging agents for detecting cancer noninvasively in deep tissue/organ. Collectively, our findings reveal that multimodal cGdots can be used for phototherapy, through photothermal or photodynamic effects, and for noninvasive optical imaging of deep tissues and tumors simultaneously.

Oral absorption mechanism and anti-angiogenesis effect of taurocholic acid-linked heparin-docetaxel conjugates.

Oral delivery is the preferred route to deliver therapeutics via nanoparticles due to ease of administration and patient acceptance. Here, we report on the findings of the absorption pathway of taurocholic acid (TCA)-linked heparin and docetaxel (DTX) conjugate, which we refer to as HDTA. We studied the oral absorption of HDTA using a Caco-2 cell transport system and an animal model. We have also used other absorption enhancers, such as ethylene glycol tetraacetic acid (EGTA), or inhibitors, such as sodium azide, to compare the relative permeability of HDTA conjugates. In vivo comparative studies were conducted using free TCA as a pre-administration and exhibited the maximum absorption site of the organ after oral administration of HDTA conjugates. HDTA was found to be absorbed mainly in the ileum and Caco-2 cell monolayer through passive diffusion and bile acid transporters. High fluorescence intensity of HDTA in mice came from the ileum, and it was eliminated from the body through colon. This novel formulation could be further investigated by clinical trials to find the prospect of oral anti-cancer drug delivery through anti-angiogenic treatment strategies.

In vivo biodistribution and toxicology of carboxylated graphene quantum dots.

Photoluminescent graphene quantum dots (GQDs) have fascinating optical and electronic properties with numerous promising applications in biomedical engineering. In this work, we first studied the in vivo biodistribution and the potential toxicity of carboxylated photoluminescent GQDs. KB, MDA-MB231, A549 cancer cells, and MDCK normal cell line were chosen as in vitro cell culture models to examine the possible adverse effects of the carboxylated photoluminescent GQDs. The carboxylated GQDs are desirable for increased aqueous solubility. All cancer cells efficiently took up the carboxylated GQDs. No acute toxicity or morphological changes were noted in either system at the tested exposure levels. A long-term in vivo study revealed that the GQDs mainly accumulated in liver, spleen, lung, kidney, and tumor sites after intravenous injection. To reveal any potential toxic effect of the GQDs on treated mice, serum biochemical analysis and histological evaluation were performed. The toxicity results from serum biochemistry and complete blood count study revealed that the GQDs do not cause appreciable toxicity to the treated animals. Finally, we observed no obvious organ damage or lesions for the GQDs treated mice after 21 days of administration at 5 mg/kg or 10 mg/kg dosages. With adequate studies of toxicity, both in vitro and in vivo, photoluminescent GQDs may be considered for biological application.

Surface coating of graphene quantum dots using mussel-inspired polydopamine for biomedical optical imaging.

Because of the superiority of GQDs (graphene quantum dots) in biomedical imaging, in terms of biocompatibility and toxicity of semiconductor quantum dots, GQDs bring new opportunities for the diagnosis and detection of diseases. In this study, we synthesized photoluminescent (PL) graphene quantum dots (GQDs) through a simple exfoliation and oxidation process, and then coated them with polydopamine (pDA) for enhanced stability in water and low toxicity in vivo. From the results, the GQDs coated with pDA showed an excellent stability of PL intensity. It showed that the PL intensity of noncoated GQDs in PBS solution rapidly decreased with time, resulting in a 45% reduction of the PL intensity for 14 days of incubation in PBS solution. After coating with polydopamine, PL intensities of polydopamine-coated GQDs was maintained more stably for 14 days compared with uncoated GQDs. We have observed the in vitro and in vivo biocompatibility of pDA-coated GQDs in nude mice. The overall observation revealed that pDA-coated GQDs could be used as a long-term optical imaging agent as well as a biocompatible drug carrier.

Oral delivery of taurocholic acid linked heparin-docetaxel conjugates for cancer therapy.

We have synthesized taurocholic acid (TCA) linked heparin-docetaxel (DTX) conjugates for oral delivery of anticancer drug. The ternary biomolecular conjugates formed self-assembly nanoparticles where docetaxel was located inside the core and taurocholic acid was located on the surface of the nanoparticles. The coupled taurocholic acid in the nanoparticles had enhanced oral absorption, presumably through the stimulation of a bile acid transporter of the small intestine. The oral absorption profile demonstrated that the concentration of the conjugates in plasma is about 6 fold higher than heparin alone. An anti-tumor study in MDA-MB231 and KB tumor bearing mice showed significant tumor growth inhibition activity by the ternary biomolecular conjugates. Ki-67 histology study also showed evidence of anticancer activity of the nanoparticles. Finally, noninvasive imaging using a Kodak Molecular Imaging System demonstrated that the nanoparticles were accumulated efficiently in tumors. Thus, this approach for oral delivery using taurocholic acid in the ternary biomolecular conjugates is promising for treatment of various types of cancer.

Near infra-red photoluminescent graphene nanoparticles greatly expand their use in noninvasive biomedical imaging.

A simple reaction process is developed to synthesize blue, green, yellow and red colour graphene nanoparticles (GNPs) from carbon fibers. Here, we have focused on synthesis of near infra-red GNPs and their biological application for optical imaging of deep tissues and organs.

Heparin based nanoparticles for cancer targeting and noninvasive imaging.

Numerous papers on heparin nanoparticles have been reported regarding targeting therapy and biomedical imaging. Here, we have summarized the prospects and opportunities of heparin as a carrier for cancer targeting and imaging. First, we proposed heparin-anticancer drug conjugates showing higher anticancer activity than free drug. The conjugated heparin (heparin-deoxycholate sodium) retained its ability to bind with angiogenic factors, showing a significant decrease in endothelial tubular formation. Second, targeting ligands conjugated heparin derivatives have introduced for a receptor mediated delivery of anticancer drug. Heparin-folic acid-retinoic acid (HFR) bioconjugates for treating cancer cells showed 3 fold higher efficacy than heparin-retinoic acid (HR). Besides active and passive targeting drug delivery, several papers have been reported regarding delivery of imaging agents by heparin nanoparticles. Finally, this research highlight has covered imaging agents such as gold nanoparticles and quantum dots (QDs) for noninvasive biomedical imaging. Very recently our group demonstrated that semiconductor QDs loaded heparin nanoparticles could also be administered through orally for noninvasive imaging. Due to promising features of heparin such as less toxic polysaccharide and easier modification, it was considered as a potent carrier for imaging agent and drug delivery.

Imaging of the GI tract by QDs loaded heparin-deoxycholic acid (DOCA) nanoparticles.

This study presents an approach to deliver non invasive, near-IR imaging agent using oral delivery system. Low molecular weight heparin (LMWH)-deoxycholic acid (DOCA)/(LHD) nanoparticles formed by a self-assembly method was prepared to evaluate their physicochemical properties and oral absorption in vitro and in vivo. Near-IR QDs were prepared and loaded into LHD nanoparticles for imaging of the gastro-intestinal (GI) tract absorption. Q-LHD nanoparticles were almost spherical in shape with diameters of 194-217 nm. The size and fluorescent intensity of the Q-LHD nanoparticles were stable in 10% FBS solution and retained their fluorescent even after 5 days of incubation. Cell viability of Q-LHD nanoparticles maintained in the range of 80-95% for 24h incubation. No damage was found in tissues or organs during animal experiments. The in vivo oral absorption of Q-LHD was observed in SKH1 mice for 3h under different doses. From the results, we confirmed that Q-LHD was absorbed mostly into the ileum of small intestine containing intestinal bile acid transporter as observed in TEM and molecular imaging system. Our designed nanoparticles could be administered orally for bio-imaging and studying the bio-distribution of drug.

Oral delivery of near-infrared quantum dot loaded micelles for noninvasive biomedical imaging.

The purpose of this study is to design, develop, and characterize an optical imaging agent for oral administration. The hydrophobic, nanosized (7 nm), near-infrared (NIR) quantum dots (QDs) have been loaded into deoxycholic acid (DOCA) conjugated low molecular weight heparin (LMWH) micelles. The QD-loaded LMWH-DOCA (Q-LHD) nanoparticles have been characterized by electrophoretic light scattering (ELS) and a transmission electron microscope (TEM) which shows the average particle size was 130-220 nm in diameter. The Q-LHD nanoparticles also show the excellent stability in different pH conditions, and the release profile demonstrates the slow release of QDs after 5 days of oral administration. Concfocal laser microscopic scanning images show that the Q-LHD nanoparticles penetrate the cell membrane and are located inside the cell membrane. The real time pharmacokinetics studies show the absorption, distribution, metabolism, and elimination profile of Q-LHD nanoparticles, observed by the Kodak molecular imaging system (KMIS). This study has demonstrated that the orally administered Q-LHD nanoparticles are absorbed in the small intestine through the bile acid transporter and eliminated through the kidneys.

Blood compatible graphene/heparin conjugate through noncovalent chemistry.

Blood compatible graphene/heparin conjugate is simply formulated through noncovalent interaction between chemically reduced graphene and heparin. Charge repulsion of negatively charged heparin on graphene plates renders hydrophobic graphene to be solublized in aqueous media without any precipitation or aggregation even after 6 months. Unfractioned heparin (UFH) with higher molecular weight was effective for graphene solubilization while low molecular weight heparin (LMWH) was not. Noncovalently interacting heparin chains on graphene plates preserve their anticoagulant activity after conjugation with graphene. Graphene/UFH conjugate shows much enhanced anti factor Xa (FXa) activity of 29.6 IU/mL compared with pristine graphene oxide (GO; 1.03 IU/mL).