Micellar Nanocarriers Research Articles

Denaturants and Solutol® HS15 in ophthalmic formulations: Insights into their combined effects

In the field of ophthalmology, significant attention is dedicated to developing micellar carriers to enhance ocular drug delivery. Urea is a well-known denaturant and has been used as an excipient in several ocular formulations due to its efficacy as an ocular hypotensive agent. The presence of urea as an excipient may influence the characteristics of the micellar nanocarrier in the formulation and needs to be investigated. Solutol® HS15, a well-known nonionic surfactant and a commonly used nanocarrier in drug formulations, enhances the solubilization and stability of ocular drugs. However, a detailed study of its interaction with various pharmaceutical excipients is still lacking. With this intention, the present study focuses on comprehending the interaction between Solutol® HS15 micelles with urea and its derivatives. Here, we present a detailed analysis on the influence of urea and its derivatives (methylurea, dimethylurea) on Solutol® HS15 using small-angle neutron scattering (SANS), dynamic light scattering (DLS), and cloud point (CP) measurements. The presence of urea and its derivatives strongly affects the CP, leading to a significant increase in its values when urea derivatives are present. Additionally, the SANS and DLS results also indicate a significant decrease in micellar size, suggesting demicellization. The observed effects of urea derivatives on Solutol® HS15 micelles underscore the importance of considering solvent-surfactant interactions in understanding the behavior of surfactant-based systems. This research will provide greater insight into the interactions between urea and its derivatives and Solutol® HS15, which will assist in understanding the morphology and size distribution of surfactant micelles for drug delivery applications.

Alpha-Bisabolol-Loaded Cosmetic Micellar Solution with Cleansing and Antimicrobial Action for Facial Skin Hygiene

The current research is focused on the discovery and optimization of an effective cosmetic carrier of alpha-bisabolol as a first step in the development of a cosmetic product with cleansing and antimicrobial action for facial skin hygiene. A micellar solution of Poloxamer 407 was selected as a cosmetic base because of the good washing ability, easy application, and high tolerability of this polymeric surfactant. The solubilization capacity of a 5% micellar solution with respect to α-bisabolol was investigated by applying varying solubilization techniques and increasing concentrations of the oily active substance. The test samples were subjected to an accelerated physical stability test, viscosimetry, dynamic light scattering (DLS), electrophoretic light scattering (ELS), foamability test, and antimicrobial screening. Over the course of this research, the advantage of the film-hydration method over direct solubilization was demonstrated by the narrower size distribution and smaller hydrodynamic size of the micellar nano-carriers (ranging from 29.02 to 116.5 nm) and the respective higher physical stability of the dispersions. The optimized composition was found to be suitable for application on large skin areas in terms of viscosity in the temperature range from 20 °C to 40 °C (3.4–2.3 mPa.s). Preservation of the washing capacity of the micellar solution in the presence of solubilized α-bisabolol was established. The active composition demonstrated inhibitory activity against Staphylococcus aureus and Escherichia coli and fungicidal activity against Candida albicans. This study concludes that the optimal concentration of α-bisabolol to be solubilized in a 5% Poloxamer 407 micellar solution by the film-hydration technique is 1%, considering the desirable physical endurance and antimicrobial activity.

Direct radiolabeling of Folate with Tc-99m using QbD approach: A step closer to folate based diagnostic agent

The aim of the presented work was to develop folate based radiolabeled compound intended to be used as diagnostic aid for the various folate-receptor overexpressing cancers eg. breast cancer, brain tumors, lung cancer etc. Folate was directly radiolabeled with Tc-99m using Quality-by-Design and encapsulated in micellar nanocarriers. The authors are of the view that the stable radiolabeled folate could be of potential diagnostic value in cancers overexpressing folate receptors thereby opening novel possibilities to diagnostic applications of radiolabeled folate. Summary for technical notesFolic acid was directly radiolabeled with Tc-99m utilizing a quality by design approach. The experimental trials were designed using the Box-Behenken design with the concentration of drug, concentration of reducing agent and the incubation time as dependent variable and percent radiolabeling as the response for the same. The applied design in the method section was validated with a series of experiments and the percent labeling of the FA with Tc-99m was found to be around 94%. The radiolabeled compound was imperilled to stability evaluation by incubating the same with serum and physiological pH and the same was found to be stable at the end of 4h. On subjecting to DTPA challenge test, the compound displayed no change in the radiolabeling percentage thereby indicating the robustness of the formed Tc-99m-FA complex, The radiolabeled Tc-99m-FA was further encapsulated into micellar nanocarriers and the same were also found to be robust and stable.

Poly(allylamine)-adorned heptylcarboxymethyl galactomannan nanocarriers of canagliflozin for controlling type-2 diabetes: Optimization by Box-Behnken design and in vivo performance

In the past three decades, the prevalence of type-2 diabetes has arisen dramatically in countries of all income levels. A novel, most effective nanotechnology-based strategy may reduce the prevalence of diabetes. Recently, the shell-crosslinked polysaccharide-based micellar nanocarriers (MNCs) have shown great promise in terms of stability, controlled drug release, and improved in vivo performance. In this study, heptyl carboxymethyl guar gum was synthesized and characterized by ATR-FTIR, 1HNMR spectroscopy, surface charge, critical micelle concentration (23.9 μg/mL), and cytotoxicity analysis. Box-Behnken design was used to optimize the diameter, zeta potential, drug entrapment efficiency (DEE), and drug release characteristics of poly (allylamine)-crosslinked MNCs containing canagliflozin. The optimized MNCs revealed spherical morphology under TEM and had 149.3 nm diameter (PDI 21.2 %), +53.8 mV zeta potential, and 84 % DEE. The MNCs released about 63 % of the drug in 12 h under varying pH of the simulated gastrointestinal fluid. DSC and x-ray analyses suggested amorphous dispersion of drugs in the MNCs. CAM assay demonstrated the biocompatibility of the MNCs. The MNCs showed hemolysis of <1 %, 85 % mucin adsorption, and stability over three months. The MNCs demonstrated excellent anti-diabetic efficacy in streptozotocin-nicotinamide-induced diabetic rats, continuously lowering blood glucose levels up to 12 h.

Nanosized Complexes of the Proteolytic Enzyme Serratiopeptidase with Cationic Block Copolymer Micelles Enhance the Proliferation and Migration of Human Cells.

In this study, we describe the preparation of the cationic block copolymer nanocarriers of the proteolytic enzyme serratiopeptidase (SER). Firstly, an amphiphilic poly(2-(dimethylamino)ethyl methacrylate)-b-poly(ε-caprolactone)-b-poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA9-b-PCL35-b-PDMAEMA9) triblock copolymer was synthesized by reversible addition-fragmentation chain-transfer (RAFT) polymerization. Then, cationic micellar nanocarriers consisting of a PCL hydrophobic core and a PDMAEMA hydrophilic shell were formed by the solvent evaporation method. SER was loaded into the polymeric micelles by electrostatic interaction between the positively charged micellar shell and the negatively charged enzyme molecules. The particle size, zeta potential, and colloid stability of complexes as a function of SER concentration were investigated by dynamic and electrophoretic light scattering. It was found that SER retained its proteolytic activity after immobilization in polymeric carriers. Moreover, the complexes have a concentration-dependent enhancing effect on the proliferation and migration of human keratinocyte HaCaT and gingival fibroblast HGF cells.

Napthalimide-based nuclease inhibitor: A multifunctional therapeutic material to bolster MRSA uptake by macrophage-like cells and mitigate pathogen adhesion on orthopaedic implant

The healthcare burden rendered by methicillin-resistant Staphylococcus aureus (MRSA) warrants the development of therapeutics that offer a distinct benefit in the clinics as compared to conventional antibiotics. The present study describes the potential of napthalimide-based synthetic ligands (C1-C3) as inhibitors of the staphylococcal nuclease known as micrococcal nuclease (MNase), a key virulence factor of the pathogen. Amongst the ligands, the most potent MNase inhibitor C1 rendered non-competitive inhibition, reduced MNase turnover number (Kcat) and catalytic efficiency (Kcat/Km) with an IC50 value of ~950 nM. CD spectroscopy suggested distortion of MNase conformation in presence of C1. Flow cytometry and confocal microscopy indicated that C1 restored the ability of activated THP-1 cells to engulf DNA-entrapped MRSA cells. Interestingly, C1 could inhibit MRSA adhesion onto collagen. For potential application, C1-loaded pluronic F-127 micellar nanocarrier (C1-PMC) was generated, wherein the anti-adhesion activity of the pluronic carrier (PMC) and C1 was harnessed in tandem to deter MRSA cell adhesion onto collagen. MRSA biofilm formation was hindered on C1-PMC-coated titanium (Ti) wire, while eluates from C1-PMC-coated Ti wires were non-toxic to HEK 293, MG-63 and THP-1 cells. The multifunctional C1 provides a blueprint for designing therapeutic materials that hold translational potential for mitigation of MRSA infections.

Tailoring micellar nanocarriers for pemetrexed in breast cancer: design, fabrication and in vitro evaluation.

Aim: To investigate the pemetrexed encapsulated polymeric mixed micelles (PMMs) against breast cancer treatment.Methods: We meticulously optimized the formulation and conducted extensive characterizations, including photon correlation spectroscopy for micellization, advanced analytical techniques and in vitro cell line assessments.Results: The PMM exhibited favorable characteristics, with a spherical morphology, hydrodynamic particle size of 19.58±0.89nm, polydispersity index of 0.245±0.1, and a surface charge of -9.70±0.61mV. Encapsulation efficiency and drug payload reached 96.16±0.37% and 4.5±0.32%, respectively. Cytotoxicity analysis indicated superior efficacy of the PMM over the drug solution.Conclusion: The PMM formulation exhibited controlled release of the drug, and demonstrated enhanced cytotoxicity against breast cancer cells, highlighting its therapeutic promise.

Key Transdermal Patch Using Cannabidiol-Loaded Nanocarriers with Better Pharmacokinetics in vivo.

Cannabidiol (CBD) is a promising therapeutic drug with low addictive potential and a favorable safety profile. However, CBD did face certain challenges, including poor solubility in water and low oral bioavailability. To harness the potential of CBD by combining it with a transdermal drug delivery system (TDDS). This innovative approach sought to develop a transdermal patch dosage form with micellar vesicular nanocarriers to enhance the bioavailability of CBD, leading to improved therapeutic outcomes. A skin-penetrating micellar vesicular nanocarriers, prepared using nano emulsion method, cannabidiol loaded transdermal nanocarriers-12 (CTD-12) was presented with a small particle size, high encapsulation efficiency, and a drug-loaded ratio for CBD. The skin permeation ability used Strat-M™ membrane with a transdermal diffusion system to evaluate the CTD and patch of CTD-12 (PCTD-12) within 24 hrs. PCTD-12 was used in a preliminary pharmacokinetic study in rats to demonstrate the potential of the developed transdermal nanocarrier drug patch for future applications. In the transdermal application of CTD-12, the relative bioavailability of the formulation was 3.68 ± 0.17-fold greater than in the free CBD application. Moreover, PCTD-12 indicated 2.46 ± 0.18-fold higher relative bioavailability comparing with free CBD patch in the ex vivo evaluation. Most importantly, in the pharmacokinetics of PCTD-12, the relative bioavailability of PCTD-12 was 9.47 ± 0.88-fold higher than in the oral application. CTD-12, a transdermal nanocarrier, represents a promising approach for CBD delivery, suggesting its potential as an effective transdermal dosage form.

Photo-induced drug release at interfaces with arylazopyrazoles.

Smart responsive materials have spurred the progress in high-precision drug delivery. Enormous attention has been given to characterizing drug release in bulk aqueous solutions, however, aqueous-hydrophobic interfaces are vital components of biological systems which serve as the point of entry into cells. These interfaces are involved in many key biomolecular interactions, and while the potential for drug molecules to adsorb to these interfaces is recognized, their specific role in the context of drug release remains largely unexplored. We present a fundamental investigation on the release of encapsulated drugs at the air-water interface as a representative model to mimic the organic/aqueous interface of cells. Combining the advantages of light as an external stimulus and the superiority of arylazopyrazoles (AAP) over conventional azobenzene photoswitches, we report a micellar nanocarrier for the capture and release of the chemotherapeutic drug doxorubicin. Using a powerful combination of interface-sensitive techniques such as the Langmuir-Blodgett technique, surface tensiometry, and the interface-specific vibrational sum-frequency generation spectroscopy, we demonstrate the photoresponsive release of doxorubicin encapsulated in the micelles of AAP photosurfactants to the air-water interface. Complementary fluorescence measurements corroborate additional drug release in bulk aqueous solutions.

Reaching the Tumor: Mobility of Polymeric Micelles Inside an In Vitro Tumor-on-a-Chip Model with Dual ECM.

Degradable polymeric micelles are promising drug delivery systems due to their hydrophobic core and responsive design. When applying micellar nanocarriers for tumor delivery, one of the bottlenecks encountered in vivo is the tumor tissue barrier: crossing the dense mesh of cells and the extracellular matrix (ECM). Sometimes overlooked, the extracellular matrix can trap nanoformulations based on charge, size, and hydrophobicity. Here, we used a simple design of a microfluidic chip with two types of ECM and MCF7 spheroids to allow "high-throughput" screening of the interactions between biological interfaces and polymeric micelles. To demonstrate the applicability of the chip, a small library of fluorescently labeled polymeric micelles varying in their hydrophilic shell and hydrophobic core forming blocks was studied. Three widely used hydrophilic shells were tested and compared, namely, poly(ethylene glycol), poly(2-ethyl-2-oxazoline), and poly(acrylic acid), along with two enzymatically degradable dendritic hydrophobic cores (based on hexyl or nonyl end groups). Using ratiometric imaging of unimer:micelle fluorescence and FRAP inside the chip model, we obtained the local assembly state and dynamics inside the chip. Notably, we observed different micelle behaviors in the basal lamina ECM, from avoidance of the ECM structure to binding of the poly(acrylic acid) formulations. Binding to the basal lamina correlated with higher uptake into MCF7 spheroids. Overall, we proposed a simple microfluidic chip containing dual ECM and spheroids for the assessment of the interactions of polymeric nanocarriers with biological interfaces and evaluating nanoformulations' capacity to cross the tumor tissue barrier.

PH-responsive star-shaped poly (ε-carprolactone)-co-poly maleic anhydride micelles for synergistic breast cancer combination chemotherapy

Polymeric micelles produced from amphiphilic copolymers, are considered promising drug delivery platforms. Because of their ability to co-deliver hydrophilic (Dox) and hydrophobic (natural sesquiterpene coumarin, Conf) drugs through their shell and core, these nanosized micelles can benefit adjuvant therapy by modulating MDR proteins and increasing cellular uptake. In this study, a novel star-shaped biodegradable pH-sensitive pentaerythritol-grafted anhydride maleic copolymerized with Poly(ε-caprolactone) (PEE-g-PMA-co-PCL) was synthesized and developed as micellar nano-carriers for combination therapy of MDA-MB-231 breast cancer cell line. The physicochemical, characteristics of the synthesized copolymers and micelles were validated using Nuclear Magnetic Resonance Spectroscopy (NMR), Fourier Transform Infrared Spectroscopy (FTIR), CHNS elemental analysis, Dynamic Light Scattering (DLS), Zeta potential, Scanning Electron Microscopy (SEM), and Differential Scanning Calorimetry (DSC). The engineered micelles exhibited nearly 100% encapsulation efficiency for both Dox and Conf. Micelles possess a CMC value of 0.1 μg/mL, an average size of 40.3 nm with uniform distribution; ζ-potential of −11.5 mV in blank form and + 6.82 mV in co-drug-loaded form. Furthermore, micelles' in vitro biodegradation and drug release profiles followed an intensive pH-dependent pattern that benefited targeted delivery. The results of MTT, cellular uptake, cell cycle, and apoptosis by Annexin V assay on MDA-MB-231 cell line cells treated by co-drug loaded micelles (E2D) demonstrated higher cytotoxicity, more cellular uptake, superior inhibitory yield on DNA duplication, and greater apoptosis with a lower necrosis rate compared to monotherapy (ED and EC) and free drugs (Conf, Dox and 2D) which confirmed the synergistic effect of this combination therapy system (CI < 1) in a reduced Dox dosage. In addition, western blot and RT-PCR showed that co-drug-loaded micelles triggered an apoptotic response via the mitochondrial pathway. In conclusion, the novel developed multi-functional pH-sensitive micelles here could open a new perspective for the development of nanomedicine for combination chemo-adjuvant therapy against malignant cancer.

Copolymeric Micelles of Poly(ε-caprolactone) and Poly(methacrylic acid) as Carriers for the Oral Delivery of Resveratrol.

In this study, we report the development of a micellar system based on a poly(methacrylic acid)-b-poly(ε-caprolactone)-b-poly(methacrylic acid) triblock copolymer (PMAA16-b-PCL35-b-PMAA16) for the oral delivery of resveratrol. The micellar nanocarriers were designed to comprise a PCL core for solubilizing the poorly water-soluble drug and a hydrated PMAA corona with bioadhesive properties for providing better contact with the gastrointestinal mucosa. The micelles were first formed in an aqueous media via the solvent evaporation method and then loaded with resveratrol (72% encapsulation efficiency). Studies by transmission electron microscopy (TEM) and dynamic and electrophoretic light scattering (DLS and PALS) revealed a spherical shape, nanoscopic size (100 nm) and a negative surface charge (-30 mV) of the nanocarriers. Loading of the drug slightly decreased the hydrodynamic diameter (Dh) and increased the ƺ-potential of micelles. In vitro dissolution tests showed that 80% and 100% of resveratrol were released in 24 h in buffers with pH 1.2 and 6.8, respectively, whereas for the same time, not more than 10% of pure resveratrol was dissolved. A heat-induced albumin denaturation assay demonstrated the advantage of the aqueous micellar formulation of resveratrol, which possessed anti-inflammatory potential as high as that of the pure drug. Further, the micellar resveratrol (5 µM) exerted a strong protective effect and maintained viability of mucosa epithelial HT-29 cells in a co-cultural model, representing the production of inflammatory cytokines. For comparison, the pure resveratrol at the same concentration did not protect the damaged HT-29 cells at all. Thus, the present study revealed that the PMAA-b-PCL-b-PMAA copolymeric micelles might be considered appropriate nanocarriers for the oral delivery of resveratrol.

PEG2000-PLA-based nanoscale polymeric micelles reduce paclitaxel-related toxicity in beagle dogs

Nanoplatform-based drug delivery plays an important role in clinical practice. Polymeric micellar (Pm) nanocarriers have been demonstrated to reduce the toxicity of paclitaxel in rats and non-small cell lung cancer (NSCLC) patients. However, the underlying toxicological profile needs to be further illustrated. Here, we used beagles as study subjects and sought to further observe the toxicological profile of polymeric micellar paclitaxel (Pm-Pac) via acute toxicity tests and short-term and long-term toxicity tests. The results from the acute toxicity test indicated that the lethal dose of Pm-Pac in beagles was 20–30 mg/kg, and the acute toxicity-targeted organs were the digestive system and immuno-haematopoietic system. The short-term toxicity test suggested that paclitaxel-induced toxicity (peripheral neuropathy toxicity, haemopoietic toxicity, heart system toxicity, and so on) in beagles can be reduced when paclitaxel is delivered via the Pm delivery system. The long-term toxicity test suggested that Pm-Pac can reduce haemopoietic toxicity in beagles. Collectively, this study provides novel insight into the toxicological profile of Pm-Pac in healthy beagles and provides a potential basis for promising clinical combination strategies in the future.

Pluronic® P-123 as a reductant and stabilizing agent for gold nanoparticles (AuNPs) combined with methylene blue for photodynamic and photothermal therapy

The search for more effective drugs and therapies for the treatment of microbial diseases has driven the development of nanomedicine in recent years. In this sense, the present work shows the combination of photodynamic therapy (PDT) and photothermal therapy (PTT) using the photoactive drugs: methylene blue (MB) and gold nanoparticles (AuNPs). The ABA triblock Pluronic® P-123 copolymer was employed both as a micellar nanocarrier and reductant/stabilizing agent for AuNPs. The synthesis of gold nanoparticles (AuNPs) was carried out in situ through the redox process of AuCl3 gold salt in the presence of different concentrations of P-123 ranging from 0.25 % to 8.00 % ( % w/V) following the solid dispersion method. The MB was incorporated into the copolymeric micellar system by passive and active incorporation methods. In general, the system containing 1.00 % and 2.00 % (w/V) of P-123 was the more efficient and reproducible to obtain P-123/AuNPs/MB samples. The AuNPs synthesized presented plasmonic resonance peaks ranging from 535 to 554 nm, characteristic of spherical AuNPs. Dynamic Light Scattering and transmission electronic microscopy confirm the structure of the polymeric micelle around 20 nm and the AuNPs 3 nm diameters. The fluorescence emission showed to be dependent on the excitation wavelength, a promising feature for biological applications, especially when considering an image-guided diagnosis. Furthermore, the Stern-Volmer study by fluorescence quenching with iodide showed that active incorporation favors greater internalization of MB at the hydrophobic core of the micelle. On the other hand, the passive incorporation method placed MB in the most hydrophilic region in the micelle. The photodynamic effect was confirmed by singlet oxygen generation using ABDA as a probe. Thermal Lens spectroscopy and heating studies also confirms the heat generation by the system. In addition, the results point to synergism both in the generation of 1O2 and heat. The in vitro susceptibility of the samples was evaluated in Candida albicans strain. Better antifungal activity was observed in the sample of 2.00 % P-123/AuNPs/MB by Passive incorporation, illuminated with red and green LEDs. The biological study in bacteria strains of E. coli and S. aureus has shown that both percentages of P-123 with MB and AuNPs/MB by passive incorporation were efficient in controlling the evaluated bacteria. In this way, the present work showed promise for the treatment of antimicrobials through the combined therapy of PDT and PTT.

Enhanced solubilization and encapsulation of direct dyes through self-assembled single and mixed micellar nanocarriers

This manuscript provides insights into the solubilization of two direct dyes, direct green 6 (DG-6) and direct yellow 44 (DY-44), in different surfactant systems. It reports the interaction and applicability of surfactants to elevate the solubility of direct dyes in aqueous medium. Different combinations of cationic (cetyltrimethylammonium bromide) and nonionic surfactants (Triton X-100, Tween-20) have been employed for said purpose. Inclusion of nonionic surfactants to micellar media of ionic ones enhances space within micelle to accommodate more solubilizate within it. Conductometric and spectroscopic measurements were applied for investigating the interaction of dyes in these surfactant solutions. The properties of surfactants, their behavior in aqueous systems, and thermodynamics have been evaluated in terms of critical micelle concentration (CMC), and change in Gibbs energy (ΔGm), enthalpy (ΔHm), and entropy (ΔSm) of micellization. While the solubilization capability of different surfactant systems was explored with the help of binding (ΔKb) and partition (ΔKx) parameters. Moreover, the stability of the process has been revealed by calculating the Gibbs energies of binding (ΔGb) and partition (ΔGp). The results revealed that mixed surfactants are more suitable agents for the solubilization of dyes. It was also observed that the partition of dye molecules is greatly dependent on their interaction with the surfactant molecules. This study will provide the basis for choosing the suitable surfactant system to be used in various surfactant-based dye removal techniques.

Polymyxin B stabilized DNA micelles for sustained antibacterial and antibiofilm activity against P. aeruginosa.

Nucleic acid-based materials showcase an increasing potential for antimicrobial drug delivery. Although numerous reports on drug-loaded DNA nanoparticles outline their pivotal antibacterial activities, their potential as drug delivery systems against bacterial biofilms awaits further studies. Among different oligonucleotide structures, micellar nanocarriers derived from amphiphilic DNA strands are of particular interest due to their spontaneous self-assembly and high biocompatibility. However, their clinical use is hampered by structural instability upon cation depletion. In this work, we used a cationic amphiphilic antibiotic (polymyxin B) to stabilize DNA micelles destined to penetrate P. aeruginosa biofilms and exhibit antibacterial/antibiofilm properties. Our study highlights how the strong affinity of this antibiotic enhances the stability of the micelles and confirms that antibacterial activity of the novel micelles remains intact. Additionally, we show that PMB micelles can penetrate P. aeruginosa biofilms and impact their metabolic activity. Finally, PMB micelles were highly safe and biocompatible, highlighting their possible application against P. aeruginosa biofilm-colonized skin wounds.

Targeted delivery of harmine to xenografted human pancreatic islets promotes robust cell proliferation

Type 1 diabetes (T1D) occurs as a consequence of the autoimmune destruction of insulin-producing pancreatic beta (β) cells and commonly presents with insulin deficiency and unregulated glycemic control. Despite improvements in the medical management of T1D, life-threatening complications are still common. Beta-cell replication to replace lost cells may be achieved by using small-molecule mitogenic drugs, like harmine. However, the safe and effective delivery of such drugs to beta cells remains a challenge. This work aims to deploy an antibody conjugated nanocarrier platform to achieve cell-specific delivery of candidate therapeutic and imaging agents to pancreatic endocrine cells. We approached this goal by generating core–shell type micellar nanocarriers composed of the tri-block copolymer, Pluronic®F127 (PEO100–PPO65–PEO100). We decorated these nanocarriers with a pancreatic endocrine cell-selective monoclonal antibody (HPi1), with preference for beta cells, to achieve active targeting. The PPO-based hydrophobic core allows encapsulation of various hydrophobic cargoes, whereas the PEO-based hydrophilic shell curbs the protein adhesion, hence prolonging the nanocarriers' systemic circulation time. The nancarriers were loaded with quantum dots (QDots) that allowed nanocarrier detection both in-vitro and in-vivo. In-vitro studies revealed that HPi1 conjugated nanocarriers could target endocrine cells in dispersed islet cell preparations with a high degree of specificity, with beta cells exhibiting a fluorescent quantum dot signal that was approximately five orders of magnitude greater than the signal associated with alpha cells. In vivo endocrine cell targeting studies demonstrated that the HPi1 conjugated nanocarriers could significantly accumulate at the islet xenograft site. For drug delivery studies, the nanocarriers were loaded with harmine. We demonstrated that HPi1 conjugated nanocarriers successfully targeted and delivered harmine to human endocrine cells in a human islet xenograft model. In this model, targeted harmine delivery yielded an ~ 41-fold increase in the number of BrdU positive cells in the human islet xenograft than that observed in untreated control mice. By contrast, non-targeted harmine yielded an ~ 9-fold increase in BrdU positive cells. We conclude that the nanocarrier platform enabled cell-selective targeting of xenografted human pancreatic endocrine cells and the selective delivery of the hydrophobic drug harmine to those cells. Further, the dramatic increase in proliferation with targeted harmine, a likely consequence of achieving higher local drug concentrations, supports the concept that targeted drug delivery may promote more potent biological responses when using harmine and/or other drugs than non-targeting approaches. These results suggest that this targeted drug delivery platform may apply in drug screening, beta cell regenerative therapies, and/or diagnostic imaging in patients with type 1 diabetes.

Synergy between pH- and hypoxia-responsiveness in antibiotic-loaded micelles for eradicating mature, infectious biofilms

Antibiotic-loaded PEG/PAE-based micelles are frequently considered for eradicating infectious biofilms. At physiological pH, PEG facilitates transport through blood. Near an acidic infection-site, PAE becomes protonated causing micellar targeting to a biofilm. However, micellar penetration and accumulation is confined to the surface region of a biofilm. Especially matured biofilms also possess hypoxic regions. We here designed dual-responsive PEG/PAE-b-P(Lys-NBCF) micelles, responding to both acidity and low oxygen-saturation level in matured biofilms. Dual, pH- and hypoxia-responsive micelles targeted and accumulated evenly over the depth of 7- to 14-days old biofilms. Delineation demonstrated that pH-responsiveness was responsible for targeting of the infection-site and accumulation of micelles in the surface region of the biofilm. Hypoxia-responsiveness caused deep penetration in the biofilm. Dual, pH- and hypoxia-responsive micelles loaded with ciprofloxacin yielded more effective, synergistic eradication of 10-days old, matured Staphylococcus aureus biofilms underneath an abdominal imaging-window in living mice than achieved by ciprofloxacin in solution or single, pH- or hypoxia responsive micelles loaded with ciprofloxacin. Also, wound-healing after removal of window and its frame proceeded fastest after tail-vein injection of ciprofloxacin-loaded, dual, pH- and hypoxia-responsive micelles. Concluding, pH- and hypoxia-responsiveness are both required for eradicating mature biofilms and advancing responsive antibiotic nanocarriers to clinical application. Statement of significancepH-responsive antibiotic nanocarriers have emerged as a possible new strategy to prevent antimicrobial-resistant bacterial infections from becoming the leading cause of death. In this paper, we show that commonly studied, pH-responsive micellar nanocarriers merely allow self-targeting to an infectious biofilm, but do not penetrate deeply into the biofilm. The dual-responsive (acidic pH- and hypoxia) antibiotic-loaded micelles designed here not only self-target to an infectious biofilm, but also penetrate deeply. The in vitro and in vivo advantages of dual-responsive nanocarriers are most obvious when studied in infectious biofilms grown for 10 viz a viz the 2 days, usually applied in the literature. Significantly, clinical treatment of bacterial infection usually starts more than 2 days after appearance of the first symptoms.

Aggregation-Induced Ignition of Near-Infrared Phosphorescence of Non-Symmetric [Pt(C^N*N'^C')] Complex in Poly(caprolactone)-based Block Copolymer Micelles: Evaluating the Alternative Design of Near-Infrared Oxygen Biosensors.

In the present work, we described the preparation and characterization of the micelles based on amphiphilic poly(ε-caprolactone-block-ethylene glycol) block copolymer (PCL-b-PEG) loaded with non-symmetric [Pt(C^N*N’^C’)] complex (Pt1) (where C^N*N’^C’: 6-(phenyl(6-(thiophene-2-yl)pyridin-2-yl)amino)-2-(tyophene-2-yl)nicotinate). The obtained nanospecies displayed the ignition of near-infrared (NIR) phosphorescence upon an increase in the content of the platinum complexes in the micelles, which acted as the major emission component at 12 wt.% of Pt1. Emergence of the NIR band at 780 nm was also accompanied by a 3-fold growth of the quantum yield and an increase in the two-photon absorption cross-section that reached the value of 450 GM. Both effects are believed to be the result of progressive platinum complex aggregation inside hydrophobic poly(caprolactone) cores of block copolymer micelles, which has been ascribed to aggregation induced emission (AIE). The resulting phosphorescent (Pt1@PCL-b-PEG) micelles demonstrated pronounced sensitivity towards molecular oxygen, the key intracellular bioanalyte. The detailed photophysical analysis of the AIE phenomena revealed that the NIR emission most probably occurred due to the excimeric excited state of the 3MMLCT character. Evaluation of the Pt1@PCL-b-PEG efficacy as a lifetime intracellular oxygen biosensor carried out in CHO-K1 live cells demonstrated the linear response of the probe emission lifetime towards this analyte accompanied by a pronounced influence of serum albumin on the lifetime response. Nevertheless, Pt1@PCL-b-PEG can serve as a semi-quantitative lifetime oxygen nanosensor. The key result of this study consists of the demonstration of an alternative approach for the preparation of NIR biosensors by taking advantage of in situ generation of NIR emission due to the nanoconfined aggregation of Pt (II) complexes inside the micellar nanocarriers.

Glycyrrhizin micellar nanocarriers for topical delivery of baicalin to the hair follicles: A targeted approach tailored for alopecia treatment

Alopecia affected approximately 16.6% of all people in China, however, treatment options remain limited due to the side effects. Plant bioactive compound baicalin (BC) possesses hair growth-promotion activity, but poor water solubility and unsuitable log P value restrict its topical application, and natural Glycyrrhizin (GL) can exactly overcome these drawbacks. Here, BC was encapsulated in GL to form GL-BC micelles for alopecia treatment. Simultaneously, tween 80 (TW) as carriers was incorporated in the GL-BC to form GL-TW-BC micelles. The topical penetration, penetration pathways, cellular uptake and the underlying mechanisms behind the hair loss reconstruction of the GL micelles were investigated. We found the optimal GL-BC and GL-TW-BC formulations significantly improved the penetration and accumulation of BC in the porcine skin predominantly through the hair follicles pathways without causing skin irritation, which resulted in a targeted treatment. The proliferation of human dermal papilla cells (hDPCs) and effective cellular uptake was also enhanced. Moreover, the activation of the Wnt/β-catenin pathway, up-expression of vascular endothelial growth factor (VEGF), α-melanocyte-stimulating hormone (α-MSH) and interleukin-10 (IL-10) were the mechanisms of micelles for the hair recovery. Interestingly, GL and BC exhibited a synergistic treatment of alopecia. Collectively, GL-BC and GL-TW-BC can be used as promising approaches for the treatment of alopecia.