Safety tests and clinical research on buccal and nasal microneedle swabs for genomic analysis.

Conventional swabs have been used as a non-invasive method to obtain samples for DNA analysis from the buccal and the nasal mucosa. However, swabs may not always collect pure enough genetic material. In this study, buccal and nasal microneedle swab is developed to improve the accuracy and reliability of genomic analysis. A cytotoxicity test, a skin sensitivity test, and a skin irritation test are conducted with microneedle swabs. Polymer microneedle swabs meet the safety requirements for clinical research and commercial use. When buccal and nasal microneedle swabs are used, the amount of genetic material obtained is greater than that from commercially available swabs, and DNA purity is also high. The comparatively short microneedle swab (250 µm long) cause almost no pain to all 25 participants. All participants also report that the microneedle swabs are very easy to use. When genotypes are compared at five SNP loci from blood of a participant and from that person's buccal or nasal microneedle swab, the buccal and nasal microneedle swabs show 100% concordance for all five SNP genotypes. Microneedle swabs can be effectively used for genomic analysis and prevention through genomic analysis, so the utilization of microneedle swabs is expected to be high.

Development of Spleen Targeting H2S Donor Loaded Liposome for the Effective Systemic Immunomodulation and Treatment of Inflammatory Bowel Disease.

Nanoparticles are primarily taken up by immune cells after systemic administration. Thus, they are considered an ideal drug delivery vehicle for immunomodulation. Because the spleen is the largest lymphatic organ and regulates the systemic immune system, there have been studies to develop spleen targeting nanoparticles for immunomodulation of cancer and immunological disorders. Inflammatory bowel disease (IBD) includes disorders involving chronic inflammation in the gastrointestinal tract and is considered incurable despite a variety of treatment options. Hydrogen sulfide (H2S) is one of the gasotransmitters that carries out anti-inflammatory functions and has shown promising immunomodulatory effects in various inflammatory diseases including IBD. Herein, we developed a delicately tuned H2S donor delivering liposome for spleen targeting (ST-H2S lipo) and studied its therapeutic effects in a dextran sulfate sodium (DSS) induced colitis model. We identified the ideal PEG type and ratio of liposome for a high stability, loading efficiency, and spleen targeting effect. In the treatment of the DSS-induced colitis model, we found that ST-H2S lipo and conventional long-circulating liposomes loaded with H2S donors (LC-H2S lipo) reduced the severity of colitis, whereas unloaded H2S donors did not. Furthermore, the therapeutic effect of ST-H2S lipo was superior to that of LC-H2S lipo due to its better systemic immunomodulatory effect than that of LC-H2S lipo. Our findings demonstrate that spleen targeting H2S lipo may have therapeutic potential for IBD.

Corrigendum: Development of a microneedle swab for acquisition of genomic DNA from buccal cells.

[This corrects the article DOI: 10.3389/fbioe.2022.829648.].

Preparation of particle-attached microneedles using a dry coating process.

The standard process for manufacturing microneedles containing API requires a way to process the API, including dissolving the API in a co-solvent and a drying process. In this study, the authors introduce a novel microneedle system that involves physically attaching API particles to the biocompatible adhesive surface of the microneedles. To manufacture particle-attached microneedles, an adhesive surface was prepared by coating polydimethylsiloxane (PDMS) mixed with an elastomer base and a curing agent at a ratio of 40:1 (PDMS40) onto polylactic acid microneedles (PLA), and then attaching ovalbumin (OVA) particles with a mean diameter of 10 µm to the PDMS adhesive layer. The OVA particles were delivered for 5 min into porcine skin with a delivery efficiency of 93% ex vivo and into mouse skin with a delivery efficiency of over 90% in vivo. Finally, mouse experiments with OVA particle-attached microneedles showed a value of OVA antibody titer similar to that produced by intramuscular administration. Particle-attached microneedles are a novel microneedle system with a dry coating process and rapid API delivery into the skin. Particle-attached microneedles can provide a wide range of applications for administering drugs and vaccines.

Self-Assembled DNA-Protein Hybrid Nanospheres: Biocompatible Nano-Drug-Carriers for Targeted Cancer Therapy.

We developed hybrid nanospheres comprised of two of the most important biomolecules in nature, DNA and proteins, which have excellent biocompatibility, high drug payload capacity, in vivo imaging ability, and in vitro/in vivo cancer targeting capability. The synthesis can be done in a facile one-pot assembly system that includes three steps: step-growth polymerization of two DNA oligomers, addition of streptavidin to assemble spherical hybrid nanostructures, and functionalization of hybrid nanospheres with biotinylated aptamers. To test the feasibility of cancer targeting and drug-loading capacity of the hybrid nanospheres, MUC1-specific aptamers (MA3) were conjugated to nanosphere surfaces (apt-nanospheres), and doxorubicin (Dox) was loaded into nanospheres by DNA intercalation. The successful construction of nanospheres and apt-nanospheres was confirmed by agarose gel electrophoresis and dynamic light scattering (DLS). Their uniform spherical morphology was confirmed by transmission electron microscopy (TEM). Fluorescence spectra of nanospheres demonstrated high Dox-loading capability and slow-release characteristics. In vitro MUC1-specific binding of the apt-nanospheres was confirmed by flow cytometry and confocal microscopy. Dox-loaded apt-nanospheres significantly increased cytotoxicity of the MUC1-positive cancer cells due to aptamer-mediated selective internalization, as shown via cell viability assays. Apt-nanospheres could also be imaged in vivo through the synthesis of hybrid nanospheres using fluorescent dye-conjugated DNA strands. Finally, in vivo specific targeting ability of apt-nanospheres was confirmed in a MUC1-positive 4T1 tumor-bearing mouse model, whereas apt-nanospheres did not cause any sign of systemic toxicity in normal mice. Taken together, our self-assembled DNA-streptavidin hybrid nanospheres show promise as a biocompatible cancer targeting material for contemporary nanomedical technology.

M1 Macrophage-Derived Exosome-Mimetic Nanovesicles with an Enhanced Cancer Targeting Ability.

Extracellular vesicles (EVs) have been found to be effective therapeutic drug delivery vehicles in a wide range of human diseases, including cancer and neurodegenerative diseases. Proinflammatory (M1) macrophages can modulate the suppressive immune environment of tumor tissues to be more inflammatory and have been considered as candidates for cancer immunotherapy. Furthermore, macrophage-derived exosome-mimetic nanovesicles (MNVs) could effectively induce antitumor response and enhance the efficacy of immune checkpoint inhibitors in a recent paper. However, multiple studies indicate that EVs were rapidly cleared by the reticuloendothelial system, and therefore, their tumor targeting efficiencies were limited. Herein, we developed a simple surface modification method of MNVs using polyethylene glycol (PEG) to enhance the in vivo tumor targeting efficiency. PEG-MNVs had 7-fold higher blood circulation than bare MNVs in the animal tumor model. Also, MNVs had a 25-fold higher protein amount than exosomes. Overall, the nanovesicle preparation strategies presented in this study may expedite the clinical translation of EV-based therapeutics in various diseases.

Development of a Microneedle Swab for Acquisition of Genomic DNA From Buccal Cells.

A swab is a tool for obtaining buccal DNA from buccal mucus for biological analysis. The acquisition of a sufficient amount and high quality of DNA is an important factor in determining the accuracy of a diagnosis. A microneedle swab (MN swab) was developed to obtain more oral mucosal tissues non-invasively. Eight types of MN swabs were prepared with varying combinations of patterns (zigzag or straight), number of MNs, intervals of MNs, and sharpness of tips. When MN swab was applied up to 10 times, the tissue amount and DNA yield increased compared to commercial swabs. A zigzag pattern of microneedles was found to be more efficient than a straight pattern and increasing the number of microneedles in an array increased the DNA yield. The MN swab collected about twice the DNA compared to the commercial swab. In an in vivo test using mini pigs, the lower cycle threshold values of mucosal samples collected with MN swabs compared to samples collected with commercial swabs indicated that a greater amount of DNA was collected for SNP genotyping. A polymer MN swab is easy to manufacture by a single molding process, and it has a greater sampling capacity than existing commercial swabs.

Development of theranostic dual-layered Au-liposome for effective tumor targeting and photothermal therapy.

BACKGROUND: Photothermal therapy (PTT) is an emerging anti-cancer therapeutic strategy that generates hyperthermia to ablate cancer cells under laser irradiation. Gold (Au) coated liposome (AL) was reported as an effective PTT agent with good biocompatibility and excretory property. However, exposed Au components on liposomes can cause instability in vivo and difficulty in further functionalization. RESULTS: Herein, we developed a theranostic dual-layered nanomaterial by adding liposomal layer to AL (LAL), followed by attaching polyethylene glycol (PEG) and radiolabeling. Functionalization with PEG improves the in vivo stability of LAL, and radioisotope labeling enables in vivo imaging of LAL. Functionalized LAL is stable in physiological conditions, and 64Cu labeled LAL (64Cu-LAL) shows a sufficient blood circulation property and an effective tumor targeting ability of 16.4%ID g-1 from in vivo positron emission tomography (PET) imaging. Also, intravenously injected LAL shows higher tumor targeting, temperature elevation in vivo, and better PTT effect in orthotopic breast cancer mouse model compared to AL. The tumor growth inhibition rate of LAL was 3.9-fold higher than AL. CONCLUSION: Based on these high stability, in vivo imaging ability, and tumor targeting efficiency, LAL could be a promising theranostic PTT agent.

Epicutaneous Allergen Administration with Microneedles as a Novel Method of Immunotherapy for House Dust Mite (HDM) Allergic Rhinitis.

PURPOSE: Epicutaneous immunotherapy (EPIT) is being studied as a method for treating allergic rhinitis because of skin immunology, user convenience and enhanced patient compliance. However, the use of EPIT is limited because of the very low skin permeability of the allergen. In this study, the limitations of EPIT were overcome by using sophisticated delivery with microneedles. The immunological efficacy of this method was studied in a murine model of house dust mite (HDM) allergic rhinitis. METHODS: The length of the microneedles was 400 µm, and the coating formulation containing HDM was locally distributed near the end of the microneedle tips. The change of distribution of FITC-dextran in porcine skin in vitro was observed over time using a confocal microscope. The effect of immunotherapy in the allergic rhinitis model, sensitized by HDM-coated microneedles (HDM MNs), was observed according to the amount of HDM applied. RESULTS: The microneedles delivered the coating formulation with precision into the porcine skin layer, and the coated formulation on the microneedles was all dissolved in the porcine skin in vitro within 20 min of administration and then gradually diffused into the skin layer. When HDM MNs were administered to mice, a 0.1-µg dose of HDM provided the most effective immunization, and improved efficacy was shown between 0.1- and 0.5- µg doses of HDM. CONCLUSIONS: Effective immunotherapy can be achieved by precision delivery of the allergen into the skin layer, and microneedles can provide effective immunological therapy by delivering the appropriate amount of allergen.

Multi-Quantum Dots-Embedded Silica-Encapsulated Nanoparticle-Based Lateral Flow Assay for Highly Sensitive Exosome Detection.

Exosomes are attracting attention as new biomarkers for monitoring the diagnosis and prognosis of certain diseases. Colorimetric-based lateral-flow assays have been previously used to detect exosomes, but these have the disadvantage of a high limit of detection. Here, we introduce a new technique to improve exosome detection. In our approach, highly bright multi-quantum dots embedded in silica-encapsulated nanoparticles (M-QD-SNs), which have uniform size and are brighter than single quantum dots, were applied to the lateral flow immunoassay method to sensitively detect exosomes. Anti-CD63 antibodies were introduced on the surface of the M-QD-SNs, and a lateral flow immunoassay with the M-QD-SNs was conducted to detect human foreskin fibroblast (HFF) exosomes. Exosome samples included a wide range of concentrations from 100 to 1000 exosomes/µL, and the detection limit of our newly designed system was 117.94 exosome/µL, which was 11 times lower than the previously reported limits. Additionally, exosomes were selectively detected relative to the negative controls, liposomes, and newborn calf serum, confirming that this method prevented non-specific binding. Thus, our study demonstrates that highly sensitive and quantitative exosome detection can be conducted quickly and accurately by using lateral immunochromatographic analysis with M-QD-SNs.

Live Vaccinia Virus-Coated Microneedle Array Patches for Smallpox Vaccination and Stockpiling.

Although smallpox has been eradicated globally, the potential use of the smallpox virus in bioterrorism indicates the importance of stockpiling smallpox vaccines. Considering the advantages of microneedle-based vaccination over conventional needle injections, in this study, we examined the feasibility of microneedle-based smallpox vaccination as an alternative approach for stockpiling smallpox vaccines. We prepared polylactic acid (PLA) microneedle array patches by micromolding and loaded a second-generation smallpox vaccine on the microneedle tips via dip coating. We evaluated the effect of excipients and drying conditions on vaccine stability in vitro and examined immune responses in female BALB/c mice by measuring neutralizing antibodies and interferon (IFN)-γ-secreting cells. Approximately 40% of the virus titer was reduced during the vaccine-coating process, with or without excipients. At -20 °C, the smallpox vaccine coated on the microneedles was stable up to 6 months. Compared to natural evaporation, vacuum drying was more efficient in improving the smallpox vaccine stability. Microneedle-based vaccination of the mice elicited neutralizing antibodies beginning 3 weeks after immunization; the levels were maintained for 12 weeks. It significantly increased IFN-γ-secreting cells 12 weeks after priming, indicating the induction of cellular immune responses. The smallpox-vaccine-coated microneedles could serve as an alternative delivery system for vaccination and stockpiling.

Progress in microneedle array patch (MAP) for vaccine delivery.

A microneedle array patch (MAP) has been developed as a new delivery system for vaccines. Preclinical and clinical trials with a vaccine MAP showed improved stability, safety, and immunological efficacy compared to conventional vaccine administration. Various vaccines can be delivered with a MAP. Currently, microneedle manufacturers can mass-produce pharmaceutical MAP and cosmetic MAP and this mass-production system can be adapted to produce a vaccine MAP. Clinical trials with a vaccine MAP have shown comparable efficacy with conventional administration, and discussions about regulations for a vaccine MAP are underway. However, there are concerns of reasonable cost, mass production, efficacy, and safety standards that meet FDA approval, as well as the need for feedback regarding the best method of administration. Currently, microneedles have been studied for the delivery of many kinds of vaccines, and preclinical and clinical studies of vaccine microneedles are in progress. For the foreseeable future, some vaccines will continue to be administered with syringes and needles while the use of a vaccine MAP continues to be improved because of the advantages of less pain, self-administration, improved stability, convenience, and safety.

Brown adipose tissue imaging using the TSPO tracer [18F]fluoromethyl-PBR28-d2: A comparison with [18F]FDG.

INTRODUCTION: Currently, the reference method of brown adipose tissue (BAT) imaging is 18F-fluorodeoxyglucose positron emission tomography ([18F]FDG PET). BAT imaging by [18F]FDG PET requires additional stimulation process, which is inconvenient and hard to be standardized. The translocator protein 18 kDa (TSPO) PET has been found to be effective for visualization of BAT. Herein, we evaluated the feasibility of [18F]fluoromethyl-PBR28-d2 ([18F]fmPBR28-d2), a TSPO PET tracer, for interscapular BAT imaging in comparison with [18F]FDG PET. METHODS: C57BL/6 mice were used for the [18F]fmPBR28-d2 and [18F]FDG PET imaging. [18F]fmPBR28-d2 PET was performed in the thermoneutral condition (n = 5) and after cold exposure (4 °C for 4 h) on the next day using the same mice. [18F]FDG PET was performed in the thermoneutral and cold exposure conditions with the same method with [18F]fmPBR28-d2 PET. Ex vivo biodistribution study of [18F]fmPBR28-d2 was performed in ten C57BL/6 mice (5: thermoneutral, 5: cold exposure). TSPO immunohistochemistry was done in interscapular BAT. RESULTS: The [18F]fmPBR28-d2 PET images showed prominent interscapular BAT uptakes under both thermoneutral and cold exposure conditions. While, the BAT uptake was significantly higher under the cold exposure condition than the thermoneutral condition (12.83 ± 5.06 vs. 22.50 ± 6.03, P = 0.007). Also, [18F]FDG PET imaging showed higher BAT uptake under the cold exposure condition than thermoneutral condition (8.40 ± 0.63 vs. 21.41 ± 4.03, P = 0.001). The interscapular BAT to background (thigh muscle) ratio was higher in [18F]fmPBR28-d2 PET than [18F]FDG PET under both thermoneutral and cold exposure conditions. Ex vivo biodistribution study using [18F]fmPBR28-d2 also showed higher BAT uptake under cold exposure than the thermoneutral condition (8.86 ± 1.74 vs.16.93 ± 4.74, P = 0.036). Also, IHC demonstrated that TSPO expression was significantly increased in the cold exposure group. CONCLUSIONS: [18F]FmPBR28-d2 PET demonstrated prominent interscapular BAT uptakes regardless of additional stimulation, and showed a higher BAT to background ratio than [18F]FDG PET. Also, we found that [18F]fmPBR28-d2 PET uptake and TSPO expression of BAT increased under cold exposure condition. Further works are warranted to assess the clinical significance of TSPO PET uptake in BAT.

Patchless administration of canine influenza vaccine on dog's ear using insertion-responsive microneedles (IRMN) without removal of hair and its in vivo efficacy evaluation.

Microneedles provide the advantages of convenience and compliance by avoiding the pain and fear of needles that animals often experience. Insertion-responsive microneedles (IRMN) were used for administration to a hairy dog without removing the dog's hair. Canine H3N2 vaccine was administered with IRMN attached to the dog's ears ex vivo and the conventional microneedle system (MN) was administered for 15 min to compare puncture performance and delivery efficiency. The vaccine was also administered to compare antibody formation using IRMN with the use of intramuscular injection. The veterinarian observed the behavior of the dog during the course of the administration and compared the response to IRMN with that of intramuscular administration. The tips of IRMN were separated from the base and delivered into the hairy skin successfully. Puncture performance of IRMN were the same as that of coated microneedles (95%), but delivery efficiency of IRMN were 95% compared to less than 1% for coated microneedles. The H3N2 vaccine inoculated into the dog's ears showed the same antibody formation as the intramuscular injection. The dog appeared to be more comfortable with IRMN administration compared to syringe administration. IRMN are the first microneedle system to deliver a canine vaccine successfully into a hairy dog without removal of the dog's hair. The use of IRMN can provide both convenience and compliance for both the dog and the owner.

Changes in Pharyngeal Width Over Time as an Indicator of Dysphagia in Stroke Patients.

OBJECTIVE: To verify the pharyngeal width at rest as a measurement that could be used to assess changes in the degree of dysphagia over time in stroke patients. METHODS: In a cohort of stroke patients, we performed serial measurements of the pharyngeal width at the midpoints of the second (C2) and third (C3) cervical vertebral bodies using lateral neck X-rays while the patients were at rest. The JOSCYL width, a parameter named after the first initial of each developers' surname and defined as the average value of the upper and lower pharyngeal widths, was used to formulate the JOSCYL scale, which was calculated as the JOSCYL width × 100/neck circumference. All patients also underwent serial videofluoroscopic swallowing studies (VFSSs). The Spearman correlation analysis was used to detect correlations between the serial VFSS results, JOSCYL widths, and JOSCYL scale values. RESULTS: Over time, we observed significant positive and negative correlations of change in the JOSCYL width and scale with changes in the Penetration-Aspiration Scale and the Dysphagia Outcome and Severity Scale scores, respectively. CONCLUSION: The JOSCYL width and JOSCYL scale clearly reflected changes in dysphagia in stroke patients over time. These parameters may provide an easier method for evaluating whether post-stroke dysphagia has been alleviated.

Preclinical study of influenza bivalent vaccine delivered with a two compartmental microneedle array.

Multiple vaccines can be mixed into a single combination to be a single product. However, combination vaccines have problems of complexity. In this study, microneedles were utilized in a compartmental microneedle array (CMA) to deliver two influenza vaccine strains without mixing. In this study, the CMA had two compartments, and two rectangular structures were attached to each end of the array to enable integration of the compartments with the coating equipment. The coating solution, which contained influenza vaccines for B/Yamagata (B-Y) and B/Victoria (B-V), was filled into the two reservoirs of the container. The CMA was aligned with the container for dipping the first compartment of the array into the first reservoir and the second compartment into the second reservoir. The CMA containing B-Y and B-V separately was administered to mice, and weight change and survival were compared with other groups of mice administered (a) combination vaccines with microneedles, (b) two monovalent vaccines with microneedles, (c) intramuscularly with a combination vaccine, and (d) intramuscularly with two monovalent vaccines. Plaque reduction neutralization tests were also performed to compare the CMA group with the other groups. The CMA showed a relative standard error of less than 7% between samples in dose uniformity. It also showed comparable antibody-forming efficacy compared to other groups, especially by B/Yamagata virus challenge. The CMA mice group showed better survival and weight change than mice that received intramuscular (IM) injection of the combination vaccine. In the neutralizing antibody experiment, all microneedle groups showed a higher neutralizing antibody than the IM groups. Vaccines were administered without mixing by a single administration using a CMA, and the CMA showed comparable efficacy with IM administration of the combination vaccine. Multivalent vaccines can be delivered without mixing as a single product by using a CMA.

Increased white matter diffusivity associated with phantom limb pain.

BACKGROUND: We utilized diffusion tensor imaging (DTI) to evaluate the cerebral white matter changes that are associated with phantom limb pain in patients with unilateral arm amputation. It was anticipated that this would complement previous research in which we had shown that changes in cerebral blood volume were associated with the cerebral pain network. METHODS: Ten patients with phantom limb pain due to unilateral arm amputation and sixteen healthy age-matched controls were enrolled. The intensity of phantom limb pain was measured by the visual analogue scale (VAS) and depressive mood was assessed by the Hamilton depression rating scale. Diffusion tensor-derived parameters, including fractional anisotropy, mean diffusivity, axial diffusivity (AD), and radial diffusivity (RD), were computed from the DTI. RESULTS: Compared with controls, the cases had alterations in the cerebral white matter as a consequence of phantom limb pain, manifesting a higher AD of white matter in both hemispheres symmetrically after adjusting for individual depressive moods. In addition, there were associations between the RD of white matter and VAS scores primarily in the hemispheres related to the missing hand and in the corpus callosum. CONCLUSIONS: The phantom limb pain after unilateral arm amputation induced plasticity in the white matter. We conclude that loss of white matter integrity, particularly in the hemisphere connected with the missing hand, is significantly correlated with phantom limb pain.

Preparation of H1N1 microneedles by a low-temperature process without a stabilizer.

During the manufacture of H1N1 microneedles, a stabilizer is usually added to maintain the antigenicity of the vaccine. However, finding a suitable stabilizer is difficult, and the addition of a stabilizer can limit the antigen dose and the addition of an adjuvant because of the limited volume of the microneedles. In this study, the authors evaluated whether H1N1 microneedles could be fabricated without a stabilizer by keeping the production environment at a low temperature. H1N1 microneedle patches without a stabilizer were prepared in a process that involved maintaining a low temperature of 10 °C. The protective immune response to this method of drug application was investigated by comparing it with traditional intramuscular (IM) immunization and with the use of H1N1 microneedles with a stabilizer. A process-sensitive antigen, H1N1, was stabilized without the use of a stabilizer in a process that maintained a low temperature of 10 °C. The preparation process consisted of coating and drying processes. In animal experiments, mice were immunized using an array of low-temperature H1N1 microneedles without a stabilizer (LT-MN), and they showed strong antibody responses. Compared to three other application methods of traditional IM immunization, low-temperature H1N1 microneedles with a stabilizer (LT-MN-T), and room-temperature H1N1 microneedles with a stabilizer (RT-MN-T), LT-MN produced comparable results in inducing protective immunity. A plaque reduction neutralization test found that LT-MN and LT-MN-T provided greater immunity compared with IM and RT-MN-T. A process in which the temperature is maintained at 10 °C can provide successful vaccination with H1N1 microneedles without the addition of a stabilizer. This process can be applied to various temperature-sensitive biologics.

Skin immunization with third-generation hepatitis B surface antigen using microneedles.

L-HBsAg is a third-generation hepatitis vaccine capable of inducing antibodies in non-responders and thus providing potentially therapeutic treatment. In this study, L-HBsAg was administered using microneedles (MN) without an adjuvant to induce intradermal (ID) immunization, and the efficacy of ID immunization was compared with that of intramuscular (IM) immunization that uses a conventional formulation with an adjuvant of aluminum hydroxide (L-HBsAg-AL-IM). The L-HBsAg was dip-coated onto 800-µm-long microneedles made of polylactic acid (PLA). Delivery efficiency and administration time were determined through in vitro experiments using porcine skin. The denaturation of the formulation against sterilization by gamma rays was observed. A storage test and a freeze-thaw cycle test of the microneedles with trehalose as a stabilizer (L-HBsAg-MN-Tre) were observed. An antibody titer of L-HBsAg-MN-Tre was compared with that of the conventional IM immunization of the L-HBsAg solution with aluminum hydroxide (L-HBsAg-AL-IM). The formulation containing L-HBsAg was located on the upper third of the microneedle tips. The formulation on the MN was dissolved and delivered within 30 min of insertion into porcine skin in vitro. Trehalose was selected as a stabilizer, and the stabilizing effect increased with the increase of trehalose content in the solidified formulation. L-HBsAg-MN with 15% of trehalose was stable for 7 days at 40 °C and showed increased stability compared to the conventional liquid formulations. L-HBsAg-MN-Tre showed improved stability during the freeze-thaw cycle. The antibody titer of L-HBsAg-MN-Tre at 28 days was higher than that of L-HBsAg-AL-IM. ID administration of L-HBsAg-MN-Tre showed better efficacy and improved thermal and freeze thaw stability compared to L-HBsAg-AL-IM. Therefore, L-HBsAg-MN-Tre administration showed the possibility of ID delivery of L-HBsAg without the use of an adjuvant for the efficacy, convenience, and safety of pediatric vaccination.

Spray-Formed Layered Polymer Microneedles for Controlled Biphasic Drug Delivery.

In this study we present polymeric microneedles composed of multiple layers to control drug release kinetics. Layered microneedles were fabricated by spraying poly(lactic-co-glycolic acid) (PLGA) and polyvinylpyrrolidone (PVP) in sequence, and were characterized by mechanical testing and ex vivo skin insertion tests. The compression test demonstrated that no noticeable layer separation occurred, indicating good adhesion between PLGA and PVP layers. Histological examination confirmed that the microneedles were successfully inserted into the skin and indicated biphasic release of dyes incorporated within microneedle matrices. Structural changes of a model protein drug, bovine serum albumin (BSA), in PLGA and PVP matrices were examined by circular dichroism (CD) and fluorescence spectroscopy. The results showed that the tertiary structure of BSA was well maintained in both PLGA and PVP layers while the secondary structures were slightly changed during microneedle fabrication. In vitro release studies showed that over 60% of BSA in the PLGA layer was released within 1 h, followed by continuous slow release over the course of the experiments (7 days), while BSA in the PVP layer was completely released within 0.5 h. The initial burst of BSA from PLGA was further controlled by depositing a blank PLGA layer prior to forming the PLGA layer containing BSA. The blank PLGA layer acted as a diffusion barrier, resulting in a reduced initial burst. The formation of the PLGA diffusion barrier was visualized using confocal microscopy. Our results suggest that the spray-formed multilayer microneedles could be an attractive transdermal drug delivery system that is capable of modulating a drug release profile.