Sodium Hyaluronate/Chitosan Composite Microneedles as a Single-Dose Intradermal Immunization System.

Enhancing the immune response to vaccines and minimizing the need for repeated inoculations remain a challenge in clinical vaccination. This study developed a composite microneedle (MN), composed of a sodium hyaluronate (HA) tip and a chitosan base, for biphasic antigen release and evaluated the potential of using this MN formulation as an intradermal delivery system for single-dose vaccination. Upon skin insertion, the dissolvable HA tip dissolved within the skin for rapid release of the encapsulated antigens, thus priming the immune system, while the biodegradable chitosan base remained in the dermis for prolonged antigen release for 4 weeks, thus further boosting the stimulated immunity. Our results showed that a single immunization with the HA/chitosan MN containing ovalbumin (OVA) (100 µg × 1) stimulated both T helper type 1 (Th1) and Th2 immune responses in rats and induced considerably higher and more durable antibody responses than a traditional two-dose (100 µg OVA × 2) or double-dose (200 µg OVA × 1) subcutaneous vaccination. Thus, the proposed MN exerts strong adjuvanticity to greatly augment the antigen's immunogenicity. Moreover, given its unique rapid and sustained release properties, the HA/chitosan MN formulation has the potential to replace the conventional prime-boost regimen to serve as an effective single-dose vaccine formulation.

Near-infrared light-responsive composite microneedles for on-demand transdermal drug delivery.

This study presents near-infrared (NIR) light-responsive polymer-nanostructure composite microneedles used for on-demand transdermal drug delivery. Silica-coated lanthanum hexaboride (LaB6@SiO2) nanostructures were incorporated into polycaprolactone microneedles, serving as an NIR absorber. When the microneedles were irradiated with NIR light, light-to-heat transduction mediated by the LaB6@SiO2 nanostructures caused the microneedle melting at 50 °C. This increased the mobility of the polymer chains, enabling drug release from the matrix. Drug release from the microneedles was evaluated for four laser on/off cycles. In each cycle, the samples were irradiated until the temperature reached 50 °C for 3 min (laser on); the laser was then turned off for 30 min (laser off). The results showed that light-induced phase transition in the polymer triggered drug release from the melted microneedles. A stepwise drug-release behavior was observed after multiple cycles of NIR light exposure. No notable drug leakage was found in the off state. This NIR-light-triggerable device exhibits excellent reproducibility, low off-state leakage, and noninvasive triggerability and, thus, represents an advance in transdermal delivery technology.

Double-layered PLGA/HA microneedle systems as a long-acting formulation of polyphenols for effective and long-term management of atopic dermatitis.

Atopic dermatitis (AD) is a chronic, relapsing inflammatory disorder that requires long-term treatment to achieve optimal control. Topical corticosteroids or calcineurin inhibitors are the mainstay of treatment, but the safety and efficacy of their daily use remain a concern. Here, we report a double-layered poly(lactic-co-glycolic acid) (PLGA)/sodium hyaluronate (HA) microneedle (MN) patch as a long-acting formulation for sustained delivery of natural polyphenols, curcumin (CUR) and gallic acid (GA), into the inflamed skin. Upon insertion into the skin, the HA layer is rapidly dissolved within 5 min for triggering GA release; the PLGA tip is embedded into the dermis for sustained release of CUR for 2 months. Initially, CUR and GA are simultaneously released from the MNs to exert synergistic antioxidant and anti-inflammatory effects, thus promptly relieving AD symptoms. After the complete release of GA, the extended CUR release can maintain the improvement obtained for at least 56 days. Our results revealed that compared with the CUR-only MN and untreated AD groups, the administration of CUR/GA-loaded MNs not only rapidly reduced the dermatitis score from Day 2 but also significantly inhibited epidermal hyperplasia and mast cell accumulation, reduced serum IgE and histamine levels, and downregulated reactive oxygen species production in the skin lesions of Nc/Nga mice on Day 56. These findings demonstrated that the double-layered PLGA/HA MN patch can serve as an effective dual-polyphenol delivery system for rapid and long-term management of AD.

Polyphenol-assisted assembly of Au-deposited polylactic acid microneedles for SERS sensing and antibacterial photodynamic therapy.

3D SERS microneedles with self-assembled AuNPs were fabricated with tannic acid (chemical glue and reductant) on polylactic acid microneedles for in-depth chemical and biomolecular analysis, with LOD values below 200 ppb for small molecules and 102 CFU cm-2 for bacteria. The MB/Au-microneedles were used for photodynamic therapy with SERS-monitored photosensitizer degradation.

Chitosan microneedle patches for sustained transdermal delivery of macromolecules.

This paper introduces a chitosan microneedle patch for efficient and sustained transdermal delivery of hydrophilic macromolecules. Chitosan microneedles have sufficient mechanical strength to be inserted in vitro into porcine skin at approximately 250 µm in depth and in vivo into rat skin at approximately 200 µm in depth. Bovine serum albumin (BSA, MW=66.5 kDa) was used as a model protein to explore the potential use of chitosan microneedles as a transdermal delivery device for protein drugs. In vitro drug release showed that chitosan microneedles can provide a sustained release of BSA for at least 8 days (approximately 95% of drugs released in 8 days). When the Alexa Fluor 488-labeled BSA (Alexa 488-BSA)-loaded microneedles were applied to the rat skin in vivo, confocal microscopic images showed that BSA can gradually diffuse from the puncture sites to the dermal layer and the fluorescence of Alexa 488-BSA can be observed at the depth of 300 µm. In addition, encapsulation of BSA within the microneedle matrix did not alter the secondary structure of BSA, indicating that the gentle nature of the fabrication process allowed for encapsulation of fragile biomolecules. These results suggested that the developed chitosan microneedles may serve as a promising device for transdermal delivery of macromolecules in a sustained manner.

Highly stable gold nanoparticle-antigen conjugates with self-adjuvanting property for induction of robust antigen-specific immune responses.

Poor long-term stability and formation of irreversible aggregates when subjected to a freeze-drying process greatly limits the clinical application of gold nanoparticles (GNPs) as a vaccine carrier. In this study, we synthesized a GNP-antigen conjugate with high colloidal stability by using a thiolated polyethylene glycol (PEG) linker to conjugate a model antigen (ovalbumin; OVA) onto the GNP surface (i.e. GNP-OVA) and demonstrated this conjugate had self-adjuvanting properties to augment antigen-specific immune responses. The synthesized GNP had an average hydrodynamic size of 13.8 ± 2.1 nm (n = 3); after conjugation of OVA, the diameter increased to 28.6 ± 7.3 nm (n = 3). The obtained GNP-OVA can maintain a stable dispersion state in aqueous solutions for at least 12 months and withstand stresses during lyophilization without creating irreversible aggregates. Compared with OVA alone or a mixture of PEG-functionalized GNP (GNP-PEG) and OVA (i.e. GNP-PEG/OVA), the chemical conjugation of OVA onto GNP-PEG substantially increased antigen uptake and upregulated major histocompatibility complex class II expression in macrophages. This indicated that the GNP can function as not only an adjuvant to promote the phagocytic activity of macrophages but also a carrier to deliver the conjugated antigen into the immune cells for the enhancement of its antigen presentation capability. Importantly, OVA-specific immunoglobulin G levels in the mice immunized with GNP-OVA were 4.1 and 2.9 times higher than those in the mice injected with OVA and GNP-PEG/OVA, respectively. These results demonstrated that the GNP-antigen conjugate exhibited remarkable stability either in liquid or freeze-dried form, which makes it attractive for further pharmaceutical applications. Moreover, covalently linking antigens onto the GNP surface was enabled to enhance the immunogenicity of antigens and boost immune responses, showing the potential of the GNP conjugation strategy for vaccine development.

Screen-printed carbon electrodes modified with cobalt phthalocyanine for selective sulfur detection in cosmetic products.

Cobalt phthalocyanine (CoPc) films were deposited on the surface of a screen-printed carbon electrode using a simple drop coating method. The cyclic voltammogram of the resulting CoPc modified screen-printed electrode (CoPc/SPE) prepared under optimum conditions shows a well-behaved redox couple due to the (Co(I)/Co(II)) system. The CoPc/SPE surface demonstrates excellent electrochemical activity towards the oxidation of sulfur in a 0.01 mol·L(-1) NaOH. A linear calibration curve with the detection limit (D(L), S/N = 3) of 0.325 mg·L(-1) was achieved by CoPc/SPE coupled with flow injection analysis of the sulfur concentration ranging from 4 to 1120 mg·L(-1). The precision of the system response was evaluated (3.60% and 3.52% RSD for 12 repeated injections), in the range of 64 and 480 mg·L(-1) sulfur. The applicability of the method was successfully demonstrated in a real sample analysis of sulfur in anti-acne creams, and good recovery was obtained. The CoPc/SPE displayed several advantages in sulfur determination including easy fabrication, high stability, and low cost.

Epigallocatechin gallate/L-ascorbic acid-loaded poly-γ-glutamate microneedles with antioxidant, anti-inflammatory, and immunomodulatory effects for the treatment of atopic dermatitis.

Epigallocatechin gallate (EGCG) is a potential therapeutic agent for treatment of atopic dermatitis (AD) due to its antioxidant and anti-inflammatory activities. However, inherent instability of EGCG greatly limits its bioavailability and clinical efficacy. In this study, we developed a poly-γ-glutamate (γ-PGA)-based microneedle (MN) formulation capable of maintaining EGCG's stability and efficiently delivering EGCG into the skin to ameliorate AD symptoms. The γ-PGA MN can not only protect EGCG from oxidation, but also serve as an immunomodulator to downregulate T helper type 2 (Th2)-type immune responses. Encapsulation of EGCG into the γ-PGA MN and utilization of L-ascorbic acid (AA) as a stabilizer preserved 95% of its structural stability and retained 93% of its initial antioxidant activity after 4 weeks of storage. Once-weekly administration of EGCG/AA-loaded MNs to an Nc/Nga mouse model of AD for 4 weeks significantly ameliorated skin lesions and epidermal hyperplasia by reducing serum IgE (from 12156 ± 1344 to 5555 ± 1362 ng/mL) and histamine levels (from 81 ± 18 to 40 ± 5 pg/mL) and inhibiting IFN-γ (from 0.10 ± 0.01 to 0.01 pg/mg total protein) and Th2-type cytokine production, when compared to the AD (no treatment) group (p < 0.05). Notably, once-weekly MN therapy was at least as effective as the daily topical application of an EGCG + AA solution but markedly reduced the administration frequency and required dose. These results show that EGCG/AA-loaded γ-PGA MNs may be a convenient and promising therapeutic option for AD treatment. STATEMENT OF SIGNIFICANCE: This study describes epigallocatechin gallate (EGCG)/L-ascorbic acid (AA)-loaded poly-γ-glutamate (γ-PGA) microneedles (MN) capable of providing antioxidant, anti-inflammatory, and immunomodulatory effects on inflamed skin for ameliorating atopic dermatitis (AD) symptoms in Nc/Nga mice. After skin insertion, the γ-PGA MN can be quickly dissolved in the skin and remain in the dermis for sustained release of encapsulated active ingredients for 6 days. We demonstrated that once-weekly MN therapy effectively alleviated skin lesions and modulated immune response to relieve Th2-polarized allergic response in mice. Once-weekly MN dosing regimen may provide patients with a more convenient, therapeutically equivalent option to daily topical dosing, and may increase compliance and long-term persistence with AD therapy.

A Facile Approach for Rapid Prototyping of Microneedle Molds, Microwells and Micro-Through-Holes in Various Substrate Materials Using CO2 Laser Drilling.

CO2 laser manufacturing has served as an enabling and reliable tool for rapid and cost-effective microfabrication over the past few decades. While a wide range of industrial and biological applications have been studied, the choice of materials fabricated across various laser parameters and systems is often confounded by their complex combinations. We herein presented a unified procedure performed using percussion CO2 laser drilling with a range of laser parameters, substrate materials and various generated microstructures, enabling a variety of downstream tissue/cellular-based applications. Emphasis is placed on delineating the laser drilling effect on different biocompatible materials and proof-of-concept utilities. First, a polydimethylsiloxane (PDMS) microneedle (MN) array mold is fabricated to generate dissolvable polyvinylpyrrolidone/polyvinyl alcohol (PVP/PVA) MNs for transdermal drug delivery. Second, polystyrene (PS) microwells are optimized in a compact array for the formation of size-controlled multicellular tumor spheroids (MCTSs). Third, coverglass is perforated to form a microaperture that can be used to trap/position cells/spheroids. Fourth, the creation of through-holes in PS is validated as an accessible method to create channels that facilitate medium exchange in hanging drop arrays and as a conducive tool for the growth and drug screenings of MCTSs.

Poly-γ-Glutamate microneedles as transdermal immunomodulators for ameliorating atopic dermatitis-like skin lesions in Nc/Nga mice.

Atopic dermatitis (AD), a common, relapsing, inflammatory disorder of the skin, is associated with T helper type 2 (Th2)-biased immune responses. Despite the efficacy of existing drugs for AD treatment, their safety and side effects cause concern. The present study describes the use of dissolvable poly-γ-glutamate (γ-PGA) microneedles (MNs) with immunomodulatory effects for effectively relieving AD-like symptoms in Nc/Nga mice. γ-PGA MNs can easily penetrate the epidermis and release γ-PGA into the dendritic cell-rich dermis to interact with dendritic cells for modulating immune responses. Transdermal administration of high-molecular-weight (HMW, 1100 kDa) γ-PGA MNs significantly reduced clinical dermatitis scores, epidermal thickness, and mast cell infiltration in mice by downregulating immunoglobulin (Ig)E and IgG1 levels (Th2-associated antibodies) compared with the AD control group. However, low-molecular-weight (200-400 kDa) γ-PGA MNs ameliorated AD-like skin lesions less effectively than HMW γ-PGA MNs, thus indicating that the MW of γ-PGA may affect its immunomodulatory properties. Notably, the mouse skin quickly recovered its barrier function within 4 h after MN application. No weight loss or abnormality was observed in the MN-treated mice during the 8-week treatment period. These results suggest that the γ-PGA MNs represent an innovative, safe, and reliable therapeutic strategy for AD management. STATEMENT OF SIGNIFICANCE: This study is the first to explore the feasibility of using poly-γ-glutamate (γ-PGA) microneedles (MNs) as transdermal immunomodulators for improving atopic dermatitis (AD) symptoms and to evaluate their immunomodulatory effect in mice with spontaneously developed AD. Transdermal administration of γ-PGA MNs enables the γ-PGA to localize in the skin for activation of dermal dendritic cells, thus modulating immune responses. We demonstrate that high-molecular-weight γ-PGA MNs can be retained in the skin for at least 6 days and effectively suppress AD-like skin lesions in mice by reducing infiltration of mast cells and downregulating Th2-associated antibody production (IgE and IgG1). The developed MN device has the potential to replace conventional therapy and to become an innovative treatment strategy for AD.

Implantable microneedles with an immune-boosting function for effective intradermal influenza vaccination.

This study details effective influenza vaccination via sustained intradermal (ID) release of vaccines using implantable and patch-free chitosan microneedles (MNs). The microneedle (MN) patch is composed of vaccine-loaded chitosan MNs with a dissolvable supporting array that gives extra length for complete insertion of MNs and is dissolved within the skin during insertion. Chitosan MNs can be quickly and entirely implanted into the dermis to function as a depot and an immune-boosting agent for the extended release of vaccines and simultaneous activation of the immune system. We found the influenza virus-specific antibody levels induced by chitosan MN vaccination were significantly higher than those elicited by intramuscular (IM) immunization with influenza vaccine alone. The MN induced immune-enhancing effect was obvious 4 week after the vaccination and lasted for at least 16 weeks. Most importantly, MN-immunized mice were completely protected from H1N1 viral challenge without major weight loss, whereas mice receiving IM injection at the same dose had a mortality rate of 60% and experienced notable weight loss after challenge. Our results suggest that the chitosan MNs cannot only be a viable tool for precise ID vaccine delivery but also exert strong adjuvanticity to enhance vaccine potency and induce protective immunity against influenza virus infections. STATEMENT OF SIGNIFICANCE: There is an urgent need for generating a new vaccination strategy to address the threat of global pandemic influenza. This study presents implantable chitosan microneedles (MNs) with immune-boosting function for effective influenza vaccination. We demonstrate that the chitosan MN can not only be an efficient tool for sustained intradermal delivery but also serve as an immunological adjuvant to boost vaccine efficacy. Continuous antigen exposure and immune stimulation provided by the implanted MNs may enhance the immunogenicity of influenza vaccines and evoke long-lasting immune responses to completely protect mice from lethal influenza challenge. The proposed MN system has great potential to be used as a new adjuvanted vaccine formulation and make influenza vaccination more effective and more accessible.

Enhancing immunogenicity of antigens through sustained intradermal delivery using chitosan microneedles with a patch-dissolvable design.

Reducing the dosage required for vaccination is highly desirable, particularly in cases of epidemic emergencies. This study evaluated the potential of a chitosan microneedle (MN) system with a patch-dissolvable design for low-dose immunization. This system comprises antigen-loaded chitosan MNs and a hydrophilic polyvinyl alcohol/polyvinyl pyrrolidone supporting array patch, which provides extra strength to achieve complete MN insertion and then quickly dissolves in the skin to reduce patch-induced skin irritation. After insertion, MNs could be directly implanted in the dermal layer as an intradermal (ID) depot to allow a sustained release of the model antigen ovalbumin (OVA) for up to 28 days. We found that rats immunized with MNs containing low-dose OVA (approximately 200 µg) had persistently high antibody levels for 18 weeks, which were significantly higher than those observed after an intramuscular injection of full-dose OVA (approximately 500 µg), demonstrating at least 2.5-fold dose sparing. Moreover, OVA-encapsulated chitosan MNs had superior immunogenicity to OVA plus chitosan solution, indicating that MN-based delivery and prolonged skin exposure can further enhance chitosan's adjuvanticity. Therefore, this patch-dissolvable MN system offers a needle-free, accurate, and reliable ID delivery of antigens and has potential as a sustained ID delivery device to improve vaccine efficacy and facilitate dose sparing with existing vaccines. STATEMENT OF SIGNIFICANCE: This study developed implantable chitosan microneedles (MNs) with a patch-dissolvable design for the sustained intradermal (ID) delivery of antigens and demonstrated their antigen dose-sparing potential. We found that rats immunized with chitosan MNs containing low-dose OVA had persistently high antibody levels for 18 weeks, which were significantly higher than those observed after an intramuscular injection of full-dose OVA, demonstrating at least 2.5-fold dose sparing. Our results indicate that chitosan MNs can not only serve as an efficient vaccine delivery system but also exert their promising adjuvant activity by forming an ID depot for prolonged antigen exposure and activating dendritic cells for promoting immune responses.

Shell-crosslinked Pluronic L121 micelles as a drug delivery vehicle.

Pluronic block copolymers (PBCs) have been shown to reverse multidrug resistance (MDR) by inhibiting the P-glycoprotein (P-gp) pump in cancer cells. One of the problems encountered with the use of PBCs is that the micelles disassociate at low concentrations. The study focused on the stabilization of PBC L121 micelles by the formation of crosslinks within their outer shells. To form crosslinks, the two terminal alcohols on L121 were first chemically converted into aldehydes (L121-CHO) using the Dess-Martin periodinane. Diamine compounds were then used to bridge the converted aldehyde termini on L121-CHO via conjugated Schiff bases. After crosslinking, the morphology of the L121 micelles remained spherical in shape and the mean particle sizes of the micelles before and after crosslinking were comparable (100nm). After exposure of MDR KBv cells to free rhodamine-123 (R123), the accumulation of R123 in cells was limited due to the function of P-gp. In contrast, crosslinking of L121 micelles within their outer shells significantly reduced their critical micelle concentration and greatly enhanced their stability, while maintaining their ability to inhibit P-gp function in resistant cells. The results indicated that the L121 micelles with shell crosslinks may be useful as a drug delivery vehicle for cancer chemotherapy.

Aglycone geniposidic acid, a naturally occurring crosslinking agent, and its application for the fixation of collagenous tissues.

A natural compound, aglycone geniposidic acid (aGSA), originated from the fruits of Gardenia jasminoides ELLIS was used for the fixation of collagenous tissues. The presumed crosslinking reaction mechanism of collagenous tissues with aGSA was inferred by reacting aGSA with a bifunctional amine, 1,6-hexanediamine, using a series of (1)H NMR, FT-IR, and UV/Vis spectra analyses. aGSA reacted with 1,6-hexanediamine by a nucleophilic attack on the olefinic carbon atom at C-2 of deoxyloganin aglycone, followed by opening the dihydropyran ring to form heterocyclic amine compounds. It is inferred that aGSA may form intramolecular and intermolecular crosslinks with a heterocyclic structure within collagen fibers in tissues. The degrees of tissue fixation by aGSA at different pH values were investigated by examining the fixation indices and denaturation temperatures of test samples. It was found that the fixation indices and denaturation temperatures of test samples fixed at neutral or basic pH (pH 7.4 or pH 8.5) were significantly greater than at acidic pH (pH 4.0). The results obtained in this study may be used to elucidate the crosslinking mechanism and optimize the fixation process for developing bioprostheses fixed by aGSA.

Efficient delivery of nanoparticles to deep skin layers using dissolvable microneedles with an extended-length design.

Skin pretreatment with microneedles (MNs) increases drug permeation through the skin by creating microchannels in the skin. However, because of skin's inherent elasticity and self-healing ability, these microchannels shrink or reseal rapidly, thus limiting the nanoparticle (NP) delivery efficiency. This study reports dissolvable polyvinyl alcohol/polyvinylpyrrolidone (PVA/PVP) MNs with an extended-length design for the efficient transdermal delivery of NPs. In this system, poly(d,l-lactide-co-glycolide) NPs are encapsulated within the pyramidal structure of the MNs. The extended length of the PVA/PVP MN allows it to counteract skin indentation during insertion, thus enabling complete insertion of the pyramidal structure into the skin to deliver the NPs. In contrast to MN pretreatments that require passive diffusion of NPs through the skin, the extended PVA/PVP MNs can directly bring the NPs into the deeper skin layers, and then rapidly dissolve in 3 min to release the payload. An in vivo transdermal delivery study showed that approximately 90% of the loaded NPs were delivered to the viable epidermis and dermis, whereas only <2% of topically applied NPs were detected in the skin after being treated with a commercial 3M™ MN product. The NPs delivered by the extended MN remained at the insertion site for 5 days, enabling a sustained release of active agents to the diseased tissue. The proposed MN system could be a promising tool for the transdermal delivery of NPs to treat deep skin diseases such as bacterial infections and malignant tumors.

Implantable polymeric microneedles with phototriggerable properties as a patient-controlled transdermal analgesia system.

Adequate pain control can be achieved using a patient-controlled drug delivery system that can provide analgesia to patients as needed. To achieve this objective, we developed a phototriggered microneedle (MN) system that enables the on-demand delivery of pain medications to the skin under external near-infrared (NIR) light stimulation. In this system, polymeric MNs, containing NIR absorbers and analgesics, are combined with a poly(l-lactide-co-d,l-lactide) supporting array. A "removable design" of the supporting array enables the quick implantation of the MNs into the skin to act as a drug depot, thus shortening the patch application time. Upon irradiation with NIR light, the NIR absorbers in the implanted MNs can absorb light energy and induce a phase transition in the MNs to activate drug release. We demonstrated that lidocaine release can be modulated or repeatedly triggered by varying the duration of irradiation and controlling the on and off status of the laser. Lidocaine delivered by the implanted MNs can be rapidly absorbed into the blood circulation within 10 min and has a bioavailability of at least 95% relative to the subcutaneous injection, showing that the proposed system has the potential to provide a rapid onset of pain relief. Such an implantable device may allow pain sufferers receiving the painkiller without the need for multiple needle injections, and may enable controlling pain more conveniently and comfortably.

Transdermal Delivery of Luteinizing Hormone-releasing Hormone with Chitosan Microneedles: A Promising Tool for Androgen Deprivation Therapy.

Long-term administration of luteinizing hormone-releasing hormone analogs (LHRHa) is the main type of androgen-deprivation therapy (ADT) for lethal prostate cancer. A fully insertable microneedle system, composed of embeddable chitosan microneedles and a dissolvable polyvinyl alcohol/polyvinyl pyrrolidone supporting array, was developed for sustained delivery of LHRHa to the skin. A porcine cadaver skin test showed that chitosan microneedles can be fully embedded within the skin and microneedle-created micropores reseal within 7 days. The measured LHRHa loading amount was 73.3±2.8 µg per microneedle patch. After applying goserelin-containing microneedles to mice, serum LH levels increased initially and then declined below baseline at day 7. In contrast, serum testosterone levels increased to reach a peak at day 14 and then declined to a castration level at day 21. Additionally, such a castration level was maintained for 2 weeks. Therefore, transdermal delivery of goserelin with embeddable chitosan microneedles can produce a castrated state in mice. Such a system is a promising, feasible means of delivering ADT.

Transcutaneous immunization of Streptococcus suis bacterin using dissolving microneedles.

Vaccine delivery using microneedle (MN) patches is an easy, safe and painless alternative to traditional needle injections. In this study, we examined whether MN patches can enhance the efficacy of a Streptococcus suis serotype 2 (S. suis 2) vaccine in a mouse model. Results showed that MNs can reach 200-250µm into the skin, a depth beneficial for targeted delivery of antigens to antigen-presenting cells in the epidermis and dermis. Vaccination with prime-boost of MN induced higher levels of IgG2a antibody titer, T cell proliferation, and TH1 cytokines (IFN-γ and IL-12) as compared to intramuscular (IM) injection. In addition, single dose MN vaccination better protected mice against lethal challenge than IM vaccination. MN vaccination also conferred long-term IgG2a antibody against S. suis 2 bacteria presence for up to 7 months. Taken together, these data showed that vaccine delivery by MNs results in superior immune response and protection rate when compared to IM injections.

Paclitaxel-loaded poly(gamma-glutamic acid)-poly(lactide) nanoparticles as a targeted drug delivery system for the treatment of liver cancer.

The study was to develop paclitaxel-loaded formulations using a novel type of self-assembled nanoparticles (P/NPs) composed of block copolymers synthesized by poly(gamma-glutamic acid) and poly(lactide). For the potential of targeting liver cancer cells, galactosamine was conjugated on the prepared nanoparticles (Gal-P/NPs). In the in vitro studies, it was found that both the P/NPs and the Gal-P/NPs had a similar release profile of paclitaxel. The activity in inhibiting the growth of HepG2 cells by the Gal-P/NPs was comparable to that of a clinically available paclitaxel formulation (Phyxol), while the P/NPs displayed a significantly less activity (p<0.05). The biodistribution and anti-tumor efficacy of the prepared nanoparticles were studied in hepatoma-tumor-bearing nude mice. It was found that the groups injected with Phyxol, the P/NPs or the Gal-P/NPs significantly delayed the tumor growth as compared to the control group injected with PBS (p<0.05). Among all studied groups, the group injected with the Gal-P/NPs appeared to have the most significant efficacy in the reduction of the size of the tumor. This is because a large number of the Gal-P/NPs were observed at the tumor site, and subsequently released their encapsulated paclitaxel to inhibit the growth of the tumor. The aforementioned results indicated that the Gal-P/NPs prepared in the study had a specific interaction with the hepatoma tumor induced in nude mice via ligand-receptor recognition. Therefore, the prepared Gal-P/NPs may be used as a potential drug delivery system for the targeted delivery to liver cancers.

Physicochemical, antimicrobial, and cytotoxic characteristics of a chitosan film cross-linked by a naturally occurring cross-linking agent, aglycone geniposidic acid.

The purpose of this study was to evaluate the characteristics of a chitosan film cross-linked by a naturally occurring compound, aglycone geniposidic acid (aGSA). This newly developed aGSA-cross-linked chitosan film may be used as an edible film. The chitosan film without cross-linking (fresh) and the glutaraldehyde-cross-linked chitosan film were used as controls. The characteristics of test chitosan films evaluated were their degree of cross-linking, swelling ratio, mechanical properties, water vapor permeability, antimicrobial capability, cytotoxicity, and enzymatic degradability. It was found that cross-linking of chitosan films by aGSA (at a concentration up to 0.8 mM) significantly increased its ultimate tensile strength but reduced its strain at fracture and swelling ratio. There was no significant difference in the antimicrobial capability between the cross-linked chitosan films and their fresh counterpart. However, the aGSA-cross-linked chitosan film had a lower cytotoxicity, a slower degradation rate, and a relatively lower water vapor permeability as compared to the glutaraldehyde-cross-linked film. These results suggested that the aGSA-cross-linked chitosan film may be a promising material as an edible film.