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Objective: The aim was to evaluate the ability of gelatin methacryloyl (GelMA) hydrogel eye pads loaded with amniotic extract to prevent symblepharon in rabbits., Materials and Methods: Forty-eight rabbits were divided into 3 groups. After ocular alkali burn, Group A (n=16) was treated with amniotic extract-loaded hydrogel eye pads placed in the conjunctival sac, Group B (n=16) was treated with amniotic membrane transplantation, and Group C (n=16) received no treatment. At 1, 2, 3, and 4 weeks post-injury, 4 rabbits from each group were selected to evaluate for symblepharon, determine epithelial healing rate and corneal neovascularization, conduct histopathology, and to quantify the expression of TGF-β1., Results: At 1 week post-injury, the epithelial healing rate in Groups A and B was higher than Group C (p=0.002, 0.001, respectively). At 2 weeks, corneal neovascularization in Group B was less than Group C (p=0.004). At 3 and 4 weeks, no symblepharon has been found in Group A, but it was found in some eyes in Group B and C (p=0.009, 0.013). Further, the expression of TGF-β1 in Group A was lower than in Group B and C (p<0.001). H&E staining showed that the controls in Group C had more edema and inflammatory cell infiltration in the first 2 weeks, relative to Groups A and B. At 4 weeks, Masson's Trichrome staining showed that fibers were most regularly aligned in Group A and that immuno-histochemical staining found that proliferating cell nuclear antigen was highest expressed in Group C., Conclusions: Treatment with GelMA hydrogel eye pads loaded with amniotic extract shortly after chemical injury prevented symblepharon in rabbits.

Purpose: To evaluate the safety and potential healing efficacy of the topical ocular administration of a gelatin membrane containing usnic acid/liposomes (UALs) for corneal cicatrization. UALs have shown healing activity in animal models of dermal burn lesions. We evaluated the safety of topical ocular administration of UAL and its potential healing efficacy as an ophthalmic treatment on chemical lesions in rabbit eyes., Method: The Draize test was used to check for ocular toxicity and the score was zero at each observation, indicating the ocular safety of a gelatin membrane containing usnic acid/liposome. Its potential healing efficacy as an ophthalmic treatment on chemical lesions in rabbit eyes was also assessed., Results: After epithelial removal and treatment with UAL, there was a 49.4 % reduction in injury under in vivo conditions compared with a 36.6 % reduction in the control, a gelatin membrane containing liposome without usnic acid. Histological analysis of ocular surface chemical injury-tissue sections after treatment with UAL supported these observations. The corneal expression of VEGF and TGF-β1increased by 70 % and 50 % respectively following treatment with UAL gelatin membrane., Conclusion: These results indicate the potential therapeutic application of UAL gelatin membranes as an ophthalmic treatment that may be used for corneal cicatrization., (Copyright © 2020 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

This study reports the development of a novel and simple formulation for probiotic delivery using chitosan-coated agar-gelatin gel particles. This methodology involves the production of agar-gelatin particles by thermally treating a mixture of agar and gelatin solutions at high temperatures (121 °C) and subsequently coating with chitosan. The particles were able to protect the probiotic strain Lactobacillus plantarum NCIMB 8826 during incubation for 2 h in simulated gastric fluid (pH 2), as no statistically significant loss (P > 0.05) in cell concentration was observed, and also resist dissolution in simulated intestinal fluid (pH 7.2). Interestingly, this protection is related to the fact that the intense thermal treatment affected the physicochemical properties of agars and resulted in the formation of a strong and tight polymer network, as indicated by the X-ray diffraction (XRD) analysis. Using an in vitro faecal batch fermentation model simulating the conditions of the distal part of the large intestine (pH 6.7-6.9), it was demonstrated by quantitative real-time PCR that the majority of L. plantarum cells were released from the agar-gelatin particles within 30 to 48 h. Overall, this work led to the development of a novel methodology for the production of probiotic-containing particles, which is simpler compared with current encapsulation technologies and has a lot of potential to be used for the controlled release of probiotics and potentially other solid bioactives in the large intestine.Key Points• Chitosan gel particles is a simple and scalable method of probiotic encapsulation.• Autoclaving agar-gelatin particles increases their stability at low pH.• Chitosan gel particles protected L. plantarum during gastrointestinal conditions.• Probiotics could be controlled release in the colon using chitosan gel particles.

We assessed an injectable gelatin hydrogel containing epidermal growth factor (Gtn-EGF) as a therapy for intracerebral hemorrhage (ICH). ICH was induced in rats via collagenase injection into the striatum. Two weeks later, Gtn-EGF was injected into the cavitary lesion. The hydrogel filled ICH cavities without deforming brain tissue. Immunostaining demonstrated that neural precursor cells could migrate into the matrix, and some of these differentiated into neurons along with the appearance of astrocytes, oligodendrocytes, and endothelial cells. Sensorimotor tests suggested that Gtn-EGF improved neurological recovery. This study provides proof-of-principle that injectable biomaterials may be a translationally relevant approach for treating ICH.

There is an increased demand for an ideal biodegradable biomaterial that eradicates infection, while concurrently promoting tissue regeneration in osteomyelitic bone, which eliminates the need for revision surgery. In this study, our objective was to evaluate the efficacy of a nanocomposite fibrous scaffold (silica coated nanohydroxyapatite-gelatin reinforced with poly-l-lactic acid yarns) containing vancomycin for treating methicillin-resistant Staphylococcus aureus (MRSA) induced osteomyelitis in rat models. The antibiotic was either incorporated during scaffold synthesis (SE-V) or loaded directly after the development of the scaffold (SA-V) at 5 wt% and 15 wt%. There was a sustained release of vancomycin from both the groups of scaffolds for 30 days and the released drug demonstrated antibacterial activity against MRSA. Furthermore, implantation of the composite scaffold into osteomyelitic rat femur resulted in significant bacterial reduction, mainly with 15 wt% drug and its efficacy was comparable to that of commercial graft Stimulan. Both drug entrapped and absorbed composite scaffolds promoted bone regeneration in 3 months, with no distinguishable difference between them. However, Stimulan resorbed fast and there were bone voids at the defect site after 3 months. Hence, the nanocomposite fibrous scaffold containing vancomycin can be proposed as a bi-functional graft that can reduce bacterial infection, while subsequently engineer new bone in osteomyelitis.

In this study, we evaluated a novel combination of drug delivery devices composed of holo-transferrin conjugated liposomes for siRNA (36 nM) delivery, and electrospun polycaprolactone (PCL)-gelatin (GT) microfibers for resveratrol (40 µM) release. Single- and co-cultures of cancerous K562 cells and human umbilical vein endothelial cells (HUVECs) were used to test the efficacy and targeting over eight days. BCR-ABL siRNA-encapsulated (36 nM) holo-transferrin-conjugated PEG-liposomes were characterized using dynamic light scattering, and transmission electron microscopy. RT-qPCR was performed to assess the silencing BCR-ABL gene. Two treatment protocols were explored: i) simultaneous administration ii) delayed liposomes addition by three days based on resveratrol release profile. Formed liposomes were 123 (±6.65) nm in diameter, holo-transferrin conjugation efficiency was 85.9 (±7.30)%, and siRNA loading efficiency was 92.3 (±2.57)%. Sphingosine-1-phosphate (S1P) content was analyzed by ELISA. Targeted siRNA release in combination with resveratrol release was more potent and has long-term effects compared to bolus doses. Delayed addition of liposomes increased non-viability of K562 cells to 92.7 (±2.00)% and 94.32 (±1.70)%, in the absence and presence of HUVECs, respectively. HUVECs non-viability level was significantly lower. Using two different delivery devices approach has a broader impact on cancer treatment., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Composite film dressings composed of pluronic F127 (PL)-pectin (PC) and pluronic (PL) F127-gelatin (GL) were investigated as potential drug delivery system for wound healing. Composite films were solvent cast by blending PL with PC or GL in different ratios using glycerol (2.5%) as plasticizer. Erythromycin (ER) (0.1%) was incorporated in films as model hydrophobic antibiotic. The optimized composite films were characterized for physical appearance, morphology, mechanical profile, and thermal behavior. In addition, drug release, antibacterial activity, and cytocompatibility of the films were investigated to assess their potential as drug delivery system. The composite films exhibited excellent wound dressing characters in terms of appearance, stability, and mechanical profile. Moreover, ER-loaded composite films released ER in controlled manner, exhibited antibacterial activity against Staphylococcus aureus, and were non-toxic to human skin fibroblast. These findings demonstrate that these composite films hold the potential to be formulated as antibacterial wound dressing.

Continuous drug administration with better adherence to treatment and less invasive procedures is important in treating retinal diseases such as age-related macular disease. In this study, we report a drug-refillable device consisting of a silicone reservoir and an injectable gelatin/chitosan gel (iGel). The silicone reservoir was fabricated with polydimethylsiloxane (PDMS) using a computer-aided design and manufacturing to have micropores at a releasing side for uniaxial release to the sclera. A stainless steel wire and sheet were combined in the side and bottom of the reservoir to ensure flexibility and to fit on the curvature of the eyeball and prevent irritation to the sclera through the bottom of the reservoir. The drug was injected and formulated in the reservoir by in situ crosslinking of gelatin/chitosan gel with the crosslinker; 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride. The in vitro release study using fluorescein molecules showed that the release rate from encapsulated iGel in the reservoir was slower than that from the original iGel. After reinjecting the iGel into the reservoir, the same release profile as the first injection was observed. The reservoir containing iGel was placed on the sclera of a rabbit and the distribution of 150 kDa fluorescein isothiocyanate-dextran (FD150) in the retina and choroid/retinal pigment epithelium (choroid/RPE) was studied. The cryosections showed that FD150 was observed in the choroid/RPE. Homogenates of the retina and choroid/RPE showed fluorescence during 12 weeks implantation, indicating the drug could be delivered to the retina by using the device. The drug filling was successful into the reservoir implanted on the sclera through the conjunctiva by using a needle. In conclusion, the refillable drug delivery device is a promising tool to administer drugs long-term by reinjection with less invasiveness to intraocular tissues., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In the present comparative study, gelatin microspheres (GMs) were prepared by emulsification-solvent-extraction method using well-known crosslinker: glutaraldehyde (GA) and biocompatible silane-coupling agent: glycidoxypropyltrimethoxysilane (GPTMS). Crosslinking with GA was done by a definite and common procedure, while GPTMS crosslinking potency was investigated after 5, 10, 24, and 48 h synthesis periods and the fabrication method was adjusted in order for preparation of GMs with optimized morphological and compositional characteristics. The prepared GMs were then evaluated and compared as drug delivery systems for the antibiotic vancomycin (Vm). Morphological observations, FTIR, ninhydrin assay, swelling behavior evaluation and Hydrolytic degradation analysis proved successful modification of GMs and revealed that increasing synthesis time from 5 h to 24 h and 48 h, when using GPTMS as crosslinker, led to formation of morphologically-optimized GMs with highest crosslinking degree (∼50%) and the slowest hydrolytic degradation rate. Such GMs also exhibited most sustained release period of Vm. The antibacterial test results against gram-positive bacterium Staphylococcus aureus, were in accordance with the release profiles of Vm, as well. Together, GPTMS-crosslinked GMs with their preferable characteristics and known as biocompatible gelatin-siloxane hybrids, could act as proper drug delivery systems for the sustained release of the antibiotic vancomycin., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Elevated intraocular pressure (IOP) in glaucoma is due to impairment of aqueous humor drainage via the uveoscleral or trabecular outflow pathway. Latanoprost reduces IOP by increasing the uveoscleral outflow. Despite its potency, long-term daily application of it may cause undesirable side effects and many require more than one medication for IOP control. Recent studies have suggested that oxidative stress in the trabecular meshwork (TM) play an important role in the pathogenesis of impaired trabecular outflow facility. Curcumin, a natural phenolic compound, possesses anti-oxidant and anti-inflammation properties. In this study, we developed a thermosensitive hydrogel containing latanoprost and curcumin-loaded nanoparticles (CUR-NPs), and evaluated its possible therapeutic effects with cultured human TM cells under oxidative stress. The results demonstrated that 20 μM of CUR-NPs might be the optimal concentration to treat TM cells without causing cytotoxicity. Using the newly developed system, both latanoprost and CUR-NPs displayed a sustained-release profile. Treatment with this hydrogel containing CUR-NPs effectively decreased the oxidative stress-mediated damage in TM cells via decreasing inflammation-related gene expression, mitochondrial reactive oxygen stress (ROS) production and apoptosis level. The in vivo biocompatibility revealed no signs of inflammation or damage after topical application of developed hydrogel in rabbits. These results suggest that this dual-drug delivery system might enhance both trabecular and uveoscleral outflow and is promising to develop into a novel treatment for glaucoma., (Copyright © 2018. Published by Elsevier Ltd.)

Rapidly separating genepin-crosslinked gelatin (RS-GC) microneedles (MNs) mounted on the polyvinyl alcohol (PVA)-coated polylactic acid (PLA) MNs (RS-PGC-MNs) are fabricated, in which GC-MNs deliver insulin within the skin and the PLA supporting array is easily separated by the dissolution of the PVA layer. The release of insulin is controlled by utilizing the virtue of genipin as a crosslinking agent for producing biocompatible GC-MNs. The degree of crosslinking enhances the mechanical strength as well as humidity resistance. The in vitro and in vivo insulin release tests show significant changes in the release rates in the RS-PGC-MNs with different crosslinking degree. The hypoglycemic effect in diabetic mice demonstrate that the higher crosslinking GC-MNs result in characteristic controlled insulin release compared with other treatments and prolonged effectiveness of the RS-PGC-MNs. The proposed RS-PGC-MNs is a promising device for effective use as a noninvasive and painless controlled insulin delivery system., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Purpose: Currently, microsphere technology plays a major role in the development of many new cancer therapies. In the current study, we proposed a targeted drug-delivery system to improve the treatment efficacy of one of the common conventional chemotherapeutic drugs used to treat lung tumors, 5-fluorouracil (5-FU)., Materials and Methods: Following the preparation and optimization of small, solid micro-spheres, ranging in diameter between 5 and 15 µm, the final product 5-fluorouracil gelatin (5-FUG) was formulated using a Buchi Nano Spray Dryer by varying the drug:polymer ratio., Results: Particle yield was calculated as 65% ± 1.2%, and the drug content in the formulation was recorded as 74% ± 1.6%. Particle surface morphology was examined as shriveled shape (crumpled/folded); particle size distribution displayed a binomial distribution, with a mean diameter of 9.6 µm. In vitro drug release studies revealed that ~36.4% of the 5-FU in 5-FUG was released in the first hour after injection. Clinically, this would lead to initial or burst release, facilitating a quick rise to therapeutic levels. In contrast to the pure 5-FU drug (89.2% of the drug released in the first 30 minutes), 99.1% of the drug in 5-FUG was released from the spray-dried particles for a period of 12 hours. A two-compartment model was used to generate plasma concentration-time curves. 5-FUG injection has a much different distribution in vivo in contrast to intravenous injection of 5-FU. In addition, the half-life after intravenous injection of 5-FUG, t 1/2 ( α ) = 1.23 hours and t 1/2 ( β ) = 18.3 hours, was considerably longer than that of 5-FU, t 1/2 ( α ) = 0.34 hours and t 1/2 ( β ) = 8.62 hours. Examination of stained lung tissue sections showed no histopathological tissue changes or evidence of gross pathology. In addition, the optimized formulation demonstrated an increased stability under both long-term and refrigerated storage conditions., Conclusion: Our goal was to develop similar delivery systems for other chemotherapeutic drugs that are site specific to different disease models/tumor types., Competing Interests: Disclosure The authors report no conflicts of interest in this work.

Due to growing interest in cosmetics and medical applications, therapeutic medications that reduce the amount of local subcutaneous adipose tissue have potential for obesity treatment. However, conventional methods such as surgical operation are restricted due to risk of complications. Here, we report a simple and effective method for local reduction of subcutaneous adipose tissue (AT) by using microneedle-assisted transdermal delivery of natural polymers. After in vitro screening tests, gelatin was selected as a therapeutic polymer to reduce accumulation of AT. An in vitro study showed that the level of released glycerol as an indicator of lipolysis was elevated in isolated adipocytes after gelatin treatment. In addition, gelatins suppressed expression levels of lipogenesis-associated genes. Following application of gelatin microneedle (GMN) patches to high-fat diet (HD)-induced obese rats, the amount of subcutaneous AT at the site of GMN application was significantly reduced, which was also confirmed by histological analysis and micro-computed tomography scanning. In addition, lipogenesis-associated genes were down-regulated in GMN-treated subcutaneous AT. These findings suggest that GMN patches induce lipolysis and simultaneously inhibit lipogenesis, thereby reducing deposition of subcutaneous AT. This platform using GMNs may provide a new strategy to treat excess subcutaneous AT with minimal complications. STATEMENT OF SIGNIFICANCE: (1) Significance This work reports a new approach for the local reduction of subcutaneous adipose tissue using a dissolving microneedle patch prepared using gelatin to enable suppression of lipogenesis and acceleration of lipolysis in adipocytes. The gelatin microneedle patch exhibited a significant reduction of local subcutaneous fat up to 60% compared to control groups without any change in total weight. (2) Scientific impact This is the first report demonstrating the direct anti-obesity effects of gelatin administrated in a transdermal route and the feasibility of natural polymer therapeutics for regional reduction of subcutaneous fat. We believe that our work will excite interdisciplinary readers of Acta Biomaterialia, those who are interested in the natural polymers, drug delivery, and obesity., (Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

The systemic administration of bisphosphonates (BPs) for the treatment of metabolic diseases characterized by abnormal bone loss suffers from several adverse side effects, which can be reduced by implementation of alternative modes of administration. In this work, glutaraldehyde cross-linked gelatin scaffolds are proposed as delivery systems of calcium alendronate monohydrate (CaAL•H 2 O). The 3D highly porous scaffolds display a relevant interconnected porosity (>94%), independently from CaAL•H 2 O content (0, 3, and 6 wt%). At variance, pore size varies with composition. The relative increase of the number of smaller pores on increasing BP content is in agreement with the parallel significant increase of the compressive modulus and collapse strength. The scaffolds exhibit a sustained CaAL•H 2 O release profile, and a significant amount of the drug is retained in the scaffolds even after 14 d. In vitro tests are carried out using cocultures of osteoblast (OB) and osteoclast (OC). The evaluation of differentiation markers is performed both on the supernatants of cell culture and by means of quantitative polymerase chain reaction. The results indicate that BP containing scaffolds support osteoblast proliferation and differentiation, whereas they inhibit osteoclast viability and activity, displaying a promising beneficial role on bone repair processes., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

To overcome the drawbacks associated with conventional antiglaucoma eye drops, this work demonstrated the feasibility of an effective alternative strategy to administer pilocarpine directly via intracameral injections of drug-containing biodegradable in situ gelling GN copolymers composed of gelatin and poly(N-isopropylacrylamide). Specifically, this study aims to understand the importance of Bloom number of gelatin, a physicochemical parameter, to the development of GN carriers for intracameral drug delivery in glaucoma therapy. Our results showed that both imino acid and triple-helix contents increased with increasing Bloom index from 75-100 to 300. The drug encapsulation efficiency in response to temperature-triggered phase transition in GN copolymers was affected by the Bloom index of gelatin. In addition, the differences in protein secondary structure significantly influenced the degradation rates of GN carriers, which were highly correlated with drug release profiles. The increase in released pilocarpine concentration led to a high intracellular calcium level in rabbit ciliary smooth muscle cell cultures, indicating a beneficial pharmacological response to a drug. Irrespective of Bloom number of gelatin, all carrier materials exhibited excellent in vitro and in vivo biocompatibility with corneal endothelium. In a glaucomatous rabbit model, intracameral injections of pilocarpine-containing GN synthesized from gelatins with various Bloom numbers had different abilities to improve ocular hypertension and induce pupillary constriction, indicating distinct antiglaucoma efficacies due to in vivo drug release. It is concluded that the effects on pharmacological treatment using GN carriers for intracameral pilocarpine administration demonstrate a strong dependence on the Bloom number of gelatin., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Recently, electrospun nanofibrous scaffolds are vastly taken into consideration in the bone tissue engineering due to mimicking the natural structure of native tissue. In our study, surface features of nanofibers were modified through simultaneous electrospining of the synthetic and natural polymers using poly l-lactide (PLLA) and gelatin to fabricate the hybrid scaffold (PLLA/gelatin). Then, hydroxyapatite nanoparticles (nHA) were loaded in electrospun PLLA nanofibers (PLLA,nHA/gelatin) and also dexamethasone (DEX) was incorporated in these fibers (PLLA,nHA,DEX/gelatin) in the second experiment. Fabricated nanofibrous composite scaffolds were characterized via SEM, FTIR spectroscopy, contact angle, tensile strength measurements, DEX release profile and MTT assay. After seeding adipose derived mesenchymal stem cells, osteoinductivity and osteoconductivity of fabricated scaffolds were analyzed using common osteogenic markers such as alkaline phosphatase activity, calcium depositions and gene expression. These results confirmed that all properties of nanofibers were improved by modifications. Moreover, osteogenic differentiation of stem cells increased in PLLA,nHA/gelatin group in comparison with PLLA/gelatin. The sustained release of DEX was obtained from PLLA,nHA,DEX/gelatin which subsequently led to more osteogenic differentiation. Taken together, PLLA,nHA,DEX/gelatin showed significant potential to support the stem cell proliferation and ostogenic differentiation, and can be a good candidates for tissue engineering and regenerative medicine applications., (Copyright © 2016 Elsevier B.V. All rights reserved.)

This work reports intercalation of a sparingly soluble antibiotic (ciprofloxacin) into layered nanostructure silicate, montmorillonite (MMT) and its reaction with bone derived polypeptide, gelatin that yields three-dimensional composite hydrogel. Drug intercalation results in changes in MMT layered space and drug loaded MMT and gelatin creates 3D morphology with biodegradable composite hydrogels. These changes can be correlated with electrostatic interactions between the drug, MMT and the gelatin polypeptides as confirmed by X-ray diffraction patterns, thermal, spectroscopic analyses, computational modeling and 3D morphology revealed by SEM and TEM analysis. No significant changes in structural and functional properties of drug was found after intercalation in MMT layers and composite hydrogels. In vitro drug release profiles showed controlled release up to 150h. The drug loaded composite hydrogels were tested on lung cancer cells (A549) by MTT assay. The results of in vitro cell migration and proliferation assay were promising as composite hydrogels induced wound healing progression. In vitro biodegradation was studied using proteolytic enzymes (lysozyme and protease K) at physiological conditions. This new approach of drug intercalation into the layered nanostructure silicate by ion-exchange may have significant applications in cost-effective wound dressing biomaterial with antimicrobial property., (Copyright © 2014 Elsevier B.V. All rights reserved.)

This paper proposed a natural gelatin capped mesoporous silica nanoparticles (MSN@Gelatin) based pH-responsive delivery system for intracellular anticancer drug controlled release. In this system, the gelatin, a proteinaceous biopolymer derived from the processing of animal collagen, was grafted onto the MSN to form a capping layer via temperature-induced gelation and subsequent glutaraldehyde mediated cross-linking, resulting in gelatin coated MSN. At neutral pH, the gelatin capping layer could effectively prohibit the release of loaded drug molecules. However, the slightly acidic environment would lead to enhanced electrostatic repulsion between the gelatin and MSN, giving rise to uncapping and the subsequent controlled release of the entrapped drug. As a proof-of-concept, doxorubicin (DOX) was selected as the model anticancer drug. The loading and pH-responsive release experiments demonstrated that the system had excellent loading efficiency (47.3 mmol g(-1) SiO2), and almost no DOX was leaked at neutral. After being in the slightly acidic condition, the DOX release from the DOX-loaded MSN@Gelatin (DOX/MSN@Gelatin) occurred immediately. The cellular uptake and release studies using Hep-G2 hepatoma cells indicated that the DOX/MSN@Gelatin could be endocytosed and accumulated within lysosomes. Triggered by acidic endosomal pH, the intracellular release of the loaded DOX was obviously eventuated. Further cell viability results demonstrated that DOX/MSN@Gelatin exhibited dose-dependent toxicity and high killing efficacy (IC50 = 17.27 ± 0.63 μg mL(-1)), whereas the MSN@Gelatin showed negligible cytotoxicity (IC50 > 100 μg mL(-1)). This biocompatible and effective delivery system will provide great potential for developing delivery of cancer therapeutic agents.

Background: Ceftiofur is an effective antibiotic against respiratory infections in livestock. However, ceftiofur concentration that is found in lungs after intravenous injection is not effective. Fortunately, ceftiofur-loaded gelatin microsphere (Cef-MS) enjoys advantages of lung-targeting and can achieve an effective concentration. However, no study has been reported on this modality of drug delivery., Objective: We investigated the properties of this delivery modality--lung targeting ceftiofur-Cef-MSs., Methods: We prepared Cef-MS and investigated drug loading, stability and release characteristics in vitro and studied tissue distribution patterns and potential lung injury in mice., Results: Results showed that the average size and span value are 21.26 μm and 1.07, respectively. Drug loading and loading efficiency were 15.31 and 76.55%, respectively. Cef-MSs were stable in light, heat and humidity, except that agglutinative phenomenon was observed in 90% humidity after 10 days. Cef-MS presented a slower in vitro release pattern compared to ceftiofur. Cef-MS mainly concentrates in lungs after intravenous administration. Furthermore, histopathological studies showed that Cef-MS only induces mild and reversible lung injury and is biologically safe., Conclusion: Cef-MS is a promising alternative form with high lung-targeting properties for the treatment of respiratory infections.

Purpose: To investigate the effects of gelatin hydrogel (GH) containing a chymase inhibitor (CI) on intraocular pressure (IOP) and conjunctival scarring in a canine model of glaucoma surgery., Methods: Glaucoma surgery models were made in beagles. As the first experiment, GH was implanted. IOP was measured for 4 weeks, followed by histologic evaluation. As the second experiment, GH containing a CI or GH alone was implanted. IOP and bleb features were evaluated for 12 weeks. The densities of proliferative cell nuclear antigen (PCNA)-positive cells, fibroblasts, and mast cells were quantified. The mRNA levels of transforming growth factor-β (TGF-β) and chymase were determined by real-time PCR., Results: In the first experiment, IOP was significantly lower in the eyes treated with GH than that in the control eyes. The conjunctival area normalized by the scleral area was reduced in the treated eyes. In the second experiment, IOP reduction was maintained for 12 weeks in the eyes treated with GH containing a CI, but not in the eyes treated with GH alone. In addition, the bleb score was larger, whereas the adhesion score and densities of PCNA-positive cells, fibroblasts, mast cells, and chymase-positive cells were lower in the eyes treated with GH containing a CI. The mRNA levels of TGF-β and chymase were significantly decreased in the eyes treated with GH containing a CI., Conclusions: Implanting GH alone maintained IOP reduction, whereas GH containing a CI enhanced the IOP-reducing effect by suppressing cell proliferation. This drug delivery system might be useful for maintaining filtering blebs for a longer duration after glaucoma surgery.

Objective: To compare owner-assessed ease of administration and overall acceptability of 3 chemically inactive formulations administered PO to cats., Animals: 90 healthy client-owned cats., Procedures: Cats were randomly assigned to receive 1 of 3 formulations PO once daily for 14 days: medium chain triglyceride (MCT) oil, dissolving thin film strips (proprietary ingredients), or gelatin capsules filled with microcrystalline cellulose. Owners administered the formulations and rated ease of administration daily on a 10-cm visual analogue scale (VAS). At the end of the study, owners rated overall acceptability of formulations from their own perspective and their overall perception of acceptability to their cat., Results: Mean VAS scores for daily ease of administration of MCT oil and film strips were significantly higher than scores for gelatin capsules at all time points, except on days 2, 4, and 7. There was no difference between MCT oil and film strip formulation scores. Mean VAS scores were 8.8 (MCT oil), 8.9 (film strips), and 7.4 (gelatin capsules) for overall acceptability to owners and 8.0 (MCT oil), 8.3 (film strips), and 6.7 (gelatin capsules) for overall owner-perceived acceptability to cats., Conclusions and Clinical Relevance: Daily ease of administration on 11 of 14 days and overall owner-perceived acceptability to cats were scored significantly higher for film strips and MCT oil, compared with scores for gelatin capsules. Overall acceptability to owners followed a similar pattern; however, the differences were not significant. Dissolving thin film strip or MCT oil vehicles may allow for easier PO administration of medication to cats than does administration of gelatin capsules.

Objective: We developed a new liquid embolic agent, an aqueous solution of thermoreversible gelation polymer (TGP) for the treatment of cerebral aneurysms. This polymer solution has the unique characteristics that allow it to solidify at a specific temperature without solvent. We performed an experimental aneurysm embolization using this liquid embolic agent with and without different protective devices to evaluate its technical feasibility for the treatment of aneurysms., Methods: Fourteen side-wall aneurysms were surgically constructed on 14 common carotid arteries of 7 swine. Embolizations were conducted in combination with balloon protection (balloon group, n = 4), microstent protection (stent group, n = 4), and microcoil and microstent protection (stent-coil group, n = 4). Two aneurysms were used as controls. One control aneurysm was not embolized, and the other received control stent placement only. Angiographic follow-up was performed on day 14 and was followed by histopathological evaluation., Results: Successful TGP solution delivery was conducted in all cases. Complete aneurysm occlusion was achieved in all cases without TGP migration. Follow-up angiograms demonstrated complete occlusion in the stent and stent-coil groups. A small recurrence was observed in the balloon group. Histopathological findings demonstrated neoendothelialization across the necks of the aneurysms., Conclusion: Experimental aneurysms were safely embolized using TGP. Further modifications related to mechanical stability and long-term safety evaluation results are necessary before clinical application.

A phenolic hydroxyl group was incorporated into gelatin, using aqueous-phase carbodiimide activation chemistry, to obtain in situ gellable and injectable protein-based materials for drug delivery and tissue engineering applications. By this means, gelatin derivatives that were gellable via a peroxidase-catalyzed reaction were obtained. The enzymatically cross-linked gelatin gels did not melt at 37 degrees C and showed tunable proteolytic degradability. The time necessary for gelation decreased with increasing content of the phenolic hydroxyl (Ph) group, peroxidase concentration and decreasing H(2)O(2) concentration. Resistance to gel compression also depended on the content of Ph groups, with the gel containing the lowest Ph group content showing the greatest resistance to compression. We encapsulated L929 fibroblast cells in gelatin gels under conditions that induced gelation in about 10 s. The encapsulated cells showed about 95% viability. In addition, L929 cells seeded on the gels showed the same growth profiles as those seeded on an unmodified gelatin-coated dish. Subcutaneous rodent injection experiments demonstrated successful in situ formation of gels at the injected site.

Aim: Localized delivery of growth factors has significant potential as a future therapeutic strategy in tissue engineering and regenerative medicine. A nanoparticle vehicle was created and evaluated in this study with the intent to deliver growth factors for periodontal regeneration., Methods: Novel composite nanoparticles based on glycidyl methacrylate derivatized dextrans (Dex-GMA) and gelatin were fabricated by a facile method without using any organic solvents. The configurations of the resultant nanoparticles were evaluated by transmission electron microscopy, scanning electron microscopy, and atomic force microscope. Their surfaces were characterized by zeta-potential measurements, after which their properties including swelling, degradation, drug release, and cytotoxicity were also investigated using in vitro models., Results: The particle size of Dex-GMA/gelatin nanoparticles (DG-NPs) ranged from 20 to 100 nm and showed a mono-disperse size distribution (mean diameter 53.7 nm) and a strongly negative surface zeta potential (-20 mV). The DG-NPs were characterized by good swelling and degradation properties in media including dextranase. The in vitro drug release studies showed that the efficient bone morphogenetic protein (BMP) release from DG-NPs was maintained for more than 12 d under degradation conditions, where more than 90% of the loaded BMP was released. No any relevant cell damage caused by DG-NPs was found in the cytotoxicity tests for a period of 24 h., Conclusion: These combined results demonstrate that DG-NPs fulfill the basic prerequisites for growth factor delivery. With further in vivo studies, those nanoparticles may offer a promising vehicle for the delivery of active drugs to the periodontium.

Polysaccharide-based colonic drug delivery requires that the polysaccharide in question avoids pancreatic digestion but undergoes fermentation by the colonic bacteria. Resistance of such dosage forms to pancreatic enzyme digestion is generally only tested in the fasted state, despite the higher enzymatic challenge in the fed state. Theophylline pellets coated with a polysaccharide-based (amylose) colon-specific film were administered to seven healthy volunteers (two-way crossover study, fed/fasted). The transit of the pellets through the gut was followed by gamma scintigraphy. The amount of drug released in the gut from the theophylline pellets was calculated after recovering and assaying any intact pellets in the faecal material. Of the drug released, the amount absorbed was measured using plasma profiling. Gastric empyting of pellets was delayed in the fed state, and this translated to a delayed colon arrival time. In both fed and fasted states, there was no drug release in the stomach or small intestine confirming the ability of the amylose in the coating to resist pancreatic digestion despite elevated enzyme levels in the fed state. Drug plasma levels were detected after the pellets arrived in the colon and there was a delayed T(max) in the fed state; the mean caecal arrival time in the fasted state was 5.5 +/- 1.1 h and the T(max) was 9.3 +/- 0.5 h, whereas in the fed state the mean caecal arrival time was 6.9 +/- 2.1 h and the T(max) was 10.3 +/- 0.8 h. On average, over 92% of the drug was released in the colon; the remaining was removed in faecal material. Bioavailability was similar (p>0.05) in both feeding states (26.0 +/- 6.4 microg h/ml fasted and 24.4 +/- 5.1 microg h/ml fed). In conclusion, feeding has no detrimental effects on the behaviour of this polysaccharide-based colonic delivery concept.

Injectable and thermo-reversible physical combination gels were formed in aqueous solution by preparing complex coacervate with two oppositely charged biomacromolecules that composed of negatively charged chondroitin 6-sulfate and positively charged high molecular weight gelatin type A and co-formulating with a negative, thermo-sensitive polysaccharide, methylcellulose containing a salting-out salt, ammonium sulfate. The combination of complex coacervation and a thermo-reversible gel demonstrated synergistic effects on the complex coacervate formation the release rates of model proteins and in situ gel depot formation. Gels indicated sustained release patterns of the protein over 25 days with minimal initial bursts. Optimized novel in situ gel depot systems containing dual advantages of complex coacervation and temperature responsiveness demonstrated a potential for efficient protein drug delivery in terms of high protein loading, sustained protein release, ease of administration, an aqueous environment without toxic organic solvents, and a simple fabrication method.

This study sought to clarify the effectiveness of bFGF-gelatin hydrogel complex on bone regeneration around implants for the development of a new drug delivery system for bone augmentation. Twenty-four titanium implants (03.3 mmX 10 mm) were placed into edentulous areas of the mandibles of four beagle dogs with the upper four screw threads exposed at buccal side. bFGF-gelatin hydrogel complex with 0, 0.1, 1, 10, 100 microg bFGF or autogenous bone (as control) then filled the bone defect site to cover the exposed screw threads. After eight weeks, tissue specimens including implants were evaluated histologically and histomorphometrically. Histological observation showed new bone formation around exposed screw threads in the groups with 1, 10, 100 microg bFGF and autogenous bone-a striking contrast to the groups with contents of 0 and 0.1 microg bFGF. These results thus suggested that bFGF-gelatin hydrogel complex using an optimum amount of bFGF was useful for bone augmentation around implants.

The study purpose was to explore whether dichloromethylene diphosphonate (Cl(2)MDP)-loaded gelatin particles can induce the depletion of macrophage in reticuloendothelial system of liver and spleen or can depress the immunity of macrophage in SD rat models of immune thrombocytopenic purpura (ITP) to treat the ITP rats. New Zealand rabbits were immunized with platelets of SD rats to prepare rabbit anti-rat platelet serum, and the serum was intravenously injected into SD rats to produce the ITP model. In experimental ITP models, 150 microl of anti-platelet serum was intravenously injected into SD rats per 24 hours. The platelet counts maintained pathological level and were persistently less than 50 x 10(9)/L in the models during experiment process. The MTT test of macrophage RAW264.7 was carried out by means of Cl(2)MDP-loaded gelatin particles in vitro. After intravenous injection of a group dose of Cl(2)MDP-gelatin particles, the platelet counts of the rats were measured at the time of 4 hours, 24 hours, 48 hours, 72 hours and 96 hours, respectively, and bleeding times were detected in 24 hours. The results showed that Cl(2)MDP-loaded gelatin particles increased the platelet counts of ITP models to mean of 180 x 10(9)/L, a physiological level in 24 hours after injection, and kept this platelet level through whole process of 120 hours. Furthermore, rats pre-treated with Cl(2)MDP-loaded gelatin particles avoided the decrease of platelet counts significantly when they were injected anti-platelet serum. It is concluded that Cl(2)MDP-loaded gelatin particles restrain multiplication of macrophage RAW264.7, and promptly, effectively restore platelet counts of ITP models to physiological level in a dose dependent manner. So, the targeting therapy of drug-loaded gelatin particles offers a new idea and approach to treat ITP, and this strategy is worthy of further studies.

Objective: The objective of this study was to develop an embolization material of hollow fiber combined with gelatin hydrogel for the controlled release of basic fibroblast growth factor (bFGF). We examined feasibility of the material in embolization healing aneurysm by bFGF-induced tissue organization., Methods: An aneurysm was prepared at the common carotid artery of 60 rabbits by the end-to-side anastomosis of jugular venous pouch. The hollow fibers combined with or without 100 microg free bFGF or gelatin hydrogel incorporating 0, 10, 50, or 100 microg bFGF were applied to the aneurysm. Tissue appearance or histological observation was performed 1, 2, 3, and 6 weeks after application to evaluate the area embolized by fibrous organization in the aneurysm and the neointima formation at the aneurysm orifice., Results: When applied with the hollow fibers combined with gelatin hydrogel containing 100 microg bFGF, the aneurysm was histologically occupied by fibrous tissue newly formed 3 weeks later, whereas neointima was formed at the aneurysm orifice. The histological area occupied by fibrous tissue was significantly larger than that of hollow fibers combined with 100 microg bFGF. No influence of bFGF dose on the aneurysm healing by the fibers combined with hydrogels incorporating bFGF was observed., Conclusion: Local, controlled release of bFGF from the hollow fibers combined with gelatin hydrogel incorporating bFGF accelerated the aneurysm healing by tissue organization.

Purpose: The aim of this study was to evaluate cationized gelatin nanoparticles as biodegradable and low cell toxic alternative carrier to existing DNA delivery systems., Methods: Native gelatin nanoparticles were produced using a two step desolvation method. In order to bind DNA by electrostatic interactions onto the surface of the particles, the quaternary amine cholamine was covalently coupled to the particles. The modified nanoparticles were loaded with different amounts of plasmid in varying buffers and compared to polyethyleneimine-DNA complexes (PEI polyplexes) as gold standard. Transfection ability of the loaded nanoparticles was tested on B16 F10 cells. Additionally, the cell toxicity of the formulations was monitored., Results: Different setups resulted in efficient gene delivery displayed by exponential increase of gene expression. The gene expression itself occurred with a certain delay after transfection. In contrast to PEI polyplexes, cationized gelatin nanoparticles almost did not show any significant cytotoxic effects., Conclusions: Cationized gelatin nanoparticles have shown the potential of being a new effective carrier for nonviral gene delivery. The major benefit of gelatin nanoparticles is not only the very low cell toxicity, but also their simple production combined with low costs and multiple modification opportunities offered by the matrix molecule.

This work describes the development of a non-invasive means of simultaneously delivering insulin-like growth factor-1 (IGF-1) and transforming growth factor-beta1 (TGF-beta1) to injured cartilage tissue in a controlled manner. This novel delivery technology employs the water-soluble polymer, oligo(poly(ethylene glycol) fumarate) (OPF), in the fabrication of biodegradable hydrogels which encapsulate gelatin microparticles. Release studies first examined the effect of gelatin isoelectric point (IEP) and crosslinking extent on IGF-1 release from these microparticles. In the presence of collagenase, highly crosslinked, acidic gelatin (IEP=5.0) provided sustained release of IGF-1, 95.2+/-2.9% cumulative release at day 28, while less crosslinked microparticles and microparticles of alternate IEP exhibited similar release values after only 6 days. Encapsulation of these highly crosslinked microparticles in a network of OPF provided a means to further control release, reducing final cumulative release to 70.2+/-4.7% in collagenase-containing PBS. Final release values from OPF-gelatin microparticle composites could be altered by incorporating less crosslinked, non-loaded microparticles within these constructs. Finally, this technology was extended to the dual delivery of IGF-1 and TGF-beta1 by loading these growth factors into either the OPF hydrogel phase or gelatin microparticle phase of composites. Release profiles were successfully manipulated by altering the phase of growth factor loading and microparticle crosslinking extent. For instance, by loading TGF-beta1 into the gelatin microparticle phase, a burst release of 10.8+/-0.7% was achieved, while loading this growth factor into the OPF hydrogel phase resulted in a burst release of 25.2+/-1.5%. With either system, simultaneous, slow release of IGF-1 over a 4-week period was accomplished by selectively loading this protein into highly crosslinked, encapsulated microparticles. These results demonstrate the utility of these systems in future studies to assess the interplay and time course of multiple growth factors in cartilage repair.

We devised a new transtissue drug-delivery system, based on a multiple-needle-arrayed injector that has 36 long and short needles on the needle head, to administer the drug into local points of the target tissue at a well-controlled depth and pitch. A preliminary in vitro study, focusing the time-dependent depth profiling of protein injected in agarose gel as a model tissue using confocal laser scanning microscope, was conducted to evaluate the performance of the multiple-needle-arrayed injector coupled with photoreactive gelatin (styrenated gelatin: St-gelatin) as the sustained-release vehicle. Rhodamine-conjugated albumin, which was mixed with the St-gelatin buffer solution, was the model drug of the in vitro study, and the mixture was injected into agarose gel using the multiple-needle-arrayed injector by single injection, followed by visible-light irradiation to photocure the gelatin solution. Time-dependent distribution from the injected material into the surrounding agarose gel was observed using a confocal laser scanning microscope up to seven days. Injection of the drug material and concomitant withdrawal of the syringe (termed multirod method) enabled the long- and short-rod-like injections into the agarose gel at the same locations of the injected sites. The model drug gradually diffused throughout the agarose gel. In an in vivo study, the comparison of the efficacy of the angiogenic protein (bFGF: 10 microg for each) with placebo was performed using the non-ischemic hind limb model of rabbits. Four weeks after injection, a significant increase in the number of angiogenic capillaries was observed in the mixed St-gelatin/bFGF group compared with that of placebo. The multiple-needle-arrayed injector coupled with a sustained-release vehicle may be an effective drug delivery system for realizing the spatio-regional distribution of angiogenic protein.

Lambda-carrageenan is an anionic polymer able to ionically interact with alkaline drugs. This results in a complex that releases the drug slowly, due to displacement by the counterions of the release medium. The aim of this work was to assess the possible ophthalmic employment of such a complex. As a model drug, an alkaline anti-glaucoma drug, timolol maleate, was chosen. Systems in which lambda-carrageenan interacted both with the drug and a mucoadhesive polymer such as gelatin were studied. The combination of carrageenan and gelatin in different ratios proved to be useful in modulating the drug release profiles, the rheological properties of the hydrated formulations and their mucoadhesive properties. Both films and microspheres were prepared and tested in vitro. A microsphere formulation was also tested in vivo in albino rabbits. The drug concentration and bioavailability in the aqueous humour were significantly high in comparison with commercial formulations.

The crosslinking process of natural macromolecules with microwave energy should have the potentiality to overcome the problems due to the toxicity of the residuals of chemical crosslinking agents and moreover of the "in vivo" biodegradation products of the chemical crosslinked macromolecule. To evaluate the effective crosslinking of the gelatin forming the microspheres, the water-soluble fraction at 37 degrees C, the water absorption capability, the free amino and free carboxylic acid groups of the gelatin were determined. The structural change in the gelatin microspheres has been detected by the porosity studies. Moreover, both the "in vitro" biodegradability and the biocompatibility of the gelatin microspheres microwave-treated after a subcutaneous injection into female albino guinea pigs were tested. As the results suggest only the gelatin microspheres microwave-treated for 10 min at an inlet temperature of 250 degrees C could have been modified by the crosslink formation among the macromolecular chains. The gelatin microspheres treated with the microwave energy were very well biodegraded as indicated both by the "in vitro" enzymatic degradation studies and mainly by the histopathological examination. This latter study has also demonstrated the biocompatibility of the gelatin microspheres crosslinked with the microwave energy. In order to evaluate the feasibility of the microwave crosslinking process for pharmaceutical applications, both the drug loading and the drug release processes were evaluated using diclofenac as drug model, either as acidic form or as sodium salt. The microspheres were swollen in aqueous solution of diclofenac sodium salt, followed by a washing procedure with cool water to maintain the sodium salt into the microspheres or with pH 1.5 HCl to induce the diclofenac precipitation. To increase the amount of diclofenac acid form in the microspheres, the procedure was repeated three times washing with pH 1.5 HCl after each swelling process. Both the X-ray diffractometry and thermal analysis investigations showed a different physical state of the two drug forms in the microspheres, i.e. the amorphous state of the sodium salt and the crystalline state of the acidic form. According to the experimental results, the drug is released from gelatin microspheres according to the drug loading and the drug solubility.

Purpose: In order to develop a safe and effective systemically-administered biodegradable nanoparticle delivery system for solid tumors, the comparative biodistribution profiles of gelatin and poly(ethylene-glycol)(PEG)-modified (PEGylated) gelatin nanoparticles was examined in subcutaneous Lewis lung carcinoma (LLC)-bearing female C57BL/6J mice., Methods: Type-B gelatin and PEGylated gelatin nanoparticles were radiolabeled ((125)I) for the in vivo biodistribution studies after intravenous (i.v.) administration through the tail vein in LLC-bearing mice. At various time intervals, the mice were sacrificed and blood, tumor, and major organs harvested for analysis of radioactivity corresponding to the localization of the nanoparticles. Percent recovered dose was determined and normalized to the weight of the fluid or tissue sample. Non-compartmental pharmacokinetic analysis was performed to determine the long-circulating property and preferential tumor targeting potential of PEGylated gelatin nanoparticles in vivo., Results: From the radioactivity in plasma and various organs collected, it was evident that the majority of PEGylated nanoparticles were present either in the blood pool or taken up by the tumor mass and liver. For instance, after 3 h, the concentrations of PEGylated gelatin nanoparticles was almost 2-fold higher in the blood pool than the control gelatin nanoparticles. PEGylated gelatin nanoparticles remained in the blood pool for a longer period of time due to the steric repulsion effect of the PEG chains as compared to the gelatin nanoparticles. In addition, approximately 4-5% of the recovered dose of PEGylated gelatin nanoparticles was present in the tumor mass for up to 12 h. The plasma and the tumor half-lives, the mean residence time, and the area-under-the-curve of the PEGylated gelatin nanoparticles were significantly higher than those for the gelatin nanoparticles., Conclusions: The results of this study show that PEGylated gelatin nanoparticles do possess long circulating properties and can preferentially distribute in the tumor mass after systemic delivery.

Objective: The aims of this study were to develop an endovascular delivery system containing gelatin hydrogels for the controlled release of basic fibroblast growth factor (bFGF) with the use of polyethylene terephthalate fiber coils and to analyze whether such a system would promote healing in an experimental aneurysm., Methods: Carotid aneurysms were constructed in 66 rabbits with venous pouches. The polyethylene terephthalate fiber coils coated with and without gelatin hydrogels with different water volumes containing 0, 10, 50, and 100 microg bFGF were implanted into the aneurysms. Histological specimens were harvested at 1, 2, and 3 weeks and at 6 months after implantation. A histological evaluation was performed while the area occupied by the fibrosis in the aneurysms was calculated., Results: Three weeks after the application of the coils coated with gelatin hydrogels (95 vol%) containing 100 microg bFGF, all aneurysmal orifices were completely closed with neointima. When the coils coated with gelatin hydrogel (98 vol%) containing 100 microg bFGF were used, the orifices in three of the six aneurysms were closed. In contrast, the orifice of the aneurysm was not obliterated when other materials were used. After implanting the coils coated with gelatin hydrogel (95 vol%) containing 100 microg bFGF more than 3 weeks later, the aneurysm was histologically suffused with fibrous tissue, and the area occupied by fibrosis was significantly larger than that observed in the other groups (P < 0.05)., Conclusion: Local, controlled release of sufficient amounts of bFGF with polyethylene terephthalate fiber coils coated with gelatin hydrogel accelerated the organization of aneurysms.

Gelatin-containing, electrically conducting, rigid water-in-oil (w/o) microemulsion-based organogels (MBG), both with and without the presence of a model drug, have been prepared using pharmaceutically acceptable oils and surfactants. As a precursor to MBG formation, preliminary formulation work was carried out investigating the factors affecting the preparation of w/o microemulsions containing large amounts of dispersed aqueous phase. From these studies isopropyl myristate (IPM) was favoured as oil due to its ability to support w/o microemulsion formation over a wide range of compositions. The single most effective surfactant for stabilising the w/o microemulsions was found to be Aerosol-OT (AOT), although synergistic effects on the extent of w/o microemulsion formation were observed upon its combination with a variety of non-ionic surfactants. Upon addition of gelatin to the w/o microemulsion, MBG could be formed when using AOT as stabiliser with most of the oils investigated (with the exception of the medium and large triglyceride oils, Miglyol 812 and soybean oil, respectively) and with a number of AOT/non-ionic surfactant/IPM combinations (both in the presence and absence of model drugs such as sodium salicylate). MBG could not however be formed with non-ionic surfactants alone, or when used in combination with another non-ionic surfactant (regardless of the oil used). This latter observation was found to be not only a result of the inadequate level of water available for hydration of the surfactant head group and any gelatin present but also a consequence of the inability of these systems to form, upon heating, the percolated microstructures necessary to facilitate the supramolecular assembly of gelatin at the macroscopic level, a pre-requisite for MBG formation.

Purpose: The objective of this study was to develop and characterize long-circulating, biodegradable, and biocompatible nanoparticulate formulation as an intracellular delivery vehicle., Methods: Poly(ethylene glycol) (PEG)-modified gelatin was synthesized by reacting Type-B gelatin with PEG-epoxide. The nanoparticles, prepared by pH and temperature controlled ethanol-water solvent displacement technique, were characterized for mean size, size distribution, and surface morphology. Electron spectroscopy for chemical analysis (ESCA) was used to confirm the surface presence of PEG chains. In vitro release of tetramethylrhodamine-labeled dextran (TMR-dextran, Mol. wt. 10,000 daltons) from the nanoparticle formulations was examined in PBS, with and without 0.2-mg/ml protease, at 37 degrees C. Relative cytotoxicity profile of control and PEGylated gelatin was evaluated in BT-20 a human breast cancer cell line. The nanoparticles were incubated with BT-20 cells to determine uptake and cellular distribution using confocal microscopy., Results: Gelatin and PEGylated gelatin nanoparticles were found to be spherical in shape with a smooth surface in a size range of 200-500 nm and a unimodal size distribution. ESCA results showed an increase in the ether carbon (-C-O-) peak in the PEGylated gelatin nanoparticles due to the presence of PEG chains. The presence of PEG chains decreased the percent release of TMR-dextran in the presence of proteolytic enzyme due to steric repulsion. Cytotoxicity assays indicated that both gelatin and PEGylated gelatin were completely non-toxic to the cells. A large fraction of the administered control gelatin and PEGylated gelatin nanoparticles were found to be concentrated in the perinuclear region of the BT-20 cells after 12 hours indicating possible vesicular transport through initial uptake by endocytosis and endosomal processing., Conclusion: The results of this study show that PEGylation of gelatin may prove beneficial as long-circulating delivery system in vivo. Additionally, the nanoparticles could encapsulate hydrophilic macromolecules and are internalized by tumor cells.

Casein-gelatin beads have been prepared by emulsification extraction method and cross-linked with D,L-glyceraldehyde in an acetone-water mixture 3:1 (v/v). Casein emulsifying properties cause air bubble incorporation and the formation of large holes in the beads. The high porosity of the matrix influences the bead properties such as drug loading, drug release and floatation. These effects have been stressed by comparison with low porous beads, artificially prepared without cavities. The percentage of casein in the matrix increases the drug loading of both low and high porous matrices, although the loading of high porous matrices is lower than that of low porous matrices. As a matter of fact, the drug should be more easily removed during washing and recovery because of the higher superficial pore area of the beads. This can explain the drug release rate increase, observed in high porous matrix, in comparison with beads without cavities. This is due to the rapid diffusion of the drug through water filled pores. The study shows that cavities act as an air reservoir and enable beads to float. Therefore, casein seems to be a material suitable to the inexpensive formation of an air reservoir for floating systems.

A new microparticulate delivery system composed of a stabilizing gelatin/poloxamer microcore surrounded by a PLGA coat was designed to improve the stability of tetanus toxoid (TT) encapsulated in PLGA microspheres. Microcores were prepared by a spray-congealing technique and encapsulated within PLGA using an oil-in-oil (o/o) solvent evaporation technique. SEM analysis of the cross-sections of the microcapsules revealed the adequate encapsulation of the cores, showing an intimate contact between the core and the coating. This structure was responsible for an osmotic phenomenon observed in vitro, which led to the release of the encapsulated TT in a short period of time. Nevertheless, it was observed that the release was affected by the presence of the poloxamer in the core: microspheres without poloxamer in the core exhibit a faster release (2 h) than those that incorporate the surfactant (24 h). The in vivo evaluation of this system showed that the encapsulated toxoid induced a low but continuous levels of neutralizing antibodies (Nt), whereas those obtained for the control (aluminum phosphate-adsorbed toxoid) decreased after reaching the maximum level at 14 weeks. Moreover, the administration of a mixture of encapsulated and adsorbed TT led to significant higher and more prolonged Nt levels than those measured for the adsorbed toxoid.

Although it has been claimed that nanoparticles can be produced from gelatin, a naturally occurring polypeptide, the commercial conversion of animal collagen to gelatin results in a heterogeneous product with a wide molecular-weight range. This is probably responsible for the widely observed variation in the experimental conditions required for nanoparticle formation. In this study, 0.2% w/v aqueous B225 gelatin solutions were incubated under various conditions of time, temperature, pH and ethanol concentration and characterized by both size-exclusion high-performance liquid chromatography (HPLC) and dynamic light scattering. Gelatin was shown to be denatured when the temperature was increased to 37 degrees C (approx.) and the rate of renaturation was optimized over the temperature range 7-20 degrees C at pH 5.0, equivalent to the isoelectric point (IEP). The molecular-weight profile remained unchanged at 37 degrees C (approx.) in the pH range 5-7. When the gelatin solutions were mixed with ethanol, higher-molecular-weight fractions (microgel, delta and zeta fractions, all with molecular weights > 700 kDa) precipitated at ethanol concentrations lower than those required to precipitate the lower molecular weight material ( < 700 kDa), with maximum precipitation occurring close to the isoelectric point (pH 5.0). The molecular weight profile of gelatin in solution is evidently critically affected in a time-dependent manner by both pH and temperature. These two factors influence the noncovalent interactions responsible for the molecular structure of gelatin. The molecular weight profiles, in turn, affect the phase behaviour of gelatin in hydroalcoholic solutions. Systematically investigating the effect of time, temperature, pH and ethanol concentration on the molecular-weight-distribution profile of a gelatin solution enabled a robust method to be developed for the preparation of colloidal dispersions of non-aggregated gelatin nanoparticles 220-250 nm in diameter. This contrasts with the multiparticulate aggregates produced by earlier literature methods.

This paper describes the use of oxidized dextran as a cross-linker for the preparation of gelatin microspheres. Microspheres were obtained by a thermal gelation method and their dissolution kinetic was examined. In order to find evidence of sugar mediated cross-linking, swelling tests and gelatin microspheres dissolution experiments were performed. The obtained results indicated that oxidized dextran can form a cross-linked gelatin network which can reduce the dissolution of gelatin. More interestingly, gelatin microspheres treated by both native and oxidized dextran slow down, even if to a different extent, the release of the antitumor drug TAPP-Br used as a model compound. Taken together, our results suggest that oxidized dextran could be an interesting means to cross-link gelatin microspheres allowing the use of this delivery formulation for controlled release of drugs.