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    Applications of chitosan in prevention and treatment strategies of infectious diseases
    (2024) Sinani, Genada; Sessevmez, Melike; Şenel, Sevda
    Chitosan is the most commonly investigated functional cationic biopolymer in a wide range of medical applications due to its promising properties such as biocompatibility, biodegradability, and bioadhesivity, as well as its numerous bioactive properties. Within the last three decades, chitosan and its derivatives have been investigated as biomaterials for drug and vaccine delivery systems, besides for their bioactive properties. Due to the functional groups in its structure, it is possible to tailor the delivery systems with desired properties. There has been a great interest in the application of chitosan-based systems also for the prevention and treatment of infectious diseases, specifically due to their antimicrobial, antiviral, and immunostimulatory effects. In this review, recent applications of chitosan in the prevention and treatment of infectious diseases are reviewed, and possibilities and limitations with regards to technical and regulatory aspects are discussed. Finally, the future perspectives on utilization of chitosan as a biomaterial are discussed.
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    The efficacy of sustained-release chitosan microspheres containing recombinant human parathyroid hormone on MRONJ
    (Sociedade Brasileira De Pesquisa Odontologica, 2019) Taysi, Aysegul Erten; Cevher, Erdal; Sessevmez, Melike; Olgac, Vakur; Taysi, Nuri Mert; Atalay, Berkem
    Treatment of patients with bisphosphonate usage is a significant concern for oral surgeons because it interferes with jaw bone turnover and regeneration. In case of adverse effects manifesting related to bisphosphonate use, oral surgeons are usually treating and keep the patient's symptoms under control. In this study, we aimed to investigate a new treatment protocol for medication-related osteonecrosis of the jaw (MRONJ). This treatment protocol consisted of administering human parathyroid hormone (hPTH) loaded chitosan microspheres which were prepared by ionotropic gelation method or/and the prepared microspheres were suspended in a poloxamer gel. After in-vitro optimization studies, the efficacy of the chosen formulations was evaluated in-vivo studies. Zoledronic acid was administered daily to forty-eight adult female Sprague-Dawley rats, divided into four experimental groups, at a daily concentration of 0.11 mg/kg over three weeks to induce the MRONJ model. At the end of this period, maxillary left molar teeth were extracted. In the first group, the subjects received no treatment. In the negative control group, poloxamer hydrogel containing empty microspheres were immediately applied to the soft tissues surrounding the extraction socket. The treatment group-1 was treated with local injections of poloxamer hydrogel containing hPTH. The treatment group-2 was treated with a single local injection of poloxamer hydrogel containing hPTH-loaded chitosan microspheres. Both treatment groups received a total of 7 mu g of hPTH at the end of the treatment protocol. Our study demonstrates successful attenuation of MRONJ through a local drug delivery system combined with hPTH, as opposed to previously attempted treatment strategies.
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    Formulation, optimization and in vitro evaluation of polymer-coated liposomes encapsulating nebivolol hydrochloride
    (2023) Sessevmez, Melike; Sinani, Genada; Çevikelli, Tilbe
    Hypertension, also known as high blood pressure, is a serious medical condition that affects billions of people worldwide. Nebivolol hydrochloride, a & beta;1-adrenergic blocking agent, is used by the oral route in the treatment of hypertension and congestive heart failure. However, its lipophilic nature and poor aqueous solubility restricts its oral bioavailability. To overcome limitations related with conventional oral formulations of the drug, uncoated and polymer-coated liposomes were developed and evaluated. Liposomes loaded with nebivolol hydrochloride were prepared by thin-film hydration method and characterized. The influence of chitosan or pluronic (F127) coating on the liposome properties was evaluated in terms of physicochemical characteristics, stability in simulated gastrointestinal fluids, mucin interaction, in vitro drug release and cytotoxicity studies. It was observed that coating the liposomes with either chitosan or pluronic affected the size, surface charge and encapsulation efficiency of the formulations. The surface morphology studies confirmed the vesicular shape of liposomes. The results obtained indicated that both polymer-coated liposome formulations maintained their stability in simulated gastrointestinal fluids and showed significant in vitro interaction with mucin. Polymer-coated liposome formulations showed much better cumulative release of the drug than uncoated liposomes. No aggregation was observed at the end of four-week storage period and low toxicity in Caco-2 cells was measured. The results demonstrated that polymer coating of liposomes could enhance the in vitro release of nebivolol hydrochloride and interaction with mucin following oral administration and might be attractive alternative nanocarriers to traditional oral formulations.
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    Induction of humoral and cell-mediated immunity in mice by chitosan-curdlan composite nanoparticles administered intranasally and subcutaneously
    (Editions de Sante, 2023) Sessevmez, Melike; Sinani, Genada; Okyar, Alper; Alpar, Hazire Oya; Cevher, Erdal
    Infectious diseases seriously threaten human life. The need for novel delivery systems and adjuvants suitable to be used in clinic for antigens remains a challenge. Among various attempts that have been made to provide optimum immune responses for protein antigens with poor immunogenicity, polymeric nanoparticles offer great opportunities. In this study, carboxymethyl curdlan (CMC) as a polyanionic polymer and chitosan chloride (CC) and N-trimethyl chitosan (TMC) as polycationic polymers were synthesised in-house and composite nanoparticles (CC-CMC-BSA and TMC-CMC-BSA) loaded with bovine serum albumin (BSA) as a model antigen were prepared via polyelectrolyte complexation and reported here for the first time. Nanoparticles with an average size ranging from 153 nm to 615 nm, positive surface charge (from +24 mV to +55 mV) and encapsulation efficiency as high as 90% were obtained depending on the concentration of polymers in the formulation. The nanoparticles showed good physical stability for three months and low toxicity in Calu-3 and A549 cells. Furthermore, SDS integrity of antigen was maintained. In vivo studies in mice indicated that nasal and subcutaneous administration of composite nanoparticles could provide long-term humoral and cellular immunity as determined by serum antibody titres (IgG, IgG1, IgG2a) and cytokine (IL-2, IL-4, IL-6, IL-10 and IFN-γ) levels. Elevated sIgA levels after nasal administration of the nanoparticles showed that mucosal immunity was successfully stimulated. These findings suggest that chitosan-curdlan composite nanoparticles show optimum properties to be used as nanovaccine for nasal immunisation of protein antigens.
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    Modified chitosan-based nanoadjuvants enhance immunogenicity of protein antigens after mucosal vaccination
    (Elsevier, 2019) Sinani, Genada; Sessevmez, Melike; Gök, M. Koray; Özgümüş, Saadet; Alpar, H. Oya; Cevher, Erdal
    Nasal vaccination is considered to be an effective and convenient way of increasing immune responses both systemically and locally. Although various nanovaccine carriers have been introduced as potential immune adjuvants, further improvements are still needed before they can be taken to clinical usage. Chitosan-based nanovaccine carriers are one of the most widely studied adjuvants, owing to the ability of chitosan to open tight junctions between nasal epithelial cells and enhance particle uptake as well as its inherent immune activating role. In present study, bovine serum albumin (BSA) loaded nanoparticles were prepared using novel aminated (aChi) and aminated plus thiolated chitosan (atChi) polymers, to further enhance mucoadhesiveness and adjuvanticity of the vaccine system by improving electrostatic interactions of polymers with negatively charged glycoproteins. Nanocarriers with optimum size and surface charge, high encapsulation efficiency of model antigen and good stability were developed. Negligible toxicity was observed in Calu-3 and A549 cell lines. In vivo studies, revealed high levels of systemic antibodies (IgG, IgG(1) and IgG(2a)) throughout the study and presence of sIgA in vaginal washes showed that common mucosal system was successfully stimulated. Cytokine levels indicated a mixed Th1/Th2 immune response. A shift towards cellular immune responses was observed after nasal immunisation with antigen loaded nanoparticle formulations. These nanoparticles exhibit great potential for nasal application of vaccines.
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    Nasal vaccination with poly(beta-amino ester)-poly(D,L-lactide-co-lycolide) hybrid nanoparticles
    (Elsevier Science Bv, 2017) Sinani, Genada; Sessevmez, Melike; Gök, M. Koray; Özgümüş, Saadet; Okyar, Alper; Alpar, H. Oya; Cevher, Erdal
    Mucosal vaccination stimulates both mucosal and systemic immunity. However, mucosal applications of vaccine antigens in their free form generally result in poor systemic immune responses and need adjuvantation. In this study, bovine serum albumin loaded, new hybridised poly(beta-amino ester)-poly( D, Llactide-co-glycolide) nanoparticles were prepared by double emulsion-solvent evaporation method, characterised and evaluated in vivo as nasal vaccine carriers. Cationic spherical particles with a mean size of 240 nm, good physical stability and high encapsulation efficiency were obtained. Protein structure was not affected throughout preparation and minimal toxicity was shown in Calu-3 and A549 cells. Nasal vaccination with these nanoparticles revealed markedly higher humoral immune responses compared with free antigen following intranasal and subcutaneous immunisation. Mucosal immune response was also stimulated and cytokine titres indicated that Th1 and Th2 pathways were successfully activated. This study shows that the formulated hybrid nanoparticles can be a promising carrier for nasal immunisation of poor antigenic proteins. (C) 2017 Elsevier B.V. All rights reserved.
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    Oral tablet formulations containing cyclodextrin complexes of poorly water soluble cefdinir to enhance its bioavailability
    (Elsevier, 2020) Morina, Deniz; Sessevmez, Melike; Sinani, Genada; Mulazimoğlu, Lutfiye; Cevher, Erdal
    Cefdinir (CFD) is an oral cephalosporin antibiotic commonly used in the treatment of community-acquired infections. The oral bioavailability of CFD is limited due to its poor aqueous solubility. Cyclodextrins (CyDs) and their chemically modified derivatives are used in the pharmaceutical field to form inclusion complexes with drug molecules to improve their aqueous solubility as well as stability and to prevent side effects. In this study, CFD was complexed with CyDs such as beta-cyclodextrin (beta-CyD), gamma-cyclodextrin (gamma-CyD), hydroxypropyl-beta-cyclodextrin (HP-beta-CyD), and sulphobutyl ether 7-beta-cyclodextrin (SBE7-beta-CyD) to increase its aqueous solubility and to reduce its side effects without decreasing the antimicrobial activity. Phase solubility studies were performed and the stability constant of the CFD:CyD inclusion complexes was determined. The solubility of CFD was increased after complexation with CyDs as indicated by phase solubility studies, in the order beta-CD < HP-beta-CyD < gamma-CyD < SBE7-beta-CyD, a result that depends on the conditions of complexation formation. Complex formation between CFD and CyDs was evaluated using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and powder x-ray diffractometry (PXRD) studies. The antimicrobial activity of the complexes against Staphylococcus aureus and Escherichia coli strains were evaluated and the strains showed higher susceptibility to CFD:HP-beta-CyD complex. Oral tablet formulations were fabricated using Avicel (R) PH 102 or Ludipress (R) as direct compression agent and magnesium stearate as lubricant. Using CFD:HP-beta-CyD complex in tablets significantly improved the dissolution rate of the drug when compared with that of formulation containing CFD alone.