Self-Assembled Short Peptide Nanostructures: ‘’Dipeptides’’

Dipeptides are short peptide molecules formed by the peptide bond between two amino acids, and they play significant roles in various biological processes (such as protein synthesis, nutrient absorption, cellular signaling, immune response). Short peptides have a prominent place in the design of self-assembling materials. In particular, dipeptides have gained considerable attention in the field of biotechnology as a type of self-organizing nanostructure due to their low cost, simplicity of synthesis, biocompatibility, and tunability of functionality. However, there is limited knowledge about peptide and protein-based nanostructures in the literature. Therefore, more information is needed on dipeptide nanostructures, especially in terms of their potential applications for biomedical purposes. This review focuses on dipeptide nanostructures, particularly their potential uses in biomedical applications, and provides a broader perspective on the advantages, challenges, synthesis, interactions, and applications of these nanostructures

Preparation of composite membrane embedded with Cu2+ attached O-carboxymethly chitosan Schiff base complexes and investigation for protein adsorption performance

Bu çalışma kapsamında, lizozimin etkin bir şekilde ayrılması için afinite kromatografisi yöntemleri arasında, son yıllarda yoğun bir uygulama alanı bulan, İmmobilize Metal Afinite Kromatografisi (İMAK) kullanılmıştır. Bu amaçla, suda çözünebilir O-karboksimetil kitosan Schiff bazı-4a kompleksleri sentezlenmiştir ve Cu2+ iyonu takılmıştır. Monomer olarak poli(2-hidroksietil metakrilat), çapraz bağlayıcı olarak N,Nˈ-metilen-bis-akrilamid, başlatıcı/aktivatör olarak N,N,N´,N´- tetrametilen diamin (TEMED)/amonyum persülfat (APS) kullanılmış ve radikal kriyokopolimerizasyon yöntemiyle 5 mL'lik plastik tüplerde sentezlenmiştir. Hazırlanan Cu2+ takılı O-karboksimetil kitosan Schiff bazı kompleksleri gömülü kompozit kriyojel şişme testleri, taramalı elektron mikroskobu (SEM), FT-IR ile karakterize edilmiştir. Sulu çözeltiden lizozim adsorpsiyonuna pH'nın, başlangıç protein derişiminin, akış hızının, iyonik şiddetin ve sıcaklığın etkisi incelenmiştir. Maksimum adsorpsiyon pH 8 fosfat tamponunda, 3 mg/mL başlangıç lizozim derişiminde, 0,5 mL/dak akış hızında ve 25 oC ortam sıcaklığında 103,3 mg/g partikül olarak gerçekleşmiştir. Ayrıca, süpermakro-gözenekli kriyojellere proteinin defelarca adsorplanıp desorplanabildiği belirlenmiştir.In this study, Immobilized Metal Affinity Chromatograph (IMAC) finding a wide application area among affinity chromatography methods was used for removal of lysozyme efficiently from aqueous solutions. For this purpose, water soluble Ocarboxymethyl chitosan complexes was synthesised, Cu2+ ions was attached onto them. The composite cryogels were prepared by free radical polymerization using N,N,N´,N´-tetramethylene diamine (TEMED) and ammonium persulfate (APS) as initiator/activator pair, N,N´-methylene-bis-acrylamide (MBAAm) as cross-linker in a plastic syringe of 5 mL. Prepared composit cryogel embedded with Cu2+ -attached Ocarboxymethyl chitosan Schiff base complexes was characterized by FT-IR, SEM, swelling tests measurements. The effect of pH, ionic strength, initial lysozyme concentration, temparature and flow rate on adsorption were investigated. The maximum amount of lysozyme adsorption from aqueous solution was at 103,3 mg/g particles in phosphate buffer at pH 8 with initial lysozyme concentration of 3 mg/mL. On the other hand, the most efficent adsorption was carried out at 0,5 mL/min, at 25oC temparature. It was also observed that enzyme could be repeatedly adsorbed and desorbed on the Cu2+ attached O-carboxymethyl chitosan Schiff base complexes croygels

Development of quartz crystal microbalance (QCM) based biosensor for determination of lactons by molecular imprinting methods

Yüksek canlılar birbirleriyle iletişim için ses ve sözcükleri kullanırken, bakteriler bu işlevi bazı iletişim molekülleri ile sağlamaktadırlar. Bu iletişim molekülleri, "Quorum Sensing" (QS) veya çevreyi algılama sistemi tarafından üretilen ve bakterilerce iletişimde kullanılan kimyasallar olarak ifade edilmektedir. Gram-negatif bakterilerin ana sinyal molekülleri olan N-açil-homoserin-laktonlar (AHL) patojenitede etkin virülans faktörlerini eksprese edebilirler ve dolayısıyla Quorum Sensing sistemi, bu virülans faktörlerinin belirlenmesinde önemli bir rol oynayabilir. Düşük konsantrasyonlarda üretilen AHL'lerin genel tekniklerle tespit edilmesi oldukça zordur. Bu çalışma kapsamında; QCM çipler üzerinde 6 karbonlu laktona (C6-HSL) özgü moleküler baskılanmış polimerik membranlar hazırlanıp; moleküler baskılanmış QCM çipler ile sulu ortamdan yüksek hassasiyette C6-HSL tanımlanması yapılmıştır. Moleküler baskılanmış yapıyı oluşturmak için, N-Heksanoil-L-homoserin lakton (C6-HSL) (hedef molekül) ve fonksiyonel monomerin (akrilamid) ikincil kuvvetlerle ön-organizasyonunun ardından, monomer olarak 2-hidroksietil metakrilat (HEMA), çapraz bağlayıcı olarak etilen glikol dimetakrilat (EGDMA), başlatıcı olarak azobisizobutironitril (AIBN) eşliğinde UV başlatıcılı polimerizasyon ile C6-HSL baskılanmış polimerik membranlar sentezlenmiştir. Sentezlenen polimerlerin karakterizasyonu AFM, SEM, temas açısı ve FTIR-ATR spektrofotometre analizleri ile gerçekleştirilmiştir. C6-HSL-akrilamid arasındaki optimum ön organizasyon (çözücü olarak DMF), pH 7.0'da oluşmuştur. C6-HSL baskılanmış QCM çip yüzeyindeki en yüksek lakton adsorpsiyonu ise 1000 ng/mL Ayrıca, GC-MS sonuçları çalışmalarımızın sonuçlarıyla korelasyon göstermiş ve sentezlenen polimerlerin C6-HSL'ye duyarlılığının olduğunu GC-MS ile de konfirme edilmiştir.While high living organisms use sounds and words to communicate with each other, bacteria provide this function with some communication molecules. These communication molecules are expressed as "Quorum Sensing" (QS) or chemicals produced by the environment sensing system and used by bacteria to communicate. N-acyl-homoserine-lactones (AHL) that are the main signaling molecules of Gram-negative bacteria, may express the pathogenic factors, and the Quorum Sensing system may play an important role in the identification of the being virus. AHLs are produced at low concentrations that are difficult to detect with general techniques. In this study, molecularly imprinted polymeric membranes, which are specific to lactone with 6-carbons (C6-HSL) were prepared on the QCM chips and molecularly imprinted QCM chips were utilized to detect N-Hexanoyl-L-homoserine lactone (C6-HSL) with high sensitivity from the aqueous medium. After pre-oganization of C6-HSL (template molecule) and functional monomer (acrylamide) with the secondary forces to form molecular imprinting structure, C6-HSL imprinted polymeric membrans in the presence of 2-hydroxyethyl methacrylate (HEMA) as monomer, ethylene glycol dimethacrylate (EGDMA) as crosslinker, and azobisisobutyronitrile (AIBN) as initiator were polymerized with the aid of UV-initiated polymerization. Characterization of the synthesized polymers were come true by AFM, SEM, contact angle and FTIR-ATR spectrophotometer analyzes. The optimal pre-organization between the C6-HSL-acrylamide (DMF as solvent) was determined at pH 7.0. The maximum C6-HSL adsorption on the C6-HSL imprinted QCM chip surface was observed at 1000 ng/mL concentration, pH 7.0. Moreover, the GC-MS results correlated with the results of our studies, and they confirmed the sensitivity of synthesized the polymers toward C6-HSL

Detection of N-hexanoyl-L-homoserine lactone via MIP-based QCM sensor: preparation and characterization

While high living organisms use sounds and words to communicate with each other, bacteria provide this function with some communication molecules. These communication molecules are expressed as “Quorum Sensing” (QS) or chemicals produced by the environment sensing system and used by bacteria to communicate. This case revealed that bacteria are talking. N-acyl-homoserine-lactones (AHL), which are the main signaling molecules of gram-negative bacteria, may express the pathogenic factors, and Quorum Sensing (QS) system may play an important role in the identification of the being virus. AHLs are produced at low concentrations that are difficult to detect with general techniques. In this study, molecularly imprinted polymeric membranes, which are specific to lactone with 6-carbons (C6-HSL) were prepared on QCM chips, and molecularly imprinted QCM chips were utilized to detect N-hexanoyl-L-homoserine lactone (C6-HSL) with high sensitivity from the aqueous medium. Characterization of the synthesized polymers were analyzed by AFM, SEM, contact angle and FTIR-ATR spectrophotometer analyzes. The maximum C6-HSL adsorption on the C6-HSL imprinted QCM chip surface was observed at 1000 ng/mL concentration, pH 7.0. Moreover, GC–MS results correlated with the results of our studies, and they confirmed the sensitivity of synthesized polymers toward C6-HSL in solution containing competitor molecules

N-acyl homoserine lactone molecules assisted quorum sensing: effects consequences and monitoring of bacteria talking in real life

Bacteria utilize small signal molecules to monitor population densities. Bacteria arrange gene regulation in a method called Quorum Sensing (QS). The most widespread signalling molecules are N-Acyl Homoserine Lactones (AHLs/HSLs) for Gram-negative bacteria communities. QS plays significant role in the organizing of the bacterial gene that adapts to harsh environmental conditions for bacteria. It is involved in the arrangement of duties, such as biofilm formation occurrence, virulence activity of bacteria, production of antibiotics, plasmid conjugal transfer incident, pigmentation phenomenon and production of exopolysaccharide (EPS). QS obviously impacts on human health, agriculture and environment. AHL-related QS researches have been extensively studied and understood in depth for cell to cell intercommunication channel in Gram-negative bacteria. It is understood that AHL-based QS research has been extensively studied for cell-to-cell communication in Gram-negative bacteria; hence, a comprehensive study of AHLs, which are bacterial signal molecules, is required. The purpose of this review is to examine the effects of QS-mediated AHLs in many areas by looking at them from a different perspectives, such as clinic samples, food industry, aquatic life and wastewater treatment system

“Lab-on-pol” colormatic sensor platforms: Melamine detection with color change on melamine imprinted membranes

There is an urgent need to improve a specific, equipment-free and user friendly technique for detecting melamine in food samples. Here, melamine imprinted polymeric membranes were synthesized, and tested for selectivity in aqueous solutions against cyromazine used as competitor agent, and real milk samples spiked with melamine. Scanning electron microscope, atomic force microscopy, energy-dispersive X-ray and optical profilometer devices were used for characterization. Fe+3 ions were used as marker to obtain color change based on melamine concentration. The color intensity on MIP membranes was monitored by means of a color analysis application (Image J software) via a smartphone. Some obtained results as fallows: Melamine binding to 3D cavities of membrane came true in about 20 min. The linear regression plot showed a correlation coefficient (R2) of 0.995 in the range of 10 μM-50 μM according to Beer Lambert's law. A low concentration of melamine, (e.g., 10 µM) was determined in raw milk. Melamine imprinted polymeric membranes showed 7.575 times more sensitivity for melamine than cyromazine. Limit of detection (LOD) and limit of quantification (LOQ) were computed as 9.9 µM and 30.2 µM, respectively. Here, a new kind of smart polymer was designed, and successfully applied for the easy, portable and on-site colorimetric analysis via imprinted polymers, and named as “lab-on-pol”system. HPLC analysis method was also used to validate this new analysis method

Assessment of a new dual effective combo polymer structure for separation of lysozyme from hen egg white

Water-soluble O-carboxymethyl chitosan (O-CMCS) Schiff base granules were prepared, and Cu2+ ions were decorated. Then, dual effective combo cryogel structures were prepared by free radical polymerization using Cu2+-O-CMCS granules as embedding agent. 2-Hydroxyethyl methacrylate and N,N '-methylene-bis-acrylamide were used as monomer and cross-linker pair, respectively. Prepared combo structures were characterized by FTIR, SEM and swelling tests measurements, and investigated for lysozyme adsorption. Maximum lysozyme adsorption was observed in phosphate buffer of pH 8.0 as 103.3 mg/g with initial lysozyme concentration of 3 mg/mL. On the other hand, the most efficient adsorption was carried out at 0.5 mL/min, at 25 degrees C. It was also observed that combo cryogels could be repeatedly used for adsorption and desorption cycles of lysozyme molecules. The purification efficiency of adsorbent was highlighted as 83.4% with 88.2% purification yield from hen egg white via sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE)...

Alpha-Amylase immobilized composite cryogels: some studies on kinetic and adsorption factors

*İnanan, Tülden ( Aksaray, Yazar )Stability of enzymes is a significant factor for their industrial feasibility. alpha-Amylase is an important enzyme for some industries, i.e., textile, food, paper, and pharmaceutics. Pumice particles (PPa) are non-toxic, natural, and low-cost alternative adsorbents with high adsorption capacity. In this study, Cu2+ ions were attached to pumice particles (Cu2+-APPa). Then, Cu2+-APPa embedded composite cryogel was synthesized (Cu2+-APPaC) via polymerization of gel-forming agents at minus temperatures. Characterization studies of the Cu2+-APPaC cryogel column were performed by X-ray fluorescence spectrometry (XRF), scanning electron microscopy (SEM), and Brunauer, Emmett, Teller (BET) method. The experiments were carried out in a continuous column system. alpha-Amylase was adsorbed onto Cu2+-APPaC cryogel with maximum amount of 858.7 mg/g particles at pH 4.0. Effects of pH and temperature on the activity profiles of the free and the immobilized alpha-amylase were investigated, and results indicate that immobilization did not alter the optimum pH and temperature values. k(cat) value of the immobilized alpha-amylase is higher than that of the free alpha-amylase while K-M value increases by immobilization. Storage and operational stabilities of the free and the immobilized alpha-amylase were determined for 35 days and for 20 runs, respectively

Inhibition of bacterial adhesion by epigallocatechin gallate attached polymeric membranes

Microbial adhesion and formation of biofilms cause a serious problem in several areas including but not limited to food spoilage, industrial corrosion and nosocomial infections. These microbial biofilms pose a serious threat to human health since microbial communities in the biofilm matrix are protected with exopolymeric substances and difficult to eradicate with antibiotics. Hence, the prevention of microbial adhesion followed by biofilm formation is one of the promising strategies to prevent these consequences. The attachment of antimicrobial agents, coatings of nanomaterials and synthesis of hybrid materials are widely used approach to develop surfaces having potential to hinder bacterial adhesion and biofilm formation. In this study, epigallocatechin gallate (EGCG) is attached on p(HEMA-co-GMA) membranes to prevent the bacterial colonization. The attachment of EGCG to membranes was proved by Fourier-transform infrared spectroscopy (FT-IR). The synthesized membrane showed porous structure (SEM), and desirable swelling degree, which are ideal when it comes to the application in biotechnology and biomedicine. Furthermore, EGCG attached membrane showed significant potential to prevent the microbial colonization on the surface. The obtained results suggest that EGCG attached polymer could be used as an alternative approach to prevent the microbial colonization on the biomedical surfaces, food processing equipment as well as development of microbial resistant food packaging systems