Methylene Blue Release Research Articles

Methylene Blue Solid Alginate Gels for Photodynamic Therapy: The Peculiarities of Production and Controlled Release of the Dye

The purpose of this work is to establish the influence of the nature of solid alginate gels (alginic acid, AAG; calcium alginate, CAG) and the conditions of methylene blue (MB) introduction to alginate matrices upon its release into aqueous media. MB is an active photosensitizer, which is used in the photodynamic therapy of tumors and purulent wounds. Solid alginate gels based on AAG and CAG were obtained by adding hydrochloric acid and calcium chloride to sodium alginate. The dye was introduced into the matrix either at the stage of gelation or by immersing the gel in an aqueous solution of the dye. It has been shown that the strength of the dye’s attachment to AAG is higher than that of CAG, which leads to a higher rate of MB release from CAG into aqueous media. It has also been shown that, when introduced at the stage of gel formation, MB is released into both the water and buffer solutions. When MB is introduced by gel immersion into an MB solution, the dye may be released only into salt solutions. An alginate gel with immobilized MB can be used as a solid photosensitizing system with the controlled release of the photoactive agent into the wound cavity for photodynamic treatment.

Tannic Acid-Based Self-Assembling Nanocarriers with Antiphotobleaching and Controlled Releasing Properties for Collaborative Near-Infrared Photothermal/Photodynamic Therapy.

Near-infrared (NIR) organic materials have been widely developed for tumor phototherapy due to their deep tumor penetration, good biodegradability, and high photothermal conversion (PCE). However, most of the NIR organic dyes are easily destroyed by photooxidation due to their big and long conjugated structures, such as cyanine dyes. Under light irradiation, the reactive oxygen species (ROS) produced by these NIR dyes can easily break their conjugated skeleton, resulting in a dramatic decrease in phototherapeutic efficiency. Herein, an NIR organic dye cyanine dye (CyS) and a photosensitizer methylene blue (MB) were chosen to prepare nanocarrier CMTNPs by facile self-assembling with a natural antioxidant, tannic acid (TA). TA can greatly enhance the stability of NIR cyanine dyes by scavenging ROS. Furthermore, CMTNPs have a character of pH/thermal dual response, allowing for controlled release of MB in the slightly acidic tumor environment during photothermal therapy. The released MB can turn on both fluorescence and photodynamic therapy effects. In vitro and in vivo experiments demonstrated the remarkable tumor ablation ability of CMTNPs. Thus, our study provided an antiphotobleaching and controlled release photosensitizer strategy through the introduction of antioxidant TA into the nanocarrier for efficient collaborative photothermal/photodynamic therapy.

Nanozyme coating-gated multifunctional COF composite based dual-ratio enhanced dual-mode sensor for highly sensitive and reliable detection of organophosphorus pesticides in real samples

The reliable detection of organophosphorus pesticides (OPs) in complex matrices remains an enormous challenge due to inevitable interference of sample matrices and testing factors. To address this issue, we designed a nanozyme-coated mesoporous COF with guest molecule loading, and successfully used it to construct a dual-ratio dual-mode sensor through target-regulated signal generation. The multifunctional COF-based composite (MB/COF@MnO2, MCM) featured high loading of methylene blue (MB), oxidase-like MnO2 coatings as gatekeepers, and specific recognition of thiocholine (TCh). TCh, a regulator produced from acetylcholinesterase (AChE)-catalyzed hydrolysis of acetylthiocholine, could decompose MnO2 coatings, triggering the release of abundant MB and oxidation of few o-phenylenediamine (OPD). OPs, strong inhibitors of AChE, could restrain TCh production and MnO2 decomposition, thereby controlling the release of less MB and oxidation of more OPD. This regulation boosted the dual-ratio dual-mode assay of OPs by using the released MB and oxidized OPD in the solution as testing signals, measured by both fluorescent and electrochemical methods. Experimental results demonstrated the sensitive detection of dichlorvos with LODs of 0.083 and 0.026 ng/mL via the fluorescent/electrochemical mode, respectively. This study represented a creative endeavor to develop dual-ratio dual-mode sensors for OPs detection in complex samples, offering high sensitivity, excellent selectivity, and good reliability.

Modulation of animal and plant tissue growth with collagen‐starch‐organic molybdenum networks hydrogel biomatrices

AbstractThe development of hydrogel biomatrices with potential to modulate animal and plant tissue growth is ongoing. In this study, molybdenum bio‐metal–organic frameworks (MOFs) (Mo‐bioMOFs) incorporating essential amino acids such as l‐histidine (Mo‐His), l‐phenylalanine (Mo‐Phe), and l‐tryptophan (Mo‐Trp) were encapsulated in semi‐interpenetrating polymer network (semi‐IPN) hydrogels composed of collagen and starch. The structure and properties of these materials show dependence on the amino acid that constitutes the Mo‐bioMOFs. The biomatrices have a semi‐crystalline surface with increased porosity when using Mo‐His; this system also benefits swelling. Increased crosslinking, acceleration in gelation, and mechanical improvement are observed for the system based on Mo‐Phe. Methylene blue release experiments were conducted, demonstrating that matrices including Mo‐bioMOFs exhibit controlled release profiles, indicating highly stable retention of Mo‐bioMOFs in the semi‐IPN matrix. The biomatrices enhance the metabolism and proliferation of fibroblasts and monocytes, with Mo‐Trp reducing the secretion of inflammatory cytokines like TNF‐α. The biomatrices exhibit gradual and slow mass loss when exposed to collagenase and commercial vegetable substrates. Both leaf and root cells of tomato plants (Solanum lycopersicum) show increased metabolism and growth when exposed to Mo‐Phe and Mo‐His. Notably, the biomatrix containing Mo‐Phe promotes the most substantial plant growth and foliage after 30 days. These biomatrices have potential applications in chronic wound healing and agriculture.

Visible Light-Gating Responsive Nanochannel for Controlled Release of the Fungicide.

Fungicides have been widely used to protect crops from the disease of pythium aphanidermatum (PA). However, excessive use of synthetic fungicides can lead to fungal pathogens developing microbicide resistance. Recently, biomimetic nano-delivery systems have been used for controlled release, reducing the overuse of fungicides, and thereby protecting the environment. In this paper, inspired by chloroplast membranes, visible light biomimetic channels are constructed by using retinal, the main component of green pigment on chloroplasts in plants, which can achieve the precise controlled release of the model fungicide methylene blue (MB). The experimental results show that the biomimetic channels have good circularity after and before light conditions. In addition, it is also found that the release of MB in visible light by the retinal-modified channels is 8.78 µmol·m-2·h-1, which is four times higher than that in the before light conditions. Furthermore, MB, a bactericide drug model released under visible light, can effectively inhibit the growth of PA, reaching a 97% inhibition effect. The biomimetic nanochannels can realize the controlled release of the fungicide MB, which provides a new way for the treatment of PA on the leaves surface of cucumber, further expanding the application field of biomimetic nanomembrane carrier materials.

Polydopamine-Coated Liposomes for Methylene Blue Delivery in Anticancer Photodynamic Therapy: Effects in 2D and 3D Cellular Models.

Photodynamic therapy (PDT) is a therapeutic option for cancer, in which photosensitizer (PS) drugs, light, and molecular oxygen generate reactive oxygen species (ROS) and induce cell death. First- and second-generation PSs presented with problems that hindered their efficacy, including low solubility. Thus, second-generation PSs loaded into nanocarriers were produced to enhance their cellular uptake and therapeutic efficacy. Among other compounds investigated, the dye methylene blue (MB) showed potential as a PS, and its photodynamic activity in tumor cells was reported even in its nanocarrier-delivered form, including liposomes. Here, we prepared polydopamine (PDA)-coated liposomes and efficiently adsorbed MB onto their surface. lipoPDA@MB vesicles were first physico-chemically characterized and studies on their light stability and on the in vitro release of MB were performed. Photodynamic effects were then assessed on a panel of 2D- and 3D-cultured cancer cell lines, comparing the results with those obtained using free MB. lipoPDA@MB uptake, type of cell death induced, and ability to generate ROS were also investigated. Our results show that lipoPDA@MB possesses higher photodynamic potency compared to MB in both 2D and 3D cell models, probably thanks to its higher uptake, ROS production, and apoptotic cell death induction. Therefore, lipoPDA@MB appears as an efficient drug delivery system for MB-based PDT.

K+ Ions Crosslinked Kappa-Carrageenan/Methylene Blue Composite Film. Part-1: Synthesis, Characterization and Application as Controlled Release Device for Photodynamic Therapy Application

K+ ions crosslinked (KC/MB) Methylene blue photosensitizer loaded composite film is prepared for photodynamic therapy (PDT) application as Photosensitizer released by composite film can conveniently be controlled by using different quantities of K+ ions and this application is based on dynamic interaction between light with suitable wavelength, photosensitizer and molecular oxygen, promoting the death of the target tissue or bacterial cells. In this work, the Methylene Blue (MB) loaded Carrageenan polymeric film was prepared by the method of direct addition of MB into pre-polymerization solution of Carrageenan (KC). This composite film and plain KC film were characterized by FTIR, XRD and SEM analysis. The characteristic peaks of MB photosensitizer were obtained in FTIR spectrum of composite film. The composite film KC/MB shows prominence of amorphous nature may be due to MB is present in very small quantity. The SEM analysis reveals that the composite film (KC/MB) having much more smooth surface texture throughout the film. Finally, the result of effect of variation in degree of crosslinking on amount of MB release is, as the amount of K+ ions used to crosslink the film increases, MB release decreases.

Electrochemical biosensor for rapid and sensitive monitoring of sulfadimethoxine based on nanoporous carbon and aptamer system

In this study, a straightforward electrochemical aptasensor was developed to detect sulfadimethoxine (SDM). It included a glassy carbon electrode decorated by boron nitride quantum dots (BNQDs) and aptamer-functionalized nanoporous carbon (APT/CZ). CZ was first synthesized by calcinating a zeolitic imidazolate framework (ZIF-8). Then, the electroactive dye methylene blue (MB) was entrapped inside its pores. By attaching aptamer to the CZ surface, APT/CZ acted as a bioguard, which prevented the MB release. Therefore, the electrochemical signal of the entrapped MB was high in the absence of SDM. Introducing SDM caused the conformation of aptamers to change, and a large number of MB was released, which was removed by washing. Therefore, the detection strategy was done based on the change in the electrochemical signal intensity of MB. The aptasensor was applied to detect SDM at a concentration range of 10−17 to 10−7 M with a detection limit of 3.6 × 10−18 M.

In Situ Single-Cell Bacterial Imaging Provides Mechanistic Insight into the Photodynamic Action of Photosensitizer-Loaded Hydrogels.

Hydrogels, three-dimensional hydrophilic polymeric networks with high water retaining capacity, have gained prominence in wound management and drug delivery due to their tunability, softness, permeability, and biocompatibility. Electron-beam polymerized poly(ethylene glycol) diacrylate (PEGDA) hydrogels are particularly useful for phototherapies such as antimicrobial photodynamic therapy (aPDT) due to their excellent optical properties. This work takes advantage of the transparency of PEGDA hydrogels to investigate bacterial responses to aPDT at the single-cell level, in real-time and in situ. The photosensitizer methylene blue (MB) was loaded in PEGDA hydrogels by using two methods: reversible loading and irreversible immobilization within the 3D polymer network. MB release kinetics and singlet oxygen generation were studied, revealing the distinct behaviors of both hydrogels. Real-time imaging of Escherichia coli was conducted during aPDT in both hydrogel types, using the Min protein system to report changes in bacterial physiology. Min oscillation patterns provided mechanistic insights into bacterial photoinactivation, revealing a dependence on the hydrogel preparation method. This difference was attributed to the mobility of MB within the hydrogel, affecting its direct interaction with bacterial membranes. These findings shed light on the complex interplay between hydrogel properties and the bacterial response during aPDT, offering valuable insights for the development of antibacterial wound dressing materials. The study demonstrates the capability of real-time, single-cell fluorescence microscopy to unravel dynamic bacterial behaviors in the intricate environment of hydrogel surfaces during aPDT.

Evaluation of antimicrobial photodynamic action of a pluronic and pectin based film loaded with methylene blue against methicillin resistant Staphylococcus aureus

Antimicrobial wound dressings play a crucial role in treatment of wound infections. However, existing commercial options fall short due to antibiotic resistance and the limited spectrum of activity of newly emerging antimicrobials against bacteria that are frequently encountered in wound infections. Antimicrobial photodynamic therapy (aPDT) is very promising alternative therapeutic approach against antibiotic resistant microbes such as methicillin resistant Staphylococcus aureus (MRSA). However, delivery of the photosensitizer (PS) homogeneously to the wound site is a challenge. Though polymeric wound dressings based on synthetic and biopolymers are being explored for aPDT, there is paucity of data regarding their in vivo efficacy. Moreover, there are no studies on use of PS loaded, pluoronic (PL) and pectin (PC) based films for aPDT. We report development of a polymeric film for potential use in aPDT. The film was prepared using PL and PC via solvent casting approach and impregnated with methylene blue (MB) for photodynamic inactivation of MRSA in vitro and in vivo. Atomic force microscopic imaging of the films yielded vivid pictures of surface topography, with rough surfaces, pores, and furrows. The PL:PC ratio (2:3) was optimized that would result in an intact film but exhibit rapid release of MB in time scale suitable for aPDT. The film showed good antibacterial activity against planktonic suspension, biofilm of MRSA upon exposure to red light. Investigations on MRSA infected excisional wounds of mice reveal that topical application of MB loaded film for 30 min followed by red light exposure for 5 min (fluence; ∼30 J cm−2) or 10 min (fluence; ∼60 J cm−2) reduces ∼80% or ∼92% of bioburden, respectively. Importantly, the film elicits no significant cytotoxicity against keratinocytes and human adipose derived mesenchymal stem cells. Taken together, our data demonstrate that PS-loaded PL-PC based films are a promising new tool for treatment of MRSA infected wounds.

An acidity-triggered aggregation nanoplatform based on degradable mesoporous organosilica nanoparticles for precise drug delivery and phototherapy of focal bacterial infection.

It is crucial to precisely strike the bacterially infected area and avoid damaging healthy tissue in bacterial infection treatment. Herein, we report an acidity-triggered aggregation antibacterial nanoplatform based on biodegradable mesoporous organic silica nanoparticles (MON NPs). The surface of MON NPs modified with polydopamine (PDA) encapsulated ciprofloxacin (CIP) and methylene blue (MB) and was then further grafted with glycol chitosan to obtain MB/CIP@MON-PDA-GCS NPs (MCMPG NPs). In the bacterial infection environment with acidic characteristics, glycol chitosan (GCS) becomes positively charged. Consequently, the positively charged acidity-triggered GCS enables MCMPG NPs to accumulate on the negatively charged bacterial surfaces in the infected area and not in healthy tissue. The targeted method allows for the precise release of CIP and MB, ensuring the spatial accuracy of photodynamic therapy (PDT) and photothermal therapy (PTT) for effective bacteria-specific treatment.

Controlled electroactive release from solid-state conductive elastomer electrodes

This work highlights the development of a conductive elastomer (CE) based electrophoretic platform that enables the transfer of charged molecules from a solid-state CE electrode directly to targeted tissues. Using an elastomer-based electrode containing poly (3,4-ethylenedioxythiophene) nanowires, controlled electrophoretic delivery of methylene blue (MB) and fluorescein (FLSC) was achieved with applied voltage. Electroactive release of positively charged MB and negatively charged FLSC achieved 33.19 ± 6.47 μg release of MB and 22.36 ± 3.05 μg release of FLSC, a 24 and 20-fold increase in comparison to inhibitory voltages over 1 h. Additionally, selective, and sequential release of the two oppositely charged molecules from a single CE device was demonstrated, showing the potential of this device to be used in multi-drug treatments.

A sequential sustained-release hydrogel with potent antimicrobial, anti-inflammatory, and osteogenesis-promoting properties for the treatment of periodontitis

Periodontitis is a pathological disorder characterized by inflammation and tissue destruction; it is primarily attributed to bacterial infection and immune responses. Nevertheless, existing strategies for drug delivery in periodontal treatment are insufficient to accommodate the intricate anatomical morphology of the periodontium and the complex oral environment. Furthermore, the disordered release of antibacterial agents and bone-promoting substances are not conducive to the natural healing of periodontal tissues, thus resulting in suboptimal therapeutic outcomes for periodontitis. In this study, we successfully co-loaded methylene blue (MB) and poly(lactic-co-glycolic acid) microspheres encapsulating Sema3A into a dopamine-grafted sodium alginate hydrogel (SA-DA). Experimental evidence indicates that MB/Sema3A@SA-DA exhibits favorable injectability, adhesion, and compression resistance characteristics, thus allowing it to adapt to the intricate therapeutic conditions of the oral cavity. The prompt release of MB (within 14 h) demonstrates its high antibacterial efficacy against periodontal pathogens upon exposure to 660 nm light, thereby establishing a microenvironment conducive to osteogenesis devoid of bacterial interference. Furthermore, the protracted release of Sema3A (within 28 d) shows noteworthy osteogenic capabilities and facilitates the polarization of macrophages toward the M2 phenotype. In a rat model of periodontitis, MB/Sema3A@SA-DA can be perfectly applied in situ to local periodontal lesions, and the sequential release of MB and Sema3A effectively achieved antibacterial, anti-inflammatory, and osteogenic effects. This therapeutic system avoids the abuse of antibiotics, surgical trauma, and repetitive administration. Hence, MB/Sema3A@SA-DA emerges as a safe, effective, minimally invasive, comfortable, and cost-effective treatment strategy with considerable potential for clinical implementation in periodontitis management.

Dual-mode transfer response based on electrochemical and fluorescence signals for the detection of amyloid-beta oligomers (AβO).

An aptamer sensor has been developedutilizing a dual-mode and stimuli-responsive strategy for quantitative detection of AβO (amyloid-beta oligomers) through simultaneous electrochemical and fluorescence detection. To achieve this, we employed UIO-66-NH2 as a carrier container to load MB (Methylene Blue), and Fe3O4 MNPs (iron oxide magnetic nanoparticles) with aptamer (ssDNA-Fe3O4 MNPs) fixed on their surface for biological gating. The ssDNA-Fe3O4 MNPs were immobilized onto the surface of UIO-66-NH2 through hydrogen bonding between the aptamer and the -NH2 group on the surface of UIO-66-NH2, thereby encapsulating MB and forming ssDNA-Fe3O4@MB@UIO-66-NH2. During the detection of AβO, the aptamer selectively reacted with AβO to form the AβO-ssDNA-Fe3O4 complex, leading to its detachment from the surface of UIO-66-NH2. This detachment facilitated the release of MB, enabling its electrochemical detection. Simultaneously, the AβO-ssDNA-Fe3O4 complex was efficiently collected and separated using a magnet after leaving the container's surface. Furthermore, the addition of NaOH facilitated the disconnection of biotin modifications at the 3' end of the aptamer from the avidin modifications on the Fe3O4 MNPs. Consequently, the aptamer detached from the surface of Fe3O4 MNPs, resulting in the restoration of fluorescence intensity of FAM (fluorescein-5'-carboxamidite) modified at its 5' end for fluorescence detection. The dual-mode sensor exhibited significantly enhanced differential pulse voltammetry signals and fluorescence intensity compared to those in the absence of AβO. The sensor demonstrated a wide detection range of 10 fM to 10 μM, with a detection limit of 3.4 fM. It displayed excellent performance in detecting actual samples and holds promising prospects for early diagnosis of Alzheimer's disease.

Pilot Formulation Study of Ph-sensitive Gels

Abstract Drugs remain for a short time on mucus membranes, such as oral, ocular, or nasal mucus, which are washed with physiological fluids. One of the possibilities to overcome this obstacle is the application of solutions that, due to the physiological environment or stimulus, turn into more viscous gels. These gels often also have mucoadhesive properties and the drug is released from them for a longer period. Carbomer 940 (C940), polycarbophil (PCP), and chitosan (CH) are gel-forming excipients, and the consistency of their solutions changes due to the concentration of protons (pH); therefore, they are referred to as pH-sensitive gelling agents. The aim of this study was to prepare pH-sensitive solutions that form gels in the pH of the oral cavity. We prepared water solutions with various concentrations of gel-forming excipients and evaluated the appearance, pH of the solution, injectability of the solution, and pH of gelation. By determining the pH of gelation, suitable concentrations (w/w) of the used polymers were found, namely, 0.1% C940, 0.225% PCP, and 2.5% CH with medium molecular weight (CHM). The 0.1% C940 and 0.225% PCP solutions were injectable through the syringe with the smallest 0.5 mm needle diameter. The 2.5% CHM solution was not injectable even through the syringe with the largest 0.8 mm needle diameter. Solgels prepared at the determined concentrations were evaluated by a dissolution test in a pH 6.8 phosphate buffer using methylene blue (MB) as a model substance. After 60 min of dissolution, 77.04% ± 5.94%, 48.85% ± 5.74%, and 77.35% ± 4.98% of MB were released from samples with C940, PCP, and CHM, respectively. The dissolution of the C940 and CHM samples took place according to the Korsmeyer–Peppas kinetic model (R2 0.999 ± 0.001, 0.978 ± 0.003) and of the PCP samples took place according to the first-order model (R2 0.994 ± 0.001). The 0.225% PCP pH-sensitive gel showed the most advantageous properties in terms of injectability, pH gelation, and prolonged release of MB.

Preparation of Magnetic Molecularly Imprinted Polymer for Methylene Blue Capture

Hybrid magnetic molecularly imprinted polymers (MMIPs) have the advantages of the technology of molecularly imprinted material and magnetic nanoparticles. The magnetic properties of MMIPs allow easy magnetic separation of various pollutants and analytes. A convenient and simple approach has been developed for the preparation of MMIPs based on polyamide (nylon-6) and magnetic nanoparticles. The polymer matrix was formed during the transition of nylon-6 from a dissolved state to a solid state in the presence of template molecules and Fe3O4 nanoparticles in the initial solution. Methylene blue (MB) was used as a model imprinted template molecule. The MMIPs exhibited a maximum adsorption amount of MB reached 110 µmol/g. The selectivity coefficients toward MB structural analogs were estimated to be 6.1 ± 0.6 and 2.1 ± 0.3 for 15 μM hydroxyethylphenazine and toluidine blue, which shows high MMIP selectivity. To prove the MMIPs’ specificity in MB recognition, magnetic nonimprinted polymers (MNIPs) were synthesized without the presence of a template molecule. MMIPs exhibited much higher specificity in comparison to MNIPs. To show the remarkable reusability of the MMIP sorbent, more than four MB absorption and release cycles were carried out, demonstrating almost the same extraction capacity step by step. We believe that the proposed molecular imprinting technology, shown in the MB magnetic separation example, will bring new advances in the area of MMIPs for various applications.

Toxic Effects of Methylene Blue on the Growth, Reproduction and Physiology of Daphnia magna.

Methylene blue (MB) is a disinfectant used in aquaculture to prevent and treat fish diseases. However, the release of MB can pose a risk to the receiving water bodies. Zooplankton are the most sensitive organisms among aquatic life. Hence, this study examined the acute and chronic toxic effects of MB on zooplankton using Daphnia magna (D. magna) as a test organism to provide basic data for risk assessment. The results show that 48 h-EC50 and 24 h-LC50 were 61.5 ± 2.3 and 149.0 ± 2.2 μg/L, respectively. Chronic exposure to MB affected the heart rate, beat frequency of the thoracic limbs, and reproductive ability of D. magna at environmental concentrations higher than 4.7 μg/L. The cumulative molts, time to production of the first brood, and total number of living offspring were affected at different MB concentrations, while "abortions" were observed in high-exposure groups. The activity of superoxide dismutase was increased, while glutathione S-transferase activity was stimulated at low concentrations and inhibited at high concentrations. In addition, the malondialdehyde content increased with increasing concentrations of MB. Our findings demonstrate the impact of MB on the reproduction and growth of freshwater species, as well as their physiological responses. These results have implications for establishing guidelines on the use of MB in aquaculture and setting discharge standards.

Synthesis, Swelling, Diffusion and Cationic Dye Adsorption Studies of Semi‐IPN Sodium Alginate/ Poly(HEMA‐co‐MA) Hydrogels

AbstractIn this study, the novel pH‐sensitive s‐IPN consist of sodium alginate integrated with poly(HEMA‐co‐MA) hydrogel matrix are prepared by using two‐step methodology. In the first step, 2‐hydroxyethyl methacrylate (HEMA)/maleic acid (MA) copolymeric hydrogels are prepared by gamma radiation polymerization. Then, poly(HEMA‐co‐MA) hydrogel was immersed in sodium alginate solution (SA) and finally gamma radiation polymerization was carried out. The swelling, pH‐sensivity and diffusion properties of the prepared s‐IPN gels in deionized water and in dye solutions were investigated. Methylene Blue (MB) was used as a model dye. MB adsorption capacities of the hydrogels were found to be 0.26, 0.40 and 13.77 mg MB/g dry gel in PHEMA, P(HEMA‐co‐MA) and s‐IPN SA/P(HEMA‐co‐MA) hydrogels, respectively. MB release data was fitted to various kinetic models to study the dye release behavior. The MB release from all the prepared hydrogels fitted the Korsmeyer‐Peppas model. Swelling, diffusion and MB adsorption properties of the new s‐IPN hydrogel were improved with the inclusion of SA and MA in the gel structure.

Multi-mode label-free biosensor based on methylene blue sensitized C3N4/BiVO4 heterostructure for ultrasensitive detection of miRNA-122

In this work, a multi-mode label-free biosensor based on methylene blue (MB) sensitized C3N4/BiVO4 heterostructure was proposed to achieve ultrasensitive detection of miRNA-122. It was found that MB had a strong photosensitization effect on BiVO4 for the first time, but the adsorption interaction of MB on BiVO4 surface was poor. Therefore, a C3N4/BiVO4 heterostructure with Π-Π conjugate effect was constructed by electrostatic reaction, achieving a large amount of MB adsorption. The photoelectric sensitization amplitude of C3N4/BiVO4 reached two orders compared with pure BiVO4. Moreover, C3N4 displayed excellent electrochemiluminescence (ECL) signals at both negative and positive potentials. It was unexpectedly found that MB could effectively absorb luminescence of C3N4 at positive potential, and an astonishing quenching efficiency reached 98.4 %. In addition, MB can be widely used for electrochemical detection. Therefore, when MB was entrapped in mesoporous silica nanoparticles (MSNs), and capped by DNA, target miRNA-122 can trigger quantitative release of MB. So this work could realize multi-mode detection including photoelectrochemistry (PEC), ECL and differential pulse voltammetry (DPV) by using MB. This biosensor was simple, fast, convenient and accurate, which was promising for biochemical analysis, food safety, and other fields.

Experimental Demonstration of Compact Polymer Mass Transfer Device Manufactured by Additive Manufacturing with Hydrogel Integration to Bio-Mimic the Liver Functions.

In this paper, we designed and demonstrated a stimuli-responsive hydrogel that mimics the mass diffusion function of the liver. We have controlled the release mechanism using temperature and pH variations. Additive manufacturing technology was used to fabricate the device with nylon (PA-12), using selective laser sintering (SLS). The device has two compartment sections: the lower section handles the thermal management, and feeds temperature-regulated water into the mass transfer section of the upper compartment. The upper chamber has a two-layered serpentine concentric tube; the inner tube carries the temperature-regulated water to the hydrogel using the given pores. Here, the hydrogel is present in order to facilitate the release of the loaded methylene blue (MB) into the fluid. By adjusting the fluid's pH, flow rate, and temperature, the deswelling properties of the hydrogel were examined. The weight of the hydrogel was maximum at 10 mL/min and decreased by 25.29% to 10.12 g for the flow rate of 50 mL/min. The cumulative MB release at 30 °C increased to 47% for the lower flow rate of 10 mL/min, and the cumulative release at 40 °C climbed to 55%, which is 44.7% more than at 30 °C. The MB release rates considerably increased when the pH dropped from 12 to 8, showing that the lower pH had a major impact on the release of MB from the hydrogel. Only 19% of the MB was released at pH 12 after 50 min, and after that, the release rate remained nearly constant. At higher fluid temperatures, the hydrogels lost approximately 80% of their water in just 20 min, compared to a loss of 50% of their water at room temperature. The outcomes of this study may contribute to further developments in artificial organ design.