Surface Amino Research Articles

Controllable Synthesis of Amino-Functionalized Silica Particles via Co-condensation of Tetraethoxysilane and (3-Aminopropyl)triethoxysilane.

Amino-functionalized silica has attracted a great deal of interest due to its high surface reactivity and potential for diverse applications across various fields. While the classical co-condensation method is commonly used to synthesize amino-functionalized silica particles, the mechanism of the reaction between (3-aminopropyl)triethoxysilane (APTES) and tetraethoxysilane under different conditions remains unclear, leading to unexpected self-nucleation or cross-linking between silica particles and consequently hindering rational control over the extent of functionalization. To address this issue, we systematically explored the co-condensation growth mechanism of amino-functionalized silica particles in the Stöber method by investigating the effects of APTES concentration and water content on the hydrolysis and condensation of silanes. The experimental results revealed that APTES could decrease the rate of hydrolysis/condensation, while the moderate water content promoted both the rate of hydrolysis/condensation and the overall quality of the silica particles. Consequently, we successfully demonstrated the rational synthesis of amino-functionalized silica particles with diameters ranging from 213 to 670 nm and a nitrogen content of ≤2.8 wt %. The relationship between the APTES concentration and particle properties exhibited a biphasic trend. At low APTES concentrations (≤2.0 mM), the particle size remained stable while the isoelectric point increased rapidly. Further increasing the APTES concentration from 2.0 to 100.0 mM induced a decrease in particle size due to APTES's inhibitory effect on silica growth, with nitrogen content continuing to increase even after the isoelectric point remained unchanged. These silica particles, featuring varying surface amino group densities, were utilized as matrices for loading Au nanoparticles. The resulting functionalized particles exhibited distinctive catalytic ability in the reduction of 4-nitroaniline, demonstrating significant potential for applications across various fields.

Electrochemical synthesis of multicolor carbon dots with room temperature phosphorescence to thermally activated delayed fluorescence via surface state modulation

Solid-state multicolor carbon dots (CDs) have attracted tremendous attention due to their wide applications. However, the fluorescence quenching of solid-state CDs occurs due to the π-π stacking or energy transfer between adjacent carbon dots. In addition, it is difficult to observe the afterglow of solid-state CDs due to their self-quenching and deliquescence. Here, electrochemically prepared multicolor CDs emit the solid-state fluorescence and afterglow emission with lifetimes up to 657 ms by embedding the CDs into urea matrix. More importantly, the surface amino groups and C = O bonds regulate the afterglow emission of CDs from phosphorescence and thermally activated delayed fluorescence at room temperature. Surface amino groups of multicolor CDs can enhance the spin–orbit coupling, increase the intersystem crossing (ISC) and reverse intersystem crossing (RISC). Thus it can promote the generation of triple excited states and regulate the singlet–triplet energy gap value from 0.384 to 0.026 eV. The formation of covalent bonds stabilizes the single and triple excited states and inhibits the non-radiative recombination, which achieves the enhanced fluorescence and visual afterglow of multicolor CDs. The fluorescence and afterglow CDs can be applied to dual signal imaging and anti-counterfeiting, which broadens the practical applications for solid-state CDs via surface state modulation.

Chitin Nanowhisker/Gold Nanocluster Hybrids with an Excellent Dispersion Stability via Poly(ethylene glycol) Grafting.

Hybrid nanoparticles composed of chitin nanowhiskers (ChNWs) and gold nanoclusters (AuNCs) having an improved stability were prepared. The grafting of monomethoxypoly(ethylene glycol) (mPEG) and subsequent surface adsorption of AuNCs enabled the steric stabilization of ChNW/AuNC hybrids. mPEGs with terminal formyl groups and diethylacetal protecting groups were grafted via in situ deprotection and reductive amination with the surface amino groups (SAGs) of ChNWs. The treatment of chitin with a 30% sodium hydroxide solution improved the SAG contents of the ChNWs obtained from acid hydrolysis, resulting in an enhancement in mPEG grafting. The obtained sterically stabilized ChNW/AuNC hybrids exhibited remarkable dispersion stability at higher AuNC and electrolyte concentrations.

Characterisation Analysis of Sulphur and Phosphorous Doped and Co-doped Graphitic Carbon Nitride (g-C3N4) Materials

Graphitic carbon nitride (g-C3N4) is tailored with doping of different non-metals (Sulphur and Phosphorus). For synthesis through thermal condensation method, the mixtures of urea and dopant with diverse concentrations have been added for preparation of materials. The basic effect of doping and its concentration on the structural morphology and absorption spectra of the samples is investigated in detail. Pure g-C3N4 suffers from high recombination rate of photogenerated electron-hole pairs resulting in low photocatalytic activity. Different techniques like X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transforms infrared (FTIR) spectroscopy, and Photoluminescence spectroscopy (PL) have been used for the characterization. X-ray diffraction studies confirm the formation of the g-C3N4 structure and SEM images reveal crumpled sheets and irregular plate like shapes of the doped graphitic nitride samples. FTIR analysis identify the presence of surface amino (N-H) and water (O-H) groups, cyano terminal group (C≡N), (C≡C), C–N) and (C=N) bonds and breathing mode of the tri-s-triazine units in the samples. PL spectra shows that the sulphur and phosphorus co-doped PSGCN (8 wt.%) sample is better for photocatalytic activity.

Enhanced pyrophosphate detection: Utilizing oPD-derived carbon dots and Fe3+ interactions in a paper strip biosensor

The development of portable, cost-effective, and straightforward DNA biosensors holds immense importance in various fields, including healthcare, environmental monitoring, and food safety. This study contributes to the objective by introducing an innovative approach for synthesizing carbon dots (Cdots) with high quantum yield (QY) and remarkable selectivity for Fe3+ ions. Utilizing o-phenylenediamine as a precursor, the study achieved a straightforward and environmentally friendly synthesis method, enabling the efficient detachment of metal ions from the Cdot surface upon introducing pyrophosphate (PPi). The presence of surface hydroxyl and amino groups facilitated specific Fe3+ recognition. Employing D-optimal response surface methodology, the study optimized Cdot synthesis parameters, identifying temperature and heating time as critical factors influencing QY. Statistical analysis confirmed the model's reliability, predicting maximum QY of 48.8 % with minimal deviation from experimental results. Characterization studies revealed the amorphous nature of Cdots through HR-TEM, XRD, and FTIR analysis. Furthermore, the proposed LAMP/PPi biosensing technique demonstrated higher sensitivity, specificity, and repeatability, with negligible interference from common anions and efficacy across varying pH levels. The limit of detection (LOD) of 0.079 (±0.01) μM and the detection range of 0.1 μM–2 mM underscore the biosensor's practical utility. This study highlights a promising direction for developing paper-based LAMP/PPi biosensors with potential diagnostics and environmental monitoring applications. Significantly, the biosensing technique is applicable to any DNA amplification method generating pyrophosphate (PPi) as a by-product.

Zinc-based organophyllosilicate nanosheets as novel carbonic anhydrase-like nanozyme for efficient CO2 fixation

The unparalleled catalytic activity of carbonic anhydrases (CAs) towards CO2 hydrolysis can potentially contribute to carbon capture, utilization, and storage technology aimed at global decarbonization; however, the high cost and low stability of CAs significantly limit their practical applications. Recently, the development of robust and effective nanozymes with CA-mimicking activity has been proposed as a promising solution to this challenge. Herein, a novel zinc-based organophyllosilicate (ZnAC) nanozyme with CA-like catalytic activity was synthesized by a facile one-pot sol–gel method for the first time, leading to a Zn-O coordination structure that mimicked the catalytic center fragments of natural CAs, with surface amino groups acting as the affinity sites and proton shuttles. The synergistic effect of the two components on the open surface of the layered structure resulted in excellent CA-like activity with a Michaelis–Menten constant (Km) of 4.071 mM, maximum velocity (Vmax) of 0.220 mM/s, and turnover number (kcat) of 11.213 /s at 25 °C and pH=7.5, which were superior to those of most previously reported CA-like nanozymes. The catalytic performance of ZnAC significantly improved with increasing pH and temperature; furthermore, ZnAC exhibited excellent stability, maintaining high catalytic activity after the exposure to extreme temperatures or pH values, eight reaction cycles, and 30 d of storage. Additionally, ZnAC significantly increased the rate of CO2 hydration and the extent of CO2 mineralization and precipitation. This work proposes a new strategy for designing and constructing efficient CA-like nanozymes, providing valuable insights into the structure–activity relationship and new perspectives for the implementation of CO2 fixation.

Far-Red Aggregation-Induced Emission Hydrogel-Reinforced Tissue Clearing for 3D Vasculature Imaging of Whole Lung and Whole Tumor.

Understanding the vascular formation and distribution in metastatic lung tumors is a significant challenge due to autofluorescence, antibody/dye diffusion in dense tumor, and fluorophore stability when exposed to solvent-based clearing agents. Here, an approach is presented that redefines 3D vasculature imaging within metastatic tumor, peritumoral lung tissue, and normal lung. Specifically, a far-red aggregation-induced emission nanoparticle with surface amino groups (termed as TSCN nanoparticle, TSCNNP) is designed for in situ formation of hydrogel (TSCNNP@Gel) inside vasculatures to provide structural support and enhance the fluorescence in solvent-based tissue clearing method. Using this TSCNNP@Gel-reinforced tissue clearing imaging approach, the critical challenges are successfully overcome and comprehensive visualization of the whole pulmonary vasculature up to 2µm resolution is enabled, including its detailed examination in metastatic tumors. Importantly, features of tumor-associated vasculature in 3D panoramic views are unveiled, providing the potential to determine tumor stages, predict tumor progression, and facilitate the histopathological diagnosis of various tumor types.

New Insights into the Dynamics of Poly(amidoamine) Dendrimers with Amino Surface Groups from Segmental Relaxation and Ionic Conductivity

New Insights into the Dynamics of Poly(amidoamine) Dendrimers with Amino Surface Groups from Segmental Relaxation and Ionic Conductivity

Biochar as a highly efficient adsorption carrier for sewage sludge-derived nutrients and biostimulants: component fixation and mechanism

Production of liquid fertilizers containing nitrogenous nutrients and biostimulants from sewage sludge (SS-NB) has been attracting increasing attention due to its excellent fertilization effect and resource recycling attributes. To better understand the functional effects of nutrients and biostimulants in SS-NB on soil, the adsorption capacity and mechanism of straw biochar (SB) and wood chip biochar (WCB) for alkaline and neutral SS-NB components were investigated. The adsorption of total organic carbon (TOC) from alkaline and neutral SS-NB by WCB was 61.14% and 89.73%, respectively, higher than that by SB, which was 56.25% and 83.36%. Moreover, TOC from neutral SS-NB was more readily adsorbed, especially for fulvic and humic acids. SB had a strong adsorption capacity for calcium ions and nitrogen (TKN, nitrate N, protein, amino acid) and released large amounts of P. In addition, WCB and SB showed a strong affinity for macromolecules (proteins) and reducing substances (lignin and lipids) and excellent fixation ability for phytohormones and allelochemicals. However, WCB adsorbed more types of molecular substances than SB while maintaining a high immobilization rate. Analysis of the adsorption mechanism showed that surface amino groups of the biochar were involved in adsorption, while WCB had additionally high adsorption efficiencies through pore adsorption, hydrogen bonding adsorption and pore size-exclusion effects. The study revealed that biochar can be used as an efficient adsorption carrier for SS-NB to improve soil fertility management.Graphical

Urease-producing bacteria enhance the adsorption of Cd on organo-Fe hydroxide coprecipitates

Microorganisms, organic carbon, and iron oxides are important active components in soil that control the availability of heavy metals. In the extensive cultivation areas based on wheat–maize rotation, returning corn straw to the field increases the content of dissolved organic carbon (DOC) in the soil, affecting heavy metal adsorption by iron oxides and thereby threatening the safety of wheat. However, the effects and underlying mechanisms of maize straw-derived DOC on Cd adsorption by ferrihydrite (Fh) are unclear, and the effects of functional strains on Cd adsorption by organo-Fe hydroxide coprecipitates (OFCs) need further study. The effect of DOC on the adsorption of Cd by Fh was studied through batch solution adsorption experiments. Moreover, the mechanisms underlying the synergistic adsorption of Cd by the urease-producing bacterium Enterobacter sp. TJ6 and OFC were studied in adsorption experiments via scanning electron microscopy and X-ray photoelectron spectroscopy. The results showed that DOC inhibited the adsorption of Cd by OFC, while strain TJ6 enhanced the adsorption of Cd by OFC. Fe-OH and Fe-O bonds on the surface of Fh were important Cd adsorption sites. DOC affected the adsorption of Cd by Fe-OH and Fe-O, thereby inhibiting the adsorption of Cd by OFC. DOC also served as a reducing agent, reducing Fe2O3 on the surface of OFC to FeO and thus inhibiting OFC adsorption of Cd. The mechanisms by which strain TJ6 enhanced Cd adsorption by OFC included the following: 1) strain TJ6 utilized its own oxidation ability to oxidize FeO on the surface of OFC to Fe2O3, promoting the secondary precipitation of Cd during the redox process and enhancing the Cd adsorption capacity of OFC; and 2) strain TJ6 immobilized Cd2+ through ion exchange between Cd2+ and H+ in surface amino groups. In conclusion, this study has revealed the mechanism by which urease-producing bacteria regulate the adsorption of Cd by OFC and provides a theoretical basis for safe straw return to Cd-polluted farmland. This study also provides technical approaches and bacterial resources for the remediation of heavy metal-contaminated soil under straw return.

Cadmium biosorption and mechanism investigation using two cadmium-tolerant microorganisms isolated from rhizosphere soil of rice

Microbial remediation of cadmium-contaminated soil offers advantages like environmental friendliness, cost-effectiveness, and simple operation. However, the efficacy of this remediation process relies on obtaining dominant strains and a comprehensive understanding of their Cd adsorption mechanisms. This study identified two Cd-resistant bacteria, Burkholderia sp. 1–22 and Bacillus sp. 6–6, with significant growth-promoting effects from rice rhizosphere soil. The strains showed remarkable Cd resistance up to ∼200 mg/L and alleviated Cd toxicity by regulating pH and facilitating bacterial adsorption of Cd. FTIR analysis showed crucial surface functional groups, like carboxyl and amino groups, on bacteria played significant roles in Cd adsorption. The strains could induce CdCO3 formation via a microbially induced calcium precipitation (MICP) mechanism, confirmed by SEM-EDS, X-ray analysis, and elemental mapping. Pot experiments showed these strains significantly increased organic matter and enzyme activity (e.g., urease, sucrase, peroxidase) in the rhizosphere soil versus the control group. These changes are crucial for restricting Cd mobility. Furthermore, strains 6–6 and 1–22 significantly enhance plant root detoxification of Cd, alleviating toxicity. Notably, increased pH likely plays a vital role in enhancing Cd precipitation and adsorption by strains, converting free Cd into non-bioavailable forms.

Rapid and facile quantification of surface amino groups on chitin nanowhiskers and nanofibers via spectrophotometry

Rapid and facile quantification of surface amino groups on chitin nanowhiskers and nanofibers via spectrophotometry

Functionalized Green Carbon dots for Specific Detection of Copper in Human Serum Samples and Living Cells.

Intracellular copper ion (Cu2+) is irreplaceable and essential in regulation of physiological and biological processes, while excessive copper from bioaccumulation may cause potential hazards to human health. Hence, effective and sensitive recognition is urgently significant to prevent over-intake of copper. In this work, a novel highly sensitive and green carbon quantum dots (Green-CQDs) were synthesized by a low-cost and facile one-step microwave auxiliary method, which utilized gallic acid, carbamide and PEG400 as carbon source, nitrogen source and surface passivation agent, respectively. The decreased fluorescence illustrated excellent linear relationship with the increasing of Cu2+ concentration in a wide range. Substantial surface amino and hydroxyl group introduced by PEG400 significantly improved selectivity and sensitivity of Green-CQDs. The surface amino chelation mechanism and fluorescence internal filtration effect were demonstrated by the restored fluorescence after addition of EDTA. Crucially, the nanosensor illustrated good cell permeability, high biocompatibility and recovery rate, significantly practical application in fluorescent imaging and biosensing of intracellular Cu2+ in HepG-2 cells, which revealed a potential and promising biological applications in early diagnosis and treatment of copper ion related disease.

Triggering Long Persistent Luminescence From Functionalizable Carbon Dots‐in‐Carbon Nitrides Composites Via Production of Deep‐Traps

AbstractDispersible and functionalizable long persistent luminescent (LPL) materials are highly desired for flexible use of LPL in various fields. However, synthesizing metal‐free LPL systems with stable long‐lived intermediates and reactive surface groups, which are key requirements for robust LPL and the ability to be functionalized, has proven to be challenging. Herein, the microwave‐assisted preparation of carbon dots (CDs)‐based LPL materials is demonstrated with abundant surface amino groups via in situ embedding of CDs into carbon nitrides (CNs). The incorporation of CDs leads to the formation of deep traps and promotes exciton transmission between CDs and trap states, contributing to the generation of LPL. By varying the embedded CDs, tunable LPL ranging from blue to yellow can be achieved, with a duration exceeding 10 min. Due to the covalent bonding between CDs and CNs, the materials (named CDs@CNs) exhibit robust LPL under ambient conditions and evenly dispersed in water through ultrasonic treatment. Furthermore, the surface amino groups serve as sites for further modification, allowing for on‐demand performance design and control, such as adjustable hydrophilicity–hydrophobicity for various applications. This work provides new insights into designing superior flexible CDs‐based LPL materials and expanding the domain of metal‐free LPL materials.

Low‐temperature bonding of glasses: The role of plasma‐engrafted surface amino groups

AbstractLow‐temperature (<∼200°C) bonding of glasses is a key technology for utilizing them for microfluidics, optical applications, and microelectromechanical systems. In the present study, bonding strength of SiO2 glasses was examined for those after several surface treatment methods. As a result, it was found that two‐step (H2O→ NH3) plasma treatment remarkably strengthened the bonding strength (>1 J/m2) at the annealing temperature of 150°C. The improvement was achieved even when only one side of the bonded surfaces was plasma‐treated. X‐ray photoelectron spectroscopy revealed that the two‐step plasma treatment generated Si–NH2 groups on the topmost surface. Upon the annealing (<200°C), the engrafted Si–NH2 was desorbed from the bonded interface, indicating that the Si–NH2 effectively reacted with Si–OH on the other side to form Si–O–Si covalent bonds. This study contributes to understanding of the role of surface functional groups for bonding reaction. Furthermore, the method proposed here would be promising as a production technology because it enables glass bonding at lower temperatures with a simple plasma system.

Effect of surface modification of Fe/g-C3N4 catalyst on the product distribution in CO hydrogenation

Carbon nitride (g-C3N4) prepared using thermal condensation of urea was pretreated by H2O2/NH3·H2O and used as support to obtain Fe/g-C3N4 catalyst via impregnation method. The catalytic performance of the catalysts both before and after modification was investigated in CO hydrogenation. Combining detailed characterizations, such as XRD, SEM, TEM, FT-IR, TG, CO2-TPD, CO-TPD, H2-TPR, contact angle measurement, and N2 physical adsorption and desorption, we investigated the effects of surface pretreatment on the texture properties of Fe/g-C3N4 catalysts and the product distribution of CO hydrogenation. The results demonstrate that various pretreatment techniques have significant influences on the textural properties and catalytic performance of the catalysts. The prepared g-C3N4 with a typical honeycomb structure has strong interaction with highly dispersed Fe. Both before and after modification, the materials are hydrophilic, and the hydrophilicity is increased after treatment with H2O2 and NH3·H2O. Treatment with H2O2 enhances surface hydroxyl groups. NH3·H2O treatment improves surface amino groups, promotes CO adsorption, and facilitates the formation of Fe(NCN) phase. The surface basicity of all pretreated catalysts is enhanced. The water gas shift (WGS) reaction activity of the two-step modified catalyst Fe/AM-g-C3N4 was lower, and the CO2 selectivity in CO hydrogenation was reduced to 11.61%. Due to the enhanced basicity of Fe/AM-g-C3N4, the secondary hydrogenation ability of olefins was inhibited to obtain higher olefin selectivity with C= 2–C= 4 of 32.37% and an O/P value of 3.23.

Oxidative stress and energy metabolic response of Isochrysis galbana induced by different types of pristine and aging microplastics and their leachates

The aging process and leachate composition of different types of MPs (PS, PS-NH2, PS-COOH and PMMA) with a particle size of 1.0 μm were characterized, and marine microalgae Isochrysis galbana OA3011(I. galbana) was used as test organism to investigate the 96 h toxic effects of MPs before and after aging as well as leachate exposure. Except for polymethyl methacrylate (PMMA), all other tested microplastics showed significant aggregation in seawater, which increased with the presence of surface amino and carboxyl groups, in addition, the increase in polymer dispersibility index (PDI) values after aging reflected more severe aggregation. Fourier transform infrared spectrometer (FTIR) showed that the surface amino groups were shed during the aging of PS-NH2, which can likewise be demonstrated by the change in surface electric potential from positive to negative before and after aging. PMMA, due to the addition of plasticizers (HEHP and DIBP detected in high concentration) and its own structure, has stronger resistance to aging than the other three microplastics, and no significant aging phenomenon occurs. As for I. galbana, growth inhibition, oxidative stress and energy metabolism were tested after exposure to different microplastics and their leachate. It was found that high concentrations of A-PS had a greater negative impact on I. galbana, while the toxic effects of PS-NH2 and PS-COOH on I. galbana behaved in a diametrically opposite way before and after aging compared to PS with the inhibitory effect decreasing after aging, which was caused by the shedding of surface groups. As for PMMA, the differences in the toxic effects on microalgae before and after aging were not significant. The inhibitory effect of low concentrations of PAEs (Phthalate acid esters) in the leachate of PS-COOH on I. galbana was not significant, and the stronger inhibitory effect of 4 d L-PS-NH2 was presumed to be the shedding of positively charged groups.

Overcoming biological barriers BBB/BBTB by designing PUFA functionalised lipid-based nanocarriers for glioblastoma targeted therapy

A major obstacle for chemotherapeutics in Glioblastoma (GB) is to reach the tumour cells due to the presence of the blood-brain barrier (BBB) and chemoresistance of anticancer drugs. The present study reports two polyunsaturated fatty acids, gamma-linolenic acid (GLA) and alpha-linolenic acid (ALA) appended nanostructured lipid carriers (NLCs) of a CNS negative chemotherapeutic drug docetaxel (DTX) for targeted delivery to GB. The ligand appended DTX-NLCs demonstrated particle size < 160 nm, PDI < 0.29 and a negative surface charge. The successful linkage of GLA (41 %) and ALA (30 %) ligand conjugation to DTX- NLCs was confirmed by diminished surface amino groups on the NLCs, lower surface charge and FTIR profiling. Fluorophore labelled GLA-DTX-NLCs and ALA-DTX-NLCs permeated the in-vitro 3D BBB model with Papp values of 1.8 × 10−3 and 1.9 × 10−3 cm/s respectively. Following permeation, both formulations showed enhanced uptake by GB immortalised cells while ALA-DTX-NLCs showed higher uptake in patient-derived GB cells as evidenced in an in-vitro 3D blood brain tumour barrier (BBTB) model. Both surface functionalised formulations showed higher internalisation in GB cells as compared to bare DTX-NLCs. ALA-DTX-NLCs and GLA-DTX-NLCs showed 13.9-fold and 6.8-fold higher DTX activity respectively at 24 h as indicated by IC50 values when tested in patient-derived GB cells. ALA-DTX-NLCs displayed better efficacy than GLA-DTX-NLCs when tested against 3D tumour spheroids and patient-derived cells. These novel formulations will contribute widely to overcoming biological barriers for treating glioblastoma.

Fluorescence “Turn‐Off‐On” Detection of Heparin and Protamine Based on Bovine Serum Albumin‐Stabilized Carbon Dots (BSA‐CDs)

AbstractHeparin and protamine are two therapeutically significant biomolecules utilized in surgeries and extracorporeal therapy. Hence, real time monitoring of their concentration levels in body fluids is quite requisite. Herein, we developed, Bovine Serum Albumin stabilized carbon dots by a microwave‐assisted synthesis for the detection of heparin and protamine. Heparin has sulfate and carboxy groups that can interact with the positively charged surface amino groups of protamine through electrostatic interactions and hydrogen bonds. The blue fluorescence exhibited by BSA‐Carbon dots shows decrease in fluorescence emission on addition of negatively charged heparin. When cationic protein protamine is introduced to this system, the fluorescence is recovered due to electrostatic interaction with heparin. The system shows a Limit of detection (LOD) of 0.014 mM and 0.053 mM on addition of heparin and protamine respectively. The probe exhibited positive results with good selectivity and sensitivity towards other coexisting biomolecules and ions that appear in body fluids. The study was extended in biological matrix such as human serum and urine and found good recovery percentage in between 90–120%. The practical applicability was analyzed using a paper strip assay. Hence, a sensitive “turn‐off‐on” probe was effectively developed for the detection of heparin and protamine on a clinical basis.

Tissue-Adhesive Hydrogel Spray System for Live Cell Immobilization on Biological Surfaces.

Gelatin hydrogels are used as three-dimensional cell scaffolds and can be prepared using various methods. One widely accepted approach involves crosslinking gelatin amino groups with poly(ethylene glycol) (PEG) modified with N-hydroxysuccinimide ester (PEG-NHS). This method enables the encapsulation of live cells within the hydrogels and also facilitates the adhesion of the hydrogel to biological tissues by crosslinking their surface amino groups. Consequently, these hydrogels are valuable tools for immobilizing cells that secrete beneficial substances in vivo. However, the application of gelatin hydrogels is limited due to the requirement for several minutes to solidify under conditions of neutral pH and polymer concentrations suitable for live cells. This limitation makes it impractical for use with biological tissues, which have complex shapes or inclined surfaces, restricting its application to semi-closed spaces. In this study, we propose a tissue-adhesive hydrogel that can be sprayed and immobilized with live cells on biological tissue surfaces. This hydrogel system combines two components: (1) gelatin/PEG-NHS hydrogels and (2) instantaneously solidifying PEG hydrogels. The sprayed hydrogel solidified within 5 s after dispensing while maintaining the adhesive properties of the PEG-NHS component. The resulting hydrogels exhibited protein permeability, and the viability of encapsulated human mesenchymal stem/stromal cells (hMSCs) remained above 90% for at least 7 days. This developed hydrogel system represents a promising approach for immobilizing live cells on tissue surfaces with complex shapes.