Cellulose hydrogels physically crosslinked by glycine: Synthesis, characterization, thermal and mechanical properties

Nanocellulose-based hydrogels as versatile materials with interesting functional properties for tissue engineering applications

Tissue engineering has emerged as a remarkable field aiming to restore or replace damaged tissues through the use of biomimetic constructs. Among the diverse materials investigated for this purpose, nanocellulose-based hydrogels have garnered attention due to their intriguing biocompatibility, tunable mechanical properties, and sustainability. Over the past few years, numerous research works have been published focusing on the successful use of nanocellulose-based hydrogels as artificial extracellular matrices for regenerating various types of tissues. The review emphasizes the importance of tissue engineering, highlighting hydrogels as biomimetic scaffolds, and specifically focuses on the role of nanocellulose in composites that mimic the structures, properties, and functions of the native extracellular matrix for regenerating damaged tissues. It also summarizes the types of nanocellulose, as well as their structural, mechanical, and biological properties, and their contributions to enhancing the properties and characteristics of functional hydrogels for tissue engineering of skin, bone, cartilage, heart, nerves and blood vessels. Additionally, recent advancements in the application of nanocellulose-based hydrogels for tissue engineering have been evaluated and documented. The review also addresses the challenges encountered in their fabrication while exploring the potential future prospects of these hydrogel matrices for biomedical applications.

A review of recent advances of cellulose-based intelligent-responsive hydrogels as vehicles for controllable drug delivery system

To realize the maximum therapeutic activity of medicine and protect the body from the adverse effects of active ingredients, drug delivery systems (DDS) featured with targeted transportation sites and controllable release have captured extensive attention over the past decades. Hydrogels with unique three-dimensional (3D) porous structures present tunable capacity, controllable degradation, various stimuli sensitivity, therapeutic agents encapsulation, and loaded drugs protection properties, which endow hydrogels with bred-in-the-bone advantages as vehicles for drug delivery. In recent years, with the impressive consciousness of the "back-to-nature" concept, biomass materials are becoming the 'rising star' as the hydrogels building blocks for controlled drug release carriers due to their biodegradability, biocompatibility, and non-toxicity properties. In particular, cellulose and its derivatives are promising candidates for fabricating hydrogels as their rich sources and high availability, and various smart cellulose-based hydrogels as targeted carriers under exogenous such as light, electric field, and magnetic field or endogenous such as pH, temperature, ionic strength, and redox gradients. In this review, we summarized the main synthetic strategies of smart cellulose-based hydrogels including physical and chemical cross-linking, and illustrated the detailed intelligent-responsive mechanism of hydrogels in DDS under external stimulus. Additionally, the ongoing development and challenges of cellulose-based hydrogels in the biomedical field are also presented.

Histological evaluation of the regenerative potential of a novel photocrosslinkable gelatin-treated dentin matrix hydrogel in direct pulp capping: an animal study

BACKGROUND

To assess histologically the success of the pulp capping approach performed in traumatically exposed dogs' teeth using a novel injectable gelatin-treated dentin matrix light cured hydrogel (LCG-TDM) compared with LCG, MTA and TheraCal LC.

METHODS

Sixty-four dogs' teeth were divided into two groups (each including 32 teeth) based on the post-treatment evaluation period: group I: 2 weeks and group II: 8 weeks. Each group was further subdivided according to the pulp capping material into four subgroups (n = 8), with subgroup A (light-cured gelatin hydrogel) as the control subgroup, subgroup B (LCG-TDM), subgroup C (TheraCal LC), and subgroup D (MTA). Pulps were mechanically exposed in the middle of the cavity floor and capped with different materials. An assessment of periapical response was performed preoperatively and at 8 weeks. After 2 and 8-week intervals, the dogs were sacrificed, and the teeth were stained with hematoxylin-eosin and graded by using a histologic scoring system. Statistical analysis was performed using the chi-square and Kruskal-Wallis tests (p = 0.05).

RESULTS

All subgroups showed mild inflammation with normal pulp tissue at 2 weeks with no significant differences between subgroups (p ≤ 0.05), except for the TheraCal LC subgroup, which exhibited moderate inflammation (62.5%). Absence of a complete calcified bridge was reported in all subgroups at 2 weeks, while at 8 weeks, the majority of samples in the LCG-TDM and MTA-Angelus subgroups showed complete dentin bridge formation and absence of inflammatory pulp response with no significant differences between them (p ≤ 0.05). However, the formed dentin in the LCG-TDM group was significantly thicker, with layers of ordered odontoblasts identified to create a homogeneous tubular structure and numerous dentinal tubule lines suggesting a favourable trend towards dentin regeneration. TheraCal LC samples revealed a reasonably thick dentin bridge with moderate inflammation (50%) and LCG showed heavily fibrous tissue infiltrates with areas of degenerated pulp with no signs of hard tissue formation.

CONCLUSIONS

LCG-TDM, as an extracellular matrix-based material, has the potential to regenerate dentin and preserve pulp vitality, making it a viable natural alternative to silicate-based cements for healing in vivo dentin defects in direct pulp-capping procedures.

Influence of drug and polymer molecular weight on release kinetics from HEMA and HPMA hydrogels

Drug release kinetics in two compositions of methacrylate hydrogels were monitored as a function of the hydrogel and drug molecular weight. Through modifying the molecular weight of hydrogels, it was demonstrated how the release could be tuned, allowing for increased stability of hydrogels and enhanced release performance. Spectroscopy techniques such as FTIR and UV-Vis-NIR provided inferences into the chemical structure, target molecule concentration, and optical performance of the studied hydrogels. By studying the 30-day target molecule loading stability of the hydrogels, a relationship between the drug and hydrogel molecular weight, and the drug release kinetics could be determined.

Enhancing the mechanical properties of hydrogels with vinyl-functionalized nanocrystalline cellulose as a green crosslinker

Hydrogels have gained significant attention in scientific communities for their versatile applications, but several challenges need to be addressed to exploit their potential fully. Conventional hydrogels suffer from poor mechanical strength, limiting their use in many applications. Moreover, the crosslinking agents used to produce them are often toxic, carcinogenic, and not bio-friendly. This study presents a novel approach to overcome these limitations by using bio-friendly modified nanocrystalline cellulose as a crosslinker to prepare highly stretchable and tough thermosensitive hydrogels. The surface of nanocrystalline cellulose was modified with 3-methacryloxypropyltrimethoxysilane (MPTS) to obtain modified nanocrystalline cellulose (M-NCC) crosslinker and used during free radical polymerization of thermosensitiveN-isopropyl acrylamide (NIPA) monomer to synthesize NIPA/M-NCC hydrogel. The resulting nanocomposite hydrogels exhibit superior mechanical, thermal, and temperature-responsive swelling properties compared to conventional hydrogels prepared with traditional bi-functionalN,N'-methylene bis (acrylamide) (MBA) as a crosslinker. The elongation at break, tensile strength, and toughness of the NIPA/M-NCC hydrogels significantly increase and Young's modulus decrease than conventional hydrogel. The designed M-NCC crosslinker could be utilized to improve the mechanical strength of any polymeric elastomer or hydrogel systems produced through chain polymerization.

Green Synthesis and Bioactivity of Aliphatic N-Substituted Glycine Derivatives

Standard amino acids have an asymmetric α-carbon atom to which -COOH, -NH2, -H, and -R groups are bonded. Among them, glycine is the simplest (R = -H) with no asymmetric carbon, and other natural amino acids are C-substituted of glycine. Here, we have designed and made a green synthesis of some new N-substituted glycine derivatives with R-(NH)CH2-COOH formula, where R is flexible and hydrophobic with different chain lengths and benches of the type propyl, butyl, sec-butyl, tert-butyl, pentyl, isopentyl, tert-pentyl, hexyl, 2-aminoheptyl, and octyl. These glycine derivatives were characterized by recording their melting points and FT-IR, mass, 1H NMR, and 13C NMR spectra. DFT studies revealed that 2-aminoheptyl glycine had the highest electronegativity value and can thus act as a good bidentate ligand for the metal centers. ADME comparative results and bioavailability radars indicated that both octyl- and 2-aminoheptyl glycine had the most lipophilicity, making them good agents in cell passing. Furthermore, lipophilicity determination showed that octyl glycine was the best and propylgly was more soluble than others. Based on solubility, lipophilicity, and dipole moment values, propyl- and 2-aminoheptyl-glycine were considered for bio-macromolecular interaction studies. Thus, the interaction of these two agents with DNA and HSA was studied using absorption spectroscopy and circular dichroism techniques. Due to the presence of the R-amine group, they can interact with the DNA by H-binding and hydrophobicity, while electrostatic mode could not be ruled out. Meanwhile, molecular docking studies revealed that octyl- and 2-aminoheptyl glycine had the highest negative docking energy, which reflects their higher tendency to interact with DNA. The DNA binding affinity of two candidate AAs was determined by viscosity measurement and fluorescence emission recording, which confirms that groove binding occurs. Also, the toxicity of these synthesized amino acid derivates was tested against the human foreskin fibroblast (HFF) cell line. They showed IC50 values within the range of 127-344 μM after 48 h with the highest toxicity for 2-aminoheptyl glycine.

Empowering canonical biochemicals with cross-linked novelty: Recursions in applications of protein cross-links

Diversity in the biochemical workhorses of the cell-that is, proteins-is achieved by the innumerable permutations offered primarily by the 20 canonical L-amino acids prevalent in all biological systems. Yet, proteins are known to additionally undergo unusual modifications for specialized functions. Of the various post-translational modifications known to occur in proteins, the recently identified non-disulfide cross-links are unique, residue-specific covalent modifications that confer additional structural stability and unique functional characteristics to these biomolecules. We review an exclusive class of amino acid cross-links encompassing aromatic and sulfur-containing side chains, which not only confer superior biochemical characteristics to the protein but also possess additional spectroscopic features that can be exploited as novel chromophores. Studies of their in vivo reaction mechanism have facilitated their specialized in vitro applications in hydrogels and protein anchoring in monolayer chips. Furthering the discovery of unique canonical cross-links through new chemical, structural, and bioinformatics tools will catalyze the development of protein-specific hyperstable nanostructures, superfoods, and biotherapeutics.

Photocrosslinkable gelatin-treated dentin matrix hydrogel as a novel pulp capping agent for dentin regeneration: I. synthesis, characterizations and grafting optimization

BACKGROUND

In recent years, treated dentin matrix (TDM) has been introduced as a bioactive hydrogel for dentin regeneration in DPC. However, no study has introduced TDM as a photocrosslinkable hydrogel with a natural photoinitiating system. Therefore, the present study aimed to explore the synthesis, characterizations and grafting optimization of injectable gelatin- glycidyl methacrylate (GMA)/TDM hydrogels as a novel photocrosslinkable pulp capping agent for dentin regeneration.

METHODS

G-GMA/TDM hydrogel was photocrosslinked using a new two-component photoinitiating system composed of riboflavin as a photoinitiator under visible light and glycine as a first time coinitiator with riboflavin. The grafting reaction conditions of G-GMA/TDM e.g. GMA concentration and reaction time were optimized. The kinetic parameters e.g. grafting efficiency (GE) and grafting percentage (GP%) were calculated to optimize the grafting reaction, while yield (%) was determined to monitor the formation of the hydrogel. Moreover, G-GMA/TDM hydrogels were characterized by swelling ratio, degradation degree, and cytotoxicity. The instrumental characterizations e.g. FTIR, 1H-NMR, SEM and TGA, were investigated for verifying the grafting reaction. Statistical analysis was performed using F test (ANOVA) and Post Hoc Test (P = 0.05).

RESULTS

The grafting reaction dramatically increased with an increase of both GMA concentration and reaction time. It was realized that the swelling degree and degradation rate of G-GMA/TDM hydrogels were significantly reduced by increasing the GMA concentration and prolonging the reaction time. When compared to the safe low and moderate GMA content hydrogels (0.048, 0.097 M) and shorter reaction times (6, 12, 24 h), G-GMA/TDM with high GMA contents (0.195, 0.391 M) and a prolonged reaction time (48 h) demonstrated cytotoxic effects against cells using the MTT assay. Also, the morphological surface of G-GMA/TDM freeze-dried gels was found more compacted, smooth and uniform due to the grafting process. Significant thermal stability was noticed due to the grafting reaction of G-GMA/TDM throughout the TGA results.

CONCLUSIONS

G-GMA/TDM composite hydrogel formed by the riboflavin/glycine photoinitiating system is a potential bioactive and biocompatible system for in-situ crosslinking the activated-light pulp capping agent for dentin regeneration.

A Comprehensive Review of Polysaccharide-Based Hydrogels as Promising Biomaterials

Polysaccharides have emerged as a promising material for hydrogel preparation due to their biocompatibility, biodegradability, and low cost. This review focuses on polysaccharide-based hydrogels' synthesis, characterization, and applications. The various synthetic methods used to prepare polysaccharide-based hydrogels are discussed. The characterization techniques are also highlighted to evaluate the physical and chemical properties of polysaccharide-based hydrogels. Finally, the applications of SAPs in various fields are discussed, along with their potential benefits and limitations. Due to environmental concerns, this review shows a growing interest in developing bio-sourced hydrogels made from natural materials such as polysaccharides. SAPs have many beneficial properties, including good mechanical and morphological properties, thermal stability, biocompatibility, biodegradability, non-toxicity, abundance, economic viability, and good swelling ability. However, some challenges remain to be overcome, such as limiting the formulation complexity of some SAPs and establishing a general protocol for calculating their water absorption and retention capacity. Furthermore, the development of SAPs requires a multidisciplinary approach and research should focus on improving their synthesis, modification, and characterization as well as exploring their potential applications. Biocompatibility, biodegradation, and the regulatory approval pathway of SAPs should be carefully evaluated to ensure their safety and efficacy.

4D Printing of Body Temperature-Responsive Hydrogels Based on Poly(acrylic acid) with Shape-Memory and Self-Healing Abilities

Additive manufacturing of smart materials that can be dynamically programmed with external stimuli is known as 4D printing. Among the 4D printable materials, hydrogels are the most extensively studied materials in various biomedical areas because of their hierarchical structure, similarity to native human tissues, and supreme bioactivity. However, conventional smart hydrogels suffer from poor mechanical properties, slow actuation speed, and instability of actuated shape. Herein, we present 4D-printed hydrogels based on poly(acrylic acid) that can concurrently possess shape-memory and self-healing properties. The printing of the hydrogels is achieved by solvent-free copolymerization of the hydrophilic acrylic acid (AAc) and hydrophobic hexadecyl acrylate (C16A) monomers in the presence of TPO photoinitiator using a stereolithography-based commercial resin printer followed by swelling in water. The printed hydrogels undergo a reversible strong-to-weak gel transition below and above human body temperature due to the melting and crystallization of the hydrophobic C16A domains. In this way, the shape-memory and self-healing properties of the hydrogels can be magically actuated near the body temperature by adjusting the molar ratio of the monomers. Furthermore, the printed hydrogels display a high Young's modulus (up to ∼215 MPa) and high toughness (up to ∼7 MJ/m³), and their mechanical properties can be tuned from brittle to ductile by reducing the molar fraction of C16A, or the deformation speed. Overall, the developed 4D printable hydrogels have great potential for various biomedical applications.

Adsorption of copper ions in water by adipic dihydrazide-modified kapok fibers

Kapok fibers (Ceiba pentandra) were modified for the removal of copper ions from aqueous solutions through adsorption. In this fast and facile method, the polysaccharide-like groups of kapok were oxidized with potassium periodate. The novel modification is the loading of the fibers with adipic dihydrazide (ADH) which contain nitrogen and oxygen atoms for heavy metal ion binding. Adsorption experiments have been carried out and analyzed via atom absorption spectroscopy and ultraviolet/visible spectroscopy. In preliminary adsorption experiments, different kapok-based materials have been analyzed on their adsorption capacity and removal efficiency via atom absorption spectroscopy. ADH-modified fibers showed the best results and an increase of copper removal efficiency by 30% in comparison to untreated kapok fibers and superior adsorption capacity compared to kapok fibers loaded with oxalic dihydrazide (ODH). Moreover, the impact of initial concentration and contact time on the adsorption capacity and on the removal efficiency values of the ADH-modified kapok fibers has been studied. Another comparison of the ADH-modified fibers with raw kapok which was cleaned with Milli-Q water, dichloromethane and ethylene glycol showed that the new adsorbents are best suited for copper solutions with concentration values of under 10 mg/L. The heavy metal adsorption experiments were analyzed through both isotherm models Langmuir and Freundlich. The Langmuir model is found to be a suitable model for copper ions. The value of the maximum adsorption capacity is 4.120 mg/g. The ADH-modified kapok fibers were characterized with attenuated total reflection infrared (ATR-IR) spectroscopy, magic-angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy and scanning electron microscopy (SEM).

Modulation of interfacial interactions toward strong and tough cellulose nanofiber-based transparent thin films with antifogging feature

Cross-linking is often performed to overcome the weak mechanical properties of native polymer films in order to expand their functional properties and applications. While this approach offers enhanced strength to the film, the film also suffers from low flexibility, low toughness and high brittleness. However, in view of the growing demand for strong and tough transparent thin films, this article reported our study to develop films made from cellulose nanofiber (CNF) via tailoring the interfacial bonding interactions through the application of glycerol (Gly) and glutaraldehyde (GA), which functioned as a plasticizer and cross-linking agent, respectively. Among the prepared films, the 10GA-8Gly-CNF film exhibited the best results with regard to the enhancement in the tensile strength (21.1%), Young's modulus (10.6%), elongation at break (100%) and toughness (32.7%), as compared to the native CNF film. Importantly, treating the surface of the film to radiofrequency oxygen plasma endowed the film with antifogging property, without compromising the optical clarity.

Skincare application of medicinal plant polysaccharides - A review

Polysaccharides are macromolecules with important inherent properties and potential biotechnological applications. These complex carbohydrates exist throughout nature, especially in plants, from which they can be obtained with high yields. Different extraction and purification methods may affect the structure of polysaccharides and, due to the close relationship between structure and function, modify their biological activities. One of the possible applications of these polysaccharides is acting on the skin, which is the largest organ in the human body and can be aged by intrinsic and extrinsic processes. Skincare has been gaining worldwide attention not only to prevent diseases but also to promote rejuvenation in aesthetic treatments. In this review, we discussed the polysaccharides obtained from plants and their innovative potential for skin applications, for example as wound-healing, antimicrobial, antioxidant and anti-inflammatory, antitumoral, and anti-aging compounds.

Cellulose: A Fascinating Biopolymer for Hydrogel Synthesis

The growing environmental concerns and increasing demands for eco-friendly materials have obliged researchers worldwide to explore naturally occurring biopolymers for various applications. Cellulose is a non-exhaustible polysaccharide biopolymer available almost...

Biofabrication of skin tissue constructs using alginate, gelatin and diethylaminoethyl cellulose bioink

INTRODUCTION

Biofabrication of skin tissue equivalents using 3D bioprinting technology has gained much attention in recent times due to the simplicity, the versatility of the technology and its ability in bioengineering biomimetic tissue histology. The key component being the bioink, several groups are actively working on the development of various bioink formulations for optimal skin tissue construction.

METHODS

Here, we present alginate (ALG), gelatin (GEL) and diethylaminoethyl cellulose (DCEL) based bioink formulation and its application in bioprinting and biofabrication of skin tissue equivalents. Briefly, DEAE cellulose powder was dispersed in alginate solution with constant stirring at 60 °C to obtain a uniform distribution of cellulose fibers; this was then mixed with GEL solution to prepare the bioink. The formulation was systematically characterized for its morphological, physical, chemical, rheological, biodegradation and biocompatibility properties. The printability, shape fidelity and cell-laden printing were assessed using the CellInk bioprinter.

RESULTS

The bioink proved to be a good printable, non-cytotoxic and stable hydrogel formulation. The primary human fibroblast and keratinocyte-loaded 3D bioprinted constructs showed excellent cell viability, collagen synthesis, skin-specific marker and biomimetic tissue histology.

CONCLUSION

The results demonstrated the successful formulation of ALG-GEL-DCEL bioink and its application in the development of human skin tissue equivalents with distinct epidermal-dermal histological features.

A freeze-thaw PVA hydrogel loaded with guava leaf extract: physical and antibacterial properties

A polyvinyl alcohol (PVA) hydrogel loaded with guava leaf extract (GLE) has potential applications as a wound dressing with good antibacterial activity. This study succeeded in fabricating a PVA hydrogel containing GLE using the freeze–thaw (FT) method. By varying the GLE concentration, we can adjust the physical properties of the hydrogel. The addition of GLE results in a decrease in cross-linking during gelation and an increase in the pore size of the hydrogels. The increase of the pore size made the swelling increase and the mechanical strength decrease. The weight loss of the hydrogel also increases because the phosphate buffer saline (PBS) dissolves the GLE. Increasing the GLE concentration caused the Fourier-transform infrared (FTIR) absorbance peaks to widen due to hydrogen bonds formed during the FT process. The crystalline phase was transformed into an amorphous phase in the PVA/GLE hydrogel based on the X-ray diffraction (XRD) spectra. The differential scanning calorimetry (DSC) characterization showed a significant decrease in the hydrogel weight over temperatures of 30–150 °C due to the evaporation of water from the hydrogel matrix. The zone of inhibition of the PVA/GLE hydrogel increased with antibacterial activity against Staphylococcus aureus of 17.93% per gram and 15.79% per gram against Pseudomonas aeruginosa.

A polyvinyl alcohol (PVA) hydrogel loaded with guava leaf extract (GLE) has potential applications as a wound dressing with good antibacterial activity.

Biodegradable gelatin composite hydrogels filled with cellulose for chromium (VI) adsorption from contaminated water

Biopolymers are promising materials for water treatment applications due to their abundance, low cost, expandability, and chemical structure. In this work, gelatin hydrogels filled with cellulose in the form of pristine eucalyptus residues (PER) or treated eucalyptus residues (TER) were prepared for adsorption and chromium removal in contaminated water. PER is a lignocellulosic compound, with cellulose, hemicellulose, and lignin, while TER has cellulose as a major component. FT-Raman Spectroscopy and FTIR analysis confirmed the crosslink reaction with glutaraldehyde and indicated that fillers altered the gelatin molecular vibrations and formed new hydrogen bonds, impacting the hydrogels' crystalline structure. The hydrogen bond energy was altered by the cellulosic fillers' addition and resulted in higher thermal stability (~10 °C). Hydrogels presented a Fickian diffusion, where gelatin hydrogel showed the highest swelling ability (466%), and composites showed lower values with the filler content increase. The chromium adsorption capacity presented values between 12 and 13 mg/g, i.e., featuring an excellent removal capacity which is related with hydrogel crosslinked structure and fibers surface hydroxyl groups, highlighting gelatin hydrogel TER 5% with better removal capacity. The developed hydrogels were produced from biomacromolecules with low-cost and potential application in contaminated water.

A 3D hydrogel based on chitosan and carbon dots for sensitive fluorescence detection of microRNA-21 in breast cancer cells

Hydrogels are 3D polymeric networks with great swelling capability in water and appropriate chemical, mechanical and biological features which make it feasible to maintain bioactive substances. Herein, we fabricated carbon dots-chitosan nanocomposite hydrogels via reacting carbon dots synthesized from various aldehyde precursors with chitosan after that functionalized with ssDNA probe for detection of microRNA-21 in MCF-7 cancer cells. More importantly, three fluorescent hydrogels were produced using schiff base reaction (forming imine bonds) among the amine in chitosan and aldehyde groups on the CDs surface. Furthermore, the hydrogel films, CDs and CDs-chitosan nanocomposite hydrogels were characterized by UV-vis absorption and fluorescence spectra, FT-IR, scanning electron microscope (SEM) and transmission electron microscopy (TEM). The DNA hydrogel bioassay strategy revealed a great stability and a superb sensitivity for microRNA-21, with a suitable linear range (0.1-125 fM) and a detection limit (0.03 fM). For sample analysis, the biosensors exhibited good linearity with MCF-7 cancer cell concentrations from 1000 to 25000, 1000-25000 and 1000-6000 cells mL^-1 and detection limit of 310, 364 and 552 cells mL^-1, for glutaraldehyde, nitrobezaldehyde and benzaldehyde based nanocomposite hydrogels, respectively. In addition, cell viability consequences demonstrated low probe cytotoxicity, so nanocomposite hydrogels was utilized to multicolor imaging of MCF-7 cancer cells.

Experimental modeling, optimization and comparison of coagulants for removal of metallic pollutants from wastewater

Wastewater treatment coagulation is one of the most important physicochemical operations used in industry. The adsorption capability of marigold leaf powder, tea waste and ferrous sulfate was investigated for domestic and tannery effluents. These adsorbents significantly affected the pH, electrical conductivity (EC) and turbidity of wastewater. Maximum decrease in all the attributes was observed for 10 g of adsorbents application. All the adsorbents significantly affected the physiochemical attributes of both wastewaters. Similarly, maximum adsorption potential was observed in case of tea waste powder. Maximum decrease in all physiochemical attributes such as pH (15%), EC (21%), turbidity (54%), total dissolved solids (TDS; 36%), total suspended solids (TSS; 43%), total hardness (TH; 52%), chloride contents (59%) and phosphate contents (60%) was observed with the application of 10 g of tea waste. Regarding the heavy metals, maximum decrease for cadmium (Cd; 47%), lead (Pb; 81%), arsenic (As; 44%), copper (Cu; 75%), iron (Fe; 49%), chromium (Cr; 68%) and zinc (Zn; 64%) was observed in same treatment. The decreasing order in terms of their adsorption potential for coagulants was tea waste > marigold leaf powder > ferrous sulfate. However, for the wastewater, the maximum effect of adsorbents was observed in case of domestic wastewater as compared to the tannery water. Based on these data, it is suggested that tea waste has maximum adsorption potential for the remediation of wastewater.

Stimuli-Responsive Hydrogels for Local Post-Surgical Drug Delivery

Currently, surgical operations, followed by systemic drug delivery, are the prevailing treatment modality for most diseases, including cancers and trauma-based injuries. Although effective to some extent, the side effects of surgery include inflammation, pain, a lower rate of tissue regeneration, disease recurrence, and the non-specific toxicity of chemotherapies, which remain significant clinical challenges. The localized delivery of therapeutics has recently emerged as an alternative to systemic therapy, which not only allows the delivery of higher doses of therapeutic agents to the surgical site, but also enables overcoming post-surgical complications, such as infections, inflammations, and pain. Due to the limitations of the current drug delivery systems, and an increasing clinical need for disease-specific drug release systems, hydrogels have attracted considerable interest, due to their unique properties, including a high capacity for drug loading, as well as a sustained release profile. Hydrogels can be used as local drug performance carriers as a means for diminishing the side effects of current systemic drug delivery methods and are suitable for the majority of surgery-based injuries. This work summarizes recent advances in hydrogel-based drug delivery systems (DDSs), including formulations such as implantable, injectable, and sprayable hydrogels, with a particular emphasis on stimuli-responsive materials. Moreover, clinical applications and future opportunities for this type of post-surgery treatment are also highlighted.

Facile Synthesis of Novel Carboxymethyl-Chitosan/Sodium Alginate Grafted with Amino-Carbamate Moiety/Bentonite Clay Composite for Effective Biosorption of Ni (II) from Aqueous Solution

In the present study, a novel biosorbent clay composite, based on carboxymethyl-chitosan/sodium alginate grafted with amino-carbamate moiety/bentonite clay (CA-CMC/Bt) was prepared. The produced sorbent was conditioned in the form of hydrogel beads by ionotropic gelation with Ca(II) ions, and thoroughly characterized using FTIR, XRF, XRD, SEM and zeta potential measurements. FTIR and SEM confirmed the successful grafting and intercalation of clay mineral into modified biopolymer. Hydrogel beads were observed to be very integrated and stable under a wide pH working range (from 2.0 to 12.0). CA-CMC/Bt was employed for adsorptive remediation of Ni(II) from aqueous media. Sorption process was found as a function of various parameters such as sorbent dosage, contact time, pH and initial concentration. Kinetic data could be well explained by pseudo second order rate equation (PSORE), suggesting that complexation or valence forces are playing significant role in the uptake of Ni(II) ions. Isothermal sorption data was analysed using different sorption models such as Langmuir, Freundlich and Sips. Data was well fitted with Langmuir and Sips model, maximum monolayer sorption capacity (qm) was calculated (by non-linear fitting of data) as 159 mg/g at 298 K and pH 5.5. Separation factor (RL) was found as 0 < RL < 1 which indicated favourable sorption. Thermodynamic parameters i.e. ΔGo, ΔHo and ΔSo were quantified and patterned the sorption process as exothermic, spontaneous with increase in system entropy. CA-CMC/Bt was found cost-effective, efficient and reusable material in Ni(II) competitive recovery.

Coagulation of Metallic Pollutants from Wastewater Using a Variety of Coagulants Based on Metal Binding Interaction Studies

In this study, different organic (moringa and neem leaf powder) and inorganic (alum) coagulants were used for the wastewater treatment. Results revealed that all the coagulants at various doses significantly affected the pH, electrical conductivity (EC) and turbidity of wastewater. The maximum decrease in all the attributes was observed when 10 g of coagulants were used. Similarly, maximum adsorption potential was observed in case of moringa leaf powder. Maximum decrease in all physiochemical attributes such as pH (13%), EC (65%), turbidity (75%), total dissolved solids (TDS; 51%), total suspended solids (TSS; 48%), total hardness (TH; 29%), chloride contents (66%) and phosphate contents (44%) was observed. Regarding the heavy metals, maximum decrease for Cadmium (Cd; 96%), Lead (Pb; 88%), Arsenic (As; 23%), Iron (Fe; 90%), Manganese (Mn; 96%) and Zinc (Zn; 48%) was observed in same treatment. The decreasing order in terms of their adsorption potential for coagulants was moringa leaf powder > Alum > neem leaf powder. However, the maximum effect of coagulants was observed in case of textile wastewater as compared to the hospital wastewater. Based on the analyses, it is concluded that the moringa leaf powder has maximum adsorption potential for the remediation of wastewater.

Rheological Investigation of GO Doped p(APTMACl) Composite Hydrogel

The aim of the present work is an approach towards the exploration of comprehension of rheological work on polymer composites synthesized by ex-situ dispersion of graphene oxide (GO) in poly(3-acrylamidopropyl trimethyl ammonium chloride (APTMACl) cationic hydrogel template. FTIR was carried out for confirmation of polymer synthesis and existence of GO in hydrogel network. The rheological investigation via frequency sweep curve (shear measurement) and oscillatory sweep (dynamic mechanical analysis) at different temperature 20, 25, 30, 35, 40 and 45 °C was performed. The storage (G′) and loss (G′′) moduli as a function of angular frequency, yield stress, tangent loss, damping factor and retention property were also studied to confirm the visco-elastomeric nature of the GO@p(APTMACl) composite and their semi solid response at different range of temperature. Various rheological models like Bingham model, modified Bingham model and Ostwald’s power law were applied. The temperature dependency was further tested via Arrhenius-Frenkel-Eyring equation. The sample showed best fitting in the modified Bingham model, which justified the pseudo plastic semi solid behavior of GO@p(APTMACl) composite within the linear visco-elastic region (LVER). All the properties from rheological study show best mechanical property and make the composite hydrogel good for drug delivery and for other environmental applications.