A stable delivery system for curcumin: Fabrication and characterization of self-assembling acylated kidney bean protein isolate nanogels

The construction of protein-based nano-gels as curcumin delivery system effectively enhances the stability and bioavailability of curcumin. In this study, acylation modification and self-assembly techniques were jointly employed to construct acylated kidney bean protein isolate (AKBPI)-nanogels. Optimal conditions for AKBPI-nanogels were determined to be pH 7, concentration of 2 mg/mL, and temperature at 90℃ for 30 min. The optimized AKBPI-nanogels exhibited excellent uniformity as evidenced by decreasing average particle size (137.35 nm) and polydispersity index (0.38). Acylation enhanced the intermolecular interactions within the nanogel by reducing the polarity of tyrosine microenvironment and free sulfhydryl groups. AKBPI-nanogels demonstrated remarkable characteristics in terms of pH sensitivity, salt concentration, and storage tolerance. The curcumin-loaded AKBPI-nanogels exhibited an encapsulation efficiency of 92.30 % and maintained high antioxidant activity. In simulated gastrointestinal digestion, AKBPI-nanogels facilitated the controlled release and higher bioavailability of curcumin. Therefore, AKBPI-nanogels can be a stable tool for delivering curcumin.

Preparation and properties of hydrogel photonic crystals assembled by biodegradable nanogels

Thermally induced physical hydrogels formed through the sol-gel transition of nanogels usually lose structural color above phase transition temperature (Tp). Herein, temperature/pH/redox-responsive nanogels that undergo sol-gel transition still keep structural colors above the Tp have been synthesized and studied. N-isopropylacrylamide (NIPAm) was copolymerized with N-tert-butylacrylamide (TBA) and N-acrylamido-l-phenylalanine (Aphe) to form P(NIPAm/TBA/Aphe) nanogel crosslinked with N,N'-bis(acryloyl)cystine (BISS) (referred to as PNTA-BISS). PNTA-BISS nanogel with a broad range of biodegradable crosslinker BISS content can achieve a reversible sol-gel transition above the Tp, surprisingly, while PNTA nanogels with a comparable content of biodegradable N,N'-Bis(acryloyl)cystam (BAC) crosslinker (referred to as PNTA-BAC) didn't form sol-gel transition. Although BISS and BAC possess same disulfide bonds with redox properties, BISS, unlike BAC, is water-soluble and features two carboxyl groups. The mechanism by which PNTA-BISS nanogels form hydrogel photonic crystals has been deeply explored with temperature-variable NMR. The results showed the introduction of Aphe with both steric hindrance and carboxyl groups greatly slowed down the shrinkage of PNTA-BISS nanogels. Therefore, PNTA-BISS nanogels can form sol-gel transition and further structural color of hydrogel photonic crystals due to carboxyl groups above the Tp. Furthermore, the properties of biodegradable hydrogel photonic crystals above the Tp were investigated for the first time, attributed to the presence of the strong reducing agent 1,4-dithiothreitol (DTT). When loaded with doxorubicin (DOX), PNTA-BISS exhibited favorable degradation properties under the influence of DTT. In summary, the PNTA-BISS nanogel, in addition to its in-situ gelation capabilities, demonstrated degradability, potentially providing a novel nanoplatform for applications in drug delivery, biotechnology, and related fields.

Smart chitosan nanogel for targeted doxorubicin delivery, ensuring precise release, and minimizing side effects in Ehrlich ascites carcinoma-bearing mice

In recent decades, bio-polymeric nanogels have become a forefront in medical research as innovative in-vivo drug carriers. This study introduces a pH-sensitive chitosan nanoparticles/P(N-Isopropylacrylamide-co-Acrylic acid) nanogel (CSNPs/P(NIPAm-co-AAc)), making significant advancements. The nanogel effectively encapsulated doxorubicin hydrochloride (Dx. HCl), a model drug, within its compartments through electrostatic binding. Comparing nano chitosan (CSNPs) before and after integrating copolymerized P(NIPAm-co-AAc), highlighting an improved and adaptable nanogel structure with responsive behaviors. The intraperitoneal delivery of Dx-loaded nanogel (Dx@N.gel) to Ehrlich ascites carcinoma (Eh)-bearing mice at doses equivalent to 1.5 and 3 mg/kg of Dx per day for 14 days exhibited superiority over the administration of free Dx. Dx@N.gel demonstrated heightened anticancer activity, significantly improving mean survival rates in Eh mice. The nanogel's multifaceted defense mechanism mitigated oxidative stress, inhibited lipid peroxidation, and curbed nitric oxide formation induced by free Dx. It effectively countered hepatic DNA deterioration, normalized elevated liver and cardiac enzyme levels, and ameliorated renal complications. This pH-responsive CSNPs/P(NIPAm-co-AAc) nanogel loaded with Dx represents a paradigm shift in antitumor drug delivery. Its efficacy and ability to minimize side effects, contrasting sharply with those of free Dx, offer a promising future where potent cancer therapies seamlessly align with patient well-being.

Nanogels: Smart tools to enlarge the therapeutic window of gene therapy

Gene therapy can potentially treat a great number of diseases, from cancer to rare genetic disorders. Very recently, the development and emergency approval of nucleic acid-based COVID-19 vaccines confirmed its strength and versatility. However, gene therapy encounters limitations due to the lack of suitable carriers to vectorize therapeutic genetic material inside target cells. Nanogels are highly hydrated nano-size crosslinked polymeric networks that have been used in many biomedical applications, from drug delivery to tissue engineering and diagnostics. Due to their easy production, tunability, and swelling properties they have called the attention as promising vectors for gene delivery. In this review, nanogels are discussed as vectors for nucleic acid delivery aiming to enlarge gene therapy's therapeutic window. Recent works highlighting the optimization of inherent transfection efficiency and biocompatibility are reviewed here. The importance of the monomer choice, along with the internal structure, surface decoration, and responsive features are outlined for the different transfection modalities. The possible sources of toxicological endpoints in nanogels are analyzed, and the strategies to limit them are compared. Finally, perspectives are discussed to identify the remining challenges for the nanogels before their translation to the market as transfection agents.

pH-responsive nanogels with enhanced antioxidant and antitumor activities on drug delivery and smart drug release

pH-responsive nanogels have played an increasingly momentous role in tumor treatment. The focus of this study is to design and develop pH-responsive benzimidazole-chitosan quaternary ammonium salt (BIMIXHAC) nanogels for the controlled release of doxorubicin hydrochloride (DOX) while enhancing its hydrophilicity. BIMIXHAC is crosslinked with carboxymethyl chitosan (CMC), hyaluronic acid sodium salt (HA), and sodium alginates (SA) using an ion crosslinking method. The chemical structure of chitosan derivatives was verified by 1H NMR and FT-IR techniques. Compared to hydroxypropyl trimethyl ammonium chloride chitosan (HACC)-based nanogels, BIMIXHAC-based nanogels exhibit better drug encapsulation efficiency and loading capacity (BIMIXHAC-D-HA 91.76 %, and 32.23 %), with pH-responsive release profiles and accelerated release in vitro. The series of nanogels formed by crosslinking with three different polyanionic crosslinkers have different particle size potentials and antioxidant properties. BIMIXHAC-HA, BIMIXHAC-SA and BIMIXHAC-CMC demonstrate favorable antioxidant capability. In addition, cytotoxicity tests showed that BIMIXHAC-based nanogels have high biocompatibility. BIMIXHAC-based nanogels exhibit preferable anticancer effects on MCF-7 and A549 cells. Furthermore, the BIMIXHAC-D-HA nanogel was 2.62 times less toxic than DOX to L929 cells. These results suggest that BIMIXHAC-based nanogels can serve as pH-responsive nanoplatforms for the delivery of anticancer drugs.

Dual-functional DNA nanogels for anticancer drug delivery

DNA hydrogels with unique sequence programmability on nucleic acid framework manifest remarkable attributes, such as high payload capacities, biocompatibility and biosafety. The availability of DNA nanogels with multimodal functionalities remains limited due to the absence of facile gelation methods applicable at the nanometer scale. Here, we developed a one-step assembly of DNA dendrimers into nanogels (DNG) with couple hundred nanometers size. DNG showed robust stability against physical forces and biological degradation for easy purification and sustainable drug release. Long-term stability either in powder or aqueous solution endows DNG easy for shipping, handling and storage. By encoding dual functionalities into separate branches on DNA dendrimers, DNG can accommodate chemodrugs and aptamers with distinctive loading moduli. DNG significantly enhanced the drug efficacy against cancerous cells while minimizing cytotoxicity towards somatic cells, as demonstrated in vitro and in xenografted mice models of breast cancer. Thus, due to their facile assembly and storage, bi-entity encoding, and inherent biocompatibility, DNG exhibits immense prospects as nanoscale vesicles for the synergistic delivery of multimodal theranostics in anticancer treatments. STATEMENT OF SIGNIFICANCE: DNA nanogels were self-assembled via a facile protocol utilizing a DNA dendrimer structure. These nanogels displayed robust stability against physical forces, permitting long term storage in concentrated solutions or as a powder. Furthermore, they exhibited resilience to biological degradation, facilitating sustained drug release. The bi-entity encoded dendritic branches conferred dual functionalities, enabling both chemodrug encapsulation and the presentation of aptamers as targeting motifs. In vivo investigations confirmed the nanogels provide high efficacy in tumor targeting and chemotherapy with enhanced drug efficacy and reduced side effects.

Pulmonary administration of tetrandrine loaded Zinc-Alginate nanogels attenuates pulmonary fibrosis in rats

Pulmonary fibrosis is a chronic and progressive disease, current systemic administration is not fully effective with many side effects, such as gastrointestinal and liver injury. The pulmonary delivery system for pulmonary fibrosis may contribute to maximize therapeutic benefit. Natural compounds might have prominence as potential drug candidates, but the low bioavailabilities affect their clinical use. Tetrandrine is a natural alkaloid with good anti-inflammatory, antifibrogenetic and antioxidant effects, and it is used as a clinical therapeutic drug for the treatment of silicosis in China. In the present study, we explore a new strategy of pulmonary delivery system to improve low solubility and pesticide effect of tetrandrine. Tetrandrine was loaded into alginate nanogels by reverse microemulsion method. The release behavior of tetrandrine reached zero-order kinetics release and the maximum free radical clearance rates reached up to 90%. The pulmonary fibrosis rats were treated with tetrandrine nanogels by using ultrasonic atomizing inhalation. Tetrandrine nanogels decreased the development and progression of fibrosis by reducing inflammation response and bating the deposition of extra cellular matrix. In conclusion, ultrasonic atomizing inhalation of tetrandrine nanogels provided a new therapeutic strategy for pulmonary fibrosis.

On-demand release of enrofloxacin-loaded chitosan oligosaccharide-oxidized hyaluronic acid composite nanogels for infected wound healing

In this study, enrofloxacin (ENR) was encapsulated by oxidized hyaluronic acid (OHA) containing aldehyde groups and chitosan oligosaccharide (COS) containing amino groups through Schiff's base reaction to achieve on-demand release in the micro-environment (pH 5.5 and HAase) of bacterial-infected wounds (Escherichia coli and Staphylococcus aureus). The formation mechanism, physicochemical characterization, responsive release performance, in vitro and in vivo antimicrobial activities, and in vivo regeneration in full-thickness wounds in a bacterial-infected mouse model of the ENR nanogels were systematically studied. According to the single-factor experiment and Design-Expert software, the optimized formula was 3.8 mg/ml COS, 0.5 mg/ml OHA, and 0.3 mg/ml ENR, respectively. The mean particle diameter, polydispersity index, zeta potential, loading capacity, and encapsulation efficiency were 35.6 ± 1.7 nm, -6.7 ± 0.5 mV, 0.25 ± 0.02, 30.4 % ± 1.3 %, and 76.3 % ± 2.6 %, respectively. The appearance, optical microscopy images, SEM, TEM, PXRD, and FTIR showed that the ENR nanogels were successfully prepared. The ENR nanogels exhibited obvious pH and HAase-responsiveness by swelling ratios and in vitro release and had stronger antibacterial activity with time-dependent and concentration-dependent effects, as well as accelerating infected wound healing. In vitro and in vivo biosafety studies suggested the great promise of ENR nanogels as biocompatible wound dressings for infected wounds.

Effect of lactobacillus reuteri-derived probiotic nano-formulation on recurrent aphthous stomatitis: a double-blinded randomized clinical trial

OBJECTIVES

We aimed to assess the therapeutic effects of a topical probiotic nano-formulation derived from Lactobacillus reuteri on treating recurrent aphthous stomatitis.

MATERIALS AND METHODS

60 participants were randomly allocated into two groups (control and probiotic). Probiotic group administered topical probiotic nano-formulation three times a day for seven days. The control group administered a standard analgesic oral rinse. The size of ulcer(s) and pain severity were recorded on days 0, 3, 5, and 7 after intervention.

RESULTS

Before the intervention, the groups had no significant differences in terms of pain severity (P-value = 0.28) and lesion size (P-value = 0.24). Both groups exhibited significant reductions in pain severity and lesion size over the course of the intervention. After one week, the probiotic group had a notably larger lesion size reduction than the control group (P-value = 0.01). The probiotic group also showed a significantly greater reduction in pain severity than the control group (P-value = 0.04).

CONCLUSIONS

Applying topical probiotic nano-formulation derived from Lactobacillus reuteri three times a day decreased lesion size and pain severity in RAS patients faster than the local analgesic oral rinse.

CLINICAL RELEVANCE

Lactobacillus reuteri-derived probiotic nano-formulation might be a promising treatment option for RAS.

Enhanced antidepressant effects of BDNF-quercetin alginate nanogels for depression therapy

BACKGROUND

Brain-derived neurotrophic factor (BDNF) with neuronic development and function is a promising therapeutic agent for treating depressive disorder, according to the neurotrophin hypothesis. However, the delivery of BDNF into the brain is not easy as these large protein molecules cannot efficiently cross the blood-brain barrier (BBB) and easily suffer oxidative damage in vivo. Therefore, the quercetin-based alginate nanogels (quercetin nanogels) loaded with BDNF have been developed, which could efficiently bypass the BBB via the nose-to-brain pathway and protect BDNF from oxidative damage, providing an effective route for the therapy of depressive disorders by intranasal delivery.

RESULTS

Quercetin nanogels exhibited uniform size distribution, excellent biocompatibility, and potent antioxidant and anti-inflammatory activities. Quercetin nanogels in the thermosensitive gel achieved sustained and controlled release of BDNF with non-Fick's diffusion, exhibited rapid brain distribution, and achieved nearly 50-fold enhanced bioavailability compared to oral quercetin. Quercetin nanogels as a therapeutic drug delivery carrier exerted antidepressant effects on reserpine-induced rats, effectively delivered BDNF to reverse despair behavior in stress-induced mice, and exhibited antidepressant effects on chronic mild unpredictable stimulation (CUMS) rats. These antidepressant effects of BDNF-Quercetin nanogels for CUMS rats are associated with the regulation of the glutamatergic system, PI3K-Akt, and BDNF-TrkB signaling pathway.

CONCLUSIONS

In this study, we provide a promising strategy for brain delivery of BDNF for treating depressive disorders, effectively achieved through combining quercetin nanogels and intranasal administration.

Ferrocene/ β-cyclodextrin based supramolecular nanogels as theranostic systems

A supramolecular redox responsive nanogel (NG) with the ability to sense cancer cells and loaded with a releasing therapeutic agent was synthesized using hostguest interactions between polyethylene glycol-grafted-β-cyclodextrin and ferrocene boronic acid. Cyclic voltammetry matched with other spectroscopy and microscopy methods provided strong indications regarding host-guest interactions and formation of the NG. Moreover, the biological properties of the NG were evaluated using fluorescence silencing, confocal laser scanning microscopy, and cell toxicity assays. Nanogel with spherical core-shell architecture and 100-200 nm sized nanoparticles showed high encapsulation efficiency for doxorubicin (DOX) and luminol (LU) as therapeutic and sensing agents. High therapeutic and sensing efficiencies were manifested by complete release of DOX and dramatic quenching of LU fluorescence triggered by 0.05 mM H2O2 (as an ROS component). The NGs showed high ROS sensitivity. Taking advantage of a high loading capacity, redox sensitivity, and biocompatibility, the NGs can be used as strong theranostic systems in inflammation-associated diseases.

Toward function starch nanogels by self-assembly of polysaccharide and protein: From synthesis to potential for polyphenol delivery

Nanogels formed by self-assembly of natural proteins and polysaccharides have attracted great interest as potential carriers of bioactive molecules. Herein, we reported that carboxymethyl starch-lysozyme nanogels (CMS-Ly NGs) were prepared using carboxymethyl starch and lysozyme by green and facile electrostatic self-assembly, and the nanogels served as epigallocatechin gallate (EGCG) delivery systems. The dimensions and structure of the prepared starch-based nanogels (i.e., CMS-Ly NGs) were characterized by dynamic light scattering (DLS), ζ-potential, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and thermal gravimetric analyzer (TGA). FT-IR and 1H NMR spectra together confirmed the formation of CMS; FT-IR spectra confirmed the formation of CMS-Ly NGs; XRD spectra confirmed the disruption of the crystal structure of lysozyme after electrostatic self-assembly with CMS, and further confirmed the formation of nanogels. TGA demonstrated the thermal stability of nanogels. More importantly, the nanogels showed a high EGCG encapsulation rate of 80.0 ± 1.4 %. The CMS-Ly NGs encapsulated with EGCG exhibited regular spherical structure and stable particle size. Under the simulated gastrointestinal environmental conditions, CMS-Ly NGs encapsulated with EGCG showed the controlled release potential, which increased its utilization. Additionally, anthocyanins can also be encapsulated in CMS-Ly NGs and showed slow-release properties during gastrointestinal digestion in the same way. Cytotoxicity assay also demonstrated good biocompatibility between CMS-Ly NGs and CMS-Ly NGs encapsulated with EGCG. The findings of this research suggested the potential application of protein and polysaccharides-based nanogels in the delivery system of bioactive compounds.

A comparative study between two carboxymethylated polysaccharides/protein electrostatic and cross-linked nanogels constructed for caffeic acid and eugenol delivery

In response to the pressing demand for functional nanomaterials synthesis and applications, two polyelectrolyte complexes (PECs) [electrostatic and cross-linked nanogels (NGs)] loaded individually with caffeic acid (CafA) and eugenol (Eug) demonstrating multifunctionalities were proposed for the first time. Curdlan (Curd) and glucomannan (GM) were carboxymethylated (CMCurd and CMGM) successfully and polymeric ratios of 1:1 and 4:1 (v/v) for chitosan (Cs): CMCurd and lactoferrin (Lf): CMGM were selected for the synthesis of Cs/CMCurd and Lf/CMGM NGs. Due to the use of EDC/NHS, Cs/CMCurd/CafA and Lf/CMGM/Eug NGs possessed very uniform particles sizes of 177 ± 18 and 230 ± 17 nm with marked encapsulation efficiencies (EEs) of 76 ± 4 and 88 ± 3 %, respectively. The formation of a carbonyl-amide linkage in both cross-linked NGs was confirmed by FTIR. It should be noted, the self-assembly was not reliable in retaining enough of the encapsulated compounds. Owing to the excellent physicochemical characteristics of the loaded cross-linked NGs, they were prioritized over the electrostatic ones. Both Cs/CMCurd/CafA and Lf/CMGM/Eug NGs exhibited high colloidal stability over 12 weeks, elevated hemocompatibility, and in vitro serum stability. The generated NGs were also tailored to possess controlled release profiles for CafA and Eug over 72 h. Cs/CMCurd/CafA and Lf/CMGM/Eug NGs had promising antioxidant efficacies and could remarkably inhibit 4 bacterial pathogens at low 2-16 μg/mL concentration of encapsulated NGs compared to their unencapsulated counterparts. Interestingly, the respective NGs could significantly decline the IC₅₀ against colorectal cancer HCT-116 than conventional drugs. Based on these data, it was conferred that the investigated NGs could be promising candidates for functional foods and pharmaceutics.

Fabrication and characterization of succinylated and glycosylated soy protein isolate and its self-assembled nanogel

In this study, we used succinic anhydride (SA) acylation and dextran (DX) glycosylation modified soybean isolate protein (SPI) to develop self-assembled SPI-SA-DX adduct-based nanogels. Degree of modification, SDS-PAGE, and FT-IR studies showed that the amino group of the SPI was replaced by hydrophilic dextran and succinic acid carboxyl groups. Dextran chain and anhydride group attachment to the soybean protein surface enhanced hydrophilicity and spatial site blocking. Modification-induced protein structure unfolding, free sulfhydryl groups to be converted to disulfide bonds, and reduced surface hydrophobicity (H₀). H₀ was lowest at 33,750 ± 1008.29 when SA content = 10 % protein content (SPI-SA₃-DX). The nanometer gel based on SPI-SA₃-DX had the maximum turbidity and clear transparent solution without precipitation. Its particle size and polymer dispersibility index (PDI) were also the smallest, with values of (106.87 ± 4.51) nm and 0.21 ± 0.009, respectively. Transmission electron microscopy showed that nanogels had subspherical shell-core structures. Nanogels were stable under different pH, ionic strength, high temperature, and storage conditions.

Guar gum modified tilmicosin-loaded sodium alginate/gelatin composite nanogels for effective therapy of porcine proliferative enteritis caused by Lawsonia intracellularis

In order to overcome the treatment difficulty of Lawsonia intracellularis (L.intracellularis) using antibiotics, the tilmicosin (TIL)-loaded sodium alginate (SA)/gelatin composite nanogels modified with bioadhesive substances were designed. The optimized nanogels were prepared by electrostatic interaction between SA and gelatin at a mass ratio of 1:1 and CaCl₂ as an ionic crosslinker and further modified with guar gum (GG). The optimized TIL-nanogels modified with GG had a uniform spherical shape with a diameter of 18.2 ± 0.3 nm, LC of 29.4 ± 0.2 %, EE of 70.4 ± 1.6 %, PDI of 0.30 ± 0.04, and ZP of -32.2 ± 0.5 mv. The FTIR, DSC, and PXRD showed that GG was covered on the surface of TIL-nanogels in a pattern of staggered arrangements. The TIL-nanogels modified with GG had the strongest adhesive strength amongst those with I-carrageenan and locust bean gum and the plain nanogels, and thus significantly enhanced the cellular uptake and accumulation of TIL via clathrin-mediated endocytosis. It exhibited an increased therapeutic effect against L.intracellularis in vitro and in vivo. This study will provide guidance for developing nanogels for intracellular bacterial infection treatment.

Different Applications of Temperature responsive nanogels as a new drug delivery system mini review

Temperature-sensitive drug delivery systems (TSDDS) are one of the systems that have received more attention in medical science these days due to their advantages. As these systems are sensitive to temperature, drug delivery to the target becomes more specific. Temperature-sensitive nanogels have many applications, including microbial infections, cancer therapy, transdermal use and tissue repair. These systems are characterized by minimal toxicity, improved therapeutic efficacy and reduced exposure to normal cells. This mini-review is prepared with different types of temperature-sensitive nanogel formation, release mechanisms, and their different applications. Various systems reported under these categories for targeted and controlled delivery of different classes of drugs, such as anti-cancer and antibiotic drugs with special emphasis on anti-cancer drugs and tissue healing, are discussed in this mini-review.

Crosslinking konjac-glucomannan with kappa-carrageenan nanogels: A step toward the design of sacrificial materials

The challenge in designing sacrificial materials is to obtain materials that are both mechanically stable and easily dissolvable. This research aimed to meet this challenge by fabricating a new polymer-nanogel hydrogel based solely on hydrogen bonds between two polysaccharides. The study focused on hydrogels formed from soluble konjac-glucomannan and nanogels synthesized from kappa-carrageenan. This novel hydrogel exhibited self-healing and shear-thinning properties due to its weak physical interactions. The hydrogel dissolved simultaneously with its swelling. Changes in temperature or nanogel concentration, or the addition of potassium ions, altered the swelling and dissolution rates. Furthermore, adding KCl to the as-prepared hydrogel increased its compression and tensile moduli and its strength. The new formulation opens numerous possibilities as a potential sacrificial material for different applications since it is mechanically stable yet rapidly dissolves in physiological conditions without applying high temperatures or using chelating agents.

Chemical, physical, and biological stimuli-responsive nanogels for biomedical applications (mechanisms, concepts, and advancements): A review

The development of nanotechnology has influenced the advancements in biomedical and pharmaceutical fields. The design and formulation of stimuli-responsive nano-drug delivery systems, also called smart drug delivery systems, have attracted significant research worldwide and have been seen as a breakthrough in nanomedicines. The ability of these nanocarriers to respond to external and internal stimuli, such as pH, temperature, redox, electric and magnetic fields, enzymes, etc., has allowed them to deliver the cargo at targeted sites in a controlled fashion. The targeted drug delivery systems limit the harmful side effects on healthy tissue by toxic drugs and furnish spatial and temporal control drug delivery, improved patient compliance, and treatment efficiency. The polymeric nanogels (hydrogel nanoparticles) with stimuli-responsive characteristics have shown great potential in various biomedical, tissue engineering, and pharmaceutical fields. It is primarily because of their small size, biocompatibility, biodegradability, stimuli-triggered drug deliverability, high payload capacity, and tailored functionality. This comprehensive review deals distinctively with polymeric nanogels, their chemical, physical, and biological stimuli, the concepts of nanogels response to different stimuli, and recent advancements. This document will further improve the current understanding of stimuli-responsive materials and drug delivery systems and assist in exploring advanced potential applications of these intelligent materials.

Targeted Delivery Strategies of Herbal-Based Nanogels: Advancements and Applications

The objective of this review is to thoroughly investigate herbal nano gels as a promising drug delivery approach for the management of various chronic and acute disorders. Herbal nano gels are a novel and promising drug delivery technique, offering special benefits for better therapeutic efficacy. This review offers a comprehensive analysis of the herbal nano gels with a particular emphasis on their evaluation concerning conventional dosage forms, polymer selection criteria, drug release mechanisms, and applications. The comparison study demonstrates that herbal nano gels have different benefits over conventional dose forms. In the areas of oral administration for improved bioavailability and targeted delivery to the gastrointestinal tract, topical drug delivery for dermatological conditions, and targeted delivery strategies for the site-specific treatment of cancer, inflammatory diseases, and infections, they demonstrate encouraging results in transdermal drug delivery for systemic absorption. A promising platform for improved medication delivery and therapeutic effectiveness is provided by herbal nanogels. Understanding drug release mechanisms further contributes to the controlled and sustained delivery of herbal therapeutics. Some of the patents are discussed and the comparative analysis showcases their superiority over conventional dosage forms, and the polymer selection criteria ensure the design of efficient and optimized formulations. Herbal-based nano gels have become a potential approach for improving drug administration. They provide several advantages such as better stability, targeted delivery, and controlled release of therapeutic components. Herbal nano gels are a promising therapeutic approach with the ability to combat a wide range of conditions like cancer, wound healing and also improve patient compliance.

Formulation, Characterization, and Evaluation of Wound Healing Potency of a Novel Mattan tailam Nanogel Based on a Famous Traditional Siddha Formula

Background

The Mattan tailam mixture has been extensively used to heal ulcerous wounds in traditional Siddha practice. The present study aimed to synthesize a Mattan tailam nanogel and evaluate the enhancement of wound healing potential in an experimental wound model.

Methods

Mattan tailam nanogel was synthesized using the high-energy milling approach, and characterization of nanogel and potency of wound healing was investigated. The novelty of this study was the nanogel preparation of Mattan tailam.

Results

As expected, a synthesized novel nanogel of Mattan tailam has a distinct, prominent peak with a spherical form, is negatively charged and has an average particle size of 20-30 nm. Mattan tailam nanogel treated rats showed a remarkable reduction (p<0.001) in the wound area. On the 16th day, 10% Mattan tailam nanogel treatment resulted in a higher percentage of wound contraction. The 10% Mattan tailam nanogel group exhibited a faster epithelialization time (14.33 days) and a greater hydroxyproline concentration than the others. The topical application of 10% Mattan tailam nanogel increased tensile strength, signifying a better therapeutic indication.

Conclusion

The present findings prove that polyherbal Mattan tailam nanogel formulation significantly improves collagen production, wound contraction, and tensile strength.

Nanogel-based Transdermal Drug Delivery System: A Therapeutic Strategy with Under Discussed Potential

The application of nanoparticles in medication delivery has revolutionized the field of therapeutic biology. To improve medical efficacy, currently, drug nanocarriers are employed to control the release and stability, expand its circulation time, or protect it from cell clearance or premature breakdown. A crosslinked polymeric framework is used to crosslink the hydrogel nanoparticle dispersions for safer and stable delivery on target sites. Nanogels have developed in the last two decades as potential biomaterials with a wide variety of applications. Later attributes of nanogels are mainly due to large surface areas, retention of molecules, size flexibility, and water-based formulations that have made them popular as drug delivery vehicles, as seen by several in vivo uses. The gel matrix containing the nanoparticle drug demonstrated a considerable increase in drug penetration in transdermal drug and topical delivery methods. This review aims to understand why and how nanogels are considered so innovative as a drug delivery method. It also examines their preparation methods and applications in the pharmaceutical and biomedical fields and discusses the benefits of nanogels, including swelling capacity and stimulus stimuli sensitivity. Nanogels, on the other hand, have recently been investigated for applications outside the field of biomedicine. Since there are many possible uses for nanogels, we have comprehensively reviewed the current state of the art for all feasible nanogel applications and manufacturing methods.

Formulation studies and physico-chemical characterization

The development of a successful strategy to ensure a full recovery in patients affected by peripheral nerve injury (PNI), one of the most debilitating pathologies, is, still today, a major clinical challenge. Herein, spermidine (SP), an endogenous polyamine, is employed with a dual role: as cross-linking agent for alginate (ALG) and as antioxidant and anti-inflammatory compound. In particular, micro/nanogels based on the ionic interaction between ALG and SP were obtained via ionotropic gelation. Different ALG concentrations and viscosity grades and different SP concentrations were considered. The influence of such variables on micro/nanogels size was investigated by means of a Design of Experiments (DoE) approach (full factorial design). The formation of micro/nanogels was proved by Scanning Electron Microscope (SEM) analysis and by rheological and profilometry measurements. Fourier Transform Infrared (FTIR) measurements performed on nanogels of optimal composition confirmed SP-ALG interaction. The addition of trehalose as cryoprotectant agent to nanogel dispersion was considered in view of the employment of freeze-drying process to obtain a stable product. Moreover, in vitro studies on Schwann cells proved the ability of SP of expressing antioxidant and anti-inflammatory properties, even if involved in the formation of nanogels.

Thermoresponsive nanogels based on polyelectrolyte complexes between polycations and functionalized hyaluronic acid

A novel kind of thermoresponsive polyelectrolyte complex-based nanogels (PEC-NGs) was elaborated by mixing hyaluronic acid (HA) functionalized with Jeffamine® M-2005 (M2005, a thermoresponsive amine-terminated polyether) and diethylaminoethyl dextran (DEAE-D) or poly-l-lysine (PLL) in water. The presence of M2005 grafts led to PEC-NGs with larger particle size, lower net surface charge and thermoresponsiveness, namely shrinkage with increasing hydrophobicity at higher temperature. Both M2005 grafts and replacing DEAE-D with PLL as polycation allowed PEC-NGs to have higher stability against salinity and better encapsulation of curcumin, most probably through intraparticle hydrophobic interactions, whereas interparticle hydrophobic interactions may facilitate particle aggregation over time. Curcumin encapsulation can be optimized by applying higher temperature during the complexation. Enzymatic degradability of PEC-NGs was also verified through particle size evolution in the presence of hyaluronidase. These results provide new insights into the physicochemical aspect of such systems as promising nanocarriers for drug delivery.

Biotin receptor-targeting nanogels loaded with methotrexate for enhanced antitumor efficacy in triple-negative breast cancer in vitro and in vivo models

High-dose methotrexate (MTX) chemotherapeutic applications confront drug specificity and pharmacokinetic challenges, which can be overcome by utilizing targeted drug delivery systems. In the present study, biotin-PEG conjugated nanogels of carboxymethyl polyethyleneimine (Biotin-PEG-CMPEI) were developed for active targeted delivery of MTX in triple negative breast cancer (TNBC). TEM and DLS analyses revealed uniform, discrete, and spherical particles with a mean hydrodynamic diameter of about 100 nm and ζ-potential of + 15 mV (pH = 7.4). Biotin-PEG-CMPEI nanogels exhibited a zero-order MTX release kinetics at pH = 7.5 and a swelling-controlled release at pH = 5.5. In 4 T1 cells treated with the MTX-loaded Biotin-PEG-CMPEI, the IC₅₀ was reduced by about 10 folds compared to the free drug, while the unloaded nanogels showed no significant toxicity. In the model mice, the group treated with the MTX-loaded Biotin-PEG-CMPEI had a lower tumor volume and mortality rate animal model when compared to free drug. Additionally, histopathological analyses showed that the group treated with the MTX-loaded nanogels had less lung metastasis and glomerular damage caused by MTX. Overall, the MTX-loaded Biotin-PEG-CMPEI targeted directly against overexpressed biotin receptors in TNBC have been shown to improve the MTX safety and therapeutic efficacy.

Facile synthesis of chitosan-based nanogels through photo-crosslinking for doxorubicin delivery

Chitosan-based nanogels are effective carriers for drug delivery due to their biocompatibility and biodegradability. However, the chemically cross-linked nanogels usually require complicated procedures or tough conditions. Herein, we report a simple approach to generate chitosan-based nanogels by photo-crosslinking of poor solvent-induced nanoaggregates without requiring any emulsifying agent, catalyst, or external crosslinker. O-nitrobenzyl alcohol-modified carboxymethyl chitosan was synthesized and self-crosslinked into the nanogels in a mixed solution of ethanol and water under 365 nm light irradiation due to UV-induced primary amine and o-nitrobenzyl alcohol cyclization. The nanogels (CMC-NBA NPs) and lactobionic acid-decorated nanogels (LACMC-NBA NPs) displayed a uniform diameter (~200 nm) and excellent stability under physiological conditions. Notably, the nanogels exhibited a high loading content (~28 %) due to π-π stacking and electrostatic interactions between doxorubicin (DOX) and the carriers. These DOX-loaded nanogels showed rapid drug release under slightly acidic conditions. The cell and animal experiments confirmed that LACMC-NBA NPs increased cellular uptake, improved cytotoxicity in tumor cells, and enhanced growth inhibition in vivo than CMC-NBA NPs. Thus, these photo-crosslinked nanogels possess great potential for DOX delivery.

Temperature/pH-responsive carmofur-loaded nanogels rapidly prepared via one-pot laser-induced emulsion polymerization

Tumor microenvironment-responsive nanogels loading antitumor drugs can improve the chemotherapy efficiency due to their suitable size, great hydrophilicity, excellent biocompatibility, and sensitivity to specific stimulation. Herein, a simple and effective strategy of one-pot laser-induced emulsion polymerization at 532 nm was developed to prepare carmofur-loaded nanogels based on biocompatible and temperature/pH-sensitive monomers including polyethylene glycol diacrylate (PEGDA), N-vinylcaprolactam (NVCL), and 2-(dimethylamino) ethyl methacrylate (DMAEMA). The nanogels loading carmofur with dual-stimuli responsive drug release properties were rapidly obtained under laser irradiation (beam diameter 2.5 mm, laser power 60 mW) for only 100 s. These nanogels exhibited an average hydrodynamic diameter of 195.9 nm and a low polydispersity index of 0.115. The effect of monomer ratio on the size, morphology, double-bond conversion, and thermo/pH-sensitivity of nanogels was investigated. The cumulative carmofur release from nanogels at pH 5.0 within 48 h was nearly three times that at pH 7.4, while the release amount at 42 °C was twice that at 25 °C, showing the controlled and sustainable release with the change of pH and temperature. The in vitro release kinetics of carmofur was in accord with first-order release model.

A hybrid thermoresponsive plasmonic nanogel designed for NIR-mediated chemotherapy

Temperature-trigger chemotherapy is one of the state-of-the-art anti-tumoral strategies in nanomedicine. However, this strategy is in close relationship with the effect of the temperature in the tumor tissue. With high temperatures, the ablation of the tumor tissue can hinder a correct chemotherapy approximation. On the other hand, with moderate temperatures a negative vascularization that promotes the tumor growing is produced and competes with the chemotherapeutic effects. We have constructed one nanogel system composed of a thermoresponsive polymer cross-linked by plasmonic gold nanoparticles (AuNPs) for temperature-trigger chemotherapy. Doxorubicin loaded in the porous interior of the nanogel is released when the thermoresponsive network of the nanogel collapses due to the heat generated by the AuNPs upon near infra-red light irradiation. The hybrid nanogel system has been tested in vitro and in vivo, where it was observed that the temperatures reached in the in vivo NIR irradiation have an undesired effect on the inhibition of the tumor growth while the drug loaded systems considerably reduced the tumor sizes. This study shows the importance of design in temperature triggered antitumoral systems, where lower temperatures usually reached in practical situations due to light attenuation produced by the tissue can be positively utilized for enhancing the antitumoral effect of loaded drugs in the system.

Adsorption of soft NIPAM nanogels at hydrophobic and hydrophilic interfaces: Conformation of the interfacial layers determined by neutron reflectivity

The application of stimuli-responsive microgels and nanogels in drug delivery, catalysis, sensing, and coatings is restricted currently by the limited understanding of the factors influencing their adsorption dynamics and structural changes at interfaces. We have used neutron reflectivity to resolve, on the Ångström scale, the structure of 5% crosslinked N-isopropylacrylamide nanogels at both hydrophobic and hydrophilic interfaces in situ, as a function of temperature and bulk nanogel concentration. Our results show that the higher flexibility given by the low crosslinker content allows for a more ordered structure and packing. The adsorption of the thermoresponsive nanogels is primarily driven by temperature, more specifically its proximity to its volume phase transition temperature, while concentration plays a secondary role. Hydrophobic interactions drive the conformation of the first layer at the interface, which plays a key role in influencing the overall nanogel structure. The mobility of the first layer at the air-water interface as opposed to the interfacial confinement at the solid (SiC8)-liquid interface, results in a different conformation, a more compact and less deformed packing structure, which ultimately drives the structure of the subsequent layers. The evidence for the different structural conformations determined by the degree of hydrophobicity of the interface provides new knowledge, which is essential for the development of further applications. The key role of hydrophobic interactions in driving adsorption and interfacial behavior was also confirmed by fluid AFM experiments which visualized adherence of the nanogels to SiC8 modified surfaces.

Film Forming Nanogels for Needle-free Transdermal Vaccination

Transcutaneous immunization (TCI) provides a valuable alternative approach to conventional vaccination because of the high accessibility and the exceptional immunological characteristics of the skin, but its application is limited by the low permeability of the stratum corneum. Although nanogels (NGs) have proven to enhance skin penetration of macromolecules with minimum damage, their use in TCI remains almost unexplored. In this context, this article evaluates the performance of novel film forming NGs (FF-NGs) as TCI. This TCI platform consists of NGs with multilobular morphology that positively combines the properties of crosslinked poly(N-vinylcaprolactam), like thermoresponsiveness and the ability to load and release a cargo, with the film forming capacity of low Tg lobes. FF-NGs and formed films were characterized at different levels. Formed films show to be able to uniformly load an antigenic protein and release it with a profile depending on the temperature and on their FF-NGs content. In-vivo studies have demonstrated that FF-NGs promote the penetration of not only an antigenic protein but also an adjuvant until the immunocompetent area of skin, generating an adjuvant-dependent specific immune response. Finally, this study provides a successful proof of concept that FF-NGs could be a powerful tool for transcutaneous release of complex formulations. This article is protected by copyright. All rights reserved.

Bioactive injectable hydrogels for on demand molecule/cell delivery and for tissue regeneration in the central nervous system

Currently there are no potential curative therapies that can improve the central nervous system (CNS) regeneration after traumatic injuries or diseases. Indeed, the regeneration of CNS is greatly impaired by limited drug penetration across the blood brain barrier (BBB), poor drug targeting, deficient progenitor neural cells and limited proliferation of mature neural cells. To overcome these limitations, bioengineered injectable hydrogels in combination with drug and cell therapy have been proposed to mimic the complexity of the CNS microenvironment and architecture. Additionally, to enhance relevant CNS regeneration, proper biophysical and biochemical cues are needed. Recently, great efforts have been devoted to tailor stimuli-responsive hydrogels as novel carrier systems which are able to guide neural tissue regeneration. This review provides an extensive overview on the most promising injectable hydrogels for neural tissue engineering. A special emphasis is made to highlight the ability of these hydrogels to deliver bioactive compounds/cells upon the exposure to internal and external stimuli. Bioactive injectable hydrogels have a broad application in central nervous system's (CNS) regeneration. This review gives an overview of the latest pioneering approaches in CNS recovery using stimuli-responsive hydrogels for several neurodegenerative disorders. STATEMENT OF SIGNIFICANCE: This review summarizes the latest innovations on bioactive injectable hydrogels, focusing on tailoring internal/external stimuli-responsive hydrogels for the new injectable systems design, able to guide neural tissue response. The purpose is to highlight the advantages and the limitations of thermo-responsive, photo responsive, magnetic responsive, electric responsive, ultrasound responsive and enzymes-triggered injectable hydrogels in developing customizable neurotherapies. We believe that this comprehensive review will help in identifying the strengths and gaps in the existing literature and to further support the use of injectable hydrogels in stimulating CNS regeneration.

Therapeutic effects of dexamethasone-loaded hyaluronan nanogels in the experimental cholestasis

A major function of the intrahepatic biliary epithelium is bicarbonate excretion in bile. Recent reports indicate that budesonide, a corticosteroid with high receptor affinity and hepatic first pass clearance, increases the efficacy of ursodeoxycholic acid, a choleretic agent, in primary biliary cholangitis patients. We have previously reported that bile ducts isolated from rats treated with dexamethasone or budesonide showed an enhanced activity of the Na⁺/H⁺ exchanger isoform 1 (NHE1) and Cl^-/HCO₃^- exchanger protein 2 (AE2) . Increasing the delivery of steroids to the liver may result in three beneficial effects: increase in the choleresis, treatment of the autoimmune or inflammatory liver injury and reduction of steroids' systemic harmful effects. In this study, the steroid dexamethasone was loaded into nanohydrogels (or nanogels, NHs), in order to investigate corticosteroid-induced increased activities of transport processes driving bicarbonate excretion in the biliary epithelium (NHE-1 isoform) and to evaluate the effects of dexamethasone-loaded NHs (NHs/dex) on liver injury induced by experimental cholestatis. Our results showed that NHs and NHs/dex do not reduce cell viability in vitro in human cholangiocyte cell lines. Primary and immortalized human cholangiocytes treated with NHs/dex show an increase in the functional marker expression of NHE1 cholangiocytes compared to control groups. A mouse model of cholangiopathy treated with NHs/dex shows a reduction in markers of hepatocellular injury compared to control groups (NHs, dex, or sham group). In conclusion, we believe that the NHs/dex formulation is a suitable candidate to be investigated in preclinical models of cholangiopathies.

Preparation and characterization of soybean protein isolate-dextran conjugate-based nanogels

Soybean protein isolate (SPI)-dextran conjugate-based nanogels were prepared via the Maillard reaction combined with protein self-assembly in this study. The dextran molecular weight (40 kDa), SPI/dextran mass ratio (1:1.75), and incubation time (3.3 d) for preparing SPI-dextran conjugate (SDC) were firstly optimized. The SDC was confirmed by analyzing the changes in protein composition and infrared absorption bands and showed loosened tertiary conformation, reduced surface hydrophobicity, decreased Z-average hydrodynamic diameter (D_h) and zeta potential, and improved emulsifying properties compared to the native SPI. Effects of conjugate concentration, pH, heating temperature, and time on D_h and polydispersity index were also evaluated. The SDC-based nanogels were translucent in aqueous solution and exhibited a spherical core-shell structure with a D_h of ∼104.4 nm and a good stability against thermal treatment, ionic strength, and storage. Results demonstrated the SDC-based nanogels possessed a potential to be used as desirable nanocarriers for encapsulating hydrophobic bioactive compounds.

Chitosan/hyaluronan nanogels co-delivering methotrexate and 5-aminolevulinic acid: A combined chemo-photodynamic therapy for psoriasis

Psoriasis does not respond adequately to the monotherapy, tailoring combined strategies for synergistical treatment remains challenging. We fabricated chitosan/hyaluronan nanogels to co-load methotrexate (MTX) and 5-aminoleavulinic acid (ALA), i.e., MTX-ALA NGs, for a combined chemo-photodynamic therapy for psoriasis. Compared with MTX-ALA suspension, the NGs enhanced the penetration and retention of MTX and ALA through and into the skin in vitro and in vivo (p < 0.001). NGs enhanced the cellular uptake (p < 0.001), protoporphyrin IX conversion (p < 0.001), and reactive oxygen species generation (3.93-fold), subsequently exerted the synergistical anti-proliferation and apoptosis on lipopolysaccharide-irritated HaCaT cells with the apoptosis rate of 78.6%. MTX-ALA NGs efficiently ameliorated the skin manifestations and down-regulated the proinflammatory cytokines of TNF-α and IL-17A in imiquimod-induced psoriatic mice (p < 0.001). Importantly, MTX-ALA NGs reduced the toxicities of oral MTX to the liver and kidney. The results support that MTX-ALA NG is a convenient, effective, and safe combined chemo-photodynamic strategy for psoriasis treatment.

The evaluation of healing effect of triclosan and flurbiprofen-loaded nanogels in experimental periodontitis in rats by morphometric analysis

Purpose

To evaluate therapeutic effectiveness of antibacterial triclosan (TCS) and anti-inflammatory flurbiprofen (FLB)-loaded nanogels system in ligature-induced experimental periodontitis in rats.

Methodology

A total of 72 Sprague-Dawley rats were used in this study. Four groups (n = 18 each) were randomly created: Group 1 - neither subjected to experimental periodontitis nor to any treatment; Group 2 - subjected to experimental periodontitis but not treated; Group 3 - subjected to experimental periodontitis and then treated with the developed nanogels; Group 4 - subjected to experimental periodontitis and then placed on a mixture of pure TCS and FLB treatment. The experimental periodontitis was induced on the lower incisors by applying a ligature which was kept for 14 days. Treatment was done for 7 days, and sampling was done at 7, 14, and 28 day of the post-induction experimental period. Morphometric analysis was conducted to assess the clinical outcomes and healing effect.

Results

The morphometric findings showed that the group treated with the developed TCS and FLB-loaded nanogels recovered better and faster than a mixture of pure TCS and FLB. At 28 day of the experimental period, there was no significant difference (p > 0.05) between the baseline control group and the nanogels treated group.

Conclusions

The developed TCS and FLB-loaded nanogels was found to be effective in the treatment of experimental periodontitis in rats. The used experimental periodontitis model was found to be simple and easily reproducible.

Dendrimer-decorated nanogels: Efficient nanocarriers for biodistribution in vivo and chemotherapy of ovarian carcinoma

Nanomedicine has revolutionized disease theranostics by the accurate diagnosis and efficient therapy. Here, the PAMAM dendrimer decorated PVCL-GMA nanogels (NGs) were developed for favorable biodistribution in vivo and enhanced antitumor efficacy of ovarian carcinoma. By an ingenious design, the NGs with a unique structure that GMA-rich domains were localized on the surface were synthesized via precipitation polymerization. After G2 dendrimer decoration, the overall charge is changed from neutral to positive, and the NGs-G2 display the whole charge nature of positively charged corona and neutral core. Importantly, the unique architecture and charge conversion of NGs-G2 have a profound impact on the biodistribution and drug delivery in vivo. As a consequence of this alteration, the NGs-G2 as nanocarriers emerge the highly sought biodistribution of reduced liver accumulation, enhanced tumor uptake, and promoted drug release, resulting in the significantly augmented antitumor efficacy with low side effects. Remarkably, this finding is contrary to some reported work that the nanocarriers with positive charge have preferential liver uptake. Moreover, the NGs-G2 also displayed thermal/pH dual-responsive behaviors, excellent biocompatibility, improved cellular uptake, and stimuli-responsive drug release. Encouragingly, this work demonstrates a novel insight into the strategy for optimizing design, improving biodistribution and enhancing theranostic efficacy of nanocarriers.

Nanogels: A novel approach in antimicrobial delivery systems and antimicrobial coatings

The implementation of nanotechnology to develop efficient antimicrobial systems has a significant impact on the prospects of the biomedical field. Nanogels are soft polymeric particles with an internally cross-linked structure, which behave as hydrogels and can be reversibly hydrated/dehydrated (swollen/shrunken) by the dispersing solvent and external stimuli. Their excellent properties, such as biocompatibility, colloidal stability, high water content, desirable mechanical properties, tunable chemical functionalities, and interior gel-like network for the incorporation of biomolecules, make them fascinating in the field of biological/biomedical applications. In this review, various approaches will be discussed and compared to the newly developed nanogel technology in terms of efficiency and applicability for determining their potential role in combating infections in the biomedical area including implant-associated infections.

Modulating acrylic acid content of nanogels for drug delivery & biocompatibility studies

Dual stimuli-responsive nanogels (NGs) have gained popularity in the field of bio medicine due to their versatile nature of applicability. Poly(N-isopropylacrylamide)-co-poly(acrylic acid) (pNIPAm-pAAc)-based NGs provide such dual stimuli-response with pNIPAm and pAAc providing thermal and pH-based responses, respectively. Studying the growth of these NGs, as well as, understanding the effect of the incorporation of pAAc in the NG matrix, is important in determining the physico-chemical properties of the NG. Studies have been conducted investigating the effect of increasing pAAc content in the NGs, however, these are not detailed in understanding its effects on the physico-chemical properties of the pNIPAm-pAAc-based NGs. Also, the biocompatibility of the NGs have not been previously reported using human whole blood model. Herein, we report the effect of different reaction parameters, such as surfactant amount and reaction atmosphere, on the growth of pNIPAm-pAAc-based NGs. It is shown that the size of the NGs can be precisely controlled from ~130 nm to ~400 nm, by varying the amount of surfactant and the reaction atmosphere. The effect of increasing incorporation of pAAc in the NG matrix on its physico-chemical properties has been investigated. The potential of these NGs as drug delivery vehicles is investigated by conducting loading and release studies of a model protein drug, cytochrome C (Cyt C) from the NGs at temperature above the volume phase transition temperature (VPTT) and acidic pH. An ex vivo human whole blood model was used to investigate biocompatibility of the NGs by quantifying inflammatory responses during NG exposure. The NGs did not induce any significant production of chemokine IL-8 or pro-inflammatory cytokines (IL-1β, IL-6, TNF-α), and the cell viability in human whole blood was maintained during 4 h exposure. The NGs did neither activate the complement system, as determined by low Terminal Complement Complex (TCC) activation and Complement Receptor 3 (CR3) activation assays, thereby overall suggesting that the NGs could be potential candidates for biomedical applications.

Construction and evaluation of ovalbumin-pullulan nanogels as a potential delivery carrier for curcumin

Preparation of protein/polysaccharide nanocomplexes for delivering environment-sensitive bioactive compounds is significant in the fields of functional foods and pharmaceuticals. In this work, ovalbumin-pullulan (OVA-Pul) nanogels were fabricated through Maillard reaction combined with heat treatment. The results of SDS-PAGE, circular dichroism and conjugation yield (84.96%) confirmed the covalent crosslinking of ovalbumin to pullulan. Dynamic light scattering measurements indicated that nanogels and curcumin-loaded nanogels exhibited small particle diameter at around 190 nm and 160 nm, and excellent polydispersity index at 0.227 and 0.146, respectively. OVA-Pul nanogels showed good encapsulation efficiency (88.38%) and loading capacity (8.78%) for curcumin. Transmission electron microscope observations and in vitro gastrointestinal digestion suggested that OVA-Pul nanogels facilitated the controlled release of curcumin and the spherical structure of curcumin-loaded nanogels was damaged during digestion. Notably, both nanogels and curcumin-loaded nanogels showed desirable storage stability during 30 d. Hence, OVA-Pul nanogels have the potential for effectively delivering nutrients and drugs.

Preparation and use of nanogels as carriers of drugs

Nanogels have high tunability and stability while being able to sense and respond to external stimuli by showing changes in the gel volume, water content, colloidal stability, mechanical strength, and other physical/chemical properties. In this article, advances in the preparation of nanogels will be reviewed. The application potential of nanogels in drug delivery will also be highlighted. It is the objective of this article to present a snapshot of the recent knowledge of nanogel preparation and application for future research in drug delivery.

Manipulation of TAMs functions to facilitate the immune therapy effects of immune checkpoint antibodies

Immune checkpoint antibodies have emerged as novel therapeutics, while many patients are refractory. Researchers had identified tumor-associated macrophages (TAMs) is the pivotal factor involved in immune resistance and that manipulation of TAMs functions would improve the immunotherapies effectively. NF-κB pathway was one of the master regulators in TAMs manipulation. Inhibition of NF-κB pathway could achieve both re-polarization M2 TAMs and downregulation the expression of programmed cell death protein 1 (PD-1) ligand 1 (PD-L1) on TAMs to improve the effect of immunotherapies. Here, IMD-0354, inhibitor of NF-κB pathway was loaded in mannose modified lipid nanoparticles (M-IMD-LNP). Then, PD-1 antibody and M-IMD-LNP were co-loaded in matrix metalloproteinase 2 (MMP2) responsive and tumor target nanogels (P/ML-NNG). P/ML-NNG could co-deliver drugs to tumor site, disintegrated by MMP2 and release drugs to different targets. Evaluation of PD-1 expression, inhibition of NF-κB pathway, expression of PD-L1 on M2 TAMs and M2 TAMs re-polarization demonstrated that P/ML-NNG could block the PD-1/PD-L1 and NF-κB pathways simultaneously. Evaluation of CD4 ⁺ T cells, CD8 ⁺ T cells, Tregs, cytokines and antitumor immunity confirmed that IMD-0354 could improve the immunotherapies effectively. Those results provided forceful references for tumor immunetherapy.

A multi-in-one strategy with glucose-triggered long-term antithrombogenicity and sequentially enhanced endothelialization for biological valve leaflets

Bioprosthetic heart valves are commonly applied in heart valve replacement, while the effectiveness is limited by inflammation, calcification and especially thrombosis. Surface modification is expected to endow the biological valves with versatility. Herein, a multi-in-one strategy was established to modify biological valves with long-term antithrombogenicity and sequentially enhanced endothelialization triggered by glucose, in which the direct thrombin inhibitor rivaroxaban (RIVA)-loaded nanogels were embedded and the detachable polyethylene glycol (PEG) was grafted. These two anticoagulant strategies were connected by glucose oxidase (GOx), which catalyzed the oxidation of glucose to produce hydrogen peroxide (H₂O₂) and local acidic environment. The generated H₂O₂ stimulated H₂O₂-responsive nanogels release RIVA to obtain continuous antithrombogenicity. Meanwhile, PEG was attached to the surface via pH-sensitive bonds, which prevented thrombus formation by resisting the serum proteins and platelets adhesion at the initial stage of material/blood contact. Sequentially, PEG gradually peeled off under the local weak acidic environment, which ultimately resulted in the endothelialization enhancement. Within such multi-in-one strategy, the biological valve leaflets induced long-term anticoagulant performance, gradually enhanced endothelialization and improved tissue affinity, including anti-calcification and anti-inflammation, indicating the potential of the response sequence matching between materials and tissues after implantation, which might improve performance of biological heart valves.

Insights into the formation mechanisms and properties of pectin hydrogel physically cross-linked with chitosan nanogels

This study explores hydrogels based on the physical interaction between soluble pectin and chitosan nanogels. A simple technique for creating chitosan nanogels of controllable size was developed based on a two-step process: physical cross-linking with tripolyphosphate (TPP) and chemical cross-linking with genipin. The particles were stable at acidic pH, which allowed hydrogel formation. Thixotropy experiments demonstrated that the concentration but not the size of the nanogels strongly affected the gel shear modulus. The influence of the post-assembly conditions, including exposure to monovalent salts (NaCl, NaI, and NaF) and pH (2.5 or 5.5), on the gel swelling and mechanical properties was studied. Small angle x-ray scattering (SAXS) results provide evidence that these physical hydrogels are indeed a cross-linked network. These experiments provided insights into the influence of hydrogen bonds and electrostatic interactions on the gel network.

Construction of carboxymethyl konjac glucomannan/chitosan complex nanogels as potential delivery vehicles for curcumin

Construction of nanoscale delivery systems from natural food biopolymer complexes have attracted increasing interests in the fields of food industries. In this study, novel carboxymethyl konjac glucomannan/ chitosan (CMKGM/CS) nanogels with and without 1-ethyl-3-(3-dimethylaminopropyl) /N-hydroxysuccinimide) (EDC/NHS)-initiated crosslinking were prepared. The physicochemical and structural properties of the CMKGM/CS nanogels and their potential to be a delivery vehicle for curcumin were investigated. Compared to original uncrosslinked nanogels, crosslinking did not alter particle size and morphology but decreased zeta potential of nanogels. Fourier transform infrared spectrum confirmed that the amide linkage was formed between CMKGM and CS, which obviously enhanced the stability of crosslinked nanogels under gastrointestinal conditions. Furthermore, the crosslinked nanogels not only had higher encapsulation efficiency of curcumin but also better sustained release behavior under simulated gastrointestinal conditions. These findings suggested that the crosslinked CMKGM/CS nanogels might be a promising delivery system for nutrients.

Nano-architectural assembly of soy proteins: A promising strategy to fabricate nutraceutical nanovehicles

Use of protein-based nanovehicles has been well recognized to be one of the most effective strategies to improve water dispersibility, stability and bioavailability of nutraceuticals or bioactive ingredients. Thanks to their health-benefiting effects and unique assembly behavior, soy proteins seem to be the perfect food proteins for fabricating nanovehicles in this regard. This review presents the state-of-art knowledge about the assembly of soy proteins into nano-architectures, e. g., nanoparticles, nanocomplexes or nanogels, induced by different physicochemical strategies and approaches. The strategies to trigger the assembly of soy proteins into a variety of nano-architectures are highlighted and critically reviewed. Such strategies include heating, enzymatic hydrolysis, pH shift, urea or ethanol treatment, reduction, and static high pressure treatment. The self-assembly behavior of soy proteins (native or denatured) is also reviewed. Besides the assembly of proteins alone, soy proteins can co-assemble with polysaccharides to form versatile nano-architectures, through different processes, e.g., heating or ultrasonication. Finally, recent progress in the development of assembled soy protein nano-architectures as nanovehicles for hydrophobic nutraceuticals is briefly summarized. With the fast increasing health awareness for natural and safe functional foods, this review is of crucial relevance for providing an important strategy to develop a kind of novel soy protein-based functional foods with dual-function health effects from soy proteins and nutraceuticals.

Strategies to load therapeutics into polysaccharide-based nanogels with a focus on microfluidics: A review

Nowadays nanoparticles are increasingly investigated for the targeted and controlled delivery of therapeutics, as suggested by the high number of research articles (2400 in 2000 vs 8500 in 2020). Among them, almost 2% investigated nanogels in 2020. Nanogels or nanohydrogels (NGs) are nanoparticles formed by a swollen three-dimensional network of synthetic polymers or natural macromolecules such as polysaccharides. NGs represent a highly versatile nanocarrier, able to deliver a number of therapeutics. Currently, NGs are undergoing clinical trials for the delivery of anti-cancer vaccines. Herein, the strategies to load low molecular weight drugs, (poly)peptides and genetic material into polysaccharide NGs as well as to formulate NGs-based vaccines are summarized, with a focus on the microfluidics approach.

Cytocompatibility, membrane disruption, and siRNA delivery using environmentally responsive cationic nanogels

Advances in the formulation of nucleic acid-based therapeutics have rendered them a promising avenue for treating diverse ailments. Nonetheless, clinical translation of these therapies is hindered by a lack of strategies to ensure the delivery of these nucleic acids in a safe, efficacious manner with the required spatial and temporal control. To this aim, environmentally responsive hydrogels are of interest due to their ability to provide the desired characteristics of a protective carrier for siRNA delivery. Previous work in our laboratory has demonstrated the ability to synthesize nanoparticle formulations with targeted pKa, swelling, and surface PEG density. Here, a library of nanoparticle formulations was assessed on their in vitro toxicity, hemolytic capacity, siRNA loading, and gene-silencing efficacy. Successful candidates exhibited the lowest degrees of cytotoxicity, pH-dependent membrane disruption potential, the highest siRNA loading, and the highest transfection efficacies.

Intelligent nanogels with self-adaptive responsiveness for improved tumor drug delivery and augmented chemotherapy

For cancer nanomedicine, the main goal is to deliver therapeutic agents effectively to solid tumors. Here, we report the unique design of self-adaptive ultrafast charge-reversible chitosan-polypyrrole nanogels (CH-PPy NGs) for enhanced tumor delivery and augmented chemotherapy. CH was first grafted with PPy to form CH-PPy polymers that were used to form CH-PPy NGs through glutaraldehyde cross-linking via a miniemulsion method. The CH-PPy NGs could be finely treated with an alkaline solution to generate ultrafast charge-reversible CH-PPy-OH-4 NGs (R-NGs) with a negative charge at a physiological pH and a positive charge at a slightly acidic pH. The R-NGs display good cytocompatibility, excellent protein resistance, and high doxorubicin (DOX) loading efficiency. Encouragingly, the prepared R-NGs/DOX have prolonged blood circulation time, enhanced tumor accumulation, penetration and tumor cell uptake due to their self-adaptive charge switching to be positively charged, and responsive drug delivery for augmented chemotherapy of ovarian carcinoma in vivo. Notably, the tumor accumulation of R-NGs/DOX (around 4.7%) is much higher than the average tumor accumulation of other nanocarriers (less than 1%) reported elsewhere. The developed self-adaptive PPy-grafted CH NGs represent one of the advanced designs of nanomedicine that could be used for augmented antitumor therapy with low side effects.

Nanogels Capable of Triggered Release

This chapter provides an overview of soft and environmentally sensitive polymeric nanosystems, which are widely known as nanogels. These particles keep great promise to the area of drug delivery due to their high biocompatibility with body fluids and tissues, as well as due to their ability to encapsulate and release the loaded drugs in a controlled manner. For a long period of time, the controlled drug delivery systems were designed to provide long-termed or sustained release. However, some medical treatments such as cancer chemotherapy, protein and gene delivery do not require the prolonged release of the drug in the site of action. In contrast, the rapid increase of the drug concentration is needed for gaining the desired biological effect. Being very sensitive to surrounding media and different stimuli, nanogels can undergo physico-chemical transitions or chemical changes in their structure. Such changes can result in more rapid release of the drugs, which is usually referred to as triggered drug release. Herein we give the basic information on nanogel unique features, methods of sensitive nanogels preparation, as well as on main mechanisms of triggered release. Additionally, the triggered release of low-molecular drugs and biomacromolecules are discussed.

Synthesis of PEG-4000-co-poly (AMPS) nanogels by cross-linking polymerization as highly responsive networks for enhancement in meloxicam solubility

Poor solubility is an ongoing issue and the graph of poorly soluble drugs has increased markedly which critically affect their dissolution, bioavailability, and clinical effects. This common issue needs to be addressed, for this purpose a series of polyethylene glycol (PEG-4000) based nanogels were developed by free radical polymerization technique to enhance the solubility, dissolution, and bioavailability of poorly soluble drug meloxicam (MLX), as improved solubility is the significant application of nanosystems. Developed nanogels formulations were characterized by FTIR, XRD, SEM, zeta sizer, percent equilibrium swelling, drug loaded content (DLC), drug entrapment efficiency (DEE), solubility studies, and in vitro dissolution studies. Furthermore, cytotoxicity studies were conducted in order to determine the bio-compatibility of the nanogels drug delivery system to biological environment. Nanogels particle size was found to be 156.19 ± 09.33 d.nm. Solubility study confirmed that the solubility of poorly soluble drug MLX was significantly enhanced up to 36 folds as compared to reference product (Mobic^®). The toxicity study conducted on rabbits and MTT assay endorsed the safety of the developed nanogels formulations to the biological system.

Building an aprismatic enamel-like layer on a demineralized enamel surface by using carboxymethyl chitosan and lysozyme-encapsulated amorphous calcium phosphate nanogels

OBJECTIVES

The purpose of this study was to prepare carboxymethyl chitosan (CMC) and lysozyme nanogels that could encapsulate amorphous calcium phosphate (ACP) for achieving its controlled delivery, thus forming an aprismatic enamel-like layer on the demineralized enamel surface.

METHODS

CMC/LYZ-ACP nanogels were developed, and the controlled delivery of ACP from the nanogels was induced by the presence of NaCl. The nanogel morphologies at various NaCl concentrations was measured by transmission electron microscopy (TEM). The particle sizes and zeta potentials (ζ-potential) of the samples were determined using a combined dynamic light scattering/particle electrophoresis instrument. Comparing the remineralization effect of the CMC/LYZ-ACP nanogels on the demineralized enamel surface with that of a fluoride treatment, the remineralization effect was examined by nanoindentation tests, X-ray diffraction (XRD), confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM).

RESULTS

CMC/LYZ-ACP nanogels were negatively charged spherical structures with a particle size of approximately 300 nm. At high concentrations of NaCl (0.15 M), ACP was dissociated from the disassembled nanogels and transformed into hydroxyapatite (HAP). Groups treated with the CMC/LYZ-ACP nanogels showed the regeneration of an aprismatic enamel-like layer on an acid-etched enamel surface, which provided increased mechanical properties (P < 0.05) and a high impermeability (P < 0.01) compared to those of the fluoride-treated group.

CONCLUSIONS

This research provides a new idea for the stable and controllable delivery of ACP from CMC/LYZ-ACP nanogels, which can form an aprismatic enamel-like layer in situ on the surface of demineralized enamel. In regard to further clinical development, this material and method may be promising for treating early enamel caries.