Dendrimer-assisted formation of fluorescent nanogels for drug delivery and intracellular imaging

Theranostic nanogels: multifunctional agents for simultaneous therapeutic delivery and diagnostic imaging

In recent years, there has been a growing interest in multifunctional theranostic agents capable of delivering therapeutic payloads while facilitating simultaneous diagnostic imaging of diseased sites. This approach offers a comprehensive strategy particularly valuable in dynamically evolving diseases like cancer, where combining therapy and diagnostics provides crucial insights for treatment planning. Nanoscale platforms, specifically nanogels, have emerged as promising candidates due to their stability, tunability, and multifunctionality as carriers. As a well-studied subgroup of soft polymeric nanoparticles, nanogels exhibit inherent advantages due to their size and chemical compositions, allowing for passive and active targeting of diseased tissues. Moreover, nanogels loaded with therapeutic and diagnostic agents can be designed to respond to specific stimuli at the disease site, enhancing their efficacy and specificity. This capability enables fine-tuning of theranostic platforms, garnering significant clinical interest as they can be tailored for personalized treatments. The ability to monitor tumor progression in response to treatment facilitates the adaptation of therapies according to individual patient responses, highlighting the importance of designing theranostic platforms to guide clinicians in making informed treatment decisions. Consequently, the integration of therapy and diagnostics using theranostic platforms continues to advance, offering intelligent solutions to address the challenges of complex diseases such as cancer. In this context, nanogels capable of delivering therapeutic payloads and simultaneously armed with diagnostic modalities have emerged as an attractive theranostic platform. This review focuses on advances made toward the fabrication and utilization of theranostic nanogels by highlighting examples from recent literature where their performances through a combination of therapeutic agents and imaging methods have been evaluated.

Applications and advancements of polysaccharide-based nanostructures for enhanced drug delivery

Growing demand for highly effective, site-specific delivery of pharmaceuticals and nutraceuticals using nano-sized carriers has prompted increased scrutiny of carrier biocompatibility and biodegradability. To address these concerns, biodegradable natural polymers have emerged as a transformative domain, offering non-toxic, precisely targetable carriers capable of finely modulating cargo pharmacokinetics while generating innocuous decomposition by-products. This comprehensive review illuminates the emergence of polysaccharide-based nanoparticulate drug delivery systems. These systems establish an interactive interface between drug and targeted organs, guided by strategic modifications to polysaccharide backbones, which facilitate the creation of morphologically, constitutionally, and characteristically vibrant nanostructures through various fabrication routes, underpinning their pivotal role in biomedical applications. Advancements crucial to enhancing polysaccharide-based drug delivery, such as surface modifications and bioinspired modifications for enhanced targeting, and stimuli-responsive release, strategies to overcome biological barriers, enhance tumor penetration, and optimize therapeutic outcomes are highlighted. This review also examines some potent challenges, and the contemporary way out of them, and discusses future perspectives in the field.

Managing the immune microenvironment of osteosarcoma: the outlook for osteosarcoma treatment

Osteosarcoma, with poor survival after metastasis, is considered the most common primary bone cancer in adolescents. Notwithstanding the efforts of researchers, its five-year survival rate has only shown limited improvement, suggesting that existing therapeutic strategies are insufficient to meet clinical needs. Notably, immunotherapy has shown certain advantages over traditional tumor treatments in inhibiting metastasis. Therefore, managing the immune microenvironment in osteosarcoma can provide novel and valuable insight into the multifaceted mechanisms underlying the heterogeneity and progression of the disease. Additionally, given the advances in nanomedicine, there exist many advanced nanoplatforms for enhanced osteosarcoma immunotherapy with satisfactory physiochemical characteristics. Here, we review the classification, characteristics, and functions of the key components of the immune microenvironment in osteosarcoma. This review also emphasizes the application, progress, and prospects of osteosarcoma immunotherapy and discusses several nanomedicine-based options to enhance the efficiency of osteosarcoma treatment. Furthermore, we examine the disadvantages of standard treatments and present future perspectives for osteosarcoma immunotherapy.

Recent Advances in Nanoplatforms for the Treatment of Osteosarcoma

Osteosarcoma (OS) is the most common primary bone tumor in children and young people. Traditional surgical excision combined with chemotherapy presents many limitations, such as resistance and systemic side effects of chemotherapy drugs, postoperative recurrence, and bone defects. Given these limitations, novel therapeutic modalities for OS treatment using nanometer-sized platform-based chemotherapeutic delivery have emerged as a promising alternative therapy. This form of therapy offers multiple advantages, such as accurate delivery of the drug to the tumor site and repair of limited bone defects after tumor resection. In this review, we briefly summarize nanoplatforms, including liposomes, polymeric nanoparticles, inorganic nanoparticles, nanomicelles, dendrimers, nanocapsules, and exosomes. The essential shortcomings involved in these nanoplatforms, such as poor stability, immunogenicity, insufficient circulation, and drug leakage are also discussed, and related solutions are briefly proposed. Finally, the application prospects of nanoplatforms in the treatment of OS are discussed.

Dendrimer-Based Nanogels for Cancer Nanomedicine Applications

Recent advances in the field of nanotechnology bring an alternative approach to personalized medicine in cancer treatment. Nanogels (NGs) are among the nanosized superconstructs composed of amphiphilic or hydrophilic polymer networks. The design of different types of biodegradable polymer-based NGs in various biomedical applications has received extensive attention, due to their unique physicochemical properties such as highly porous structure, stimuli-responsiveness, and mimicking of some biological properties. In this review, we concisely surveyed the synthesis of dendrimer-based NGs synthesized via different methods including covalent conjugation, inverse nanoprecipitation, physical cross-linking, or self-assembly for various cancer nanomedicine applications, particularly for drug delivery, gene delivery, photothermal therapy, and combination therapy, as well as for biological imaging-guided chemotherapy. Additionally, we provide herein future perspective toward the new design of dendrimer-based NGs for different cancer nanomedicine uses.

Polyester Dendrimers Based on Bis-MPA for Doxorubicin Delivery

Although doxorubicin (DOX) is one of the most used chemotherapeutic drugs due to its efficacy against a wide group of cancer types, it presents severe side effects. As such, intensive research is being carried out to find new nanoscale systems that can help to overcome this problem. Polyester dendrimers based on the monomer 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) are very promising systems for biomedical applications due to their biodegradability properties. In this study, bis-MPA-based dendrimers were, for the first time, evaluated as DOX delivery vehicles. Generations 4 and 5 of bis-MPA-based dendrimers with hydroxyl groups at the surface were used (B-G4-OH and B-G5-OH), together with dendrimers partially functionalized with amine groups (B-G4-NH₂/OH and B-G5-NH₂/OH). Partial functionalization was chosen because the main purpose was to compare the effect of different functional groups on dendrimers' drug delivery behavior without compromising cell viability, which is often affected by dendrimers' cationic charge. Results revealed that bis-MPA-based dendrimers were cytocompatible, independently of the chemical groups that were present at their surface. The B-G4-NH₂/OH and B-G5-NH₂/OH dendrimers were able to retain a higher number of DOX molecules, but the in vitro release of the drug was faster. On the contrary, the hydroxyl-terminated dendrimers exhibited a lower loading capacity but were able to deliver the drug in a more sustained manner. These results were in accordance with the cytotoxicity studies performed in several models of cancer cell lines and human mesenchymal stem cells. Overall, the results confirmed that it is possible to tune the drug delivery properties of bis-MPA-based dendrimers by modifying surface functionalization. Moreover, molecular modeling studies provided insights into the nature of the interactions established between the drug and the bis-MPA-based dendrimers─DOX molecules attach to their surface rather than being physically encapsulated.

Tumor Microenvironment-Responsive Polypeptide Nanogels for Controlled Antitumor Drug Delivery

Tumor microenvironment-responsive polypeptide nanogels belong to a biomaterial with excellent biocompatibility, easily adjustable performance, biodegradability, and non-toxic properties. They are developed for selective delivery of antitumor drugs into target organs to promote tumor cell uptake, which has become an effective measure of tumor treatment. Endogenous (such as reduction, reactive oxygen species, pH, and enzyme) and exogenous (such as light and temperature) responsive nanogels can release drugs in response to tumor tissues or cells to improve drug distribution and reduce drug side effects. This article systematically introduces the research progress in tumor microenvironment-responsive polypeptide nanogels to deliver antitumor drugs and provides a reference for the development of antitumor nanoformulations.

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.

Engineered Fluorescent Carbon Dots and G4-G6 PAMAM Dendrimer Nanohybrids for Bioimaging and Gene Delivery

Carbon dots (CDs) and G4-G6 (polyamidoamine)PAMAM-NH₂ dendrimers were self-assembled to produce CDs@PAMAM nanohybrids for transfection and bioimaging purposes. CDs were synthesized by the hydrothermal method, using ascorbic acid as a starting precursor and characterized by transmission electron microscopy, UV-Vis, and fluorescence (in solution and solid-state) techniques. CDs were electrostatically combined with PAMAM dendrimers at room temperature, and the UV-Vis, fluorescence, and NMR spectroscopies were used to confirm the self-assembly. When compared to pristine CDs, nanohybrids were more photostable, resisting high acidic and basic pH. Moreover, they were considerably internalized by cells, as assessed by flow cytometry and fluorescence microscopy, and, when excited, displayed multi-color emission easily quantified and visualized. These nanoscale hybrids, coined hybridplexes, can condense pDNA and transfecting cells successfully, particularly the G5 CDs@PAMAM nanohybrids. In summary, CDs prepared in mild and smooth lab conditions, showing good optical properties, were used to prepare elegantly CDs@PAMAM nanohybrids with promising biomedical applications.

Dendrimer Architectonics to Treat Cancer and Neurodegenerative Diseases with Implications in Theranostics and Personalized Medicine

Integration of diagnostic and therapeutic functions in a single platform namely theranostics has become a cornerstone for personalized medicine. Theranostics platform facilitates noninvasive detection and treatment while allowing the monitoring of disease progression and therapeutic efficacy in case of chronic conditions of cancer and Alzheimer's disease (AD). Theranostic tools function by themselves or with the aid of carrier, viz. liposomes, micelles, polymers, or dendrimers. The dendrimer architectures (DA) are well-characterized molecular nanoobjects with a large number of terminal functional groups to enhance solubility and offer multivalency and multifunctional properties. Various noninvasive diagnostic tools like magnetic resonance imaging (MRI), computed tomography (CT), gamma scintigraphy, and optical techniques have been accomplished utilizing DAs for simultaneous imaging and drug delivery. Obstacles in the formulation design, drug loading, payload delivery, biocompatibility, overcoming cellular membrane and blood-brain barrier (BBB), and systemic circulation remain a bottleneck in translational efforts. This review focuses on the diagnostic, therapeutic and theranostic potential of DA-based nanocarriers in treating cancer and neurodegenerative disorders like AD and Parkinson's disease (PD), among others. In view of the inverse relationship between cancer and AD, designing suitable DA-based theranostic nanodrug with high selectivity has tremendous implications in personalized medicine to treat cancer and neurodegenerative disorders.

A comprehensive review on alginate-based delivery systems for the delivery of chemotherapeutic agent: Doxorubicin

Doxorubicin (DOX), an anthracycline drug, is widely used for the treatment of several cancers like osteosarcoma, cervical carcinoma, breast cancer, etc. DOX lacks target specificity; thereby it also affects normal cells thus resulting in several side-effects. A drug delivery system (DDS) can be used to deliver the drug in a controlled and sustained manner at a targeted site within the body. Various DDS like nanoemulsions, polymeric nanoparticles, and liposomes are used for loading DOX. Alginate, a polysaccharide is widely used for fabricating DDS due to its biodegradable and bio-compatible properties. Alginates, in combination with other biomaterials, have been extensively used as a novel drug delivery carrier for DOX. Alginate provides a platform for drug delivery in different forms like hydrogels, nanogels, nanoparticles, microparticles, graphene oxide systems, magnetic systems, etc. Herein, we briefly describe alginate in combination with other materials as a nanocarrier for targeted delivery of DOX for anti-cancer treatment.

New insights into the blue intrinsic fluorescence of oxidized PAMAM dendrimers considering their use as bionanomaterials

Like other bionanomaterials, dendrimers are usually labelled with fluorescent compounds in order to be optically detected within cells. However, this process can interfere with their biological properties, so it is crucial to find other solutions for their traceability. Here, the blue intrinsic fluorescence of amine-terminated poly(amidoamine) (PAMAM) dendrimers was enhanced using oxidative treatment with ammonium persulfate (APS). The effects of dendrimer generation (G3, G4, and G5) and pH on the spectroscopic behavior of both pristine and APS-treated PAMAM dendrimers were studied in aqueous solution. Overall, the results pointed out that there are at least two types of emitting electron-rich hetero-atomic sub-luminophores (HASLs) confined within the dendrimer scaffold that have very close maximum emission wavelengths and whose emission properties strongly depend on pH. The APS treatment significantly enhanced the fluorescence intensity by leading to the protonation of the interior of the dendrimer. However, fluorescence intensity was not only dependent on the number of HASLs in the dendrimer scaffold (i.e., on dendrimer generation), but also on the rigidification suffered by the dendrimer due to the acidic environment (at low pH values, APS-treated G4 was indeed the most emissive species). Moreover, photoluminescence studies with lyophilized samples were also conducted, which confirmed the coexistence of more than one type of HASLs emitting in the dendrimer structure. The APS treatment affected these HASLs to a different extent. Time-resolved fluorescence experiments always showed higher average lifetimes of HASLs for APS-treated dendrimers than for pristine ones, in accordance with the fluorescence intensity results. On the other hand, the fraction and lifetimes of HASLs in APS-treated dendrimers were similar in solution and the lyophilized form. This behaviour was different for the pristine dendrimers that presented increased luminescence upon aggregation. Finally, the highly emissive oxidized dendrimers were shown not only to be much less cytotoxic and hemotoxic than pristine dendrimers but also to be detectable inside cells upon excitation with UV light.

A glance over doxorubicin based-nanotherapeutics: From proof-of-concept studies to solutions in the market

Cancer is one of the leading causes of death worldwide and, as such, efforts are being done to find new chemotherapeutic drugs or, alternatively, novel approaches for the delivery of old ones. In this scope, when used as vehicles for drugs, nanomaterials may potentially maximize the efficacy of the treatment and reduce its side effects, for example by a change in drug's pharmacokinetics, cell targeting and/or specific stimuli-responsiveness. This is the case of doxorubicin (DOX) that presents a broad spectrum of activity and is one of the most widely used chemotherapeutic drugs as first-line treatment. Indeed, DOX is a very interesting example of a drug for which several nanosized delivery systems have been developed over the years. While it is true that some of these systems are already in the market, it is also true that research on this subject remains very active and that there is a continuing search for new solutions. In this sense, this review takes the example of doxorubicin, not so much with the focus on the drug itself, but rather as a case study around which very diverse and imaginative nanotechnology approaches have emerged.

New insights into the blue intrinsic fluorescence of oxidized PAMAM dendrimers considering their use as bionanomaterials

The fluorescence intensity of oxidized PAMAM dendrimers is not only dependent on the number of HASLs in the dendrimer scaffold (i.e., on dendrimer generation), but also on the rigidification suffered by the dendrimer due to the acidic environment.

New insights into the blue intrinsic fluorescence of oxidized PAMAM dendrimers considering their use as bionanomaterials

The fluorescence intensity of oxidized PAMAM dendrimers is not only dependent on the number of HASLs in the dendrimer scaffold (i.e., on dendrimer generation), but also on the rigidification suffered by the dendrimer due to the acidic environment.

Recent advances of drug delivery nanocarriers in osteosarcoma treatment

Osteosarcoma is the most common primary malignant bone tumor mainly occurred in children and adolescence, and chemotherapy is limited for the side effects and development of drug resistance. Advances in nanotechnology and knowledge of cancer biology have led to significant improvements in developing tumor-targeted drug delivery nanocarriers, and some have even entered clinically application. Delivery of chemotherapeutic agents by functionalized smart nanocarriers could protect the drugs from rapid clearance, prolong the circulating time, and increase the drug concentration at tumor sites, thus enhancing the therapeutic efficacy and reducing side effects. Various drug delivery nanocarriers have been designed and tested for osteosarcoma treatment, but most of them are still at experimental stage, and more further studies are needed before clinical application. In this present review, we briefly describe the types of commonly used nanocarriers in osteosarcoma treatment, and discuss the strategies for osteosarcoma-targeted delivery and controlled release of drugs. The application of nanoparticles in the management of metastatic osteosarcoma is also briefly discussed. The purpose of this article is to present an overview of recent progress of nanoscale drug delivery platforms in osteosarcoma, and inspire new ideas to develop more effective therapeutic options.

Biomaterials for Interfacing Cell Imaging and Drug Delivery: An Overview

This feature article provides an overview of different kinds of futuristic biomaterials which have the potential to be used for fluorescent imaging and drug delivery, often simultaneously. The synthesis route or preparation process, fluorescence property, release profile, biocompatibility, bioimaging, and mechanistic approaches are vividly discussed. These include bioimaging with fluorescently doped quantum dots, mesoporous silica, noble metals, metal clusters, hydrophilic/hydrophobic polymers, semiconducting polymer dots, carbon/graphene dots, dendrimers, fluorescent proteins, and other nanobiomaterials. Another section discusses the controlled and targeted drug, gene, or biologically active material delivery using various vehicles such as micelles, 2D nanomaterials, organic nanoparticles, polymeric nanohybrids, and chemically modified polymers. In the last section, we discuss biomaterials, which can deliver biologically active molecules, and imaging the cell/tissue.

Exploring the Effect of the Irradiation Time on Photosensitized Dendrimer-Based Nanoaggregates for Potential Applications in Light-Driven Water Photoreduction

Fourth generation polyamidoamine dendrimer (PAMAM, G4) modified with fluorescein units (F) at the periphery and Pt nanoparticles stabilized by L-ascorbate were prepared. These dendrimers modified with hydrophobic fluorescein were used to achieve self-assembling structures, giving rise to the formation of nanoaggregates in water. The photoactive fluorescein units were mainly used as photosensitizer units in the process of the catalytic photoreduction of water propitiated by light. Complementarily, Pt-ascorbate nanoparticles acted as the active sites to generate H2. Importantly, the study of the functional, optical, surface potential and morphological properties of the photosensitized dendrimer aggregates at different irradiation times allowed for insights to be gained into the behavior of these systems. Thus, the resultant photosensitized PAMAM-fluorescein (G4-F) nanoaggregates (NG) were conveniently applied to light-driven water photoreduction along with sodium L-ascorbate and methyl viologen as the sacrificial reagent and electron relay agent, respectively. Notably, these aggregates exhibited appropriate stability and catalytic activity over time for hydrogen production. Additionally, in order to propose a potential use of these types of systems, the in situ generated H2 was able to reduce a certain amount of methylene blue (MB). Finally, theoretical electronic analyses provided insights into the possible excited states of the fluorescein molecules that could intervene in the global mechanism of H2 generation.

Surface charge tunable catanionic vesicles based on serine-derived surfactants as efficient nanocarriers for the delivery of the anticancer drug doxorubicin

Self-assembled vesicles composed of amino acid-based cationic/anionic surfactant mixtures show promise as novel effective drug nanocarriers. Here, we report the in vitro performance of vesicles based on cationic (16Ser) and anionic (8-8Ser) serine-based surfactants using a cancer cell model for the delivery of the anticancer drug doxorubicin (DOX). This catanionic mixture yields both negatively (0.20 in the cationic surfactant molar fraction, x16Ser) and positively (x16Ser = 0.58) charged vesicles, hence providing a surface charge tunable system. Low toxicity is confirmed for concentration ranges below 32 μM in both formulations. DOX is successfully encapsulated in the vesicles, resulting in a surface charge switch to negative for the (0.58) system, making both (0.20) and (0.58) DOX-loaded vesicles highly interesting for systemic administration. High uptake by cells was demonstrated using flow cytometry and confocal microscopy. Drug accumulation results in an increase of cell uptake up to 250% and 200% for the (0.20) and (0.58) vesicles, respectively, compared to free DOX and with localizations near the nuclear regions in the cells. The in vitro cytotoxicity studies show that DOX-loaded vesicles induce cell death, confirming the therapeutic potential of the formulations. Furthermore, the efficient accumulation of the drug inside the cell compartments harbors the potential for optimization strategies including phased delivery for prolonged treatment periods or even on-demand release.

Formation of enzymatic/redox-switching nanogates on mesoporous silica nanoparticles for anticancer drug delivery

In this study, we demonstrate a simple approach to developing mesoporous nanohybrids via a process of pre-loading of an anticancer drug (doxorubicin, DOX) into mesoporous silica nanoparticles (MSN), followed by assembly with a kind of naturally-derived polymer (gelatin, cleavable by matrix metalloproteinase 2 overexpressed by tumor). The gelatin shell is then in situ crosslinked by degradable N,N'-bis(acryloyl)cystamine (BAC) to form enzymatic and redox switchable nanogates on the mesoporous nanoparticles. The nanohybrids displayed pH/redox/enzymatic sensitivity in DOX release under conditions mimicking tumor microenvironments. The nanocarriers can be effectively taken up by A549 cells (a carcinomic human alveolar basal epithelial cell line), resulting in a high DOX intracellular accumulation and an improved anticancer cytotoxicity when compared with free DOX, suggesting their potential as a nanoplatform for therapeutic delivery.

Enhancing the antitumor activity of tea polyphenols encapsulated in biodegradable nanogels by macromolecular self-assembly

Nanogels (NGs) with desirable stability have emerged as a promising platform for biomedical applications. Herein, a convenient approach was developed to encapsulate and protect tea polyphenols (TPs) by macromolecular self-assembly of lysozyme (Ly) and carboxymethyl cellulose (CMC) through a heating treatment. Biodegradable Ly–CMC NGs were formed on the basis of molecules driven by electrostatic interaction and hydrophobic forces. The particle size and morphology of the Ly–CMC NGs were analyzed using a Malvern particle size analyzer, fluorescence spectrophotometer, and scanning electron microscope. The results showed that the heated NGs were spherical with better stability and smaller particle size. The encapsulation efficiency of TP-loaded NGs was 89.05 ± 3.14%, and it indicated that the Ly–CMC NGs may have a strong binding force with TPs. Moreover, TP-loaded NGs showed a sustained release feature. The DPPH and ABTS-scavenging rates of the TP-loaded NGs were 76.5% and 86.1%, respectively. The antitumor activity of the TP-loaded NGs can effectively inhibit the proliferation of HepG₂ cells. Furthermore, TP-loaded NGs were proven to significantly enhance the induction of apoptosis in hepatoma cells and exhibit obvious cell cycle arrest. Our results demonstrate that the Ly–CMC NGs have extensive application prospects as a biocompatible and biodegradable delivery carrier of food functional factors to improve their antitumor effects.

Fabrication of biodegradable TP-loaded Ly and CMC nanogels via self-assembly and the study of their controlled release and absorption process in vivo.

PAMAM dendrimers: blood-brain barrier transport and neuronal uptake after focal brain ischemia

Drug delivery to the central nervous system is restricted by the blood-brain barrier (BBB). However, with the onset of stroke, the BBB becomes leaky, providing a window of opportunity to passively target the brain. Here, cationic poly(amido amine) (PAMAM) dendrimers of different generations were functionalized with poly(ethylene glycol) (PEG) to reduce cytotoxicity and prolong blood circulation half-life, aiming for a safe in vivo drug delivery system in a stroke scenario. Rhodamine B isothiocyanate (RITC) was covalently tethered to the dendrimer backbone and used as a small surrogate drug as well as for tracking purposes. The biocompatibility of PAMAM was markedly increased by PEGylation as a function of dendrimer generation and degree of functionalization. The PEGylated RITC-modified dendrimers did not affect the integrity of an in vitro BBB model. Additionally, the functionalized dendrimers remained safe when in contact with the bEnd.3 cells and rat primary astrocytes composing the in vitro BBB model after hypoxia induced by oxygen-glucose deprivation. Modification with PEG also decreased the interaction and uptake by endothelial cells of PAMAM, indicating that the transport across a leaky BBB due to focal brain ischemia would be facilitated. Next, the functionalized dendrimers were tested in contact with red blood cells showing no haemolysis for the PEGylated PAMAM, in contrast to the unmodified dendrimer. Interestingly, the PEG-modified dendrimers reduced blood clotting, which may be an added beneficial function in the context of stroke. The optimized PAMAM formulation was intravenously administered in mice after inducing permanent focal brain ischemia. Twenty-four hours after administration, dendrimers could be detected in the brain, including in neurons of the ischemic cortex. Our results suggest that the proposed formulation has the potential for becoming a successful delivery vector for therapeutic application to the injured brain after stroke reaching the ischemic neurons.

pH Responsive 5-Fluorouracil Loaded Biocompatible Nanogels For Topical Chemotherapy of Aggressive Melanoma

Combating melanoma via topical route is a highly challenging task due to low selectivity, poor efficacy and impeding biological environment of the skin. In the present study, we engineered a chitosan based pH responsive biodegradable nanogel (FCNGL), encapsulated with 5-FU that was effective even at very low drug doses (0.2% w/v) against melanoma. The FCNGL was synthesized by ion gelation technique exhibited nano-size particle distribution and sustained drug release kinetics. Hemolysis and coagulation analysis revealed high safety whereas MTT and apoptosis assays exhibited the efficacy of FCNGL. DMBA-Croton oil Swiss albino mice model was employed for in vivo assessment followed by gamma scintigraphic screening. Tumor burden and pharmacokinetic antioxidant stress levels along with whole-body gamma scintigraphy imaging using 99 mTc labelled nanogel exhibited selective accumulation in melanoma tumor nodules. The pH responsive behaviour of the nanogels resulted in triggered release of 5-FU in slightly acidic microenvironment, resulting in selective drug accumulation at the melanoma site. Immunohistochemistry (IHC) analysis of tumor showed improvement of subcutaneous layer alignment and regeneration of the epithelial skin layer when compared with standard 5% 5-FU and control mice group. Overall our preclinical data using the FCNGL portends to be a promising platform for efficient and sustained delivery of 5-FU for topical chemotherapy that can result in high efficacy, patient compliance and safety in the clinical set up.

Alginate/poly(amidoamine) injectable hybrid hydrogel for cell delivery

A covalently cross-linked injectable hybrid hydrogel, namely, alginate/poly(amidoamine) (PAMAM), with the objective of cell delivery was innovatively designed and synthesized using tetra-amino-functional PAMAM dendrimer as the cross-linker. With the increase in percentage of PAMAM cross-linker, the pore size and swelling ratio of hydrogels were in the range of 57 ± 18 μm to 88 ± 25 μm and 110 ± 16 to 157 ± 20, respectively. The study of attachment and proliferation of MC3T3-E1 pre-osteoblasts using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay through indirect and direct contact methods indicated a continuous increase in metabolically active live cells with time, implying non-cytotoxicity of the synthesized hydrogel. The live–dead assay showed >95% of live cells for alginate/PAMAM hydrogels, suggesting viability of the encapsulated cells. When the percentage of PAMAM cross-linker in alginate/PAMAM hydrogel was increased from 5 to 25, the percentage degradation rate decreased from 1.1 to 0.29%/day. Given that the poly(ethylene glycol) is commonly used cross-linker for hydrogel syntheses, we compared the behavior with poly(ethylene glycol). The incorporation of poly(ethylene glycol) in alginate/PAMAM hydrogel reduced the activity of MC3T3-E1 cells and their viability compared to the alginate/PAMAM hydrogels. The protonation of amino groups in alginate/PAMAM injectables under physiological conditions led to the formation of cationic hydrogels. These cationic hydrogels showed enhanced cell encapsulation and attachment ability because of electrostatic interaction with negatively charged cell surface as determined by cell adhesion and extensions from scanning electron microscope and vinculin assay and ability of in situ calcium phosphate mineralization. These observations point toward the potential use as an injectable scaffold for cell delivery and tissue engineering applications.

Advances in thermosensitive polymer-grafted platforms for biomedical applications

Studies on "smart" polymeric material performing environmental stimuli such as temperature, pH, magnetic field, enzyme and photo-sensation have recently paid much attention to practical applications. Among of them, thermo-responsive grafted copolymers, amphiphilic steroids as well as polyester molecules have been utilized in the fabrication of several multifunctional platforms. Indeed, they performed a strikingly functional improvement comparing to some original materials and exhibited a holistic approach for biomedical applications. In case of drug delivery systems (DDS), there has been some successful proof of thermal-responsive grafted platforms on clinical trials such as ThermoDox®, BIND-014, Cynviloq IG-001, Genexol-PM, etc. This review would detail the recent progress and highlights of some temperature-responsive polymer-grafted nanomaterials or hydrogels in the 'smart' DDS that covered from synthetic polymers to nature-driven biomaterials and novel generations of some amphiphilic functional platforms. These approaches could produce several types of smart biomaterials for human health care in future.

Dendrimers in combination with natural products and analogues as anti-cancer agents

For the first time, an overview of dendrimers in combination with natural products and analogues as anti-cancer agents is presented. This reflects the development of drug delivery systems, such as dendrimers, to tackle cancers. The most significant advantages of using dendrimers in nanomedicine are their high biocompatibility, good water solubility, and their entry - with or without encapsulated, complexed or conjugated drugs - through an endocytosis process. This strategy has accelerated over the years in order to develop nanosystems as nanocarriers, to decrease the intrinsic toxicity of anti-cancer agents, to decrease the drug side effects, to increase the efficacy of the treatment, and consequently to improve patient compliance.

Dendrimers in combination with natural products and analogues as anti-cancer agents

Overview of the use of dendrimers in combination with encapsulated and conjugated natural products and analogues as anti-cancer agents.

Development of bioabsorbable polylactide membrane with controllable hydrophilicity for adjustment of cell behaviours

Cell functions can be mediated through their interactions with the microenvironments, which highly depend on the surface state of the substrate. However, how to finely adjust the surface of biomaterials is still very challenging. In this study, poly(d,l-lactide) (PDLLA) with high molecular weight was synthesized via ring opening polymerization, which was hot-pressed into PDLLA membrane. In order to modify the hydrophobicity of the membrane (a limiting factor for its biomedical application), an amphiphilic monomethoxyl poly(ethylene glycol)-b-poly(d,l-lactide) (PEG-PDLLA) was selected to improve its surface hydrophilicity through a simple self-assembly approach. It was found that the contact angles of the modified membrane can be well controlled by variation of PEG-PDLLA concentrations. In vitro cell biological study indicates that optimized cell adhesion can be achieved on the modified membrane with a contact angle of around 50° via its self-assembly with an ethanol/water solution of PEG-PDLA (35 mg ml-1). The surface modification of the membrane also changed its biodegradation property in the process of its incubation period up to 240 days. The surface modification method may afford an effective way for adjustment of the surface (interface) of membrane (scaffolds) of different biomaterials, beyond polylactide.

A unique nanogel-based platform for enhanced dual mode tumor MR/CT imaging

Alginate nanogels loaded with gold nanoparticles and gadolinium can be synthesized via a nanoparticle-crosslinking approach for enhanced tumor MR/CT imaging.

Dendrimers in combination with natural products and analogues as anti-cancer agents

Overview of the use of dendrimers in combination with encapsulated and conjugated natural products and analogues as anti-cancer agents.

Mitochondrial dysfunction-induced apoptosis in breast carcinoma cells through a pH-dependent intracellular quercetin NDDS of PVPylated-TiO2NPs

In this article, we report the validation of cancer nanotherapy for treatment of cancers using quercetin (Qtn).

Drug-mediation formation of nanohybrids for sequential therapeutic delivery in cancer cells

In order to overcome the multidrug resistance (MDR) of tumor cells, it is very important to develop nanocarriers which can effectively load drugs while releasing them in a sequential way. Herein, nanohybrids with such properties have been fabricated by a first loading of one anticancer drug onto a silicate nanodisk (Laponite (LP), 25 nm in diameter and 0.92 nm in thickness) and a subsequent assembly with a pH sensitive poly(N-vinylpyrrolidone) (PVP) as a protective layer, followed by a loading of with another anticancer drug. The resulting nanohybrids (LDPM) present a high drug encapsulation efficiency and long-term colloidal stability. However, if the two drugs are loaded onto LP before PVP decoration, the formed particles tend to form microsized aggregates with poor colloidal stability. In vitro release study indicates that LDPM can deliver the anticancer drugs in a sequential way, which can be further accelerated under acidic microenvironments mimicking both solid tumor and endo-lysosomal compartments, exerting synergistic anticancer cytotoxicity. The drug-mediated formation of nanocarriers may enlighten a design of novel nanoplatform for co-delivery of therapeutic agents, beyond anticancer drugs, in a combinative way for drug delivery applications.

Nanogels in the Diagnosis and Treatment of Tuberculosis

The manifestation of tuberculosis (TB) is highly complex and there is still a pressing need to improve diagnosis, prevention, and treatment strategies to control the worldwide spread of disease. Recently, the WHO proposed the eradication of TB by 2050; such a goal requires active research directing ways to prevent infection or transmission through vaccination, diagnosis asymptomatic carriers of Mycobacterium tuberculosis (MTB), and to advance antimicrobial drug treatment responses. The progress of nano delivery systems will provide a prospect to increase the efficacy of existing drugs, which might have an important role in TB control and eradication. Nanogels encompass complex and swollen nano-sized networks formed by hydrophilic or amphiphilic polymer chains, having non-ionic or ionic nature. This chapter details the basics of nanogels composition, synthesis methods and their contribution in TB treatment and diagnosis.

Novel dendritic structure of alginate hybrid nanoparticles for effective anti-viral drug delivery

Lipid-polymer hybrid nanoparticles have recently gathered much attention as nanoplatforms for drug delivery applications due to their unique structural properties. In this study zidovudine (AZT) loaded hybrid nanoparticles of alginate (ALG) and stearic acid- poly ethylene glycol (SA-PEG) were synthesized. The structural characterization of drug loaded hybrid nanoparticles were studied using FT-IR spectroscopy, DLS and TEM analysis. These hybrid nanoparticles showed dendritic morphology and it can be used as an efficient carrier for zidovudine. In this drug loaded hybrid system of Alginate -Stearicacid/Poly (ethyleneglycol) Nanoparticles (ASNPs), AZT and alginate form the core wherein SA-PEG forms the external shell. We observed a dendritic morphology with internal voids and channels formed by the core molecule and the external shell forms the closed pack surface groups. The optimized formulation achieved a sub micron size of 407.67±19.18nm with drug encapsulation of 83.18±1.22%, and surface potential of -42.53mV, and has significant stability for six months. Haemolysis and aggregation studies revealed that there were no lysis and aggregation in WBC, RBC and platelets. In-vitro cytotoxicity and cellular uptake of the nanoparticles in Glioma, Neuro2a and Hela cells showed that ASNPs are non toxic. The results indicate that the synthesized hybrid nanoparticles represent a potential carrier for zidovudine, thus possibly increasing zidovudine's efficiency as an anti-HIV drug.

Formation of graphene oxide-hybridized nanogels for combinative anticancer therapy

The low efficacy and high toxicity of chemotherapy have been driving increasing attention on development of combined anticancer therapy technique. In the current work, graphene oxide (GO)-hybridized nanogels (AGD) were developed for delivery of an anticancer drug (doxorubicin (DOX)), which simultaneously presented photothermal therapeutic effects against cancer cells. AGD nanogels were fabricated by in situ incorporating GO nanoplatelets into a biodegradable polymer (alginate) via a double emulsion approach using a disulfide molecule as crosslinker, followed by DOX encapsulation via electrostatic interactions. The nanogels released DOX drug in an accelerated way under both acidic and reducible conditions mimicking extracellular tumor microenvironments and intracellular compartments. The stimulative release controllability of the nanogels improved the DOX internalization and long-term drug accumulation inside A549 cells (an adenocarcinoma human alveolar basal epithelial cell line), which, together with their photothermal effect, resulted in a good anticancer cytotoxicity, indicating their promising potential for combinative anticancer therapy.