An aptamer-targeting photoresponsive drug delivery system using "off-on" graphene oxide wrapped mesoporous silica nanoparticles

Aptamer-controlled stimuli-responsive drug release

Aptamers have been widely researched and applied in nanomedicine due to their programmable, activatable, and switchable properties. However, there are few reviews on aptamer-controlled stimuli-responsive drug delivery. This article highlights the mechanisms and advantages of aptamers in the construction of stimuli-responsive drug delivery systems. We summarize the assembly/reconfiguration mechanisms of aptamers in controlled release systems. The assembly and drug release strategies of drug delivery systems are illustrated. Specifically, we focus on the binding mechanisms to the target and the factors that induce/inhibit the binding to the stimuli, such as strand, pH, light, and temperature. The applications of aptamer-based stimuli-responsive drug release are elaborated. The challenges are discussed, and the future directions are proposed.

Amine-functionalized mesoporous silica nanoparticles decorated by silver nanoparticles for delivery of doxorubicin in breast and cervical cancer cells

Nanocarriers have demonstrated promising potential in the delivery of various anticancer drugs and in improving the efficiency of the treatment. In this study, silver nanoparticles (AgNPs) were green-synthesized using the extracts of different parts of the pomegranate plant, including the peel, flower petals, and calyx. To obtain the most efficient extract used for the green synthesis of AgNPs, all three types of synthesized nanoparticles were characterized. Then, (3-Aminopropyl) triethoxysilane-functionalized mesoporous silica nanoparticles (MSNs-APTES) decorated with AgNPs were fabricated via a one-pot green-synthesis method. AgNPs were directly coated on the surface of MSNs-APTES by adding pomegranate extract enriched with a source of reducing agent leading to converting the silver ion to AgNPs. The MSN-APTES-AgNPs (MSNs-AgNPs) have been thoroughly characterized using nanoparticle characterization techniques. In addition, DNA cleavage and hemolysis activities of the synthesized nanoparticles were analyzed, confirming the biocompatibility of synthesized nanoparticles. The Doxorubicin (DOX, as a breast/cervical anti-cancer drug) loading (42.8%) and release profiles were investigated via UV-visible spectroscopy. The fibroblast, breast cancer, and cervical cancer cells' viability against DOX-loaded nanoparticles were also studied. The results of this high drug loading, uniform shape, and small functionalized nanoparticles demonstrated its great potential for breast and cervical cancer management.

Graphene-based hybrid composites for cancer diagnostic and therapy

The application of graphene-based nanocomposites for therapeutic and diagnostic reasons has advanced considerably in recent years due to advancements in the synthesis and design of graphene-based nanocomposites, giving rise to a new field of nano-cancer diagnosis and treatment. Nano-graphene is being utilized more often in the field of cancer therapy, where it is employed in conjunction with diagnostics and treatment to address the complex clinical obstacles and problems associated with this life-threatening illness. When compared to other nanomaterials, graphene derivatives stand out due to their remarkable structural, mechanical, electrical, optical, and thermal capabilities. The high specific surface area of these materials makes them useful as carriers in controlled release systems that respond to external stimuli; these compounds include drugs and biomolecules like nucleic acid sequences (DNA and RNA). Furthermore, the presence of distinctive sheet-like nanostructures and the capacity for photothermal conversion have rendered graphene-based nanocomposites highly favorable for optical therapeutic applications, including photothermal treatment (PTT), photodynamic therapy (PDT), and theranostics. This review highlights the current state and benefits of using graphene-based nanocomposites in cancer diagnosis and therapy and discusses the obstacles and prospects of their future development. Then we focus on graphene-based nanocomposites applications in cancer treatment, including smart drug delivery systems, PTT, and PDT. Lastly, the biocompatibility of graphene-based nanocomposites is also discussed to provide a unique overview of the topic.

Light on Alzheimer's disease: from basic insights to preclinical studies

Alzheimer's disease (AD), referring to a gradual deterioration in cognitive function, including memory loss and impaired thinking skills, has emerged as a substantial worldwide challenge with profound social and economic implications. As the prevalence of AD continues to rise and the population ages, there is an imperative demand for innovative imaging techniques to help improve our understanding of these complex conditions. Photoacoustic (PA) imaging forms a hybrid imaging modality by integrating the high-contrast of optical imaging and deep-penetration of ultrasound imaging. PA imaging enables the visualization and characterization of tissue structures and multifunctional information at high resolution and, has demonstrated promising preliminary results in the study and diagnosis of AD. This review endeavors to offer a thorough overview of the current applications and potential of PA imaging on AD diagnosis and treatment. Firstly, the structural, functional, molecular parameter changes associated with AD-related brain imaging captured by PA imaging will be summarized, shaping the diagnostic standpoint of this review. Then, the therapeutic methods aimed at AD is discussed further. Lastly, the potential solutions and clinical applications to expand the extent of PA imaging into deeper AD scenarios is proposed. While certain aspects might not be fully covered, this mini-review provides valuable insights into AD diagnosis and treatment through the utilization of innovative tissue photothermal effects. We hope that it will spark further exploration in this field, fostering improved and earlier theranostics for AD.

Silicon-containing nanomedicine and biomaterials: materials chemistry, multi-dimensional design, and biomedical application

The invention of silica-based bioactive glass in the late 1960s has sparked significant interest in exploring a wide range of silicon-containing biomaterials from the macroscale to the nanoscale. Over the past few decades, these biomaterials have been extensively explored for their potential in diverse biomedical applications, considering their remarkable bioactivity, excellent biocompatibility, facile surface functionalization, controllable synthesis, etc. However, to expedite the clinical translation and the unexpected utilization of silicon-composed nanomedicine and biomaterials, it is highly desirable to achieve a thorough comprehension of their characteristics and biological effects from an overall perspective. In this review, we provide a comprehensive discussion on the state-of-the-art progress of silicon-composed biomaterials, including their classification, characteristics, fabrication methods, and versatile biomedical applications. Additionally, we highlight the multi-dimensional design of both pure and hybrid silicon-composed nanomedicine and biomaterials and their intrinsic biological effects and interactions with biological systems. Their extensive biomedical applications span from drug delivery and bioimaging to therapeutic interventions and regenerative medicine, showcasing the significance of their rational design and fabrication to meet specific requirements and optimize their theranostic performance. Additionally, we offer insights into the future prospects and potential challenges regarding silicon-composed nanomedicine and biomaterials. By shedding light on these exciting research advances, we aspire to foster further progress in the biomedical field and drive the development of innovative silicon-composed nanomedicine and biomaterials with transformative applications in biomedicine.

TfR Aptamer-Functionalized MSNs for Enhancing Targeted Cellular Uptake and Therapy of Cancer Cells

Mesoporous silica nanoparticles (MSNs), as novel nanocarriers for drug delivery in cancer treatment, have attracted widespread concern because of their rich pore structure, large pore capacity, ease of modification, and biocompatibility. However, the limitation of nontargeting and low uptake efficiency hindered their further application. Considering the overexpression of the transferrin receptor (TfR) on most cancer cell membranes, herein, we propose a strategy to effectively enhance the cellular internalization of MSNs by arming them with the TfR aptamer. Cellular fluorescent imaging and flow cytometry analysis demonstrated that TfR aptamer-functionalized MSNs exhibited superior cellular internalization compared to unmodified or random sequence-modified MSNs toward three different cancer cell lines, including MCF-7, HeLa, and A549. Furthermore, TfR aptamer-functionalized MSNs displayed enhanced drug delivery efficiency compared with MSNs at equivalent doses and incubation times. These results suggested that TfR aptamer-functionalized MSNs have the potential for enhanced delivery of therapeutic agents into TfR-positive cancer cells to improve therapeutic efficacy.

Recent Advances in the Application of Bionanosensors for the Analysis of Heavy Metals in Aquatic Environments

Heavy-metal ions (HMIs) as a pollutant, if not properly processed, used, and disposed of, will not only have an influence on the ecological environment but also pose significant health hazards to humans, making them a primary factor that endangers human health and harms the environment. Heavy metals come from a variety of sources, the most common of which are agriculture, industry, and sewerage. As a result, there is an urgent demand for portable, low-cost, and effective analytical tools. Bionanosensors have been rapidly developed in recent years due to their advantages of speed, mobility, and high sensitivity. To accomplish effective HMI pollution control, it is important not only to precisely pinpoint the source and content of pollution but also to perform real-time and speedy in situ detection of its composition. This study summarizes heavy-metal-ion (HMI) sensing research advances over the last five years (2019-2023), describing and analyzing major examples of electrochemical and optical bionanosensors for Hg2+, Cu2+, Pb2+, Cd2+, Cr6+, and Zn2+.

Application of graphene oxide in tumor targeting and tumor therapy

Graphene oxide (GO), as a kind of two-dimensional sp2 carbon nanomaterials, has attracted great attention in many fields in the past decade. Due to its unique physical and chemical properties, GO is showing great promise in the field of biomedicine. For GO, all the atoms on its surface are exposed to the surface with ultra-high specific surface area, and a variety of groups on the surface, such as carboxyl, hydroxyl and epoxy groups, can effectively bind/load various biomolecules. Due to the availability of these groups, GO also possesses excellent hydrophilicity and biocompatibility for the modification of the desired biocompatible molecules or polymers on the surface of GO. The nano-network structure and hydrophobicity of GO enable it to load a large number of hydrophobic drugs containing benzene rings and it has been widely used as a multi-functional nano-carrier for chemotherapeutic drug or gene delivery. This review article will give an in-depth overview of the synthesis methods of GO, the advantages and disadvantages of GO used in nano-drug delivery system, the research progress of GO as a stimulus-responsive nano-drug carrier, and the application of these intelligent systems in cancer treatment.

DNA-Based Nanomaterials as Drug Delivery Platforms for Increasing the Effect of Drugs in Tumors

DNA nanotechnology has significantly advanced and might be used in biomedical applications, drug delivery, and cancer treatment during the past few decades. DNA nanomaterials are widely used in biomedical research involving biosensing, bioimaging, and drug delivery since they are remarkably addressable and biocompatible. Gradually, modified nucleic acids have begun to be employed to construct multifunctional DNA nanostructures with a variety of architectural designs. Aptamers are single-stranded nucleic acids (both DNAs and RNAs) capable of self-pairing to acquire secondary structure and of specifically binding with the target. Diagnosis and tumor therapy are prospective fields in which aptamers can be applied. Many DNA nanomaterials with three-dimensional structures have been studied as drug delivery systems for different anticancer medications or gene therapy agents. Different chemical alterations can be employed to construct a wide range of modified DNA nanostructures. Chemically altered DNA-based nanomaterials are useful for drug delivery because of their improved stability and inclusion of functional groups. In this work, the most common oligonucleotide nanomaterials were reviewed as modern drug delivery systems in tumor cells.

Synthesis and Functionalization of Graphene Materials for Biomedical Applications: Recent Advances, Challenges, and Perspectives

Since its discovery in 2004, graphene is increasingly applied in various fields owing to its unique properties. Graphene application in the biomedical domain is promising and intriguing as an emerging 2D material with a high surface area, good mechanical properties, and unrivalled electronic and physical properties. This review summarizes six typical synthesis methods to fabricate pristine graphene (p-G), graphene oxide (GO), and reduced graphene oxide (rGO), followed by characterization techniques to examine the obtained graphene materials. As bare graphene is generally undesirable in vivo and in vitro, functionalization methods to reduce toxicity, increase biocompatibility, and provide more functionalities are demonstrated. Subsequently, in vivo and in vitro behaviors of various bare and functionalized graphene materials are discussed to evaluate the functionalization effects. Reasonable control of dose (<20 mg kg-1 ), sizes (50-1000 nm), and functionalization methods for in vivo application are advantageous. Then, the key biomedical applications based on graphene materials are discussed, coupled with the current challenges and outlooks of this growing field. In a broader sense, this review provides a comprehensive discussion on the synthesis, characterization, functionalization, evaluation, and application of p-G, GO, and rGO in the biomedical field, highlighting their recent advances and potential.

Nucleolin aptamer conjugated MSNPs-PLR-PEG multifunctional nanoconstructs for targeted co-delivery of anticancer drug and siRNA to counter drug resistance in TNBC

The emergence of drug resistance in cancer cells is among the major challenges for treating cancer. In the last few years, the co-delivery of drug and siRNA has shown promising results against drug-resistant cancers. In the present study, we developed mesoporous silica-based multifunctional nanocarrier for co-delivery against drug-resistant triple-negative breast cancer (TNBC) cells. We synthesized the nanocarrier by modifying mesoporous silica nanoparticles with poly-L-arginine, polyethylene glycol and AS1411 aptamer to impart siRNA binding ability, biocompatibility, and cancer cell specificity, respectively. We optimized the loading of doxorubicin (DOX) within the developed nanocarrier to avoid interference with siRNA binding. We ascertained the target specificity by performing a receptor blockade assay during cellular uptake studies. The cytotoxic efficacy of DOX and siRNA co-delivered using the developed nanocarrier was assessed using DOX-resistant MDA-MB-231 TNBC cells. The nanocarrier exhibited >10-fold and 40-fold reduction in the IC₅₀ values of DOX due to co-delivery with BCl-xL and BCL-2 siRNA, respectively. The results were further validated using a 3-D in vitro cell culture system. This study demonstrates that the targeted co-delivery of drug and siRNA has a strong potential to overcome drug resistance in TNBC cells.

Nanoparticles Containing Oxaliplatin and the Treatment of Colorectal Cancer

BACKGROUND

Colorectal cancer (CRC) is a highly widespread malignancy and ranks as the second most common cause of cancer-related mortality.

OBJECTIVE

Cancer patients, including those with CRC, who undergo chemotherapy, are often treated with platinum- based anticancer drugs such as oxaliplatin (OXA). Nevertheless, the administration of OXA is associated with a range of gastrointestinal problems, neuropathy, and respiratory tract infections. Hence, it is necessary to devise a potential strategy that can effectively tackle these aforementioned challenges. The use of nanocarriers has shown great potential in cancer treatment due to their ability to minimize side effects, target drugs directly to cancer cells, and improve drug efficacy. Furthermore, numerous studies have been published regarding the therapeutic efficacy of nanoparticles in the management of colorectal cancer.

METHODS

In this review, we present the most relevant nanostructures used for OXA encapsulation in recent years, such as solid lipid nanoparticles, liposomes, polysaccharides, proteins, silica nanoparticles, metal nanoparticles, and synthetic polymer-carriers. Additionally, the paper provides a summary of the disadvantages and limits associated with nanoparticles.

RESULTS

The use of different carriers for the delivery of oxaliplatin increased the efficiency and reduced the side effects of the drug. It has been observed that the majority of research investigations have focused on liposomes and polysaccharides.

CONCLUSION

This potentially auspicious method has the potential to enhance results and enhance the quality of life for cancer patients undergoing chemotherapy. However, additional investigation is required to ascertain the most suitable medium for the transportation of oxaliplatin and to assess its efficacy through clinical trials.

Tuning Mesoporous Silica Nanoparticles in Novel Avenues of Cancer Therapy

The global menace of cancer has led to an increased death toll in recent years. The constant evolution of cancer therapeutics with novel delivery systems has paved the way for translation of innovative therapeutics from bench to bedside. This review explains the significance of mesoporous silica nanoparticles (MSNs) as delivery vehicles with particular emphasis on cancer therapy, including novel opportunities for biomimetic therapeutics and vaccine delivery. Parameters governing MSN synthesis, therapeutic agent loading characteristics, along with tuning of MSN toward cancer cell specificity have been explained. The advent of MSN in nanotheranostics and its potential in forming nanocomposites for imaging purposes have been illustrated. Additionally, various hurdles encountered during the bench to bedside translation have been explained along with potential avenues to circumvent them. This also opens up new horizons in drug delivery, which could be useful to researchers in the years to come.

Cellular and subcellular interactions of graphene-based materials with cancerous and non-cancerous cells

Despite significant advances in early detection and personalized treatment, cancer is still among the leading causes of death globally. One of the possible anticancer approaches that is presently receiving a lot of attention is the development of nanocarriers capable of specific and efficient delivery of anticancer drugs. Graphene-based materials are promising nanocarriers in this respect, due to their high drug loading capacity and biocompatibility. In this review, we present an overview on the interactions of graphene-based materials with normal mammalian cells at the molecular level as well as cellular and subcellular levels, including plasma membrane, cytoskeleton, and membrane-bound organelles such as lysosomes, mitochondria, nucleus, endoplasmic reticulum, and peroxisome. In parallel, we assemble the knowledge about the interactions of graphene-based materials with cancerous cells, that are considered as the potential applications of these materials for cancer therapy including metastasis treatment, targeted drug delivery, and differentiation to non-cancer stem cells. We highlight the influence of key parameters, such as the size and surface chemistry of graphene-based materials that govern the efficiency of internalization and biocompatibility of these particles in vitro and in vivo. Finally, this review aims to correlate the key parameters of graphene-based nanomaterials specially graphene oxide, such as size and surface modifications, to their interactions with the cancerous and non-cancerous cells for designing and engineering them for bio-applications and especially for therapeutic purposes.

Engineering mesoporous silica nanoparticles for drug delivery: where are we after two decades?

The present review details a chronological description of the events that took place during the development of mesoporous materials, their different synthetic routes and their use as drug delivery systems. The outstanding textural properties of these materials quickly inspired their translation to the nanoscale dimension leading to mesoporous silica nanoparticles (MSNs). The different aspects of introducing pharmaceutical agents into the pores of these nanocarriers, together with their possible biodistribution and clearance routes, would be described here. The development of smart nanocarriers that are able to release a high local concentration of the therapeutic cargo on-demand after the application of certain stimuli would be reviewed here, together with their ability to deliver the therapeutic cargo to precise locations in the body. The huge progress in the design and development of MSNs for biomedical applications, including the potential treatment of different diseases, during the last 20 years will be collated here, together with the required work that still needs to be done to achieve the clinical translation of these materials. This review was conceived to stand out from past reports since it aims to tell the story of the development of mesoporous materials and their use as drug delivery systems by some of the story makers, who could be considered to be among the pioneers in this area.

Functionalization of Nanoparticulate Drug Delivery Systems and Its Influence in Cancer Therapy

Research into the application of nanocarriers in the delivery of cancer-fighting drugs has been a promising research area for decades. On the other hand, their cytotoxic effects on cells, low uptake efficiency, and therapeutic resistance have limited their therapeutic use. However, the urgency of pressing healthcare needs has resulted in the functionalization of nanoparticles' (NPs) physicochemical properties to improve clinical outcomes of new, old, and repurposed drugs. This article reviews recent research on methods for targeting functionalized nanoparticles to the tumor microenvironment (TME). Additionally, the use of relevant engineering techniques for surface functionalization of nanocarriers (liposomes, dendrimers, and mesoporous silica) and their critical roles in overcoming the current limitations in cancer therapy-targeting ligands used for targeted delivery, stimuli strategies, and multifunctional nanoparticles-were all reviewed. The limitations and future perspectives of functionalized nanoparticles were also finally discussed. Using relevant keywords, published scientific literature from all credible sources was retrieved. A quick search of the literature yielded almost 400 publications. The subject matter of this review was addressed adequately using an inclusion/exclusion criterion. The content of this review provides a reasonable basis for further studies to fully exploit the potential of these nanoparticles in cancer therapy.

Aptamer-conjugated carbon-based nanomaterials for cancer and bacteria theranostics: A review

Aptamers are single-stranded oligonucleotides that link to various substrates with great affinity and selectivity, including small molecules, peptides, proteins, cells, and tissues. For this reason, they can be used as imaging agents for cancer imaging techniques. Multifunctional nanomaterials combined with imaging probes and drugs are promising cancer diagnosis and treatment candidates. On the other hand, carbon-based nanomaterials (CNMs), including such as fullerene, carbon nanotubes, carbon-based quantum dots, carbon nanohorns, graphene oxide and its derivatives carbon nanodots, and nanodiamonds, are sort of smart materials that can be used in a variety of theranostic applications, including photo-triggered therapies. The remarkable physical characteristics, functionalizable chemistry, biocompatibility, and optical properties of these nanoparticles have enabled their utilization in less-invasive therapies. The theranostic agents that emerged by combining aptamers with CNMs have opened a novel alternative for personified medicine of cancer, target-specific imaging, and label-free diagnosis of a broad range of cancers, as well as pathogens. Aptamer-functionalized CNMs have been used as nanovesicles for targeted delivery of anti-cancer agents (i.e., doxorubicin and 5-fluorouracil) to tumor sites. Furthermore, these CNMs conjugated with aptamers have shown great advantages over standard CNMs to sensitively detect Mycobacterium tuberculosis, Escherichia coli, staphylococcus aureus, Vibrio parahaemolyticus, Salmonella typhimurium, Pseudomonas aeruginosa, and Citrobacter freundii. Regrettably, CNMs can form compounds defined as NOAA (nano-objects, and their aggregates and agglomerates larger than 100 nm), that accumulate in the body and cause toxic effects. Surface modification and pretreatment with albumin avoid agglomeration and increase the dispersibility of CNMs, so it is needed to guarantee the desirable interactions between functionalized CNMs and blood plasma proteins. This preliminary review aimed to comprehensively discuss the features and uses of aptamer-conjugated CNMs to manage cancer and bacterial infections.

Aptamer-Enabled Nanomaterials for Therapeutics, Drug Targeting and Imaging

A wide variety of nanomaterials have emerged in recent years with advantageous properties for a plethora of therapeutic and diagnostic applications. Such applications include drug delivery, imaging, anti-cancer therapy and radiotherapy. There is a critical need for further components which can facilitate therapeutic targeting, augment their physicochemical properties, or broaden their theranostic applications. Aptamers are single-stranded nucleic acids which have been selected or evolved to bind specifically to molecules, surfaces, or cells. Aptamers can also act as direct biologic therapeutics, or in imaging and diagnostics. There is a rich field of discovery at the interdisciplinary interface between nanomaterials and aptamer science that has significant potential across biomedicine. Herein, we review recent progress in aptamer-enabled materials and discuss pending challenges for their future biomedical application.

Electrochemistry Coupling Localized Surface Plasmon Resonance for Biochemical Detection

Localized surface plasmon resonance (LSPR) associated with metal nanostructures has developed into highly useful sensor techniques. LSPR spectroscopy often shows absorption peaks which could be used for biomedical detection. Here we report nanoplasmonic sensors using LSPR on nanostructures such as nanoparticles, nanocups, and nanocones to recognize biomolecular. These sensors can be modified for quantitative detection of explosives and evaluation of enzymatic activity. Electrochemical LSPR sensors can also be designed by coupling electrochemistry and LSPR spectroscopy measurements for biochemical detection. Multiple sensing information can be obtained and electrochemical LSPR property can be investigated for biosensors. In some applications, the electrochemical LSPR biosensor can be used to quantify heavy metal ions, neurotransmitters, and sialic acid. The biosensors exhibit better performance than those of conventional optical LSPR measurements. With multitransducers, the nanoplasmonic biosensor can provide a promising approach for biochemical detection in environmental monitoring, healthcare diagnostics, and food quality control.

Drug Release Kinetics of DOX-Loaded Graphene-Based Nanocarriers for Ovarian and Breast Cancer Therapeutics

Cancer remains one of the leading causes of death worldwide despite extensive efforts at developing curative treatments. Chemotherapy, one of the most common forms of treatment, lacks specificity and can induce collateral damages to healthy surrounding tissues/cells and elicit off-target toxic side effects. The carbon-based nanomaterial graphene, can load aromatic drugs with high efficiency, has good biocompatibility, and can be easily functionalised with targeting ligands, antibodies, and biomolecules to increase the accuracy of targeting specific areas; graphene has therefore been explored as a nanocarrier for classical chemotherapy drugs. In this work, seventeen publications that report the release of doxorubicin (DOX) from 2D graphene-based nanohybrids (graphene oxide and reduced graphene oxide) for the treatment of breast and ovarian cancers have been identified based on a range of inclusion and exclusion criteria. To aid in the clinical translation of proof-of-concept studies, this work identifies the pre-clinical experimental protocols and analyses the release kinetics of these publications. Fifteen of the papers utilised a change in pH as the stimulus for drug release, and two utilised either near infrared (NIR) or ultrasound as the stimulus. The extracted drug release data from these publications were fit to four known kinetic models. It was found that the majority of these data best fit the Weibull kinetic model. The agreement between the kinetic data in previously published literature provides a predictable estimation of DOX release from graphene-based nanocarriers. This study demonstrates the potential conjugation of graphene and DOX in drug delivery applications, and this knowledge can help improve to the design and formulation of future graphene-based nanocarriers. In addition, the use of further experimental testing and the standardisation of experimental protocols will be beneficial for future work. The incorporation of computational modelling prior to pre-clinical testing will also aid in the development of controlled and sustained DOX release systems that offer efficient and efficacious results.

Aptamer-assisted tumor localization of bacteria for enhanced biotherapy

Despite bacterial-mediated biotherapies have been widely explored for treating different types of cancer, their implementation has been restricted by low treatment efficacy, due largely to the absence of tumor-specific accumulation following administration. Here, the conjugation of aptamers to bacterial surface is described by a simple and cytocompatible amidation procedure, which can significantly promote the localization of bacteria in tumor site after systemic administration. The surface density of aptamers can be easily adjusted by varying feed ratio and the conjugation is able to increase the stability of anchored aptamers. Optimal bacteria conjugated with an average of 2.8 × 105 aptamers per cell present the highest specificity to tumor cells in vitro, separately generating near 2- and 4-times higher accumulation in tumor tissue at 12 and 60 hours compared to unmodified bacteria. In both 4T1 and H22 tumor-bearing mouse models, aptamer-conjugated attenuated Salmonella show enhanced antitumor efficacy, along with highly activated immune responses inside the tumor. This work demonstrates how bacterial behaviors can be tuned by surface conjugation and supports the potential of aptamer-conjugated bacteria for both targeted intratumoral localization and enhanced tumor biotherapy.

Graphene and its derivatives: understanding the main chemical and medicinal chemistry roles for biomedical applications

Over the past few years, there has been a growing potential use of graphene and its derivatives in several biomedical areas, such as drug delivery systems, biosensors, and imaging systems, especially for having excellent optical, electronic, thermal, and mechanical properties. Therefore, nanomaterials in the graphene family have shown promising results in several areas of science. The different physicochemical properties of graphene and its derivatives guide its biocompatibility and toxicity. Hence, further studies to explain the interactions of these nanomaterials with biological systems are fundamental. This review has shown the applicability of the graphene family in several biomedical modalities, with particular attention for cancer therapy and diagnosis, as a potent theranostic. This ability is derivative from the considerable number of forms that the graphene family can assume. The graphene-based materials biodistribution profile, clearance, toxicity, and cytotoxicity, interacting with biological systems, are discussed here, focusing on its synthesis methodology, physicochemical properties, and production quality. Despite the growing increase in the bioavailability and toxicity studies of graphene and its derivatives, there is still much to be unveiled to develop safe and effective formulations.

Graphic abstract

Advanced mesoporous silica nanocarriers in cancer theranostics and gene editing applications

Targeted nanomaterials for cancer theranostics have been the subject of an expanding volume of research studies in recent years. Mesoporous silica nanoparticles (MSNs) are particularly attractive for such applications due to possibilities to synthesize nanoparticles (NPs) of different morphologies, pore diameters and pore arrangements, large surface areas and various options for surface functionalization. Functionalization of MSNs with different organic and inorganic molecules, polymers, surface-attachment of other NPs, loading and entrapping cargo molecules with on-desire release capabilities, lead to seemingly endless prospects for designing advanced nanoconstructs exerting multiple functions, such as simultaneous cancer-targeting, imaging and therapy. Describing composition and multifunctional capabilities of these advanced nanoassemblies for targeted therapy (passive, ligand-functionalized MSNs, stimuli-responsive therapy), including one or more modalities for imaging of tumors, is the subject of this review article, along with an overview of developments within a novel and attractive research trend, comprising the use of MSNs for CRISPR/Cas9 systems delivery and gene editing in cancer. Such advanced nanconstructs exhibit high potential for applications in image-guided therapies and the development of personalized cancer treatment.

Photoacoustic imaging as a highly efficient and precise imaging strategy for the evaluation of brain diseases

Photoacoustic imaging (PAI) is an emerging imaging strategy with a unique combination of rich optical contrasts, high ultrasound spatial resolution, and deep penetration depth without ionizing radiation. Taking advantage of the features mentioned above, PAI has been widely applied to preclinical studies in diverse fields, such as vascular biology, cardiology, neurology, ophthalmology, dermatology, gastroenterology, and oncology. Among various biomedical applications, photoacoustic brain imaging has great importance due to the brain's complex anatomy and the variability of brain disease. In this review, we aimed to introduce a novel and effective imaging modality for diagnosing brain diseases. Firstly, a brief overview of two major types of PAI system was provided. Then, PAI's major preclinical applications in brain diseases were introduced, including early diagnosis of brain tumors, subtle changes in the chemotherapy response, epileptic activity and brain injury, foreign body, and brain plaque. Finally, a perspective of the remaining challenges of PAI was given for future advancements.

Mesoporous Silica Nanoparticles: Properties and Strategies for Enhancing Clinical Effect

Due to the theragnostic potential of mesoporous silica nanoparticles (MSNs), these were extensively investigated as a novel approach to improve clinical outcomes. Boasting an impressive array of formulations and modifications, MSNs demonstrate significant in vivo efficacy when used to identify or treat myriad malignant diseases in preclinical models. As MSNs continue transitioning into clinical trials, a thorough understanding of the characteristics of effective MSNs is necessary. This review highlights recent discoveries and advances in MSN understanding and technology. Specific focus is given to cancer theragnostic approaches using MSNs. Characteristics of MSNs such as size, shape, and surface properties are discussed in relation to effective nanomedicine practice and projected clinical efficacy. Additionally, tumor-targeting options used with MSNs are presented with extensive discussion on active-targeting molecules. Methods for decreasing MSN toxicity, improving site-specific delivery, and controlling release of loaded molecules are further explained. Challenges facing the field and translation to clinical environments are presented alongside potential avenues for continuing investigations.

Arabinoxylan/graphene-oxide/nHAp-NPs/PVA bionano composite scaffolds for fractured bone healing

The importance of bone scaffolds has increased many folds in the last few years; however, during bone implantation, bacterial infections compromise the implantation and tissue regeneration. This work is focused on this issue while not compromising on the properties of a scaffold for bone regeneration. Biocomposite scaffolds (BS) were fabricated via the freeze-drying technique. The samples were characterized for structural changes, surface morphology, porosity, and mechanical properties through spectroscopic (Fourier transform-infrared [FT-IR]), microscopic (scanning electron microscope [SEM]), X-ray (powder X-ray diffraction and energy-dispersive X-ray), and other analytical (Brunauer-Emmett-Teller, universal testing machine Instron) techniques. Antibacterial, cellular, and hemocompatibility assays were performed using standard protocols. FT-IR confirmed the interactions of all the components. SEM illustrated porous and interconnected porous morphology. The percentage porosity was in the range of 49.75%-67.28%, and the pore size was 215.65-470.87 µm. The pore size was perfect for cellular penetration. Thus, cells showed significant proliferation onto these scaffolds. X-ray studies confirmed the presence of nanohydroxyapatite and graphene oxide (GO). The cell viability was 85%-98% (BS1-BS3), which shows no significant toxicity of the biocomposite. Furthermore, the biocomposites exhibited better antibacterial activity, no effect on the blood clotting (normal in vitro blood clotting), and less than 5% hemolysis. The ultimate compression strength for the biocomposites increased from 4.05 to 7.94 with an increase in the GO content. These exciting results revealed that this material has the potential for possible application in bone tissue engineering.

HA targeted-biodegradable nanocomposites responsive to endogenous and exogenous stimulation for multimodal imaging and chemo-/photothermal therapy

Multimodal imaging-guided accurate tumor-targeting and efficient synergistic therapy are of great importance for cancer therapy in vitro and in vivo. In this study, a biocompatible, tumor-targeted, on-demand chemo-/photothermal therapeutic nanoplatform (HIDSiGdNPs@PDA-HA) based on hollow mesoporous organic silica nanoparticles (HMONs) was used for bimodal imaging and multi-factor stepwise response for drug release and treatment. Targeted molecule hyaluronic acid (HA) promoted the endocytosis of HIDSiGdNPs@PDA-HA in HeLa cancer cells. The gatekeeper pH-/light-sensitive PDA coating was stimulated by the endogenous tumor acidic microenvironment and exogenous NIR laser to release doxorubicin (DOX). Thereafter, HMONs containing S-S bonds were reduced and degraded by endogenous glutathione (GSH), and the drug was further released rapidly to kill cancer cells. Importantly, the photothermal reagent indocyanine green (ICG) was always retained in the carrier, improving the effectiveness of photothermal therapy. The loaded Gd-doped silicon nanoparticles (SiGdNPs) combined with DOX and ICG led to multi-color fluorescence imaging in vitro and magnetic resonance imaging in vivo to realize targeted diagnosis and track drug distribution. The treatment results of tumor-bearing mice also proved the excellent synergistic therapy. It is believed that the multifunctional nanomaterials with dual mode imaging capability and targeted and controlled collaborative therapy would provide an alternative for accurate diagnosis and efficient treatment.

Tailored Mesoporous Inorganic Biomaterials: Assembly, Functionalization, and Drug Delivery Engineering

Infectious or immune diseases have caused serious threat to human health due to their complexity and specificity, and emerging drug delivery systems (DDSs) have evolved into the most promising therapeutic strategy for drug-targeted therapy. Various mesoporous biomaterials are exploited and applied as efficient nanocarriers to loading drugs by virtue of their large surface area, high porosity, and prominent biocompatibility. Nanosized mesoporous nanocarriers show great potential in biomedical research, and it has become the research hotspot in the interdisciplinary field. Herein, recent progress and assembly mechanisms on mesoporous inorganic biomaterials (e.g., silica, carbon, metal oxide) are summarized systematically, and typical functionalization methods (i.e., hybridization, polymerization, and doping) for nanocarriers are also discussed in depth. Particularly, structure-activity relationship and the effect of physicochemical parameters of mesoporous biomaterials, including morphologies (e.g., hollow, core-shell), pore textures (e.g., pore size, pore volume), and surface features (e.g., roughness and hydrophilic/hydrophobic) in DDS application are overviewed and elucidated in detail. As one of the important development directions, advanced stimuli-responsive DDSs (e.g., pH, temperature, redox, ultrasound, light, magnetic field) are highlighted. Finally, the prospect of mesoporous biomaterials in disease therapeutics is stated, and it will open a new spring for the development of mesoporous nanocarriers.

An Electrochemical Aptasensor for Pb2+ Detection Based on Metal-Organic-Framework-Derived Hybrid Carbon

A new double-shelled carbon nanocages material was synthesized and developed an aptasensor for determining Pb²⁺ in aqueous solution. Herein, nanoporous carbon materials derived from core–shell zeolitic imidazolate frameworks (ZIFs) demonstrated excellent electrochemical activity, stability, and high specificity surface area, consequently resulting in the strong binding with aptamers. The aptamer strands would be induced to form G-quadruplex structure when Pb²⁺ was introduced. Under optimal conditions, the aptasensor exhibited a good linear relationship of Pb²⁺ concentration ranging from 0.1 to 10 μg L⁻¹ with the detection limits of 0.096 μg L⁻¹. The feasibility was proved by detecting Pb²⁺ in spiked water samples and polluted soil digestion solution. The proposed aptasensor showed excellent selectivity and reproducibility, indicating promising applications in environmental monitoring.

Mesoporous Silica Nanoparticles for Targeting Subcellular Organelles

Current chemotherapy treatments lack great selectivity towards tumoral cells, which leads to nonspecific drug distribution and subsequent side effects. In this regard, the use of nanoparticles able to encapsulate and release therapeutic agents has attracted growing attention. In this sense, mesoporous silica nanoparticles (MSNs) have been widely employed as drug carriers owing to their exquisite physico-chemical properties. Because MSNs present a surface full of silanol groups, they can be easily functionalized to endow the nanoparticles with many different functionalities, including the introduction of moieties with affinity for the cell membrane or relevant compartments within the cell, thus increasing the efficacy of the treatments. This review manuscript will provide the state-of-the-art on MSNs functionalized for targeting subcellular compartments, focusing on the cytoplasm, the mitochondria, and the nucleus.

Cinnamaldehyde and Doxorubicin Co-Loaded Graphene Oxide Wrapped Mesoporous Silica Nanoparticles for Enhanced MCF-7 Cell Apoptosis

Background

Combined chemotherapy is often affected by the different physicochemical properties of chemotherapeutic drugs, which should be improved by the reasonable design of co-loaded preparations.

Purpose

A kind of simple but practical graphene oxide (GO) wrapped mesoporous silica nanoparticles (MSN) modified with hyaluronic acid (MSN@GO-HA) were developed for the co-delivery of cinnamaldehyde (CA) and doxorubicin (DOX), in order to enhance their combined treatment on tumor cells and reduce their application defects.

Methods

The MSN_CA@GO_DOX-HA was constructed by MSN_CA (loading CA via physical diffusion) and GO_DOX-HA (modified with HA and loading DOX via π–π stacking) through the electrostatic adsorption, followed by the physicochemical characterization, serum stability and in vitro release study. Cytotoxicity on different cells was detected, followed by the tumor cell uptake tests. The intracellular reactive oxygen species (ROS) changes, mitochondrial functions and activities of caspase-3/-9 in MCF-7 cells were also evaluated, respectively.

Results

The MSN_CA@GO_DOX-HA nanoparticles kept stable in FBS solution and achieved pH-responsive release behavior, which was beneficial to increase the accumulation of CA and DOX in tumor cells to enhance the treatment. MSN_CA@GO_DOX-HA exerted higher cytotoxicity to MCF-7 human breast cancer cells than H9c2 cardiac myocyte cells, which were not only attributed to the active targeting to tumor cells by HA, but also related with the activation of intrinsic apoptotic pathway in MCF-7 cells induced by CA, which was mediated by the specific ROS signal amplification and the interference with mitochondrial function. Moreover, the efficacy of DOX was also enhanced by the above process.

Conclusion

The establishment of the MSN_CA@GO_DOX-HA nanoparticles played a role in promoting strengths and restricting shortcomings of CA and DOX, thereby exerting their function and achieving efficient treatment against cancer.

Aptamers used for biosensors and targeted therapy

Aptamers are single-stranded nucleic acid sequences that can bind to target molecules with high selectivity and affinity. Most aptamers are screened in vitro by a combinatorial biology technique called systematic evolution of ligands by exponential enrichment (SELEX). Since aptamers were discovered in the 1990s, they have attracted considerable attention and have been widely used in many fields owing to their unique advantages. In this review, we present an overview of the advancements made in aptamers used for biosensors and targeted therapy. For the former, we will discuss multiple aptamer-based biosensors with different principles detected by various signaling methods. For the latter, we will focus on aptamer-based targeted therapy using aptamers as both biotechnological tools for targeted drug delivery and as targeted therapeutic agents. Finally, challenges and new perspectives associated with these two regions were further discussed. We hope that this review will help researchers interested in aptamer-related biosensing and targeted therapy research.

Aptamer-Functionalized Nanoparticles in Targeted Delivery and Cancer Therapy

Using nanoparticles to carry and delivery anticancer drugs holds much promise in cancer therapy, but nanoparticles per se are lacking specificity. Active targeting, that is, using specific ligands to functionalize nanoparticles, is attracting much attention in recent years. Aptamers, with their several favorable features like high specificity and affinity, small size, very low immunogenicity, relatively low cost for production, and easiness to store, are one of the best candidates for the specific ligands of nanoparticle functionalization. This review discusses the benefits and challenges of using aptamers to functionalize nanoparticles for active targeting and especially presents nearly all of the published works that address the topic of using aptamers to functionalize nanoparticles for targeted drug delivery and cancer therapy.

Applications of Graphene and Graphene Oxide in Smart Drug/Gene Delivery: Is the World Still Flat?

Graphene, a wonder material, has made far-reaching developments in many different fields such as materials science, electronics, condensed physics, quantum physics, energy systems, etc. Since its discovery in 2004, extensive studies have been done for understanding its physical and chemical properties. Owing to its unique characteristics, it has rapidly became a potential candidate for nano-bio researchers to explore its usage in biomedical applications. In the last decade, remarkable efforts have been devoted to investigating the biomedical utilization of graphene and graphene-based materials, especially in smart drug and gene delivery as well as cancer therapy. Inspired by a great number of successful graphene-based materials integrations into the biomedical area, here we summarize the most recent developments made about graphene applications in biomedicine. In this paper, we review the up-to-date advances of graphene-based materials in drug delivery applications, specifically targeted drug/ gene delivery, delivery of antitumor drugs, controlled and stimuli-responsive drug release, photodynamic therapy applications and optical imaging and theranostics, as well as investigating the future trends and succeeding challenges in this topic to provide an outlook for future researches.

A Review of Mesoporous Silica Nanoparticle Delivery Systems in Chemo-Based Combination Cancer Therapies

Chemotherapy is an important anti-tumor treatment in clinic to date, however, the effectiveness of traditional chemotherapy is limited by its poor selectivity, high systemic toxicity, and multidrug resistance. In recent years, mesoporous silica nanoparticles (MSNs) have become exciting drug delivery systems (DDS) due to their unique advantages, such as easy large-scale production, adjustable uniform pore size, large surface area and pore volumes. While mesoporous silica-based DDS can improve chemotherapy to a certain extent, when used in combination with other cancer therapies MSN based chemotherapy exhibits a synergistic effect, greatly improving therapeutic outcomes. In this review, we discuss the applications of MSN DDS for a diverse range of chemotherapeutic combination anti-tumor therapies, including phototherapy, gene therapy, immunotherapy and other less common modalities. Furthermore, we focus on the characteristics of each nanomaterial and the synergistic advantages of the combination therapies. Lastly, we examine the challenges and future prospects of MSN based chemotherapeutic combination therapies.

Cascade-Targeting of Charge-Reversal and Disulfide Bonds Shielding for Efficient DOX Delivery of Multistage Sensitive MSNs-COS-SS-CMC

BACKGROUND

Although pH and redox sensitiveness have been extensively investigated to improve therapeutic efficiency, the effect of disulfide bonds location and pH-triggered charge-reversal on cascade-targeting still need to be further evaluated in cancer treatment with multi-responsive nanoparticles.

PURPOSE

The aim of this study was to design multi-responsive DOX@MSNs-COS-NN-CMC, DOX@MSNs-COS-SS-CMC and DOX@MSNs-COS-CMC-SS and systematically investigate the effects of disulfide bonds location and charge-reversal on the cancer cell specificity, endocytosis mechanisms and antitumor efficiency.

RESULTS

In vitro drug release rate of DOX@MSNs-COS-SS-CMC in tumor environments was 7-fold higher than that under normal physiological conditions after 200 h. Furthermore, the fluorescence intensity of DOX@MSNs-COS-SS-CMC and DOX@MSNs-COS-CMC-SS was 1.9-fold and 1.3-fold higher than free DOX at pH 6.5 and 10 mM GSH. In addition, vesicular transport might be a factor that affects the uptake efficiency of DOX@MSNs-COS-SS-CMC and DOX@MSNs-COS-CMC-SS. The clathrin-mediated endocytosis and endosomal escape of DOX@MSNs-COS-SS-CMC enhanced cellular internalization and preserved highly controllable drug release into the perinuclear of HeLa cells. DOX@MSNs-COS-SS-CMC exhibited a synergistic chemotherapy in preeminent tumor inhibition and less side effects of cardiotoxicity.

CONCLUSION

The cascade-targeting of charge-reversal and disulfide bonds shielding would be a highly personalized strategy for cervical cancer treatment.

Targeted antimicrobial peptide delivery in vivo to tumor with near infrared photoactivated mesoporous silica nanoparticles

Antimicrobial peptide PA-C1b (chensinin-1b conjugated with palmitic acid) showed potent anticancer activity with no obvious hemolytic activity, which made it a potential agent for treating cancers. However, after in vivo administration, peptides can be degraded by proteases because there is no effective protection. In this study, a tumor-targeting photoresponsive antimicrobial peptide delivery system was developed, and the peptide PA-C1b labeled with the dye sulfo-cyanine7 (Cy7) was loaded into mesoporous silica nanoparticles (MSNs). The final MSN@Cy7-PA-C1b nanoparticles were wrapped by graphene oxide (GO), and then folic acid was conjugated to the surface of the MSNs for targeting purposes. The final MSN@Cy7-PA-C1b@FA-GO nanoparticles were constructed to allow light-mediated peptide release and folate receptor-targeted cancer therapy. The Cy7 dye serves as a real-time indicator, and GO acts as a gatekeeper to prevent leakage of the loaded peptides in the absence of near-infrared light irradiation. Upon light irradiation, the GO wrapping detaches, and the photoresponsive peptide delivery system works well both in in vitro cell experiments and during in vivo administration in mouse tumor experiments. The construction of the MSN@Cy7-PA-C1b@FA-GO platform provides a novel approach to deliver antimicrobial peptides in vivo for the treatment of infections by pathogenic microorganisms and cancers.

Therapeutic applications of AS1411 aptamer, an update review

Nucleolin or C23, is one of the most abundant non-ribosomal phosphoproteins of nucleolus. However, in several cancers, nucleolin is highly expressed both intracellularly and on the cell surface. So, it is considered as a potential target for the diagnosis and cancer therapy. Targeting nucleolin by compounds such as AS1411 aptamer can reduce tumor cell growth. In this regard, interest has increased in nucleolin as a molecular target for overcoming cancer therapy challenges. This review paper addressed recent progresses in nucleolin targeting by the G-rich AS1411 aptamer in the field of cancer therapy mainly over the past three years.

Aptamer-Based Targeted Drug Delivery Systems: Current Potential and Challenges

Aptamers are single-stranded DNA or RNA with 20-100 nucleotides in length that can specifically bind to target molecules via formed three-dimensional structures. These innovative targeting molecules have attracted an increasing interest in the biomedical field. Compared to traditional protein antibodies, aptamers have several advantages, such as small size, high binding affinity, specificity, good biocompatibility, high stability and low immunogenicity, which all contribute to their wide application in the biomedical field. Aptamers can bind to the receptors on the cell membrane and mediate themselves or conjugated nanoparticles to enter into cells. Therefore, aptamers can be served as ideal targeting ligands for drug delivery. Since their excellent properties, different aptamer-mediated drug delivery systems had been developed for cancer therapy. This review provides a brief overview of recent advances in drug delivery systems based on aptamers. The advantages, challenges and future prospectives are also discussed.

Multi-transformable nanocarrier with tumor extracellular acidity-activated charge reversal, size reduction and ligand reemergence for in vitro efficient doxorubicin loading and delivery

Various nanoparticles as drug delivery system provide significant improvements in the cancer treatment. However, their clinical success remains elusive in large part due to their inability to overcome both systemic and tumor tissue barriers. The nanosystems with nanoproperty-transformability (surface, size, stability and target) hold great promise for achieving enhanced delivery efficacy. However, currently available systems that are mainly polymer-based assemblies usually suffer from the intrinsic drawbacks of poor stability, premature leakage and low drug loading as well as limited transformability. In this study, we designed a facile strategy to build a novel multi-transformable MSNs@GO nanosystem for efficient doxorubicin (DOX) loading and delivery. This novel nanosystem was well characterized and investigated in vitro. The results indicated that the MSNs@GO can realize a very high drug loading ability due to the large pore surface area of MSNs and the demonstrated donor-acceptor (boron‑nitrogen) coordination interactions between phenylboronic acid-containing nanocarriers and electron donor-containing DOX. More importantly, the novel nanocarriers can simultaneously achieve charge reversal, size reduction and ligand reemergence by shielding/deshielding transition via acid-cleavable dynamic boronate bonds under in vitro simulated acidic microenvironment of tumor tissues, opening a new avenue for improving delivery efficiency of chemotherapeutics.

Multimodal Decorations of Mesoporous Silica Nanoparticles for Improved Cancer Therapy

The presence of leaky vasculature and the lack of lymphatic drainage of small structures by the solid tumors formulate nanoparticles as promising delivery vehicles in cancer therapy. In particular, among various nanoparticles, the mesoporous silica nanoparticles (MSN) exhibit numerous outstanding features, including mechanical thermal and chemical stability, huge surface area and ordered porous interior to store different anti-cancer therapeutics with high loading capacity and tunable release mechanisms. Furthermore, one can easily decorate the surface of MSN by attaching ligands for active targeting specifically to the cancer region exploiting overexpressed receptors. The controlled release of drugs to the disease site without any leakage to healthy tissues can be achieved by employing environment responsive gatekeepers for the end-capping of MSN. To achieve precise cancer chemotherapy, the most desired delivery system should possess high loading efficiency, site-specificity and capacity of controlled release. In this review we will focus on multimodal decorations of MSN, which is the most demanding ongoing approach related to MSN application in cancer therapy. Herein, we will report about the recently tried efforts for multimodal modifications of MSN, exploiting both the active targeting and stimuli responsive behavior simultaneously, along with individual targeted delivery and stimuli responsive cancer therapy using MSN.

Influence of the Surface Functionalization on the Fate and Performance of Mesoporous Silica Nanoparticles

Mesoporous silica nanoparticles have been broadly applied as drug delivery systems owing to their exquisite features, such as excellent textural properties or biocompatibility. However, there are various biological barriers that prevent their proper translation into the clinic, including: (1) lack of selectivity toward tumor tissues, (2) lack of selectivity for tumoral cells and (3) endosomal sequestration of the particles upon internalization. In addition, their open porous structure may lead to premature drug release, consequently affecting healthy tissues and decreasing the efficacy of the treatment. First, this review will provide a comprehensive and systematic overview of the different approximations that have been implemented into mesoporous silica nanoparticles to overcome each of such biological barriers. Afterward, the potential premature and non-specific drug release from these mesoporous nanocarriers will be addressed by introducing the concept of stimuli-responsive gatekeepers, which endow the particles with on-demand and localized drug delivery.