Progress in Remotely Triggered Hybrid Nanostructures for Next-Generation Brain Cancer Theranostics

Raman Spectroscopy: A Tool for Molecular Fingerprinting of Brain Cancer

Brain cancer is one of those few cancers with very high mortality and low five-year survival rate. First and foremost reason for the woes is the difficulty in diagnosing and monitoring the progression of brain tumors both benign and malignant, noninvasively and in real time. This raises a need in this hour for a tool to diagnose the tumors in the earliest possible time frame. On the other hand, Raman spectroscopy which is well-known for its ability to precisely represent the molecular markers available in any sample given, including biological ones, with great sensitivity and specificity. This has led to a number of studies where Raman spectroscopy has been used in brain tumors in various ways. This review article highlights the fundamentals of Raman spectroscopy and its types including conventional Raman, SERS, SORS, SRS, CARS, etc. are used in brain tumors for diagnostics, monitoring, and even theragnostics, collating all the major works in the area. Also, the review explores how Raman spectroscopy can be even more effectively used in theragnostics and the clinical level which would make them a one-stop solution for all brain cancer needs in the future.

Application of Mn x Fe1-x Fe2O4 (x = 0-1) Nanoparticles in Magnetic Fluid Hyperthermia: Correlation with Cation Distribution and Magnetostructural Properties

Optimization of manganese-substituted iron oxide nanoferrites having the composition Mn _x Fe_1-x Fe₂O₄ (x = 0-1) has been achieved by the chemical co-precipitation method. The crystallite size and phase purity were analyzed from X-ray diffraction. With increases in Mn²⁺ concentration, the crystallite size varies from 5.78 to 9.94 nm. Transmission electron microscopy (TEM) analysis depicted particle sizes ranging from 10 ± 0.2 to 13 ± 0.2 nm with increasing Mn²⁺ substitution. The magnetization (M _s) value varies significantly with increasing Mn²⁺ substitution. The variation in the magnetic properties may be attributed to the substitution of Fe²⁺ ions by Mn²⁺ ions inducing a change in the superexchange interaction between the A and B sublattices. The self-heating characteristics of Mn _x Fe_1-x Fe₂O₄ (x = 0-1) nanoparticles (NPs) in an AC magnetic field are evaluated by specific absorption rate (SAR) and intrinsic loss power, both of which are presented with varying NP composition, NP concentration, and field amplitudes. Mn_0.75Fe_0.25Fe₂O₄ exhibited superior induction heating properties in terms of a SAR of 153.76 W/g. This superior value of SAR with an optimized Mn²⁺ content is presented in correlation with the cation distribution of Mn²⁺ in the A or B position in the Fe₃O₄ structure and enhancement in magnetic saturation. These optimized Mn_0.75Fe_0.25Fe₂O₄ NPs can be used as a promising candidate for hyperthermia applications.

Miniature NIR-II Nanoprobes for Active-Targeted Phototheranostics of Brain Tumors

Nanoprobes (NPs) in the second near-infrared biowindow (NIR-II, 1000-1700 nm) are developed and widely used in cancer phototheranostics. However, most NIR-II NPs exhibit low phototheranostic efficiency due to their tedious synthetic routes, large particle sizes (>20 nm), and lack of active targeting properties. Here, miniature NIR-II NPs, named HSA-ICG-iRGD, for active-targeted NIR-II phototheranostics of brain tumors are reported. The HSA-ICG-iRGD probes are designed based on hydrophobic interactions as well as hydrogen bonds between albumin and indocyanine green derivatives (ICG-iRGD) via molecular docking. The as-prepared NPs have a compact size of 10 nm and show tumor-targeting ability by specifically binding to α_v β₃ integrin receptors which are highly expressed on the surface of brain tumor cells via iRGD peptides. The HSA-ICG-iRGD NPs are then applied to perform active-targeted NIR-II fluorescence imaging, resulting in a signal-to-background ratio of 6.85 in orthotopic glioma mouse models. Under the selected laser irradiation of 808 nm, the photothermal effect of HSA-ICG-iRGD extends the survival of the tumor-bearing mice to 55 days, significantly longer than that of the control group (30 days). These results highlight the potential of miniature NPs for active-targeted NIR-II fluorescence imaging and phototherapy of brain tumors.

Current Advancements in Self-assembling Nanocarriers-Based siRNA Delivery for Cancer Therapy

Different therapeutic practices for treating cancers have significantly evolved to compensate and/or overcome the failures in conventional methodologies. The demonstrated potentiality in completely inhibiting the tumors and in preventing cancer relapse has made nucleic acids therapy (NAT)/gene therapy as an attractive practice. This has been made possible because NAT-based cancer treatments are highly focused on the fundamental mechanisms - i.e., silencing the expression of oncogenic genes responsible for producing abnormal proteins (via messenger RNAs (mRNAs)). However, the future clinical translation of NAT is majorly dependent upon the effective delivery of the exogenous nucleic acids (especially RNAs - e.g., short interfering RNAs (siRNAs) - herein called biological drugs). Moreover, nano-based vehicles (i.e., nanocarriers) are involved in delivering them to prevent degradation and undesired bioaccumulation while enhancing the stability of siRNAs. Herein, we have initially discussed about three major types of self-assembling nanocarriers (liposomes, polymeric nanoparticles and exosomes). Later, we have majorly reviewed recent developments in non-targeted/targeted nanocarriers for delivery of biological drugs (individual/dual) to silence the most important genes/mRNAs accountable for inducing protein abnormality. These proteins include polo-like kinase 1 (PLK1), survivin, vascular endothelial growth factor (VEGF), B-cell lymphoma/leukaemia-2 (Bcl-2) and multi-drug resistance (MDR). Besides, the consequent therapeutic effects on cancer growth, invasion and/or metastasis have also been discussed. Finally, we have comprehensively reviewed the improvements achieved in the cutting-edge cancer therapeutics while delivering siRNAs in combination with clinically approved chemotherapeutic drugs.

Review of Noninvasive or Minimally Invasive Deep Brain Stimulation

Brain stimulation is a critical technique in neuroscience research and clinical application. Traditional transcranial brain stimulation techniques, such as transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), and deep brain stimulation (DBS) have been widely investigated in neuroscience for decades. However, TMS and tDCS have poor spatial resolution and penetration depth, and DBS requires electrode implantation in deep brain structures. These disadvantages have limited the clinical applications of these techniques. Owing to developments in science and technology, substantial advances in noninvasive and precise deep stimulation have been achieved by neuromodulation studies. Second-generation brain stimulation techniques that mainly rely on acoustic, electronic, optical, and magnetic signals, such as focused ultrasound, temporal interference, near-infrared optogenetic, and nanomaterial-enabled magnetic stimulation, offer great prospects for neuromodulation. This review summarized the mechanisms, development, applications, and strengths of these techniques and the prospects and challenges in their development. We believe that these second-generation brain stimulation techniques pave the way for brain disorder therapy.

Influence of Spatial Dispersion on the Electromagnetic Properties of Magnetoplasmonic Nanostructures

Magnetoplasmonics based on composite nanostructures is widely used in many biomedical applications. Nanostructures, consisting of a magnetic core and a gold shell, exhibit plasmonic properties, that allow the concentration of electromagnetic energy in ultra-small volumes when used, for example, in imaging and therapy. Magnetoplasmonic nanostructures have become an indispensable tool in nanomedicine. The gold shell protects the core from oxidation and corrosion, providing a biocompatible platform for tumor imaging and cancer treatment. By adjusting the size of the core and the shell thickness, the maximum energy concentration can be shifted from the ultraviolet to the near infrared, where the depth of light penetration is maximum due to low scattering and absorption by tissues. A decrease in the thickness of the gold shell to several nanometers leads to the appearance of the quantum effect of spatial dispersion in the metal. The presence of the quantum effect can cause both a significant decrease in the level of energy concentration by plasmon particles and a shift of the maxima to the short-wavelength region, thereby reducing the expected therapeutic effect. In this study, to describe the influence of the quantum effect of spatial dispersion, we used the discrete sources method, which incorporates the generalized non-local optical response theory. This approach made it possible to account for the influence of the nonlocal effect on the optical properties of composite nanoparticles, including the impact of the asymmetry of the core-shell structure on the energy characteristics. It was found that taking spatial dispersion into account leads to a decrease in the maximum value of the concentration of electromagnetic energy up to 25%, while the blue shift can reach 15 nm.

Recent advances in hepatocellular carcinoma therapeutic strategies and imaging-guided treatment

Hepatocellular carcinoma (HCC) is one of the most common malignant cancer in the world, which greatly threatens human health. However, the routine treatment strategies for HCC have failed to specifically eradicate the tumorigenic cells, leading to the occurrence of metastasis and recurrence. To improve treatment efficacies, the development of novel effective technologies is urgently required. Recently, nanotechnologies have gained the extensive attention in cancer targeted therapy, which could provide a promising way for HCC clinical practice. However, a successful cancer management depends on accurate diagnosis of the tumour along with precise therapeutic protocol, thereby predicting the tumour response to existing therapies. The synergistic effect of targeted therapeutic systems and imaging approaches (also called 'imaging-guided cancer treatment') may establish a more effective platform for individual cancer care. This review outlines the recent advanced nano-targeted and -traceable therapeutic strategies for HCC management. The multifunctional nano agents that have both diagnosis and therapy abilities are highlighted. Finally, we conclude with our perspectives on the future development and challenges of HCC nanotheranostics.

Nanobiotechnology-assisted therapies to manage brain cancer in personalized manner

There are numerous investigated factors that limit brain cancer treatment efficacy such as ability of prescribed therapy to cross the blood-brain barrier (BBB), tumor specific delivery of a therapeutics, transport within brain interstitium, and resistance of tumor cells against therapies. Recent breakthroughs in the field of nano-biotechnology associated with developing multifunctional nano-theranostic emerged as an effective way to manage brain cancer in terms of higher efficacy and least possible adverse effects. Keeping challenges and state-of-art accomplishments into consideration, this review proposes a comprehensive, careful, and critical discussion focused on efficient nano-enabled platforms including nanocarriers for drug delivery across the BBB and nano-assisted therapies (e.g., nano-immunotherapy, nano-stem cell therapy, and nano-gene therapy) investigated for brain cancer treatment. Besides therapeutic efficacy point-of-view, efforts are being made to explore ways projected to tune such developed nano-therapeutic for treating patients in personalized manner via controlling size, drug loading, delivery, and retention. Personalized brain tumor management based on advanced nano-therapies can potentially lead to excellent therapeutic benefits based on unique genetic signatures in patients and their individual disease profile. Moreover, applicability of nano-systems as stimulants to manage the brain cancer growth factors has also been discussed in photodynamic therapy and radiotherapy. Overall, this review offers a comprehensive information on emerging opportunities in nanotechnology for advancing the brain cancer treatment.

Photo-responsive functional gold nanocapsules for inactivation of community-acquired, highly virulent, multidrug-resistant MRSA

The indiscriminate and sporadic use of antibiotics has contributed to the emergence of drug resistance phenomenon in bacteria including but not limited to Staphylococcus aureus. These drug-resistant bacteria have been threatening safety in hospitals and adversely affecting human health. Here we report a strategy to design photo-stimulated theranostic nanoprobes against methicillin-resistant Staphylococcus aureus (MRSA) "superbug" USA300. The nanocapsule probe is based on gold nanorods (GNRs) coated with pegylated thiol, mPEG-SH, which has been further modified by adding successively a natural antibacterial compound such as curcumin, and a cell targeting deoxyribonucleic acid (DNA) aptamer. We have used this novel gold nanocapsules for near-infrared (NIR) photophysical stimulation against pathogenic bacteria. We have found that the novel nanocapsule blocks biofilm formation and kills bacteria by photothermal action that causes disruption of the bacterial cell wall and membrane. In this approach, multiple drug-resistant Staphylococcus aureus has been captured by these nanocapsules through DNA aptamer targeting. All of the trapped bacteria could be killed in 30 minutes during the NIR stimulation due to the combination of photothermal effect, the generation of reactive oxygen species (ROS) and a loss of transmembrane potential (Δψ). Importantly we did not notice any resistance developed against the photothermal treatment. This is remarkable from an anti-biofilm activity point of view. Importantly, these multifunctional nanocapsules have also shown a surface enhanced Raman spectroscopy (SERS) effect, which could be used to evaluate the success of the inactivation effect during treatment. These results indicate that nanocapsule-based photo treatment can be an alternative antibacterial strategy without contributing to antibiotic resistance, and thus can be used for both environmental and therapeutic applications.

Designing and Immunomodulating Multiresponsive Nanomaterial for Cancer Theranostics

Cancer has been widely investigated yet limited in its manifestation. Cancer treatment holds innovative and futuristic strategies considering high disease heterogeneity. Chemotherapy, radiotherapy and surgery are the most explored pillars; however optimal therapeutic window and patient compliance recruit constraints. Recently evolved immunotherapy demonstrates a vital role of the host immune system to prevent metastasis recurrence, still undesirable clinical response and autoimmune adverse effects remain unresolved. Overcoming these challenges, tunable biomaterials could effectively control the co-delivery of anticancer drugs and immunomodulators. Current status demands a potentially new approach for minimally invasive, synergistic, and combinatorial nano-biomaterial assisted targeted immune-based treatment including therapeutics, diagnosis and imaging. This review discusses the latest findings of engineering biomaterial with immunomodulating properties and implementing novel developments in designing versatile nanosystems for cancer theranostics. We explore the functionalization of nanoparticle for delivering antitumor therapeutic and diagnostic agents promoting immune response. Through understanding the efficacy of delivery system, we have enlightened the applicability of nanomaterials as immunomodulatory nanomedicine further advancing to preclinical and clinical trials. Future and present ongoing improvements in engineering biomaterial could result in generating better insight to deal with cancer through easily accessible immunological interventions.

Nanomedicine-driven molecular targeting, drug delivery, and therapeutic approaches to cancer chemoresistance

Cancer cell resistance to chemotherapeutics (chemoresistance) poses a significant clinical challenge that oncology research seeks to understand and overcome. Multiple anticancer drugs and targeting agents can be incorporated in nanomedicines, in addition to different treatment modalities, forming a single nanoplatform that can be used to address tumor chemoresistance. Nanomedicine-driven molecular assemblies using nucleic acids, small interfering (si)RNAs, miRNAs, and aptamers in combination with stimuli-responsive therapy improve the pharmacokinetic (PK) profile of the drugs and enhance their accumulation in tumors and, thus, therapeutic outcomes. In this review, we highlight nanomedicine-driven molecular targeting and therapy combination used to improve the 3Rs (right place, right time, and right dose) for chemoresistant tumor therapies.

Revealing the NIR-triggered chemotherapy therapeutic window of magnetic and thermoresponsive nanogels

The combination of magnetic nanoparticles and thermoresponsive nanogels represents an appealing strategy for the development of theranostic probes. These hybrid nanocarriers present several advantages such as outstanding properties for guided therapy, magnetic resonance imaging, and triggered release of encapsulated cargoes. Most magnetic thermoresponsive nanogels are built with strategies that comprise a physical interaction of particles with the polymeric network or the covalent attachment of a single particle to the linear polymer. Herein, we report a facile synthetic approach for the synthesis of magnetic and thermoresponsive nanogels that allows the controlled incorporation of multiple superparamagnetic inorganic cores as covalent cross-linkers. An ultrasonication-assisted precipitation-polymerization afforded nanogels with sizes in the nanometric range and similar magnetization and light transduction properties compared to the discrete magnetic nanoparticles. The theranostic capability of these nanocarriers was further investigated both in vitro and in vivo. In vivo experiments demonstrated the capacity of these materials as nanocarriers for near-infrared (NIR) triggered chemotherapy and highlighted the relevance of the correct concentration/dose in this antitumoral modality to achieve a superior therapeutic efficacy.

Perfluoropolyether Nanoemulsion Encapsulating Chlorin e6 for Sonodynamic and Photodynamic Therapy of Hypoxic Tumor

Sonodynamic therapy (SDT) has emerged as an important modality for cancer treatment. SDT utilizes ultrasound excitation, which overcomes the limitations of light penetration in deep tumors, as encountered by photodynamic therapy (PDT) which uses optical excitations. A comparative study of these modalities using the same sensitizer drug can provide an assessment of their effects. However, the efficiency of SDT and PDT is low in a hypoxic tumor environment, which limits their applications. In this study, we report a hierarchical nanoformulation which contains a Food and Drug Administration (FDA) approved sensitizer chlorin, e6, and a uniquely stable high loading capacity oxygen carrier, perfluoropolyether. This oxygen carrier possesses no measurable cytotoxicity. It delivers oxygen to overcome hypoxia, and at the same time, boosts the efficiency of both SDT and PDT. Moreover, we comparatively analyzed the efficiency of SDT and PDT for tumor treatment throughout the depth of the tissue. Our study demonstrates that the strengths of PDT and SDT could be combined into a single multifunctional nanoplatform, which works well in the hypoxia environment and overcomes the limitations of each modality. The combination of deep tissue penetration by ultrasound and high spatial activation by light for selective treatment of single cells will significantly enhance the scope for therapeutic applications.

Comprehensive approach of hybrid nanoplatforms in drug delivery and theranostics to combat cancer

To date, various chemically synthesized and biosynthesized nanoparticles, or hybrid nanosystems and/or nanoplatforms, have been developed under the umbrella of nanomedicine. These can be introduced into the body orally, nasally, intratumorally or intravenously. Successfully translating hybrid nanoplatforms from preclinical proof-of-concept to therapeutic value in the clinic is challenging. Having made significant advances with drug delivery technologies, we must learn from other areas of oncology drug development, where patient stratification and target-driven design have improved patient outcomes. This review aims to identify gaps in our understanding of the current strengths of nanomedicine platforms in drug delivery and cancer theranostics. We report on the current approaches of nanomedicine at preclinical and clinical stages.

Emerging and Innovative Theranostic Approaches for Mesoporous Silica Nanoparticles in Hepatocellular Carcinoma: Current Status and Advances

Hepatocellular carcinoma (HCC) is one of the most prevalent and lethal solid cancers globally. To improve diagnosis sensitivities and treatment efficacies, the development of new theranostic nanoplatforms for efficient HCC management is urgently needed. In the past decade, mesoporous silica nanoparticles (MSNs) with tailored structure, large surface area, high agents loading volume, abundant chemistry functionality, acceptable biocompatibility have received more and more attention in HCC theranostic. This review outlines the recent advances in MSNs-based systems for HCC therapy and diagnosis. The multifunctional hybrid nanostructures that have both of therapy and diagnosis abilities are highlighted. And the precision delivery strategies of MSNs in HCC are also discussed. Final, we conclude with our personal perspectives on the future development and challenges of MSNs.