Degradable Calcium Phosphate-Coated Upconversion Nanoparticles for Highly Efficient Chemo-Photodynamic Therapy

Intelligent Biogenic Missile for Two-Photon Fluorescence Imaging-Guided Combined Photodynamic Therapy and Chemotherapy in Tumors

Photodynamic therapy (PDT) is a significant noninvasive therapeutic modality, but it is often limited in its application due to the restricted tissue penetration depth caused by the wavelength limitations of the light source. Two-photon (TP) fluorescence techniques are capable of having an excitation wavelength in the NIR region by absorbing two NIR photons simultaneously, which offers the potential to achieve higher spatial resolution for deep tissue imaging. Thus, the adoption of TP fluorescence techniques affords several discernible benefits for photodynamic therapy. Organic TP dyes possess a high fluorescence quantum yield. However, the biocompatibility of organic TP dyes is poor, and the method of coating organic TP dyes with silica can effectively overcome the limitations. Herein, based on the TP silica nanoparticles, a functionalized intelligent biogenic missile TP-SiNPs-G4(TMPyP4)-dsDNA(DOX)-Aptamer (TGTDDA) was developed for effective TP bioimaging and synergistic targeted photodynamic therapy and chemotherapy in tumors. First, the Sgc8 aptamer was used to target the PTK7 receptor on the surface of tumor cells. Under two-photon light irradiation, the intelligent biogenic missile can be activated for TP fluorescence imaging to identify tumor cells and the photosensitizer assembled on the nanoparticle surface can be activated for photodynamic therapy. Additionally, this intelligent biogenic missile enables the controlled release of doxorubicin (DOX). The innovative strategy substantially enhances the targeted therapeutic effectiveness of cancer cells. The intelligent biogenic missile provides an effective method for the early detection and treatment of tumors, which has a good application prospect in the real-time high-sensitivity diagnosis and treatment of tumors.

Recent Innovations of Mesoporous Silica Nanoparticles Combined with Photodynamic Therapy for Improving Cancer Treatment

Cancer is a global health burden and is one of the leading causes of death. Photodynamic therapy (PDT) is considered an alternative approach to conventional cancer treatment. PDT utilizes a light-sensitive compound, photosensitizers (PSs), light irradiation, and molecular oxygen (O2). This generates cytotoxic reactive oxygen species (ROS), which can trigger necrosis and/ or apoptosis, leading to cancer cell death in the intended tissues. Classical photosensitizers impose limitations that hinder their clinical applications, such as long-term skin photosensitivity, hydrophobic nature, nonspecific targeting, and toxic cumulative effects. Thus, nanotechnology emerged as an unorthodox solution for improving the hydrophilicity and targeting efficiency of PSs. Among nanocarriers, mesoporous silica nanoparticles (MSNs) have gained increasing attention due to their high surface area, defined pore size and structure, ease of surface modification, stable aqueous dispersions, good biocompatibility, and optical transparency, which are vital for PDT. The advancement of integrated MSNs/PDT has led to an inspiring multimodal nanosystem for effectively treating malignancies. This review gives an overview of the main components and mechanisms of the PDT process, the effect of PDT on tumor cells, and the most recent studies that reported the benefits of incorporating PSs into silica nanoparticles and integration with PDT against different cancer cells.

Marine biomaterials in biomedical nano/micro-systems

Marine resources in unique marine environments provide abundant, cost-effective natural biomaterials with distinct structures, compositions, and biological activities compared to terrestrial species. These marine-derived raw materials, including polysaccharides, natural protein components, fatty acids, and marine minerals, etc., have shown great potential in preparing, stabilizing, or modifying multifunctional nano-/micro-systems and are widely applied in drug delivery, theragnostic, tissue engineering, etc. This review provides a comprehensive summary of the most current marine biomaterial-based nano-/micro-systems developed over the past three years, primarily focusing on therapeutic delivery studies and highlighting their potential to cure a variety of diseases. Specifically, we first provided a detailed introduction to the physicochemical characteristics and biological activities of natural marine biocomponents in their raw state. Furthermore, the assembly processes, potential functionalities of each building block, and a thorough evaluation of the pharmacokinetics and pharmacodynamics of advanced marine biomaterial-based systems and their effects on molecular pathophysiological processes were fully elucidated. Finally, a list of unresolved issues and pivotal challenges of marine-derived biomaterials applications, such as standardized distinction of raw materials, long-term biosafety in vivo, the feasibility of scale-up, etc., was presented. This review is expected to serve as a roadmap for fundamental research and facilitate the rational design of marine biomaterials for diverse emerging applications.

Mesoporous polyacrylic acid/calcium phosphate coated persistent luminescence nanoparticles for improved afterglow bioimaging and chemotherapy of bacterial infection

Coating mesoporous drug carriers on the surface of persistent luminescence nanoparticles (PLNPs) not only allows continuous luminous imaging without spontaneous fluorescence interference, but also provides drug release guidance. However, in most cases, the encapsulation of the drug-loaded shells significantly reduces the luminescence of PLNPs, which is unfavorable for bioimaging. In addition, conventional drug-loaded shells alone, such as silica shells, have difficulty in achieving responsive fast drug release. Herein, we report the fabrication of mesoporous polyacrylic acid (PAA)/calcium phosphate (CaP) shell-coated PLNPs (PLNPs@PAA/CaP) for improved afterglow bioimaging and drug delivery. The encapsulation of the PAA/CaP shell effectively prolonged the decay time and enhanced the sustained luminescence of PLNPs by about three times due to the passivation of the surface defects of PLNPs by the shell, and the energy transfer between the shell and PLNPs. Meanwhile, the mesoporous structure and negative charge of the PAA/CaP shells enabled the prepared PLNPs@PAA/CaP to carry the positively charged drug doxycycline hydrochloride efficiently. Under the acidic conditions of bacterial infection, the degradation of PAA/CaP shells and the ionization of PAA enabled fast drug release for effective killing of bacteria at the infection site. The excellent persistent luminescence properties, outstanding biocompatibility, and rapid responsive release feature make the prepared PLNPs@PAA/CaP a promising nanoplatform for diagnostic and therapeutic applications.

Monolayer LDH Nanosheets with Ultrahigh ICG Loading for Phototherapy and Ca2+-Induced Mitochondrial Membrane Potential Damage to Co-Enhance Cancer Immunotherapy

Tumor recurrence and metastasis are the main causes of cancer mortality; traditional chemotherapeutic drugs have severe toxicity and side effects in cancer treatment. To overcome these issues, here, we present a pH-responsive, self-destructive intelligent nanoplatform for magnetic resonance/fluorescence dual-mode image-guided mitochondrial membrane potential damage (MMPD)/photodynamic (PDT)/photothermal (PTT)/immunotherapy for breast cancer treatment with external near infrared (NIR) light irradiation. To do so, we construct multifunctional monolayer-layered double hydroxide (LDH) nanosheets (MICaP), co-loading indocyanine green (ICG) with ultrahigh loading content realized via electrostatic interactions, and calcium phosphate (Ca3(PO4)2) coating via biomineralization. Such a combined therapy design is featured by the outstanding biocompatibility and provokes immunogenic cell death (ICD) of tumors toward cancer immunotherapy. The active transport of excess Ca2+ released from pH-sensitive Ca3(PO4)2 can induce MMPD of tumor cells to minimize oxygen consumption in the tumor microenvironment (TME). The presence of ICG not only generates singlet oxygen (1O2) to induce apoptosis by photodynamic therapy (PDT) but also initiates tumor cell necrosis by photothermal therapy (PTT) under near-infrared (NIR) light radiation. Eventually, the immune response generated by MMPD/PDT/PTT greatly promotes a cytotoxic T lymphocyte (CTL) response that can limit tumor growth and metastasis. Both in vitro and in vivo studies indeed illustrate outstanding antitumor efficiency and outcomes. We anticipate that such precisely designed nanoformulations can contribute in a useful and advantageous way that is conducive to explore novel nanomedicines with notable values in antitumor therapy.

Nanocomposites based on lanthanide-doped upconversion nanoparticles: diverse designs and applications

Lanthanide-doped upconversion nanoparticles (UCNPs) have aroused extraordinary interest due to the unique physical and chemical properties. Combining UCNPs with other functional materials to construct nanocomposites and achieve synergistic effect abound recently, and the resulting nanocomposites have shown great potentials in various fields based on the specific design and components. This review presents a summary of diverse designs and synthesis strategies of UCNPs-based nanocomposites, including self-assembly, in-situ growth and epitaxial growth, as well as the emerging applications in bioimaging, cancer treatments, anti-counterfeiting, and photocatalytic fields. We then discuss the challenges, opportunities, and development tendency for developing UCNPs-based nanocomposites.

Self-assembling porphyrin conjugate-carboplatin(IV) prodrug nanoparticles for enhancing high efficacy nasopharyngeal cancer and low systemic toxicity

Nanomedicine has developed as a potential technique for successful cancer therapy. A simple supramolecular self-assembly process is a helpful strategy for generating carrier-free nanodrugs. Mixing photodynamic treatment with chemotherapy has been sought to obtain a high therapeutic impact. In this study, we effectively construct a nanocarrier (CD-Por-PEG: Ada-CPT-Pt(IV)) combined with Carboplatin prodrug (Ada-CPT-Pt(IV)) and photosensitizer porphyrin (CD-Por-PEG) by host-guest interactions to accomplish stimuli-response combination treatment. Supported by greater spatial control of the binding ratio among host-guest molecules, Carboplatin and porphyrin were independently altered with β-cyclodextrin and adamantane to produce the amphiphilic host-guest combination for sequential self-assembly into therapeutic nanoparticles. The colloidal stability of the produced CD-Por-PEG: Ada-CPT-Pt(IV)-NPs was excellent, with an average hydrodynamic diameter of ∼170 nm. The microscopy images showed that CD-Por-PEG: Ada-CPT-Pt(IV) could aggregate cells and generate ROS after light irradiation (630 nm). Monotherapy had a cytotoxicity three times greater than the CD-Por-PEG: Ada-CPT-Pt(IV) nanoparticles. Studies in mice carrying SUNE1 nasopharyngeal tumours showed that nanoparticles effectively suppressed tumour development without causing systemic damage in this examination. The current self-assembly nanosystem makes precise control over the photosensitizer and drug loading possible ratio. It reduces the systemic adverse toxicity issues of drugs carrier, making this system ideal for nasopharyngeal cancer treatment.

Cascade-responsive nanobomb with domino effect for anti-tumor synergistic therapies

The development of reactive oxygen species (ROS) generation agents that can selectively produce sufficient ROS at the tumor site without external energy stimulation is of great significance for the further clinical application of ROS-based therapies. Herein, we designed a cascade-responsive ROS nanobomb (ZnO₂@Ce6/CaP@CPPO/BSA, designated as Z@Ce6/CaP@CB) with domino effect and without external stimulation for the specific generation of multiple powerful ROS storms at the tumor site. The calcium phosphate shell and ZnO₂ core gradually degrade and release Ca²⁺, Zn²⁺ and hydrogen peroxide (H₂O₂) under acid stimulation. On the one hand, Zn²⁺ can enhance the generation of endogenous superoxide anions (·O₂^–) and H₂O₂ through the inhibition of the mitochondrial electron transport chain. On the other hand, the generation of large amounts of exogenous H₂O₂ can cause oxidative damage to tumor cells and further activate bis[2,4,5-trichloro-6-(pentyloxycarbonyl)phenyl] oxalate (CPPO)-mediated chemiexcited photodynamic therapy. In addition, the oxidative stress caused by the generated ROS can lead to the uncontrolled accumulation of Ca²⁺ in cells and further result in Ca²⁺ overload-induced cell death. Therefore, the introduction of Z@Ce6/CaP@CB nanobombs triggered the ‘domino effect’ that caused multiple heavy ROS storms and Ca²⁺ overload in tumors and effectively activated anti-tumor immune response.

Dual-Responsive and ROS-Augmented Nanoplatform for Chemo/Photodynamic/Chemodynamic Combination Therapy of Triple Negative Breast Cancer

Integrating chemodynamic therapy (CDT) and photodynamic therapy (PDT) into one nanoplatform can produce much more reactive oxygen species (ROS) for tumor therapy. Nevertheless, it is still a great challenge to selectively generate sufficient ROS in tumor regions. Meanwhile, CDT and PDT are restricted by insufficient H2O2 content in the tumor as well as by the limited tumor tissue penetration of the light source. In this study, a smart pH/ROS-responsive nanoplatform, Fe2+@UCM-BBD, is rationally designed for tumor combination therapy. The acidic microenvironment can induce the pH-responsive release of doxorubicin (DOX), which can induce tumor apoptosis through DNA damage. Beyond that, DOX can promote the production of H2O2, providing sufficient materials for CDT. Of note, upconversion nanoparticles at the core can convert the 980 nm light to red and green light, which are used to activate Ce6 to produce singlet oxygen (1O2) and achieve upconversion luminescence imaging, respectively. Then, the ROS-responsive linker bis-(alkylthio)alkene is cleaved by 1O2, resulting in the release of Fenton reagent (Fe2+) to realize CDT. Taken together, Fe2+@UCM-BBD exhibits on-demand therapeutic reagent release capability, excellent biocompatibility, and remarkable tumor inhibition ability via synergistic chemo/photodynamic/chemodynamic combination therapy.

Tumor Acidity and Near-Infrared Light Responsive Drug Delivery MoS2-Based Nanoparticles for Chemo-Photothermal Therapy

The rational design of tumor microenvironment (TME)- multifunctional stimuli-responsive nanocomposites is appealing for effective cancer treatment. However, multidrug resistance remains the main obstacles to construct responsive oncotherapy. Herein, a novel MoS₂/PDA-TPP nanocomposite loaded with chemotherapy drug of doxorubicin (DOX) is designed for TME dual-response and synergistically enhanced anti-tumor therapy based on the tumor-specific mitochondria accumulation ability and photothermal (PTT) therapy. In detail, the designed MoS₂/PDA-TPP nanoplatform can act as a pH-responsive dissociation to endow fast release of DOX under an acidic TME and simultaneously improve the efficiency of PTT. Moreover, the mechanism shows that MoS₂/PDA-TPP trigger mitochondrial-dependent apoptosis by producing reactive oxygen species (ROS) and reducing mitochondrial membrane potential (MMP). Most importantly, during PTT procedure, hyperthermia up to 50°C can effectively induce tumor cell death without causing severe inflammation to adjacent tissues. Tumor targeting double stimulation response of nanocomposites is a novel idea to overcome drug resistance, which will provide a more effective strategy for solving practical problems.

CRISPR/Cas9 delivery by NIR-responsive biomimetic nanoparticles for targeted HBV therapy

Background

Currently, there are no curative drugs for hepatitis B virus (HBV). Complete elimination of HBV covalently closed circular DNA (cccDNA) is key to the complete cure of hepatitis B virus infection. The CRISPR/Cas9 system can directly destroy HBV cccDNA. However, a CRISPR/Cas9 delivery system with low immunogenicity and high efficiency has not yet been established. Moreover, effective implementation of precise remote spatiotemporal operations in CRISPR/Cas9 is a major limitation.

Results

In this work, we designed NIR-responsive biomimetic nanoparticles (UCNPs-Cas9@CM), which could effectively deliver Cas9 RNP to achieve effective genome editing for HBV therapy. HBsAg, HBeAg, HBV pgRNA and HBV DNA along with cccDNA in HBV-infected cells were found to be inhibited. These findings were confirmed in HBV-Tg mice, which did not exhibit significant cytotoxicity and minimal off-target DNA damage.

Conclusions

The UCNPs-based biomimetic nanoplatforms achieved the inhibition of HBV replication via CRISPR therapy and it is a potential system for efficient treatment of human HBV diseases.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01233-4.

Biocompatible Mesoporous Silica-Polydopamine Nanocomplexes as MR/Fluorescence Imaging Agent for Light-Activated Photothermal-Photodynamic Cancer Therapy In Vivo

Conventional cancer phototherapy with single modality suffers from low therapeutic efficacy and undesired posttreatment damage for adjacent normal tissues. Therefore, the lower NIR laser irradiation power is vital to the reduction or preclusion of risk of scalds and burns in normal tissues. Herein, we rationally proposed a novel multifunctional nanocomplex, which enabled good magnetic resonance (MR) imaging contrast effect and promising photothermal conversion efficacy. The prepared core/shell nanocomplexes [MSN-Ce6@PDA (Mn)] were composed of chlorin e6-embedded mesoporous silica/nanoparticle composites as the cores, and then polydopamine and manganese ions were conjugated on the cores to form protective shells. The MSN-Ce6@PDA (Mn) nanocomplexes revealed superior properties in colloidal stability, photothermal conversion, reaction oxygen species generation, magnetic resonance imaging, etc. Under the guidance of MR and fluorescence imaging, these MSN-Ce6@PDA (Mn) nanocomplexes were found to be primarily accumulated in the MDA-MB-231 tumor area. Furthermore, the combined photodynamic and photothermal therapy exhibited strong inhibition to the growth of MDA-MB-231 tumor in vitro and in vivo. Besides, the MSN-Ce6@PDA (Mn) nanocomplexes also exhibited excellent biocompatibility and low damage to the healthy animals. Hence, the results demonstrated that the prepared MSN-Ce6@PDA (Mn) nanocomplex would be a promising potential for multimodal imaging-guided phototherapy.

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.

A dual-functional biomimetic-mineralized nanoplatform for glucose detection and therapy with cancer cells in vitro

Glucose detection is a crucial topic in the diagnosis of numerous diseases, such as hypoglycemia or diabetes mellitus. Research indicates that people with diabetes mellitus are at a higher risk of developing various types of cancer. A nanoplatform that combines both diabetes diagnosis and cancer therapy might be regarded as a more effective way to solve the above-mentioned problem. However, none of the known sensors has a smart strategy that can work as a fluorescent glucose sensor and a cancer therapeutic platform simultaneously. Here, we developed a pH responsive biomimetic-mineralized nanoplatform (denoted as CaCO3-PDA@DOX-GOx) for glucose detection in serum samples and applied it to treat the tumor cells combined chemotherapy with the starvation therapy in vitro. Doxorubicin (DOX) and glucose oxidase (GOx) were loaded through the mesoporous CaCO3-PDA nanoparticles (m-CaCO3-PDA NPs). The fluorescence of DOX is quenched as a result of fluorescence resonance energy transfer (FRET) caused by the broad absorption of m-CaCO3-PDA NPs. The nanoplatform would recover fluorescence under lower pH values due to the catalytic reaction of GOx with glucose or tumor microenvironment (TME), which leads to the elimination of FRET. Its application as a glucose sensor is indicated with a linear relationship in the range of 0.01-1.0 mM of glucose and limit of detection is calculated by 6 μM. This nanoplatform also has a TME-responsive antitumor effect and fluorescence imaging functionality, which provide a new idea for cancer therapy together with glucose monitoring in diabetes.

Subcellular imaging and diagnosis of cancer using engineered nanoparticles

The advances in the synthesis of nanoparticles with engineered properties are reported to have profound applications in oncological disease detection via optical and multimodal imaging and therapy. Among various nanoparticle-assisted imaging techniques, engineered fluorescent nanoparticles show great promise from high contrast images and localized therapeutic applications. Of all the fluorescent nanoparticles available, the gold nanoparticles, carbon dots, and upconversion nanoparticles are emerging recently as the most promising candidates for diagnosis, treatment, and cancer monitoring. This review addresses the recent progress in engineering the properties of these emerging nanoparticles and their application for cancer diagnosis and therapy. In addition, the potential of these particles for subcellular imaging is also reviewed here.

Design of a bi-functional NaScF4: Yb3+/Er3+ nanoparticles for deep-tissue bioimaging and optical thermometry through Mn2+ doping

An approximately monochromatic red upconversion (UC) emission is successfully realized in NaScF₄: Yb³⁺/Er³⁺ nanoparticles (NPs) through Mn²⁺ ions doping without phase transition. The Mn²⁺ ions play a role of bridge during the energy transfer process from green emission state ²H_11/2/⁴S_3/2 of Er³⁺ to red emission state ⁴F_9/2 of Er³⁺, which significantly accelerates the red UC enhancement. The strongest red luminescence is observed in the sample containing 10% Mn²⁺ ions (Mn-10) with an enhancement factor of 7.5 times. Meanwhile, an ultrasensitive optical thermometry in the physiological temperature region can be realized by utilizing the fluorescence intensity ratio (FIR) between two thermally coupled Stark transitions of Er³⁺: ⁴I_13/2 → ⁴I_15/2, locating in the near-infrared (NIR) long wavelength region of the second biological window. Its relative sensitivity S_R can be expressed by 340/T², which is much higher than most optical thermometers based on thermally coupled Stark sublevels reported by the previous papers. Beyond that, an ex vivo experiment is designed to evaluate the penetration depth of the red and NIR emission of Mn-10 in the biological tissues, revealing that they can reach depth of at least 3 mm and 5 mm respectively. More importantly, the increasing tissue thickness has almost no effect on the FIR values. All the results show that the present sample is a promising bi-functional nano probe which can be used for bioimaging and temperature sensing in the deep tissues through the strong red UC emission and ultrasensitive NIR optical thermometer, respectively.

An all-in-one theranostic nanoplatform based on upconversion dendritic mesoporous silica nanocomposites for synergistic chemodynamic/photodynamic/gas therapy

Gasotransmitters with high therapeutic efficacy and biosafety have been drawing the attention of researchers. Nevertheless, how to effectively deliver gases to and precisely control their generation at the lesion as well as integrate them with other therapies to realize precision therapy have remained elusive. Herein, we report a versatile Cu²⁺-initiated nitric oxide (NO) nanocomposite for multimodal imaging-guided synergistic chemodynamic/photodynamic/gas therapy. After the nanomedicine was ingested by tumor cells, the acidic tumor microenvironment accelerated the decomposition of CuO₂ and simultaneously triggered the Fenton-like catalytic reaction of Cu²⁺ and H₂O₂ to produce highly toxic ˙OH. By virtue of the NO generation and glutathione depletion, UMNOCC-PEG can relieve the antioxidant capacity and hypoxia of the tumor to improve the efficiency of chemodynamic therapy (CDT) and photodynamic therapy (PDT). Importantly, NO and reactive oxygen species (ROS) can generate reactive nitrogen species (RNS), which can result in DNA damage, further improving the therapeutic effect (cell apoptosis rate up to 93.4%). Moreover, the inherent properties of lanthanide ions endow UMNOCC-PEG with upconversion luminescence (UCL), CT and MRI trimodal imaging capability, achieving precise cancer treatment. By taking advantage of these features, the strategy developed here may provide a promising application foreground to conquer malignant tumors.

Photodynamic Nanophotosensitizers: Promising Materials for Tumor Theranostics

Photodynamic theranostics/therapy (PDT) is a potential strategy for selectively imaging malignant sites and treating cancer via a non-invasive therapeutic method. Photosensitizers, the crucial components of PDT, enable colocalization of photons and light, and photon/light therapy in the therapeutic window of 400-900 nm exhibits photocytotoxicity to tumor cells. Due to their high biostability and photocytotoxicity, nanophotosensitizers (NPSs) are of much interest for malignant tumor theranostics at present. NPS-activated photons transfer energy through the absorption of a photon and convert molecular oxygen to the singlet reactive oxygen species, which leads to apoptosis and necrosis. Moreover, NPSs modified by polymers, including PLGA, PEG-PLA, PDLLA, PVCL-g-PLA, and P(VCL-co-VIM)-g-PLA, exhibit excellent biocompatibility, and a tumor-targeting molecule linked on the nanoparticle surface can precisely deliver NPSs into the tumor region. The development of NPSs will accelerate the progress in tumor theranostics through the photon/light pathway.

Biodegradable calcium phosphate nanoparticles for cancer therapy

Calcium phosphate is the inorganic mineral of hard tissues such as bone and teeth. Due to their similarities to the natural bone, calcium phosphates are highly biocompatible and biodegradable materials that have found numerous applications in dental and orthopedic implants and bone tissue engineering. In the form of nanoparticles, calcium phosphate nanoparticles (CaP's) can also be used as effective delivery vehicles to transfer therapeutic agents such as nucleic acids, drugs, proteins and enzymes into tumor cells. In addition, facile preparation and functionalization of CaP's, together with their inherent properties such as pH-dependent solubility provide advantages in delivery and release of these bioactive agents using CaP's as nanocarriers. In this review, the challenges and achievements in the intracellular delivery of these agents to tumor cells are discussed. Also, the most important issues in the design and potential applications of CaP-based biominerals are addressed with more focus on their biodegradability in tumor microenvironment.