Synthesis and surface modification of mesoporous silica nanoparticles and its application as carriers for sustained drug delivery

Nanotechnology-Based Drug Delivery Systems for Treating Acute Kidney Injury

Acute kidney injury (AKI) is a disease that is characterized by a rapid decline in renal function and has a relatively high incidence in hospitalized patients. Sepsis, renal hypoperfusion, and nephrotoxic drug exposure are the main causes of AKI. The major therapy measures currently include supportive treatment, symptomatic treatment, and kidney transplantation. These methods are supportive treatments, and their results are not satisfactory. Fortunately, many new treatments that markedly improve the AKI therapy efficiency are emerging. These include antioxidant therapy, ferroptosis therapy, anti-inflammatory therapy, autophagy therapy, and antiapoptotic therapy. In addition, the development of nanotechnology has further promoted therapeutic effects on AKI. In this review, we highlight recent advances in the development of nanocarriers for AKI drug delivery. Emphasis has been placed on the latest developments in nanocarrier modification and design. We also summarize the applications of different nanocarriers in AKI treatment. Finally, the advantages and challenges of nanocarrier applications in AKI are summarized, and several nanomedicines that have been approved for clinical trials to treat diverse kidney diseases are listed.

Candesartan Cilexetil Formulations in Mesoporous Silica: Preparation, Enhanced Dissolution In Vitro, and Oral Bioavailability In Vivo

Candesartan cilexetil (CC) is one of well-tolerated antihypertensive drugs, while its poor solubility and low bioavailability limit its use. Herein, two mesoporous silica (Syloid XDP 3150 and Syloid AL-1 FP) and the corresponding amino-modified products (N-XDP 3150 and N-AL-1 FP) have been selected as the carriers of Candesartan cilexetil to prepare solid dispersion through solvent immersion, and characterized through using powder X-ray diffraction analysis, infrared spectroscopy, differential scanning calorimetry, scanning electron microscopy, and solid-state nuclear magnetic resonance spectroscopy, etc. The state of CC changed from crystalline to amorphous after loading onto the silica carriers, in which no interactions between CC and silica existed. Then, the dissolution behaviors in vitro were studied through using flow-through cell dissolution method. CC-XDP 3150 sample exhibited the most extensive dissolution, and the cumulative release of CC from it was 1.88-fold larger than that of CC. Moreover, the pharmacokinetic results in rats revealed that the relative bioavailability of CC-XDP 3150 and CC-N-XDP 3150 solid dispersions were estimated to be 326 % % and 238 % % in comparison with CC, respectively. Clearly, pore size, pore volume, and surface properties of silica carrier have remarkable effect on loading, dissolution and bioavailability of CC. In brief, this work will provide valuable information in construction of mesoporous silica-based delivery system toward poorly water-soluble drugs.

Stimuli-Responsive Silica Silanol Conjugates: Strategic Nanoarchitectonics in Targeted Drug Delivery

The design of novel drug delivery systems is exceptionally critical in disease treatments. Among the existing drug delivery systems, mesoporous silica nanoparticles (MSNs) have shown profuse promise owing to their structural stability, tunable morphologies/sizes, and ability to load different payload chemistry. Significantly, the presence of surface silanol groups enables functionalization with relevant drugs, imaging, and targeting agents, promoting their utility and popularity among researchers. Stimuli-responsive silanol conjugates have been developed as a novel, more effective way to conjugate, deliver, and release therapeutic drugs on demand and precisely to the selected location. Therefore, it is urgent to summarize the current understanding and the surface silanols' role in making MSN a versatile drug delivery platform. This review provides an analytical understanding of the surface silanols, chemistry, identification methods, and their property-performance correlation. The chemistry involved in converting surface silanols to a stimuli-responsive silica delivery system by endogenous/exogenous stimuli, including pH, redox potential, temperature, and hypoxia, is discussed in depth. Different chemistries for converting surface silanols to stimuli-responsive bonds are discussed in the context of drug delivery. The critical discussion is culminated by outlining the challenges in identifying silanols' role and overcoming the limitations in synthesizing stimuli-responsive mesoporous silica-based drug delivery systems.

Dual-Functionalized Mesoporous Silica Nanoparticles for Celecoxib Delivery: Amine Grafting and Imidazolyl PEI Gatekeepers for Enhanced Loading and Controlled Release with Reduced Toxicity

The development of targeted drug delivery systems has been a pivotal area in nanomedicine, addressing challenges like low drug loading capacity, uncontrolled release, and systemic toxicity. This study aims to develop and evaluate dual-functionalized mesoporous silica nanoparticles (MSN) for targeted delivery of celecoxib, enhancing drug loading, achieving controlled release, and reducing systemic toxicity through amine grafting and imidazolyl polyethyleneimine (PEI) gatekeepers. MSN were synthesized using the sol-gel method and functionalized with (3-aminopropyl) triethoxysilane (APTES) to create amine-grafted MSN (MSN-NH2). Celecoxib was loaded into MSN-NH2, followed by conjugation of imidazole-functionalized PEI (IP) gatekeepers synthesized via carbodiimide coupling. Characterization was conducted using Fourier-transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H-NMR). Drug loading capacity, entrapment efficiency, and in vitro drug release at pH 5.5 and 7.4 were evaluated. Cytotoxicity was assessed using the MTT assay on RAW 264.7 macrophages. The synthesized IP was confirmed by FTIR and 1H-NMR. Amine-grafted MSN demonstrated a celecoxib loading capacity of 12.91 ± 2.02%, 2.1 times higher than non-functionalized MSN. In vitro release studies showed pH-responsive behavior with significantly higher celecoxib release from MSN-NH2-celecoxib-IP at pH 5.5 compared to pH 7.4, achieving a 33% increase in release rate within 2 h. Cytotoxicity tests indicated significantly higher cell viability for IP-treated cells compared to PEI-treated cells, confirming reduced toxicity. The dual-functionalization of MSN with amine grafting and imidazolyl PEI gatekeepers enhances celecoxib loading and provides controlled pH-responsive drug release while reducing systemic toxicity. These findings highlight the potential of this advanced drug delivery system for targeted anti-inflammatory and anticancer therapies.

Evaluation of the synergistic effects of curcumin-resveratrol co-loaded biogenic silica on colorectal cancer cells

Colorectal cancer (CRC) remains a significant global health concern, being the third most diagnosed cancer in men and the second most diagnosed cancer in women, with alarming mortality rates. Natural phytochemicals have gained prominence among various therapeutic avenues explored due to their diverse biological properties. Curcumin, extracted from turmeric, and resveratrol, a polyphenol found in several plants, have exhibited remarkable anticancer activities. However, their limited solubility and bioavailability hinder their therapeutic efficacy. To enhance the bioavailability of these compounds, nanomaterials work as effective carriers with biogenic silica (BS) attracting major attention owing to their exceptional biocompatibility and high specific surface area. In this study, we developed Curcumin-resveratrol-loaded BS (Cur-Res-BS) and investigated their effects on colorectal cancer cell lines (HCT-116 and Caco-2). Our results demonstrated significant concentration-dependent inhibition of cell viability in HCT-116 cells and revealed a complex interplay of crucial proto-onco or tumor suppressor genes, such as TP53, Bax, Wnt-1, and CTNNB1, which are commonly dysregulated in colorectal cancer. Notably, Cur-Res-BS exhibited a synergistic impact on key signaling pathways related to colorectal carcinogenesis. While these findings are promising, further investigations are essential to comprehensively understand the mechanisms and optimize the therapeutic strategy. Moreover, rigorous safety assessments and in vitro studies mimicking the in vivo environment are imperative before advancing to in vivo experiments, ensuring the potential of Cur-Res-BS as an efficient treatment for CRC.

Antibiofilm activity of mesoporous silica nanoparticles against the biofilm associated infections

In pharmaceutical industries, various chemical carriers are present which are used for drug delivery to the correct target sites. The most popular and upcoming drug delivery carriers are mesoporous silica nanoparticles (MSN). The main reason for its popularity is its ability to be specific and optimize the drug delivery process in a controlled manner. Nowadays, MSNs are widely used to eradicate various microbial infections, especially the ones related to biofilms. Biofilms are sessile groups of cells that live by forming a consortium and exhibit antibacterial resistance (AMR). They exhibit AMR by extracellular polymeric substances (EPS) and various quorum sensing (QS) signaling molecules. Usually, bacterial and fungal cells are capable of forming biofilms. These biofilms are pathogenic. In the majority of the cases, biofilms cause nosocomial diseases. This review will focus on the antibiofilm activities of MSN, its mechanism of target-specific drug delivery, and its ability to disrupt the bacterial biofilms inhibiting the infection. The review will also discuss various mechanisms for the delivery of pharmaceutical molecules by the MSNs to inhibit the bacterial biofilms, and lastly, we will talk about the different types of MSNs and their antibiofilm activities.

Cistanche deserticola polysaccharide-functionalized dendritic fibrous nano-silica as oral vaccine adjuvant delivery enhancing both the mucosal and systemic immunity

Oral vaccines are a safe and convenient alternative to injected vaccines and have great potential to prevent major infectious diseases. However, the harsh gastrointestinal (GI) environment, mucus barriers, low immunogenicity, and lack of effective and safe mucosal adjuvants are the major challenges for oral vaccine delivery. In recent years, nanoparticle-based strategies have become attractive for improving oral vaccine delivery. Here, the dendritic fibrous nano-silica (DFNS) grafted with Cistanche deserticola polysaccharide (CDP) nanoparticles (CDP-DFNS) were prepared and investigated how to impact the immune responses. CDP-DFNS facilitated the antigen uptake in mouse bone marrow-derived dendritic cells (BMDCs), and induce the activation of DCs in vitro. Furthermore, in vivo experiments, the result showed that the uptake efficiency by Peyer's patches (PPs) of CDP-DFNS/BSA was the best. And CDP-DFNS/BSA then significantly activated the DCs in lamina propria (LP), and T/B cells in PPs and mesenteric lymph nodes (MLNs). Moreover, the memory T cell responses in later period of vaccination was stronger than other groups. In addition, CDP-DFNS/BSA enhanced BSA-specific antibody IgG, IgA production, and SIgA secretion, was effective at inducing a strong mixed Th1/Th2 response and mucosal antibody responses. These results indicated that CDP-DFNS deserves further consideration as an oral vaccine adjuvant delivery system.

EGFR-targeted humanized single chain antibody fragment functionalized silica nanoparticles for precision therapy of cancer

The combination of highly specific targeting ability and potent killing effect has made antibody-drug conjugates (ADCs) a popular area of focus in the development of anti-cancer drugs. However, the large molecular weight of IgG antibodies (∼ 150 kDa) often faces challenges in penetrating capillaries and stroma in tumor tissue. Moreover, when the drug-antibody ratio (DAR) is too low (DAR < 2) or too high (DAR > 6) it decreases the effectiveness of the ADC and further increases the potential for aggregation, overall clearance of the early system payload, and release rate. In this study, an EGFR-based single-chain antibody fragment (husA)-human serum albumin (HSA)-coupled FITC-labeled mesoporous silica nanoparticle (FMSN-DOX-H-husA) was developed. Chinese hamster ovarian cells express the husA, which is a single chain antibody fragment of the EGFR that has been humanized. The small molecular weight of the single chain antibody allows for shorter penetration into solid tumors and the absence of adverse effects of the Fc fragment. The modification of HSA improves the safety of the antibody nanoparticle couples by both improving the biocompatibility of the nanoparticles, prolonging the circulation time of the nanoparticles, and avoiding early release of the payload. Also, the humanization substantially reduces the immunogenicity. More importantly, the ratio of drug antibodies on nanoparticles was experimentally and computationally derived to be 11.8, providing a more accurate guide for clinical trials. The results of both in vivo and in vitro experiments indicated promising antitumor activity and safety of FMSN-DOX-H-husA. Thus, this antibody-drug conjugate provided a hopeful option for cancer treatment.

Directing cellular responses in a nanocomposite 3D matrix for tissue regeneration with nanoparticle-mediated drug delivery

Hydrogels play an important role in tissue engineering due to their native extracellular matrix-like characteristics, but they are insufficient in providing the necessary stimuli to support tissue formation. Efforts to integrate bioactive cues directly into hydrogels are hindered by incompatibility with hydrophobic drugs, issues of burst/uncontrolled release, and rapid degradation of the bioactive molecules. Skeletal muscle tissue repair requires internal stimuli and communication between cells for regeneration, and nanocomposite systems offer to improve the therapeutic effects in tissue regeneration. Here, the versatility of mesoporous silica nanoparticles (MSN) was leveraged to formulate a nanoparticle-hydrogel composite and to combine the benefits of controlled delivery of bioactive cues and cellular support. The tunable surface characteristics of MSNs were exploited to optimize homogeneity and intracellular drug delivery in a 3D matrix. Nanocomposite hydrogels formulated with acetylated or succinylated MSNs achieved high homogeneity in 3D distribution, with succinylated MSNs being rapidly internalized and acetylated MSNs exhibiting slower cellular uptake. MSN-hydrogel nanocomposites simultaneously allowed efficient local intracellular delivery of a hydrophobic model drug. To further study the efficiency of directing cell response, a Notch signaling inhibitor (DAPT) was incorporated into succinylated MSNs and incorporated into the hydrogel. MSN-hydrogel nanocomposites effectively downregulated the Notch signaling target genes, and accelerated and maintained the expression of myogenic markers. The current findings demonstrate a proof-of-concept in effective surface engineering strategies for MSN-based nanocomposites, suited for hydrophobic drug delivery in tissue regeneration with guided cues.

Understanding Fenofibrate Release from Bare and Modified Mesoporous Silica Nanoparticles

To investigate the impact of the surface functionalization of mesoporous silica nanoparticle (MSN) carriers in the physical state, molecular mobility and the release of Fenofibrate (FNB) MSNs with ordered cylindrical pores were prepared. The surface of the MSNs was modified with either (3-aminopropyl) triethoxysilane (APTES) or trimethoxy(phenyl)silane (TMPS), and the density of the grafted functional groups was quantified via ¹H-NMR. The incorporation in the ~3 nm pores of the MSNs promoted FNB amorphization, as evidenced via FTIR, DSC and dielectric analysis, showing no tendency to undergo recrystallization in opposition to the neat drug. Moreover, the onset of the glass transition was slightly shifted to lower temperatures when the drug was loaded in unmodified MSNs, and MSNs modified with APTES composite, while it increased in the case of TMPS-modified MSNs. Dielectric studies have confirmed these changes and allowed researchers to disclose the broad glass transition in multiple relaxations associated with different FNB populations. Moreover, DRS showed relaxation processes in dehydrated composites associated with surface-anchored FNB molecules whose mobility showed a correlation with the observed drug release profiles.

Constructed Tumor-Targeted and MMP-2 Biocleavable Antibody Conjugated Silica Nanoparticles for Efficient Cancer Therapy

Antibody-drug conjugates (ADC) are an inevitable trend in the development of modern "precision medicine". The goal of this work is to produce enzyme-responsive antibody nanoparticle-loaded medication (FMSN-Dox-H2-AE01) based on the EGFR antibody (AE01) and human serum albumin (HSA) shelled mesoporous silica nanoparticles. HSA and antibodies on the surface of the particlescan not only enhance the biocompatibility of the particle and avoid early drug leakage but also allow selective biodegradation triggered by matrix metalloproteinase-2 (MMP-2), which are overexpressed enzymes in some tumor tissues. The cytotoxicity test confirmed favorable safety and efficacy of the ADC. The mortality rate of cancer cells is about 85-90%. Moreover, the antibody nanoparticle-loaded drug showed distinguishing controlled release efficiency toward cancer cells induced by different levels of MMP-2 and pH. This enzyme-responsive FMSN-Dox-H2-AE01 offers a promising option for cancer therapy.

The effect of filler loading and APTES treatment on the performance of PSf/SBA-15 mixed matrix membranes

The fabrication of mixed matrix membranes (MMMs) is of particular importance due to their advantages over neat membranes. The performance of MMMs is a function of the type and fraction of the nanoparticles in the membrane. Moreover, the proper interaction of the polymer and nanoparticles affects the MMMs performance. In this study polysulfone (PSf)/SBA-15 mesoporous silicas MMMs were prepared and their performance was evaluated for CO2/CH4 gas separation. SBA-15 mesoporous silicas were previously synthesized and functionalized with 3-aminopropyltriethoxysilane by post-synthesis treatment. Fourier transform infrared spectroscopy, field emission scanning electron microscopy, N2 adsorption–desorption, and Brunauer–Emmett–Teller analysis was applied to examine the functional groups, morphology, and textural properties of the unmodified and modified mesoporous silica in the prepared membrane, respectively. The effects of modified and unmodified SBA-15 particle loading were investigated for the gas separation performance of PSf/SBA-15 membranes. The experimental results illustrate that a higher modified mesoporous silica loading leads to an increase in gas permeance and gas pair selectivity. The highest increase in permeability and selectivity was related to the incorporation of S2 and AP-S2 into the PSf matrix, respectively.

Key Parameters for the Rational Design, Synthesis, and Functionalization of Biocompatible Mesoporous Silica Nanoparticles

Over the last few years, research on silica nanoparticles has rapidly increased. Particularly on mesoporous silica nanoparticles (MSNs), as nanocarriers for the treatment of various diseases because of their physicochemical properties and biocompatibility. The use of MSNs combined with therapeutic agents can provide better encapsulation and effective delivery. MSNs as nanocarriers might also be a promising tool to lower the therapeutic dosage levels and thereby to reduce undesired side effects. Researchers have explored several routes to conjugate both imaging and therapeutic agents onto MSNs, thus expanding their potential as theranostic platforms, in order to allow for the early diagnosis and treatment of diseases. This review introduces a general overview of recent advances in the field of silica nanoparticles. In particular, the review tackles the fundamental aspects of silicate materials, including a historical presentation to new silicates and then focusing on the key parameters that govern the tailored synthesis of functional MSNs. Finally, the biomedical applications of MSNs are briefly revised, along with their biocompatibility, biodistribution and degradation. This review aims to provide the reader with the tools for a rational design of biocompatible MSNs for their application in the biomedical field. Particular attention is paid to the role that the synthesis conditions have on the physicochemical properties of the resulting MSNs, which, in turn, will determine their pharmacological behavior. Several recent examples are highlighted to stress the potential that MSNs hold as drug delivery systems, for biomedical imaging, as vaccine adjuvants and as theragnostic agents.

Exploring the Effect of Glycerol and Hydrochloric Acid on Mesoporous Silica Synthesis: Application in Insulin Loading

Mesoporous silica (MPS), a carrier for active pharmaceutical ingredients, has a wide range of particle and pore morphology. A thorough understanding of ingredients used in MPS synthesis is an important prerequisite for optimizing its physicochemical characteristics. The present study aimed to evaluate the effect of glycerol and hydrochloric acid on the characteristics of synthesized MPS. Ordered MPS materials were synthesized using the pluronic P123 template and tetraethyl orthosilicate (TEOS) precursor. A three-level factorial design was employed to study the interaction between glycerol and hydrochloric acid. The optimized MPS particles were reasonably uniform in shape (short and rod-shaped) and < 1 μm in size with a smooth surface morphology. The nitrogen adsorption-desorption analysis revealed that the uniform cylindrical pores of the prepared MPS had a diameter > 5 nm and a total surface area > 500 m²/g. With increasing acid and glycerol concentrations, the particle size of MPS decreased. However, while the glycerol increased the heterogeneity of the synthesized particles, the acid decreased it. The developed MPS was successfully loaded with a biological drug (insulin) with a 21.94% encapsulation efficiency. The MPS prepared in this study exhibits potential applications as a drug delivery carrier for drugs with a large molecular weight.

Synthesis of a theranostic platform based on fibrous silica nanoparticles for the enhanced treatment of triple-negative breast cancer promoted by a combination of chemotherapeutic agents

A new series of theranostic silica materials based on fibrous silica particles acting as nanocarriers of two different cytotoxic agents, namely, chlorambucil and an organotin metallodrug have been prepared and structurally characterized. Besides the combined therapeutic activity, these platforms have been decorated with a targeting molecule (folic acid, to selectively target triple negative breast cancer) and a molecular imaging agent (Alexa Fluor 647, to enable their tracking both in vitro and in vivo). The in vitro behaviour of the multifunctional silica systems showed a synergistic activity of the two chemotherapeutic agents in the form of an enhanced cytotoxicity against MDA-MB-231 cells (triple negative breast cancer) as well as by a higher cell migration inhibition. Subsequently, the in vivo applicability of the siliceous nanotheranostics was successfully assessed by observing with in vivo optical imaging techniques a selective tumour accumulation (targeting ability), a marked inhibition of tumour growth paired to a marked antiangiogenic ability after 13 days of systemic administration, thus, confirming the enhanced theranostic activity. The systemic nanotoxicity was also evaluated by analyzing specific biochemical markers. The results showed a positive effect in form of reduced cytotoxicity when both chemotherapeutics are administered in combination thanks to the fibrous silica nanoparticles. Overall, our results confirm the promising applicability of these novel silica-based nanoplatforms as advanced drug-delivery systems for the synergistic theranosis of triple negative breast cancer.

Mesoporous Silica Materials Loaded with Gallic Acid with Antimicrobial Potential

This paper aimed to develop two types of support materials with a mesoporous structure of mobile crystalline matter (known in the literature as MCM, namely MCM-41 and MCM-48) and to load them with gallic acid. Soft templating methodology was chosen for the preparation of the mesoporous structures—the cylindrical micelles with certain structural characteristics being formed due to the hydrophilic and hydrophobic intermolecular forces which occur between the molecules of the surfactants (cetyltrimethylammonium bromide—CTAB) when a minimal micellar ionic concentration is reached. These mesoporous supports were loaded with gallic acid using three different types of MCM—gallic acid ratios (1:0.41; 1:0.82 and 1:1.21)—and their characterizations by FTIR, SEM, XRD, BET and drug release were performed. It is worth mentioning that the loading was carried out using a vacuum-assisted methodology: the mesoporous materials are firstly kept under vacuum at ~0.1 barr for 30 min followed by the addition of the polyphenol solutions. The concentration of the solutions was adapted such that the final volume covered the wet mesoporous support and—in this case—upon reaching normal atmospheric pressure, the solution was pushed inside the pores, and thus the polyphenols were mainly loaded inside the pores. Based on the S_BET data, it can be seen that the specific surface area decreased considerably with the increasing ratio of gallic acid; the specific surface area decreased 3.07 and 4.25 times for MCM-41 and MCM-48, respectively. The sample with the highest polyphenol content was further evaluated from a biological point of view, alone or in association with amoxicillin administration. As expected, the MCM-41 and MCM-48 were not protective against infections—but, due to the loading of the gallic acid, a potentiated inhibition was recorded for the tested gram-negative bacterial strains. Moreover, it is important to mention that these systems can be efficient solutions for the recovery of the gut microbiota after exposure to antibiotics, for instance.

Nanodelivery of nucleic acids

There is growing need for a safe, efficient, specific and non-pathogenic means for delivery of gene therapy materials. Nanomaterials for nucleic acid delivery offer an unprecedented opportunity to overcome these drawbacks; owing to their tunability with diverse physico-chemical properties, they can readily be functionalized with any type of biomolecules/moieties for selective targeting. Nucleic acid therapeutics such as antisense DNA, mRNA, small interfering RNA (siRNA) or microRNA (miRNA) have been widely explored to modulate DNA or RNA expression Strikingly, gene therapies combined with nanoscale delivery systems have broadened the therapeutic and biomedical applications of these molecules, such as bioanalysis, gene silencing, protein replacement and vaccines. Here, we overview how to design smart nucleic acid delivery methods, which provide functionality and efficacy in the layout of molecular diagnostics and therapeutic systems. It is crucial to outline some of the general design considerations of nucleic acid delivery nanoparticles, their extraordinary properties and the structure-function relationships of these nanomaterials with biological systems and diseased cells and tissues.

Amino Surface Modification and Fluorescent Labelling of Porous Hollow Organosilica Particles: Optimization and Characterization

Surface modification of silica nanoparticles with organic functional groups while maintaining colloidal stability remains a synthetic challenge. This work aimed to prepare highly dispersed porous hollow organosilica particles (pHOPs) with amino surface modification. The amino-surface modification of pHOPs was carried out with 3-aminopropyl(diethoxy)methylsilane (APDEMS) under various reaction parameters, and the optimal pHOP-NH₂ sample was selected and labelled with fluorescein isothiocyanate (FITC) to achieve fluorescent pHOPs (F-HOPs). The prepared pHOPs were thoroughly characterized by transmission electron microscopy, dynamic light scattering, FT-IR, UV-Vis and fluorescence spectroscopies, and microfluidic resistive pulse sensing. The optimal amino surface modification of pHOPs with APDEMS was at pH 10.2, at 60 °C temperature with 10 min reaction time. The positive Zeta potential of pHOP-NH₂ in an acidic environment and the appearance of vibrations characteristic to the surface amino groups on the FT-IR spectra prove the successful surface modification. A red-shift in the absorbance spectrum and the appearance of bands characteristic to secondary amines in the FTIR spectrum of F-HOP confirmed the covalent attachment of FITC to pHOP-NH₂. This study provides a step-by-step synthetic optimization and characterization of fluorescently labelled organosilica particles to enhance their optical properties and extend their applications.

A Review of the Application of Resorcinarenes and SBA-15 in Drug Delivery

Due to the diseases that people face today, scientists dedicate a part of their research to the synthesis, characterization, and study of functional compounds for controlled drug delivery. On the one hand, resorcinarenes are macrocycles obtained by condensation reactions of resorcinol and aldehyde. They include an upper and a lower rim functioning with different groups that confer solubility to the macrocycle and favor interactions with other compounds, therefore the hydroxyl groups on the upper rim improve the formation of hydrogen bonds. Additionally, resorcinarenes feature a cavity studied for forming host-guest complexes. SBA-15, on the other hand, is a mesoporous silica characterized by ordered pores in its structure and a large surface area. As a result of its properties, it has been used for several purposes, including absorbents, drug delivery, catalysis, and environmental processes. This review shows the recent advances in synthesis methods, characterization, micelle formation, interaction with other compounds, and host-guest procedures, as well as techniques for evaluating toxicity, drug retention, and their preliminary uses in pharmacology for macrocycles, such as resorcin[4]arenes and SBA-15.

Multifunctional Mesoporous Silica Nanoparticles for Oral Drug Delivery

Nanotechnology has transformed engineering designs across a wide spectrum of materials and applications. Mesoporous Silica Nanoparticles (MSNs) are one of the new fabrications of nanostructures as medication delivery systems. MSNs have pore sizes varying from 2 to 50 nm, making them ideal for a variety of biological applications. They offer unique characteristics such as a tunable surface area, well-defined surface properties, and the ability to improve drug pharmacokinetic characteristics. Moreover, they have the potential to reduce adverse effects by delivering a precise dose of medications to a specific spot rather than the more frequent systemic delivery, which diffuses across tissues and organs. In addition, the vast number of pores allow drug incorporation and transportation of drugs to various sites making MSNs a feasible platform for orally administered drugs. Though the oral route is the most suitable and convenient platform for drug delivery, conventional oral drug delivery systems are associated with several limitations. Surpassing gastrointestinal barriers and the low oral bioavailability of poorly soluble medicines pose a major challenge in the pharmaceutical industry. This review provides insights into the role of MSNs and its mechanism as an oral drug delivery system.

Assessment of recombinant glutathione-S-transferase (HaGST-8) silica nano-conjugates for effective removal of pesticides

Diverse glutathione-S-transferases (GSTs) are produced by insect pests including Helicoverpa armigera (HaGSTs) for detoxification of insecticides or xenobiotic compounds that they encounter. In an earlier study, the HaGST-8 gene was isolated from H. armigera larvae exposed to pesticide mixtures and the recombinant protein was expressed in the yeast Pichia pastoris. In this investigation, HaGST-8 was successfully immobilized on glutaraldehyde-activated APTES functionalized silica nanoparticles to obtain SiAPT-HaGST-8 nano-conjugates. Although enzyme activity associated with these conjugates was comparable to that of free HaGST-8, the specific activity of the former was found to be 1.25 times higher than the latter. In comparison with the free enzyme (that demonstrated a pH optimum of 9.0), for the nano-conjugates, the pH range was extended between pH 8.0 to 9.0. The optimum temperature for activity of both forms of the enzyme was found to be 30 °C. Stability of the enzyme was improved from 20 d for free HaGST-8 to 30 d for SiAPT-HaGST-8 nano-conjugates. Some loss in GST activity was detected after every reuse cycle of nano-conjugates and in all, 63% reduction was observed after three cycles. When 3 kinds of pesticides (namely, chlorpyrifos, dichlorvos and cypermethrin) were reacted with SiAPT-HaGST-8, more than 80% reduction in levels were observed. On the basis of the results obtained, the use of such silica nanoparticle-based systems for stable enzyme conjugation followed by effective removal of pesticides from aqueous media is envisaged.

The Impact of Hydration and Dehydration on the Mobility and Location of Ibuprofen Molecules in the Voids of Ultra-Stable Zeolite Y

Mesoporous dealuminated zeolites are used as hosts for ibuprofen. This drug experiences high mobility when confined in mesopores, which is largely dependent on the water content. Zeolites are materials that are naturally hydrated under ambient conditions. Nitrogen adsorption and X-ray diffraction (XRD) show that the samples with the content of ibuprofen up to 38% have the guest phase residing only in mesopores. ¹H and ¹³C MAS NMR studies of samples in ambient conditions, after dehydration, and in hydration prove the impact of water for increased mobility of ibuprofen. Increased mobility of the introduced phase was also detected for samples with no water content. It was ascribed to ibuprofen located outside mesopores, which experiences a prolonged time of cooling to room temperature. This phenomenon is important for all the future uses of the melting method in guest-host systems and the future use of zeolites for biomedical applications.

Mesoporous silica incorporated PCL/Curcumin nanofiber for wound healing application

Electrospinning, a recent fast-emerging technique highly applicable in the production of nanofibers has gained vast recognition owing to its explicit applications in various domains. Amongst which, the production of nanoscaffolds for wound healing applications has been focused recently due to advantages over conventional wound healing methods. In the present research, a composite nanoscaffold comprising SBA-15 (Santa Barbara Amorphous), amine functionalized SBA-15 polycaprolactone (PCL) and curcumin was investigated for its potentiality in wound healing therapeutics. The high biocompatibility and cell adhesion of amine functionalized SBA-15 and the widely explored antimicrobial properties of curcumin added benefit for the wound healing target. The prepared highly interconnected electrospun fibers with porous structure were characterized through various studies such as FTIR, XRD, SEM and EDAX. Further, antibacterial studies against both Gram positive (Bacillus subtilis) and Gram negative (Escherichia coli) strains revealed an improved zone of inhibition. Major invitro studies such as cell migration, proliferation, bio-compatibility was experimented through cell adhesion and live and dead assay using Swiss 3T6 cell lines. In vivo studies on female Wister rats using the fabricated nanofibers incorporated with curcumin and amine functionalized SBA-15 showed 99% scar-less wound healing within 21 days. Re-epithelization of tissue, collagen deposition and formation of granulation tissue were observed from the results of Hematoxylin-Eosin and Masson's tri-chrome staining. From the observations, it can be concluded that the fabricated nanoscaffold could be an effective substrate for wound healing therapeutics.

The role of water in the confinement of ibuprofen in SBA-15

The introduction of ibuprofen into mesopores of SBA-15 has been accomplished using the melting method. Samples exhibit from 9 to 33% of the hydrophobic drug. They are not toxic to mouse monocyte-macrophage cells and do not stimulate a pro-inflammatory response. The sample with 25% of the drug showed no crystalline ibuprofen and almost filled the mesopores, while the sample with 33% showed a total filling of the mesopores with some crystalline ibuprofen present. By means of 1D (¹H, ¹³C HPDEC, ¹³C CP MAS) and 2D (¹H-¹H NOESY) MAS NMR spectroscopy, it has been shown that water coexists with ibuprofen in mesopores and has an impact on the mobility of ibuprofen molecules and their location within the sample (outside or inside mesopores). Studies in the dehydrated state show for the first time that the high mobility of ibuprofen in mesopores is directly connected to the presence of water. Dehydrated samples show slightly slower release rates in comparison to their hydrated counterparts.

Effect of Surface Property on the Release and Oral Absorption of Solid Sirolimus-Containing Self-microemulsifying Drug Delivery System

The combination of self-microemulsifying drug delivery system (SMEDDS) and mesoporous silica materials favors the oral delivery of poorly water-soluble drugs (PWSD). However, the influence of the surface property of the mesopores towards the drug release and in vivo pharmacokinetics is still unknown. In this study, SBA-15 with hydroxyl groups (SBA-15-H), methyl groups (SBA-15-M), amino groups (SBA-15-A), or carboxyl groups (SBA-15-C) was combined with SMEDDS containing sirolimus (SRL). The diffusion and self-emulsifying of SMEDDS greatly improved the drug release over the raw SRL and SRL-SBA-15-R (R referred to as the functional groups). Results of drug absorption and X-ray photoelectron spectroscopy (XPS) showed strong hydrogen binding between SRL and the amino groups of SBA-15-A, which hindered the drug release and oral bioavailability of SRL-SMEDDS-SBA-15-A. The favorable release of SRL-SMEDDS-SBA-15-C (91.31 ± 0.57%) and SRL-SMEDDS-SBA-15-M (91.76 ± 3.72%) contributed to enhancing the maximum blood concentration (C_max) and the area under the concentration-time curve (AUC_0→48). In conclusion, the release of SRL-SMEDDS-SBA-15-R was determined by the surface affinity of the SBA-15-R and the interaction between the SRL molecules and the surface of SBA-15-R. This study suggested that the SMEDDS-SBA-15 was a favorable carrier for PWSD, and the surface property of the mesopores should be considered for the optimization of the SMEDDS-SBA-15.

How Molecular Mobility, Physical State, and Drug Distribution Influence the Naproxen Release Profile from Different Mesoporous Silica Matrices

Aiming to evaluate how the release profile of naproxen (nap) is influenced by its physical state, molecular mobility, and distribution in the host, this pharmaceutical drug was loaded in three different mesoporous silicas differing in their architecture and surface composition. Unmodified and partially silylated MCM-41 matrices, respectively MCM-41 and MCM-41_sil, and a biphenylene-bridged periodic mesoporous organic matrix, PMO_Bph, were synthetized and used as drug carriers, having comparable pore sizes (∼3 nm) and loading percentages (∼30% w/w). The loaded guest was investigated by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, powder X-ray diffraction (XRD), differential scanning calorimetry (DSC), and dielectric relaxation spectroscopy (DRS). DSC and XRD confirmed amorphization of a nap fraction incorporated inside the pores. A narrower glass transition was detected for PMO_Bph_nap, taken as an indication of the impact of host ordering, which also hinders the guest molecular mobility inside the pores as probed by DRS. While the PMO_Bph matrix is highly hydrophobic, the unmodified MCM-41 readily adsorbs water, accelerating the nap relaxation rate in the respective composite. In the dehydrated state, the faster dynamics was found for the silylated matrix since guest-host hydrogen bond interactions were inhibited to some extent by methylation. Nevertheless, in all the prepared composites, bulk-like crystalline drug deposits outside pores in a greater extent in PMO_Bph_nap. The DRS measurements analyzed in terms of conductivity show that, upon melting, nap easily migrates into pores in MCM-41-based composites, while it stays in the outer surface in the ordered PMO_Bph, determining a faster nap delivery from the latter matrix. On the other side, the mobility enhancement in the hydrated state controls the drug delivery in the unmodified MCM-41 matrix vs the silylated one. Therefore, DRS proved to be a suitable technique to disclose the influence of the ordering of the host surface and its chemical modification on the guest behavior, and, through conductivity depletion, it provides a mean to monitor the guest entrance inside the pores, easily followed even by untrained spectroscopists.

Synthesis and Characterization of Mesoporous Mg- and Sr-Doped Nanoparticles for Moxifloxacin Drug Delivery in Promising Tissue Engineering Applications

Mesoporous silica-based nanoparticles (MSNs) are considered promising drug carriers because of their ordered pore structure, which permits high drug loading and release capacity. The dissolution of Si and Ca from MSNs can trigger osteogenic differentiation of stem cells towards extracellular matrix calcification, while Mg and Sr constitute key elements of bone biology and metabolism. The aim of this study was the synthesis and characterization of sol-gel-derived MSNs co-doped with Ca, Mg and Sr. Their physico-chemical properties were investigated by X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDX), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence spectroscopy (XRF), Brunauer Emmett Teller and Brunauer Joyner Halenda (BET/BJH), dynamic light scattering (DLS) and ζ-potential measurements. Moxifloxacin loading and release profiles were assessed with high performance liquid chromatography (HPLC) cell viability on human periodontal ligament fibroblasts and their hemolytic activity in contact with human red blood cells (RBCs) at various concentrations were also investigated. Doped MSNs generally retained their textural characteristics, while different compositions affected particle size, hemolytic activity and moxifloxacin loading/release profiles. All co-doped MSNs revealed the formation of hydroxycarbonate apatite on their surface after immersion in simulated body fluid (SBF) and promoted mitochondrial activity and cell proliferation.

Armoring bio-catalysis via structural and functional coordination between nanostructured materials and lipases for tailored applications

Nanostructured materials represent an interesting and novel class of support matrices for the immobilization of different enzymes. Owing to the high surface area, robust mechanical stability, outstanding optical, thermal, and electrical properties, nanomaterials have been rightly perceived as desired immobilization matrices for lipases immobilization with a wide array of biotechnological applications such as dairy, food technology, fine chemical, pharmaceutical, detergent, and oleochemical industries. Lipases immobilized on nanomaterials have demonstrated superior attributes than free counterparts, such as aggrandized pH and thermal stability, robustness, long-term stability, and the possibility of reuse and recycling in several times. Here we review current and state-of-the-art literature on the use of nanomaterials as novel platforms for the immobilization of lipase enzymes. The physicochemical properties and exploitation of a large number of new nanostructured materials such as carbon nanotubes, nano-silica, graphene/graphene oxide, metal nanoparticles, magnetic nanostructures, metal-organic frameworks, and hybrid nanoflowers as a host matrix to constitute robust lipases-based nanobiocatalytic systems are discussed. Conclusive remarks, trends, and future recommendations for nanomaterial immobilized enzymes are also given.

Mesoporous silica nanoparticles loaded with capsaicin and their oxidation resistance in meat preservation

In this work, capsaicin (CAP) was loaded into mesoporous silica nanoparticles (MSNs) with grain diameters of 50 nm, 100 nm and 400 nm by free diffusion to obtain the support materials Cap@MSN-50, Cap@MSN-100 and Cap@MSN-400, respectively. The loading capacity was separately calculated as 854.77, 713.86 and 649.09 (mg/g Cap/MSN) by ultraviolet spectrophotometry. An IFFM-E flow injection chemiluminescent analyzer was used for the slow-release experiment, which demonstrated that the MSN release of CAP proceeded with a slow-release effect and MSNs with a smaller grain diameter had a higher rate of slow release and stronger oxidation resistance. The prepared materials were used to maintain the freshness of ground beef by modified atmosphere packaging. After more than 5 days of storage, Cap@MSN-50 retained better oxidation resistance than CAP. The results show that loading CAP into mesoporous nanomaterials has the potential application value for long-term preservation and oxidation prevention of some foods.

Cell-penetrating peptides in oncologic pharmacotherapy: A review

Cancer is the second leading cause of death in the world and its treatment is extremely challenging, mainly due to its complexity. Cell-Penetrating Peptides (CPPs) are peptides that can transport into the cell a wide variety of biologically active conjugates (or cargoes), and are, therefore, promising in the treatment and in the diagnosis of several types of cancer. Some notable examples are TAT and Penetratin, capable of penetrating the central nervous system (CNS) and, therefore, acting in cancers of this system, such as Glioblastoma Multiforme (GBM). These above-mentioned peptides, conjugated with traditional chemotherapeutic such as Doxorubicin (DOX) and Paclitaxel (PTX), have also been shown to induce apoptosis of breast and liver cancer cells, as well as in lung cancer cells, respectively. In other cancers, such as esophageal cancer, the attachment of Magainin 2 (MG2) to Bombesin (MG2B), another CPP, led to pronounced anticancer effects. Other examples are CopA3, that selectively decreased the viability of gastric cancer cells, and the CPP p28. Furthermore, in preclinical tests, the anti-tumor efficacy of this peptide was evaluated on human breast cancer, prostate cancer, ovarian cancer, and melanoma cells in vitro, leading to high expression of p53 and promoting cell cycle arrest. Despite the numerous in vitro and in vivo studies with promising results, and the increasing number of clinical trials using CPPs, few treatments reach the expected clinical efficacy. Usually, their clinical application is limited by its poor aqueous solubility, immunogenicity issues and dose-limiting toxicity. This review describes the most recent advances and innovations in the use of CPPs in several types of cancer, highlighting their crucial importance for various purposes, from therapeutic to diagnosis. Further clinical trials with these peptides are warranted to examine its effects on various types of cancer.

Core-shell nanostructures: perspectives towards drug delivery applications

Nanosystems have shown encouraging outcomes and substantial progress in the areas of drug delivery and biomedical applications. However, the controlled and targeted delivery of drugs or genes can be limited due to their physicochemical and functional properties. In this regard, core-shell type nanoparticles are promising nanocarrier systems for controlled and targeted drug delivery applications. These functional nanoparticles are emerging as a particular class of nanosystems because of their unique advantages, including high surface area, and easy surface modification and functionalization. Such unique advantages can facilitate the use of core-shell nanoparticles for the selective mingling of two or more different functional properties in a single nanosystem to achieve the desired physicochemical properties that are essential for effective targeted drug delivery. Several types of core-shell nanoparticles, such as metallic, magnetic, silica-based, upconversion, and carbon-based core-shell nanoparticles, have been designed and developed for drug delivery applications. Keeping the scope, demand, and challenges in view, the present review explores state-of-the-art developments and advances in core-shell nanoparticle systems, the desired structure-property relationships, newly generated properties, the effects of parameter control, surface modification, and functionalization, and, last but not least, their promising applications in the fields of drug delivery, biomedical applications, and tissue engineering. This review also supports significant future research for developing multi-core and shell-based functional nanosystems to investigate nano-therapies that are needed for advanced, precise, and personalized healthcare systems.

Fabrication and Performance Evaluation of Industrial Alumina Based Graded Ceramic Substrate for CO2 Selective Amino Silicate Membrane

The present study mainly focuses on the careful design of an amino-silicate membrane integrated on an asymmetric graded membrane substrate, comprised of a cost-effective macroporous industrial alumina based ceramic support with a systematic graded assemblage of sol-gel derived γ-alumina intermediate and silica-CTAB sublayer-based multilayered interface, specifically dedicated for the separation of CO₂ gas from the binary gas mixture (CO₂/N₂) under nearly identical flue gas atmospheric conditions. The tailor-made industrial α-alumina-based porous ceramic support has been characterized in terms of apparent porosity, bulk density, flexural strength, microstructural feature, pore size, and its distribution to demonstrate its application feasibility toward the evolution of the subsequent membrane structure. The near surface morphology of the subsequent intermediate and submembrane layer has been carefully controlled via precisely scheming the colloidal chemistry and consequently implementing it during the deposition process of the respective γ-alumina and silica-CTAB precursor sols, whereas the potentiality of the quarantined amine groups in the final amino-silicate membrane has been methodically optimized by the appropriate heat treatment process. Finally, the real-time applicability of the hybrid amino-silicate membrane has been evaluated in terms of systematic analysis of the binary gas (CO₂/N₂) separation performance under variable operating conditions. The investigated ceramic membrane exhibited optimum CO₂ permeance of 46.44 GPU with a CO₂/N₂ selectivity of 12.5 at 80 °C under a trans-membrane pressure drop of 0.8 bar having a feed and sweep side water flow rate of 0.03 mL/min, which shows its performance reliability at nearly identical flue gas operating conditions.

Silica Nanoparticles in Transmucosal Drug Delivery

Transmucosal drug delivery includes the administration of drugs via various mucous membranes, such as gastrointestinal, nasal, ocular, and vaginal mucosa. The use of nanoparticles in transmucosal drug delivery has several advantages, including the protection of drugs against the harsh environment of the mucosal lumens and surfaces, increased drug residence time, and enhanced drug absorption. Due to their relatively simple synthetic methods for preparation, safety profile, and possibilities of surface functionalisation, silica nanoparticles are highly promising for transmucosal drug delivery. This review provides a description of silica nanoparticles and outlines the preparation methods for various core and surface-functionalised silica nanoparticles. The relationship between the functionalities of silica nanoparticles and their interactions with various mucous membranes are critically analysed. Applications of silica nanoparticles in transmucosal drug delivery are also discussed.

Antisolvent precipitative immobilization of micro and nanostructured griseofulvin on laboratory cultured diatom frustules for enhanced aqueous dissolution

We report for the first time an antisolvent synthesis of nanostructured hydrophobic drug formulation onto a natural diatom. The jewel of the sea, a marine diatom, which is enriched in silicon, was cultured and grown in the laboratory. Its frustules were isolated and purified. The polar functional group on its surface provided unique physical and chemical properties. Griseofulvin (GF), an antifungal drug was used as a model compound was precipitated onto and adsorbed onto hydrophilic diatom surface, while stabilizer hydroxypropyl methyl cellulose (HPMC) was used for restricting particle growth during the composite synthesis. This work demonstrates that the fine drug crystals incorporated onto the diatom silica surface. The structural and morphological properties of the drug was characterized by various techniques. The drug loading of the formulation was estimated to be 41 % by weight. The incorporation of micro/nano crystals on the diatom surface dramatically enhanced the dissolution rate, and lowered the time required for 50 % dissolution for pure drug from 240-58 min for the drug composite, and the time required for 80 % dissolution or T₈₀ was found to be 180 min for the composite while the pure drug reached a maximum of 65 % in 300 min.

Understanding the mechanisms of silica nanoparticles for nanomedicine

As a consequence of recent progression in biomedicine and nanotechnology, nanomedicine has emerged rapidly as a new discipline with extensive application of nanomaterials in biology, medicine, and pharmacology. Among the various nanomaterials, silica nanoparticles (SNPs) are particularly promising in nanomedicine applications due to their large specific surface area, adjustable pore size, facile surface modification, and excellent biocompatibility. This paper reviews the synthesis of SNPs and their recent usage in drug delivery, biomedical imaging, photodynamic and photothermal therapy, and other applications. In addition, the possible adverse effects of SNPs in nanomedicine applications are reviewed from reported in vitro and in vivo studies. Finally, the potential opportunities and challenges for the future use of SNPs are discussed.

This article is categorized under:

Nanotechnology Approaches to Biology > Nanoscale Systems in Biology

Therapeutic Approaches and Drug Discovery > Emerging Technologies

Delivery of drugs, proteins, and nucleic acids using inorganic nanoparticles

Inorganic nanoparticles provide multipurpose platforms for a broad range of delivery applications. Intrinsic nanoscopic properties provide access to unique magnetic and optical properties. Equally importantly, the structural and functional diversity of gold, silica, iron oxide, and lanthanide-based nanocarriers provide unrivalled control of nanostructural properties for effective transport of therapeutic cargos, overcoming biobarriers on the cellular and organismal level. Taken together, inorganic nanoparticles provide a key addition to the arsenal of delivery vectors for fighting disease and improving human health.

Anti-inflammatory Cotton Fabrics and Silica Nanoparticles with Potential Topical Medical Applications

The preparation of functional cotton fabrics and silica nanoparticles by direct covalent linking of nonsteroidal anti-inflammatory drugs (salicylic acid, ibuprofen, and diclofenac) through an amide group is reported. Moreover, the coating of cotton fabrics with silica nanoparticles functionalized with such antiinflamatory agents is found to increase the roughness of the surface, providing hydrophobicity to the modified fabrics. This property is enhanced by the addition of fluorinated alkyl silane in the co-condensation process to form the coating solution. Characterization of the functionalized nanoparticles and cotton textiles is accomplished by microscopic and spectroscopic techniques. The treatment of functionalized nanoparticles and cotton fabrics with model proteases and leukocytes from animal origin results in the in situ release of the drug by the selective enzymatic cleavage of the amide bond. Topical cutaneous applications in wound dressings and cream formulations for the acceleration of wound healing are envisaged.

Evaluation of silica nanoparticle mediated delivery of protease inhibitor in tomato plants and its effect on insect pest Helicoverpa armigera

The inert and surface tunable nature of silica nanoparticles (SiNPs) makes them suitable for different applications. We have evaluated the potential of SiNPs for delivering proteins in tomato (Lycopersicon esculentum) plants. SiNPs of 20 and 100 nm (Si20 and Si100) were functionalized with (3-aminopropyl) triethoxysilane (APTES) to obtain Si20APT and Si100APT, respectively, that were non-toxic toward plants. The functionalized nanoparticles were taken up by plants through roots as well as leaf surfaces. They were seen to be localized near the vasculature, particularly around the xylem. Si20APT and Si100APT nanoparticles were conjugated with soybean trypsin inhibitor (STI) to yield Si20APT-STI and Si100APT-STI, respectively. Based on the trypsin inhibitory activity of loaded nanoparticles, optimum loading was obtained for 0.4 mg of STI per 0.8 mg of NPs. Si20APT nanoparticles retained higher contents of STI than Si100APT. Exposure of STI-conjugated nanoparticles to 25°C or pH 8.0 aided release of the inhibitor. The particle bound STI inhibited bovine trypsin by 80% and Helicoverpa armigera gut proteinase (HGP) activity by 50%. Second instar H. armigera larvae ingesting STI-loaded particles (incorporated in artificial diet or leaves) showed significant retardation in growth. In choice assays, Si20APT-STI applied leaf discs were strikingly avoided by insect larvae. On the basis of the results obtained in this investigation, we recommend the use of Si20 nanoparticles for developing plant delivery vehicles in the future.

Production and use of immobilized lipases in/on nanomaterials: A review from the waste to biodiesel production

As a highly efficient and environmentally friendly biocatalyst, immobilized lipase has received incredible interest among the biotechnology community for the production of biodiesel. Nanomaterials possess high enzyme loading, low mass transfer limitation, and good dispersibility, making them suitable biocatalytic supports for biodiesel production. In addition to traditional nanomaterials such as nano‑silicon, magnetic nanoparticles and nano metal particles, novel nanostructured forms such as nanoflowers, carbon nanotubes, nanofibers and metal-organic frameworks (MOFs) have also been studied for biodiesel production in the recent years. However, some problems still exist that need to be overcome in achieving large-scale biodiesel production using immobilized lipase on/in nanomaterials. This article mainly presents an overview of the current and state-of-the-art research on biodiesel production by immobilized lipases in/on nanomaterials. Various immobilization strategies of lipase on various advanced nanomaterial supports and its applications in biodiesel production are highlighted. Influential factors such as source of lipase, immobilization methods, feedstocks, and production process are also critically discussed. Finally, the current challenges and future directions in developing immobilized lipase-based biocatalytic systems for high-level production of biodiesel from waste resources are also recommended.

Synthesis of lactoferrin mesoporous silica nanoparticles for pemetrexed/ellagic acid synergistic breast cancer therapy

Despite the clinical approval of few nanomedicines for cancer therapy, some drawbacks still impede their improved efficiency including low drug loading, off-target toxicity and development of multi-drug resistance. Herein, lactoferrin (Lf)-coupled mesoporous silica nanoparticles (MSNPs) were developed for combined delivery of the cytotoxic drug pemetrexed (PMT) and the phytomedicine ellagic acid (EA) for synergistic breast cancer therapy. While the hydrophobic EA was physically encapsulated within the pores of MSNPs via the adsorptive properties of MSNPs and the electrostatic interactions between the negatively charged EA and positively charged amino modified MSNs, the highly water soluble PMT was chemically anchored to the Lf shell through chemical conjugation to the surface of lactoferrin coated MSNPs by carbodiimide reaction to avoid pre-mature drug release and systemic toxicity. The dual drug-loaded Lf-MSNPs (284 nm) demonstrated a sequential faster release of EA followed by a sustained release of PMT. The dual drug-loaded Lf-MSNPs exhibited highest cytotoxicity against MCF-7 (Michigan Cancer Foundation-7) breast cancer cells as revealed by the lowest combination index (CI = 0.885) compared to free drugs. The combination index value (< 1) revealed synergy between both loaded drugs. Furthermore, high cellular uptake of the nanocarriers into MCF-7 breast cancer cells was observed via Lf-receptor mediated endocytosis. Altogether, the dual drug-loaded Lf-targeted MSNPs showed to be a promising carrier for breast cancer therapy through triggering different signaling pathways, and hence overcoming the multi-drug resistance and minimizing the systemic toxicity.

Multifunctional Silica-Based Nanoparticles with Controlled Release of Organotin Metallodrug for Targeted Theranosis of Breast Cancer

Three different multifunctional nanosystems based on the tethering onto mesoporous silica nanoparticles (MSN) of different fragments such as an organotin-based cytotoxic compound Ph3Sn{SCH2CH2CH2Si(OMe)3} (MSN-AP-Sn), a folate fragment (MSN-AP-FA-Sn), and an enzyme-responsive peptide able to release the metallodrug only inside cancer cells (MSN-AP-FA-PEP-S-Sn), have been synthesized and fully characterized by applying physico-chemical techniques. After that, an in vitro deep determination of the therapeutic potential of the achieved multifunctional nanovectors was carried out. The results showed a high cytotoxic potential of the MSN-AP-FA-PEP-S-Sn material against triple negative breast cancer cell line (MDA-MB-231). Moreover, a dose-dependent metallodrug-related inhibitory effect on the migration mechanism of MDA-MB-231 tumor cells was shown. Subsequently, the organotin-functionalized nanosystems have been further modified with the NIR imaging agent Alexa Fluor 647 to give three different theranostic silica-based nanoplatforms, namely, MSN-AP-Sn-AX (AX-1), MSN-AP-FA-Sn-AX (AX-2), and MSN-AP-FA-PEP-S-Sn-AX (AX-3). Their in vivo potential as theranostic markers was further evaluated in a xenograft mouse model of human breast adenocarcinoma. Owing to the combination of the receptor-mediated site targeting and the specific fine-tuned release mechanism of the organotin metallodrug, the nanotheranostic drug MSN-AP-FA-PEP-S-Sn-AX (AX-3) has shown targeted diagnostic ability in combination with enhanced therapeutic activity by promoting the inhibition of tumor growth with reduced hepatic and renal toxicity upon the repeated administration of the multifunctional nanodrug.

Nickel(ii)dibenzotetramethyltetraaza[14]annulene complex immobilized on amino-functionalized TUD-1: an efficient catalyst for immediate and quantitative epoxidation of cyclohexene under ambient conditions

Nickel(ii)dibenzotetramethyltetraaza[14]annulene complex immobilized on amino-functionalized TUD-1 as a new nanocatalyst for spontaneous and quantitative epoxidation of cyclohexene under ambient conditions.