Effect of Polymer Phase Transition Behavior on Temperature-Responsive Polymer-Modified Liposomes for siRNA Transfection

Functional aligned mesenchymal stem cell sheets fabricated using micropatterned thermo-responsive cell culture surfaces

Mesenchymal stem cells (MSCs) are frequently applied for cell transplantation and regenerative therapy because they secrete diverse therapeutic cytokines that prompt immuno-stimulatory and tissue repair processes. Furthermore, cultured MSC sheets exhibit enhanced cytokine secretion compared to their MSC suspensions, and represent a durable, versatile format for tissue engineering as singular, multi-layered, or multi-cell type sandwiched, transplantable constructs. Tissue engineered implants with various cellular orientations have been reported. In this study, patterned, temperature-responsive culture surfaces were used to prepare oriented MSC sheets. Patterned culture surfaces were fabricated by grafting polyacrylamide (PAAm) onto commercial poly(N-isopropylacrylamide) (PNIPAAm)-modified plastic via photopolymerization using a stripe-patterned photomask. Patterned surfaces were characterized using x-ray photoelectron spectroscopy, fluorescently labelled fibronectin and albumin adsorption assays, wetting (contact angle) measurements, atomic force microscopy, and scanning electron microscopy. Striped grafted patterns of PAAm were fabricated on the PNIPAAm-coated culture substrates, and PAAm polymerized within the PNIPAAm overlayer. Cell-aligned MSC sheets were then produced from MSC culture on this patterned surface, secreting higher amounts of therapeutic cytokines (vascular endothelial growth factor, hepatocyte growth factor, and transforming growth factor-β) than non-aligned MSC control sheets. In addition, aligned MSC sheets maintained enhanced cell multi-potent differentiation capabilities. New, aligned MSC sheets might exhibit improved functional properties for cell sheet transplant therapies.

Effective cell sheet preparation using thermoresponsive polymer brushes with various graft densities and chain lengths

Various cell sheets have been used as effective and useful cellular tissues in tissue engineering and regenerative therapy. Poly(N-isopropylacrylamide) (PNIPAAm)-modified surfaces have been investigated for effective cell sheet preparation. In this study, the effective PNIPAAm graft density and chain length of PNIPAAm brushes for various cell types were investigated. The PNIPAAm brush-grafted glass was prepared via silanization and subsequent atom transfer radical polymerization (ATRP). The density of the PNIPAAm brushes was modulated by changing the ATRP initiator and co-adsorber composition, while the PNIPAAm brush length was modulated by changing the monomer concentration in the ATRP. The hydrophilicity of the PNIPAAm brushes increased with increasing PNIPAAm brush length because long PNIPAAm brushes tended to hydrate. Fibronectin adsorption increased with decreasing PNIPAAm brush concentration because the exposed hydrophobic co-adsorber in the dilute PNIPAAm brush enhanced the adsorption of fibronectin. The cell-sheet fabrication ability was investigated using six types of PNIPAAm brushes. An endothelial cell sheet was fabricated using a dense, short PNIPAAm brush. NIH/3T3 sheets can be fabricated using three types of PNIPAAm brushes: dense-long PNIPAAm brushes, moderately dense-short PNIPAAm brushes, and dilute-long PNIPAAm brushes. MDCK cell sheets could not be prepared using the PNIPAAm brushes. A549 cell sheets were prepared using a dense-short PNIPAAm brush and moderately dense-short PNIPAAm brushes. These results indicate that the optimal PNIPAAm brush conditions for cell sheet preparation vary depending on cell type. Thus, modulation of PNIPAAm brush density and length is an effective approach for preparing target cell sheets.

Emerging Phytochemical Formulations for Management of Rheumatoid Arthritis: A Review

Rheumatoid arthritis (RA) is a T-cell-mediated chronic inflammatory disorder affecting 0.5-1% of the global population. The disease with unknown etiology causes slow destruction of joints, advancing to significant deterioration of an individual's quality of life. The present treatment strategy comprises the use of disease-modifying anti-rheumatic drugs (DMARDs) coupled with or without nonsteroidal anti-inflammatory drugs or glucocorticoids. Additionally, involves co-therapy of injectable biological DMARDs in case of persistent or recurrent arthritis. The availability of biological DMARDs and the implementation of the treat-to-target approach have significantly improved the outcomes for patients suffering from RA. Nevertheless, RA requires continuous attention due to inadequate response of patients, development of tolerance and severe side effects associated with long-term use of available treatment regimens. An estimated 60-90% of patients use alternative methods of treatment, such as herbal therapies, for the management of RA symptoms. Over the past few decades, researchers have exploring natural phytochemicals to alleviate RA and associated symptoms. Enormous plant-origin phytochemicals such as alkaloids, flavonoids, steroids, terpenoids and polyphenols have shown anti-inflammatory and immunomodulatory activity against RA. However, phytochemicals have certain limitations, such as high molecular weight, poor water solubility, poor permeability, poor stability and extensive first-pass metabolism, limiting absorption and bioavailability. The use of nanotechnology has aided to extensively improve the pharmacokinetic profile and stability of encapsulated drugs. The current review provides detailed information on the therapeutic potential of phytochemicals. Furthermore, the review focuses on developed phytochemical formulations for RA, with emphasis on clinical trials, regulatory aspects, present challenges, and future prospects.

Temperature-modulated separation of vascular cells using thermoresponsive-anionic block copolymer-modified glass

Introduction

Vascular tissue engineering is a key technology in the field of regenerative medicine. In tissue engineering, the separation of vascular cells without cell modification is required, as cell modifications affect the intrinsic properties of the cells. In this study, we have developed an effective method for separating vascular cells without cell modification, using a thermoresponsive anionic block copolymer.

Methods

A thermoresponsive anionic block copolymer, poly(acrylic acid)-b-poly(N-isopropylacryl-amide) (PAAc-b-PNIPAAm), with various PNIPAAm segment lengths, was prepared in two steps: atom transfer radical polymerization and subsequent deprotection. Normal human umbilical vein endothelial cells (HUVECs), normal human dermal fibroblasts, and human aortic smooth muscle cells (SMCs) were seeded onto the prepared thermoresponsive anionic block copolymer brush-modified glass. The adhesion behavior of cells on the copolymer brush was observed at 37 °C and 20 °C.

Results

A thermoresponsive anionic block copolymer, poly(acrylic acid)-b-poly(N-isopropylacrylamide) (PAAc-b-PNIPAAm), with various PNIPAAm segment lengths was prepared. The prepared copolymer-modified glass exhibited anionic properties attributed to the bottom PAAc segment of the copolymer brush. On the PAAc-b-PNIPAAm, which had a moderate PNIPAAm length, a high adhesion ratio of HUVECs and low adhesion ratio of SMCs were observed at 37 °C. By reducing temperature from 37 °C to 20 °C, the adhered HUVECs were detached, whereas the SMCs maintained adhesion, leading to the recovery of purified HUVECs by changing the temperature.

Conclusions

The prepared thermoresponsive anionic copolymer-modified glass could be used to separate HUVECs and SMCs by changing the temperature without modifying the cell surface. Therefore, the developed cell separation method will be useful for vascular tissue engineering.

Application of Injectable Hydrogels as Delivery Systems in Osteoarthritis and Rheumatoid Arthritis

Osteoarthritis and rheumatoid arthritis, though etiologically distinct, are both inflammatory joint diseases that cause progressive joint injury, chronic pain, and loss of function. Therefore, long-term treatment with a focus on relieving symptoms is needed. At present, the primary treatment for arthritis is drug therapy, both oral and intravenous. Although significant progress has been achieved for these treatment methods in alleviating symptoms, certain prominent drawbacks such as the substantial side effects and limited absorption of medications call for an urgent need for improved drug delivery methods. Injected hydrogels can be used as a delivery system to deliver drugs to the joint cavity in a controlled manner and continuously release them, thereby enhancing drug retention in the joint cavity to improve therapeutic effectiveness, which is attributed to the desirable attributes of the delivery system such as low immunogenicity, good biodegradability and biocompatibility. This review summarizes the types of injectable hydrogels and analyzes their applications as delivery systems in arthritis treatment. We also explored how hydrogels counteract inflammation, bone and cartilage degradation, and oxidative stress, while promoting joint cartilage regeneration in the treatment of osteoarthritis (OA) and rheumatoid arthritis (RA). This review also highlights new approaches to developing injectable hydrogels as delivery systems for OA and RA.

Temperature-modulated interactions between thermoresponsive strong cationic copolymer-brush-grafted silica beads and biomolecules

Thermoresponsive polymer brushes have attracted considerable research attention owing to their unique properties. Herein, we developed silica beads grafted with poly(N-isopropylacrylamide (NIPAAm)-co-3-acrylamidopropyl trimethylammonium chloride (APTAC)-co-tert-butyl acrylamide (tBAAm) and P(NIPAAm-co-APTAC-co-n-butyl methacrylate(nBMA)) brushes. The carbon, hydrogen, and nitrogen elemental analysis of the copolymer-grated silica beads revealed the presence of a large amount of the grafted copolymer on the silica beads. The electrostatic and hydrophobic interactions between biomolecules and prepared copolymer brushes were analyzed by observing their elution behaviors via high-performance liquid chromatography using the copolymer-brush-modified beads as the stationary phase. Adenosine nucleotides were retained in the bead-packed columns, which was attributed to the electrostatic interaction between the copolymers and adenosine nucleotides. Insulin was adsorbed on the copolymer brushes at high temperatures, which was attributed to its electrostatic and hydrophobic interactions with the copolymer. Similar adsorption behavior was observed in case of albumin. Further, at a low concentration of the phosphate buffer solution, albumin was adsorbed onto the copolymer brushes even at relatively low temperatures owing to its enhanced electrostatic interaction with the copolymer. These results indicated that the developed thermoresponsive strong cationic copolymer brushes can interact with peptides and proteins through a combination of electrostatic and temperature-modulated hydrophobic interactions. Thus, the developed copolymer brushes exhibits substantial potential for application in chromatographic matrices for the analysis and purification of peptides and proteins.

Harvesting methods of umbilical cord-derived mesenchymal stem cells from culture modulate cell properties and functions

Introduction

Human umbilical cord-derived mesenchymal stem cells (UC-MSCs) are promising candidates for stem cell therapy. Various methods such as enzymatic treatment, cell scraping, and temperature reduction using temperature-responsive cell culture dishes have been employed to culture and harvest UC-MSCs. However, the effects of different harvesting methods on cell properties and functions in vitro remain unclear. In this study, we investigated the properties and functions of UC-MSC using various cell-harvesting methods.

Methods

UC-MSC suspensions were prepared using treatments with various enzymes, cell scraping, and temperature reduction in temperature-responsive cell culture dishes. UC-MSC sheets were prepared in a temperature-responsive cell culture dish. The properties and functions of the UC-MSC suspensions and sheets were assessed according to Annexin V staining, lactate dehydrogenase (LDH) assay, re-adhesion behavior, and cytokine secretion analysis via enzyme-linked immunosorbent assay.

Results

Annexin V staining revealed that accutase induced elevated UC-MSC apoptosis. Physical scraping using a cell scraper induced a relatively high LDH release due to damaged cell membranes. Dispase exhibited relatively low adhesion from initial incubation until 3 h. UC-MSC sheets exhibited rapid re-adhesion at 15 min and cell migration at 6 h. UC-MSC sheets expressed higher levels of cytokines such as HGF, TGF-β1, IL-10, and IL-6 than did UC-MSCs in suspension.

Conclusions

The choice of enzyme and physical scraping methods for harvesting UC-MSCs significantly influenced their activity and function. Thus, selecting appropriate cell-harvesting methods is important for successful stem cell therapy.

Engineering aspects of lipid-based delivery systems: In vivo gene delivery, safety criteria, and translation strategies

Defects in the genome cause genetic diseases and can be treated with gene therapy. Due to the limitations encountered in gene delivery, lipid-based supramolecular colloidal materials have emerged as promising gene carrier systems. In their non-functionalized form, lipid nanoparticles often demonstrate lower transgene expression efficiency, leading to suboptimal therapeutic outcomes, specifically through reduced percentages of cells expressing the transgene. Due to chemically active substituents, the engineering of delivery systems for genetic drugs with specific chemical ligands steps forward as an innovative strategy to tackle the drawbacks and enhance their therapeutic efficacy. Despite intense investigations into functionalization strategies, the clinical outcome of such therapies still needs to be improved. Here, we highlight and comprehensively review engineering aspects for functionalizing lipid-based delivery systems and their therapeutic efficacy for developing novel genetic cargoes to provide a full snapshot of the translation from the bench to the clinics. We outline existing challenges in the delivery and internalization processes and narrate recent advances in the functionalization of lipid-based delivery systems for nucleic acids to enhance their therapeutic efficacy and safety. Moreover, we address clinical trials using these vectors to expand their clinical use and principal safety concerns.

Bioanalytical technologies using temperature-responsive polymers

In recent decades, various bioanalytical technologies have been investigated for appropriate medical treatment and effective therapy. Temperature-responsive chromatography is a promising bioanalytical technology owing to its functional properties. Temperature-responsive chromatography uses a poly(N-isopropylacrylamide)(PNIPAAm) modified stationary phase as the column packing material. The hydrophobic interactions between PNIPAAm and the analyte could be modulated by changing the column temperature because of the temperature-responsive hydrophobicity of PNIPAAm. Thus, the chromatography system does not require organic solvents in the mobile phase, making it suitable for therapeutic drug monitoring in medical settings such as hospitals. This review summarizes recent developments in temperature-responsive chromatography systems for therapeutic drug monitoring applications. In addition, separation methods for antibody drugs using PNIPAAm are also summarized because these methods apply to the therapeutic drug monitoring of biopharmaceutics. The temperature-responsive chromatography systems can also be utilized for clinical diagnosis, as they can assess multiple medicines simultaneously. This highlights the significant potential of temperature-responsive chromatography in medicine and healthcare.

Recent Advances in Engineering Carriers for siRNA Delivery

RNA interference (RNAi) technology has been a promising treatment strategy for combating intractable diseases. However, the applications of RNAi in clinical are hampered by extracellular and intracellular barriers. To overcome these barriers, various siRNA delivery systems have been developed in the past two decades. The first approved RNAi therapeutic, Patisiran (ONPATTRO) using lipids as the carrier, for the treatment of amyloidosis is one of the most important milestones. This has greatly encouraged researchers to work on creating new functional siRNA carriers. In this review, the recent advances in siRNA carriers consisting of lipids, polymers, and polymer-modified inorganic particles for cancer therapy are summarized. Representative examples are presented to show the structural design of the carriers in order to overcome the delivery hurdles associated with RNAi therapies. Finally, the existing challenges and future perspective for developing RNAi as a clinical modality will be discussed and proposed. It is believed that the addressed contributions in this review will promote the development of siRNA delivery systems for future clinical applications.

bFGF-releasing biodegradable nanoparticles for effectively engrafting transplanted hepatocyte sheet

Hepatic tissue engineering has been applied for the treatment of intractable liver diseases, and hepatocyte sheets are promising for this purpose. However, hepatocyte sheets have poor survival after transplantation because of their high metabolic activity. In this study, we aimed to develop basic fibroblast growth factor (bFGF)-releasing nanoparticles to prolong the survival of hepatocyte sheets after transplantation. The nanoparticles were prepared by electrospraying a bFGF-dispersed poly(D,l-lactide-co-glycolide) emulsion. bFGF-loaded PLGA nanoparticles can be developed by optimizing the applied electrospray voltage and the oil:water ratio of the emulsion. The prepared nanoparticles exhibited prompt release at the initial duration and continuous gradual release at the subsequent duration. Hepatocyte sheet engraftment was evaluated by transplanting hepatocyte sheets containing the prepared nanoparticles into rats. The hepatocyte sheets with the prepared nanoparticles exhibited longer survival than those without the bFGF nanoparticles or solution owing to the local and continuous release of bFGF from the nanoparticles and the subsequent enhanced angiogenesis at the transplantation site. These results indicated that the prepared bFGF-releasing nanoparticles can enhance the efficiency of hepatocyte sheet transplantation. The developed bFGF-releasing nanoparticles would be useful for the transplantation of cellular tissue with post-transplantation survival challenges.

Stimuli-Responsive Nanotechnology for RNA Delivery

Ribonucleic acid (RNA) drugs have shown promising therapeutic effects for various diseases in clinical and preclinical studies, owing to their capability to regulate the expression of genes of interest or control protein synthesis. Different strategies, such as chemical modification, ligand conjugation, and nanotechnology, have contributed to the successful clinical translation of RNA medicine, including small interfering RNA (siRNA) for gene silencing and messenger RNA (mRNA) for vaccine development. Among these, nanotechnology can protect RNAs from enzymatic degradation, increase cellular uptake and cytosolic transportation, prolong systemic circulation, and improve tissue/cell targeting. Here, a focused overview of stimuli-responsive nanotechnologies for RNA delivery, which have shown unique benefits in promoting RNA bioactivity and cell/organ selectivity, is provided. Many tissue/cell-specific microenvironmental features, such as pH, enzyme, hypoxia, and redox, are utilized in designing internal stimuli-responsive RNA nanoparticles (NPs). In addition, external stimuli, such as light, magnetic field, and ultrasound, have also been used for controlling RNA release and transportation. This review summarizes a wide range of stimuli-responsive NP systems for RNA delivery, which may facilitate the development of next-generation RNA medicines.

Thermo-Responsive Polymer-siRNA Conjugates Enabling Artificial Control of Gene Silencing around Body Temperature

PURPOSE

Controlling small interfering RNA (siRNA) activity by external stimuli is useful to exert a selective therapeutic effect at the target site. This study aims to develop a technology to control siRNA activity in a thermo-responsive manner, which can be utilized even at temperatures close to body temperature.

METHODS

siRNA was conjugated with a thermo-responsive copolymer that was synthesized by copolymerization of N-isopropylacrylamide (NIPAAm) and hydrophilic N,N-dimethylacrylamide (DMAA) to permit thermally controlled interaction between siRNA and an intracellular gene silencing-related protein by utilizing the coil-to-globule phase transition of the copolymer. The composition of the copolymer was fine-tuned to obtain lower critical solution temperature (LCST) around body temperature, and the phase transition behavior was evaluated. The cellular uptake and gene silencing efficiency of the copolymer-siRNA conjugates were then investigated in cultured cells.

RESULTS

The siRNA conjugated with the copolymer with LCST of 38.0°C exhibited ~ 11.5 nm of the hydrodynamic diameter at 37°C and ~ 9.8 nm of the diameter at 41°C, indicating the coil-globule transition above the LCST. In line with this LCST behavior, its cellular uptake and gene silencing efficiency were enhanced when the temperature was increased from 37°C to 41°C.

CONCLUSION

By fine-tuning the LCST behavior of the copolymer that was conjugated with siRNA, siRNA activity could be controlled in a thermo-responsive manner around the body temperature. This technique may offer a promising approach to induce therapeutic effects of siRNA selectively in the target site even in the in vivo conditions.

Thermoresponsive bio-affinity interfaces for temperature-modulated selective capture and release of targeted exosomes

The existing methods for exosome isolation, such as ultracentrifugation, size exclusion, and affinity separation, suffer from some limitations. Herein, we aimed to develop temperature-modulated exosome-capturing materials using thermoresponsive polymers and peptides with affinity for exosomes. Poly(2-hydroxyethyl methacrylate-co-propargyl acrylate)-b-poly(N-isopropylacrylamide) (P(HEMA-co-PgA)-b-PNIPAAm) was grafted on silica beads via a two-step process of activator regenerated by electron transfer atom transfer radical polymerization. Peptides with affinity for exosomes were conjugated to the propargyl group of the bottom P(HEMA-co-PgA) segment of the copolymer via a click reaction. The prepared copolymer-grafted beads were characterized by elemental analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, gel permeation chromatography, and the turbidity of the polymer solution. Results indicated that the copolymer and peptide were successfully modified on the silica beads. Exosomes from SK-BR-3 ​cells, a human breast cancer cell line, were selectively captured on the prepared beads at 37 ​°C, as the upper PNIPAAm segment shrank and the affinity between the peptide and exosome was enhanced. Upon lowering the temperature to 4 ​°C, the captured exosomes were released from the copolymer brush because of the extension of the PNIPAAm segment that reduced the affinity between peptides and exosomes. These findings demonstrated that the prepared copolymer brush-grafted silica beads can capture and release targeted exosomes via temperature modulation. Taken together, the developed copolymer brush-grafted silica beads would be useful for the separation of exosomes using simple procedures such as temperature modulation.

Thermoresponsive block copolymer brush for temperature-modulated hepatocyte separation

Hepatic tissue engineering may be an effective approach for the treatment of liver disease; however, its practical application requires hepatic cell separation technologies that do not involve cell surface modification and maintain cell activity. In this study, we developed hepatocyte cell separation materials using a thermoresponsive polymer and a polymer with high affinity to hepatocytes. A block copolymer of poly(N-p-vinylbenzyl-O-β-D-galactopyranosyl-(1→4)-D-gluconamide) (PVLA) and poly(N-isopropylacrylamide) (PNIPAAm) [PVLA-b-PNIPAAm] was prepared through two steps of atom transfer radical polymerization. On the prepared PVLA-b-PNIPAAm brush, HepG2 cells (model hepatocytes) adhered at 37 °C and detached at 20 °C, attributed to the temperature-modulated affinity between PVLA and HepG2. Cells from the immortalized human hepatic stellate cell line (TWNT-1) did not adhere to the copolymer brush, and RAW264.7 cells (mouse macrophage; model Kupffer cells) adhered to the copolymer brush, regardless of temperature. Using the difference in cell adhesion properties on the copolymer brush, temperature-modulated cell separation was successfully demonstrated. A mixture of HepG2, RAW264.7, and TWNT-1 cells was seeded on the copolymer brush at 37 °C for adherence. By reducing the temperature to 20 °C, adhered HepG2 cells were selectively recovered with a purity of approximately 85% and normal activity. In addition, induced pluripotent stem (iPS) cell-derived hepatocytes adhered on the PVLA-b-PNIPAAm brush at 37 °C and detached from the copolymer brush at 20 °C, whereas the undifferentiated iPS cells did not adhere, indicating that the prepared PVLA-b-PNIPAAm brush could be utilized to separate hepatocyte differentiated and undifferentiated cells. These results indicated that the newly developed PVLA-b-PNIPAAm brush can separate hepatic cells from contaminant cells by temperature modulation, without affecting cell activity or modifying the cell surface. Thus, the copolymer brush is expected to be a useful separation tool for cell therapy and tissue engineering using hepatocytes.

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

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

Chromatography columns packed with thermoresponsive-cationic-polymer-modified beads for therapeutic drug monitoring

Therapeutic drug monitoring, which is used to determine appropriate drug doses, is critical in pharmacological therapy. In this study, we developed thermoresponsive chromatography columns with various cationic properties for effective therapeutic drug monitoring. Thermoresponsive cationic copolymer poly(N-isopropylacrylamide-co-n-butyl methacrylate-co-N,N-dimethylaminopropyl acrylamide) (P(NIPAAm-co-BMA-co-DMAPAAm))-modified silica beads, which were used as the chromatographic stationary phase, were prepared by modifying the radical initiator of the silica beads, followed by radical polymerization. Characterization of the prepared silica beads demonstrated that thermoresponsive polymers with various cationic properties successfully modified the beads. The elution behavior of several steroids in the prepared bead-packed columns at various temperatures indicated that the optimal column operating temperature was 30 °C. Appropriate measurement conditions for 13 drugs were investigated by varying the cationic properties of the columns and the pH of the mobile phase. Drug concentrations in serum samples were determined using the developed columns and mobile phases with a suitable pH. Voriconazole concentrations in human serum samples were determined using the developed columns with all-aqueous mobile phases. We anticipate that the developed chromatography columns can be used for therapeutic drug monitoring because drug concentrations can be measured using all-aqueous mobile phases that are suitable in clinical settings.

Temperature-responsive mixed-mode column for the modulation of multiple interactions

In this study, mixed-mode chromatography columns have been investigated using multiple analyte interactions. A mixed-mode chromatography column was developed using poly(N-isopropylacrylamide) (PNIPAAm) brush-modified silica beads and poly(3-acrylamidopropyl trimethylammonium chloride) (PAPTAC) brush-modified silica beads. PNIPAAm brush-modified silica beads and PAPTAC brush-modified silica beads were prepared by atom transfer radical polymerization. The beads were then packed into a stainless-steel column in arbitrary compositions. The elution studies evaluated the column performance on hydrophobic, electrostatic, and therapeutic drug samples using steroids, adenosine nucleotide, and antiepileptic drugs as analytes, respectively. Steroids exhibited an increased retention time when the column temperature was increased. The retention of adenosine nucleotides increased with the increasing composition of the PAPTAC-modified beads in the column. The antiepileptic drugs were separated using the prepared mixed-mode columns. An effective separation of antiepileptic drugs was observed on a 10:1 PNIPAAm:PAPTAC column because the balance between the hydrophobic and electrostatic interactions with antiepileptic drugs was optimized for the bead composition. Oligonucleotides were also separated using mixed-mode columns through multiple hydrophobic and electrostatic interactions. These results demonstrate that the developed mixed-mode column can modulate multiple hydrophobic and electrostatic interactions by changing the column temperature and composition of the packed PNIPAAm and PAPTAC beads.

Two-dimensional temperature-responsive chromatography using a poly(N-isopropylacrylamide) brush-modified stationary phase for effective therapeutic drug monitoring

Therapeutic drug monitoring (TDM) is an effective pharmacological approach for controlling drug concentration in a patient's serum. Herein, a new two-dimensional chromatography system was developed using two poly(N-isopropylacrylamide) (PNIPAAm)-modified bead-packed columns for effective and safe drug monitoring. PNIPAAm-modified silica beads were prepared as packing materials using atom transfer radical polymerization of NIPAAm. The increase in the retention times of the drugs requiring TDM with increasing temperature, was attributed to enhanced hydrophobic interactions at elevated temperatures. The drugs and serum proteins were separated on the prepared column at 40 °C using an all-aqueous mobile phase. Differences in the hydrophobic interactions accounted for the elution of the serum proteins and drugs at short and long retention times, respectively, and a primary column was employed to separate the serum proteins and drugs. After eluting the serum proteins from the column, the drug was introduced into the secondary column, leading to a peak of its purified form and enabling determination of the drug concentration. Two-dimensional temperature-responsive chromatography can benefit TDM by allowing the drug concentration in the serum to be measured in all-aqueous mobile phases without sample preparation.

Temperature responsive chromatography for therapeutic drug monitoring with an aqueous mobile phase

Therapeutic drug monitoring is a key technology for effective pharmacological treatment. In the present study, a temperature-responsive chromatography column was developed for safe and simple therapeutic drug monitoring without the use of organic solvents. Poly(N-isopropylacrylamide) (PNIPAAm) hydrogel-modified silica beads were prepared via a condensation reaction and radical polymerization. The temperature-dependent elution behavior of the drugs was observed using a PNIPAAm-modified silica-bead packed column and an all-aqueous mobile phase. Sharp peaks with reproducible retention times were observed at temperatures of 30 °C or 40 °C because the PNIPAAm hydrogel on the silica beads shrinks at these temperatures, limiting drug diffusion into the PNIPAAm hydrogel layer. The elution behavior of the sample from the prepared column was examined using a mixture of serum and model drugs. The serum and drugs were separated on the column at 30 °C or 40 °C, and the concentration of the eluted drug was obtained using the calibration curve. The results show that the prepared chromatography column would be useful for therapeutic drug monitoring because the drug concentration in serum can be measured without using organic solvents in the mobile phase and without any need for sample preparation.

Thermally-modulated cell separation columns using a thermoresponsive block copolymer brush as a packing material for the purification of mesenchymal stem cells

Cell therapy using mesenchymal stem cells (MSCs) is used as effective regenerative treatment. Cell therapy requires effective cell separation without cell modification and cellular activity reduction. In this study, we developed a temperature-modulated mesenchymal stem cell separation column. A temperature-responsive cationic block copolymer, poly(N,N-dimethylaminopropylacrylamide)-b-poly(N-isopropylacrylamide)(PDMAPAAm-b-PNIPAAm) brush with various cationic copolymer compositions, was grafted onto silica beads via two-step atom transfer radical polymerization. Using the packed beads, the elution behavior of the MSCs was observed. At 37 °C, the MSCs were adsorbed onto the column via both hydrophobic and electrostatic interactions with the PNIPAAm and PDMAPAAm segments of the copolymer brush, respectively. By reducing the temperature to 4 °C, the adsorbed MSCs were eluted from the column by reducing the hydrophobic and electrostatic interactions attributed to the hydration and extension of the PNIPAAm segment of the block copolymer brush. From the temperature-modulated adsorption and elution behavior of MSCs, a suitable DMAPAAm composition of the block copolymer brush was determined. Using the column, a mixture of MSC and BM-CD34⁺ cells was separated by simply changing the column temperature. The column was used to purify the MSCs, with purities of 78.2%, via a temperature change from 37 °C to 4 °C. Additionally, the cellular activity of the MSCs was retained throughout the column separation step. Overall, the obtained results show that the developed column is useful for MSC separation without cell modification and cellular activity reduction.

Temperature-responsive spin column for sample preparation using an all-aqueous eluent

We present a temperature-responsive spin column using an all-aqueous eluent. The method is intended as a simple sample preparation method for protein removal from serum, which is required for serum drug analysis. As packing materials for the spin column, we prepared two types of silica beads via surface-initiated radical polymerization. The large beads (diameter, 40-63 μm) were grafted with a temperature-responsive cationic copolymer, poly(N-isopropylacrylamide-co-N,N-dimethylaminopropyl acrylamide-co-n-butyl methacrylate) (P(NIPAAm-co-DMAPAAm-co-BMA)), and the small beads (diameter, 5 μm) were grafted with a temperature-responsive hydrophobic copolymer, P(NIPAAm-co-BMA). The beads were packed into the spin column as a double layer: P(NIPAAm-co-BMA) silica beads on the bottom and P(NIPAAm-co-DMAPAAm-co-BMA) silica beads on the top. The sample purification efficacy of the prepared spin column was evaluated on a model sample analyte (the antifungal drug voriconazole mixed with blood serum proteins). At 40 °C, the serum proteins and voriconazole were adsorbed on the prepared spin column via hydrophobic and electrostatic interactions. When the temperature was decreased to 4 °C, the adsorbed voriconazole was eluted from the column with the pure water eluent, while the serum proteins remained in the column. This temperature-responsive spin column realizes sample preparation simply by changing the temperature.

Thermoresponsive interfaces obtained using poly(N-isopropylacrylamide)-based copolymer for bioseparation and tissue engineering applications

Poly(N-isopropylacrylamide) (PNIPAAm) is the most well-known and widely used stimuli-responsive polymer in the biomedical field owing to its ability to undergo temperature-dependent hydration and dehydration with temperature variations, causing hydrophilic and hydrophobic alterations. This temperature-dependent property of PNIPAAm provides functionality to interfaces containing PNIPAAm. Notably, the hydrophilic and hydrophobic alterations caused by the change in the temperature-responsive property of PNIPAAm-modified interfaces induce temperature-modulated interactions with biomolecules, proteins, and cells. This intrinsic property of PNIPAAm can be effectively used in various biomedical applications, particularly in bioseparation and tissue engineering applications, owing to the functionality of PNIPAAm-modified interfaces based on the temperature modulation of the interaction between PNIPAAm-modified interfaces and biomolecules and cells. This review focuses on PNIPAAm-modified interfaces in terms of preparation method, properties, and their applications. Advances in PNIPAAm-modified interfaces for existing and developing applications are also summarized.

Innovative lipoplexes formulations with enhanced siRNA efficacy for cancer treatment: Where are we now?

Over the past two decades, RNA interference has become an extensively studied mechanism to silence gene and treat diseases including cancer. siRNA appears as a promising strategy that could avoid some side effects related to traditional chemotherapy. Considering the weak stability of naked siRNA in blood, vectors like cationic liposomes or Lipid Nanoparticles (LNPs) are widely used to carry and protect siRNA until it reaches the tumor targeted. Despite extensive research, only three RNAi drugs are currently approved by the Food and Drug Administration, including only one LNP formulation of siRNA to treat hereditary ATTR amyloidosis. This shows the difficulty of lipoplexes clinical translation, in particular in cancer therapy. To overcome the lipoplexes limitations, searches are made on innovative lipoplexes formulations with enhanced siRNA efficacy. The present review is focusing on the recent use of pH-sensitive lipids, peptides and cell-penetrating peptides or polymers. The incorporation of some of these components in the lipoplex formulation induces a fusogenic property or an enhanced endosomal escape, an enhanced cellular uptake, an enhanced tumor targeting, an improved stability in the blood stream …These innovations appear critical to obtain an efficient siRNA accumulation in tumor cells with effective antitumor effect considering the complex tumor environment.

A multiple environment-sensitive prodrug nanomicelle strategy based on chitosan graftomer for enhanced tumor therapy of gambogic acid

A novel multiple environment-sensitive polymeric prodrug of gambogic acid (GA) based on chitosan graftomer was fabricated for cancer treatment. Folic acid-chitosan conjugates was complexed with thermosensitive amine terminated poly-N-isopropylacrylamide (NH₂-PNIPAM) to develop FA-CSPN. Gambogic acid was conjugated with the graftomer via esterification to achieve high drug-loading capacity and controlled drug release. The resulting amphiphilic prodrug, O-(gambogic acid)-N-(folic acid)-N'-(NH₂-PNIPAM) chitosan graftomer (GFCP), could self-assemble into micelles. As expected, the micelles were stable and biocompatible, featuring pH-, esterase- and temperature-dependent manner of drug release. Moreover, the anticancer effect studies of GFCP micelles were performed using a tumor-bearing mouse model and cellular assays (tumor cell uptake assay, cytotoxicity and tumor-sphere penetration). Collectively, GFCP micelles show both potential in vivo and in vitro in improving the anticancer effectiveness of GA owing to high loading capacity, targeted tumor accumulation, and multiple tumor microenvironmental responsiveness.

Effect of pore diameter on the elution behavior of analytes from thermoresponsive polymer grafted beads packed columns

Temperature-responsive chromatography using thermoresponsive polymers is innovative and can control analyte retention via column temperature. Analyte elution behavior in this type of chromatography depends on the modified thermoresponsive polymer and the structure of the base materials. In the present study, we examine the effect of the pore diameter of silica beads on analyte elution behavior in temperature-responsive chromatography. Poly(N-isopropylacrylamide-co-n-butyl methacrylate) hydrogel was applied to beads of various pore sizes: 7, 12, and 30 nm. Almost the same amount of copolymer hydrogel was applied to all beads, indicating that the efficiency of copolymer modification was independent of pore size. Analyte retention on prepared beads in a packed column was observed using steroids, benzodiazepines, and barbiturates as analytes. Analyte retention times increased with temperature on packed columns of 12- and 30-nm beads, whereas the column packed with 7-nm beads exhibited decreased retention times with increasing temperature. The difference in analyte elution behavior among the various pore sizes was attributed to analyte diffusion into the bead pores. These results demonstrate that bead pore diameter determines temperature-dependent elution behavior.

Effective Separation for New Therapeutic Modalities Utilizing Temperature-responsive Chromatography

In recent years, drug discovery and therapeutics trends have shifted from a focus on small-molecule compounds to biopharmaceuticals, genes, cell therapy, and regenerative medicine. Therefore, new approaches and technologies must be developed to respond to these changes in medical care. To achieve this, we applied a temperature-responsive separation system to purify a variety of proteins and cells. We developed a temperature-responsive chromatography technique based on a poly(N-isopropylacrylamide) (PNIPAAm)-grafted stationary phase. This method may be applied to various types of protein and cell separation applications by optimizing the properties of the modified polymers used in this system. Therefore, the developed temperature-responsive HPLC columns and temperature-responsive solid-phase extraction (TR-SPE) columns can be an effective separation tool for new therapeutic modalities such as monoclonal antibodies, nucleic acid drugs, and cells.

Polymer-Lipid Pharmaceutical Nanocarriers: Innovations by New Formulations and Production Technologies

Some issues in pharmaceutical therapies such as instability, poor membrane permeability, and bioavailability of drugs can be solved by the design of suitable delivery systems based on the combination of two pillar classes of ingredients: polymers and lipids. At the same time, modern technologies are required to overcome production limitations (low productivity, high energy consumption, expensive setup, long process times) to pass at the industrial level. In this paper, a summary of applications of polymeric and lipid materials combined as nanostructures (hybrid nanocarriers) is reported. Then, recent techniques adopted in the production of hybrid nanoparticles are discussed, highlighting limitations still present that hold back the industrial implementation.

Engineered nanomedicines for tumor vasculature blockade therapy

Tumor vasculature blockade therapy (TVBT), including angiogenesis inhibition, vascular disruption, and vascular infarction, provides a promising treatment modality for solid tumors. However, low selectivity, drug resistance, and possible severe side effects have limited the clinical transformation of TVBT. Engineered nanoparticles offer potential solutions, including prolonged circulation time, targeted transportation, and controlled release of TVBT agents. Moreover, engineered nanomedicines provide a promising combination platform of TVBT with chemotherapy, radiotherapy, photodynamic therapy, photothermal therapy, ultrasound therapy, and gene therapy. In this article, we offer a comprehensive summary of the current progress of engineered nanomedicines for TVBT and also discuss current deficiencies and future directions for TVBT development. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Selective capture and non-invasive release of cells using a thermoresponsive polymer brush with affinity peptides

Thermoresponsive block copolymer brush with cell affinity peptides was prepared via two steps of ATRP and subsequent click reaction. The prepared polymer brush can purify cells with high selectivity by simply changing temperature.

Thermal Behaviour of Common Thermoresponsive Polymers in Phosphate Buffer and in Its Salt Solutions

Thermoresponsive polymers are a promising material for drug nanocarrier preparation, which makes the study of their aggregation in physiological conditions very important. In this paper, the thermal behaviour of the thermoresponsive polymers poly(N-isopropylacrylamide), poly(2-isopropyl-2-oxazoline-co-2-n-propyl-2-oxazoline) and poly[(2-hydroxyethyl methacrylate)-co-oligo(ethylene glycol) methyl ether methacrylate] were studied in phosphate buffer (PBS) and solutions of its salts in concentration as in PBS. The thermal response of the polymers was measured using UV-Vis and dynamic light scattering (DLS). The salts shifted the cloud point temperature (TCP) of the (co)polymers to higher values compared to the TCP of aqueous polymer solutions. In PBS and NaCl solutions, all polymers exhibited an unexpected and previously unreported transmittance profile. During heating, an additional aggregation of polymers appeared above the TCP accompanied by the formation of a precipitate. In monosodium phosphate solutions and pure water, the studied polymers showed lower critical solution temperature (LCST-type) behaviour. DLS measurements showed that a salt influenced the size of the resulting polymer particles. The sizes and stability of particles depended on the heating rate. In PBS and NaCl solutions, the size of particles in the dispersion decreased above 60 °C, and the precipitate appeared on the bottom of the cuvette. The additional aggregation of polymer and its falling out of solution may hinder the removal of carriers from the body and has to be taken into account when preparing nanocarriers.

Significant advancements of 4D printing in the field of orthopaedics

Researchers, engineers and doctors are continuously focusing on the development of orthopaedics parts characterised by the required responses. So, advanced manufacturing technologies are introduced to fulfil various previously faced challenges. 4D printing provides rapid development with its capability of customization of smart orthopaedics implants and appropriate surgical procedure. This technology opens up the making of innovative, adaptable internal splints, stents, replacement of tissues and organs. Thus, to write this review based article, relevant papers on 4D printing in medical/orthopaedics and smart materials are identified and studied. 4D printed parts show the capability of shape-changing and self-assembly to perform the required functions, which otherwise manufactured parts are not providing. Smart orthopaedics implants are used for spinal deformities, fracture fixation, joint, knee replacement and other related orthopaedics applications. This paper briefs about the 4D printing technology with its major benefits for orthopaedics applications. Today various smart materials are available, which could be used as raw material in 4D printing, and we have discussed capabilities of some of them. Due to the ability of shape-changing, smart implants can change their shape after being implanted in the patient body. Finally, twelve significant advancements of 4D printing in the field of orthopaedics are identified and briefly provided. Thus, 4D printing help to provide a significant effect on personalised treatments.

Recent Advancements of Nanomedicine towards Antiangiogenic Therapy in Cancer

Angiogenesis is a process of generation of de-novo blood vessels from already existing vasculature. It has a crucial role in different physiological process including wound healing, embryonic development, and tumor growth. The methods by which therapeutic drugs inhibit tumor angiogenesis are termed as anti-angiogenesis cancer therapy. Developments of angiogenic inhibiting drugs have various limitations causing a barrier for successful treatment of cancer, where angiogenesis plays an important role. In this context, investigators developed novel strategies using nanotechnological approaches that have demonstrated inherent antiangiogenic properties or used for the delivery of antiangiogenic agents in a targeted manner. In this present article, we decisively highlight the recent developments of various nanoparticles (NPs) including liposomes, lipid NPs, protein NPs, polymer NPs, inorganic NPs, viral and bio-inspired NPs for potential application in antiangiogenic cancer therapy. Additionally, the clinical perspectives, challenges of nanomedicine, and future perspectives are briefly analyzed.

Enhanced mechanical properties and cell separation with thermal control of PIPAAm-brushed polymer-blend microfibers

Thermoresponsive microfibers with enhanced mechanical properties for temperature-modulated cell separation were developed by electrospinning of blending PVBC and PBMA, and by subsequently modifying the microfibers with PIPAAm via ATRP.