Impact of Intermittent Intraoperative Neuromonitoring (IONM) on the Learning Curve for Total Thyroidectomy by Residents in General Surgery.

INTRODUCTION: Recurrent laryngeal nerve (RNL) identification constitutes the standard in thyroidectomy. Intraoperative nerve monitoring (IONM) has been introduced as a complementary tool for RLN functionality evaluation. The aim of this study is to establish how routine use of IONM can affect the learning curve (LC) in thyroidectomy. METHODS: Patients undergoing total thyroidectomy performed by surgery residents in their learning curve course in 2 academic hospitals, were divided into 2 groups: Group A, including 150 thyroidectomies performed without IONM by 3 different residents, and Group B, including 150 procedures with routine use of intermittent IONM, by other 3 different residents. LC was measured by comparing operative time (OT), its stabilization during the development of the LC, perioperative complication rate. RESULTS: As previously demonstrated, the LC was achieved after 30 procedures, in both groups, with no differences due to the use of IONM. Similarly, there were no significant differences among the 2 groups, and between subgroups independently matched, for both OT and complications, even when comparing RLN palsy. Direct nerve visualization and IONM assessment rates were comparable in all groups, and no bilateral RLN palsy (transient or permanent) were reported. No case of interrupted procedure to unilateral lobectomy, due to evidence of RLN injury, was reported. CONCLUSIONS: The study demonstrates that the use of IONM thyroid surgery, despite requiring a specific training with experienced surgeons, does not particularly affect the learning curve of residents approaching this kind of surgery, and for this reason its routine use should be encouraged even for trainees.

Comparison of Synthetic Pathways for Obtaining Fluorescent Nanomaterials Based on Halloysite and Carbon Dots for Potential Biological Sensing.

Recently, fluorescent sensors have gained considerable attention due to their high sensitivity, low cost and noninvasiveness. Among the different materials that can be used for this purpose, carbon dots (CDs) represent valuable candidates for applications in sensing. These, indeed, are easily synthesized, show high quantum yield and are highly biocompatible. However, it was pointed out that the photoluminescence properties of these nanomaterials are strictly dependent on the synthetic and purification methods adopted. The presence of halloysite nanotubes (HNTs), a natural, low cost and biocompatible clay mineral, has been found to be efficient in obtaining small and highly monodispersed CDs without long and tedious purification techniques. Herein, we report the comparison of synthetic pathways for obtaining halloysite-N-doped CDs (HNTs-NCDs) that could be used in biological sensing. One was based on the synthesis of N-doped CDs by a bottom-up approach on HNTs' surface by a MW pyrolysis process; the other one was based on the post-modification of pristine N-doped CDs with halloysite derivatives. The evaluation of the best synthetic route was performed by different physico-chemical techniques. It was found that the bottom-up approach led to the formation of N-doped CDs with different functional groups onto the HNTs' surface. This evidence was also translated in the different fluorescence quantum yields and the existence of several functional groups in the obtained materials was investigated by potentiometric titrations. Furthermore, the ability of the synthesized nanomaterials as sensors for Fe3+ ions detection was assessed by spectroscopic measurements, and the cellular uptake was verified by confocal/fluorescence microscopies as well.

Hybrid Green Materials Obtained by PCL Melt Blending with Diatomaceous Earth.

In this work, diatomaceous earth (Diat) was explored as filler for polycaprolactone (PCL) to obtain composite green materials with promising viscoelastic and thermal properties. The composites were prepared by blending variable Diat amounts (5, 15 and 50 wt%) with a molten PCL matrix. The viscoelastic characteristics of PCL/Diat hybrids were studied by Dynamic Mechanical Analysis (DMA) under an oscillatory regime, while the thermal properties were determined by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). We detected that the presence of Diat enhances the energy storage capacity of PCL for temperatures lower than the polymer melting point. Both DMA and DSC data revealed that the PCL melting temperature is slightly affected by the Diat addition, while the TGA results showed that the thermal stability of the polymer can be significantly improved by mixing PCL with diatomaceous earth. Moreover, we observed that the dispersion of Diat into the matrix favors the crystallization process of PCL. Interestingly, the improvements of PCL properties (elasticity, thermal stability, and crystallinity) are proportional to the Diat concentration of the composites. These findings reflect the interfacial compatibility between PCL and diatomaceous earth. In conclusion, this study highlights that the preparation of PCL/Diat hybrids by melt blending is suitable for the development of composite materials for technological applications, including the remediation of air pollutants within museum environments.

Application of enhanced recovery after surgery (ERAS) protocols in adrenal surgery: A retrospective, preliminary analysis.

BACKGROUND: The present study was conducted to evaluate the impact of enhanced recovery after surgery (ERAS) pathway in patients undergoing laparoscopic adrenalectomy (LA) for primary and secondary adrenal disease, in reducing the length of primary hospital stay and return to daily activities. MATERIALS AND METHODS: This retrospective study was carried out on 61 patients who underwent LA. A total of 32 patients formed the ERAS group. A total of 29 patients received conventional perioperative care and were assigned as the control group. Groups were compared in terms of patient's characteristics (sex, age, pre-operative diagnosis, side of tumour, tumour size and co-morbidities), post-operative compliance (anaesthesia time, operative time, post-operative stay, post-operative numeric rating scale (NRS) score, analgesic assumption and days to return to daily activities) and post-operative complications. RESULTS: No significant differences in anaesthesia time ( P = 0.4) and operative time ( P = 0.6) were reported. NRS score 24 h postoperatively was significantly lower in the ERAS group ( P < 0.05). The analgesic assumption in post-operative period in the ERAS group was lower ( P < 0.05). ERAS protocol led to a significantly shorter length of post-operative stay ( P < 0.05) and to return to daily activities ( P < 0.05). No differences in peri-operative complications were reported. DISCUSSION: ERAS protocols seem safe and feasible, potentially improving perioperative outcomes of patients undergoing LA, mainly improving pain control, hospital stay and return to daily activities. Further studies are needed to investigate overall compliance with ERAS protocols and their impact on clinical outcomes.

Penile Mondor's disease after open hernia repair surgery: A case report.

Background: Penile Mondor's disease (PMD) is a rare syndrome characterized by sclerosis after superficial thrombophlebitis of the superficial penile veins. The most usual appearance of PMD is a tender, palpable, painful, and sometimes visible cord on the dorsal surface of the penis. Its pathogenesis is still unclear, and a standardized treatment has not been established. Case report: A 54-year-old male patient presented with a left-sided indirect reducible inguinal hernia. The patient underwent Lichtenstein's procedure for inguinal hernia repair. On the tenth postoperative day, he returned with PMD confirmed by Doppler ultrasonography examination. Treatment with 4000 UI low molecular weight heparin (LMWH) daily for three weeks resolved the symptoms, but mild venous ectasia just to the proximal part of the penis remained. Discussion: The exact cause of PMD is not well understood, but various studies have identified certain factors associated with an increased risk of the condition. Out of various potential factors that could trigger PMD, the repair of an inguinal hernia has been reported only once. Treatment may involve pain management, anti-inflammatory medications, anticoagulants, and, in some cases, surgery. Conclusion: PMD after open hernia repair surgery is a very rare benign condition. Correct diagnosis and prompt treatment allowed symptom resolution. Residual venous ectasia has no clinical significance other than a cosmetic appearance.

Penile Mondor's disease after open hernia repair surgery: A case report.

Background: Penile Mondor's disease (PMD) is a rare syndrome characterized by sclerosis after superficial thrombophlebitis of the superficial penile veins. The most usual appearance of PMD is a tender, palpable, painful, and sometimes visible cord on the dorsal surface of the penis. Its pathogenesis is still unclear, and a standardized treatment has not been established. Case report: A 54-year-old male patient presented with a left-sided indirect reducible inguinal hernia. The patient underwent Lichtenstein's procedure for inguinal hernia repair. On the tenth postoperative day, he returned with PMD confirmed by Doppler ultrasonography examination. Treatment with 4000 UI low molecular weight heparin (LMWH) daily for three weeks resolved the symptoms, but mild venous ectasia just to the proximal part of the penis remained. Discussion: The exact cause of PMD is not well understood, but various studies have identified certain factors associated with an increased risk of the condition. Out of various potential factors that could trigger PMD, the repair of an inguinal hernia has been reported only once. Treatment may involve pain management, anti-inflammatory medications, anticoagulants, and, in some cases, surgery. Conclusion: PMD after open hernia repair surgery is a very rare benign condition. Correct diagnosis and prompt treatment allowed symptom resolution. Residual venous ectasia has no clinical significance other than a cosmetic appearance.

Assessment of sST2 Behaviors to Evaluate Severity/Clinical Impact of Acute Pulmonary Embolism.

Pulmonary embolism (PE) is a potentially life-threatening disorder. Beyond its usefulness in the prognostic stratification of heart failure, sST2 can represent a biomarker with high utility in several acute conditions. Our study was aimed to investigate whether sST2 can be used as a clinical marker of severity and prognostic outcome in acute PE. We enrolled 72 patients with documented PE and 38 healthy subjects; we measured the plasma concentrations of sST2 to evaluate the prognostic and severity performance of different levels of sST2 according to its association with the pulmonary embolism severity index (PESI) score and several parameters of respiratory function. PE patients had significantly higher levels of sST2 compared with healthy subjects (87.74 ± 17.1 vs. 17.1 ± 0.4 ng/mL, p < 0.001); we found higher PESI scores and serum lactate values in the group of patients with sST2 > 35 ng/mL compared with patients with sST2 < 35 ng/mL (138.7 ± 14.9 vs. 103.7 ± 15.1 and 2.43 ± 0.69 vs. 1.025 ± 0.05 mmol/L, respectively; p < 0.05). Patients with sST2 > 35 ng/mL showed higher radiological severity of PE compared with patients with sST2 < 35 ng/mL. Moreover, sST2 was the strongest parameter with a discriminative capacity for the development of acute respiratory failure and a PESI score >106 with respect to C reactive protein (CRP), creatinine, d-dimer, and serum lactate. We clearly demonstrated that sST2 significantly increased in PE and that its elevation was associated with disease severity. Therefore, sST2 may be used as a clinical marker in the evaluation of PE severity. However, further studies with larger patient populations are required to confirm these findings.

New Biocide Based on Tributyltin(IV) Ferulate-Loaded Halloysite Nanotubes for Preserving Historical Paper Artworks.

Combining biologically active compounds with nanocarriers is an emerging and promising strategy for enhancing the activities of molecules while reducing their levels of toxicity. Green nanomaterials have recently gained momentum in developing protocols for treating and preserving artifacts. In this study, we designed a functional biohybrid material by incorporating tributyltin(IV) ferulate (TBT-F) into halloysite nanotubes (HNTs), generating a new formulation called HNT/TBT-F. The primary objective was to develop a formulation with robust antimicrobial properties and reinforcing features for treating paper with artistic and historical value. To characterize HNT/TBT-F, assess the HNT's loading capacity, and investigate the TBT-F release kinetics from the nanotubes, various analytical techniques, including UV-Vis and infrared spectroscopies, thermogravimetry, and microscopy analysis, were employed. Furthermore, we evaluated the antimicrobial potential of TBT-F and HNT/TBT-F against Kocuria rhizophila, a bacterial strain known for its opportunistic behavior and a cause of artifact biodeterioration. HNT/TBT-F exhibited a significantly stronger bactericidal effect than TBT-F alone against K. rhizophila cells growing planktonically or those forming a biofilm. This enhanced performance could relate to the confinement of TBT-F within the nanotubes, which likely improved its physical-chemical stability and increased the local concentration of TBT-F upon contact with the bacterial cells. Additionally, we evaluated the mechanical properties of a paper treated with HNT/TBT-F, assessing any potential alterations in its color. The findings of this study highlight the favorable attributes of the HNT/TBT-F formulation and its potential for developing protocols aimed at consolidating and preserving culturally significant paper objects.

Laparoscopic transversus abdominis plane block is useful in pain relief after laparoscopic stapled repair of diastasis recti and ventral hernia.

Background: There is still no consensus on perioperative pain control techniques in patients undergoing laparoscopic surgery; protocols of conventional therapy can be improved by the use of perioperative anaesthesiologic techniques, such as epidural or loco-regional analgesic administration as transversus abdominis plane (TAP) block. The aim of this evaluation was to investigate the role of laparoscopic-assisted TAP block during repair of diastasis recti associated with primary midline hernias in term of post-operative pain relief. Methods: This was a retrospective evaluation of a prospectively maintained database including patients undergoing laparoscopic repair of diastasis recti associated with primary ventral hernia. Patients were divided into two groups: Group A patients (n = 34) received laparoscopic-assisted bilateral TAP-block of 7.5 mg/ml ropivacaine for each side and Group B patients (n = 29) received conventional post-operative therapy. All patients received 24 h infusion of 20 mg morphine; pain was checked at 6, 24 and 48 h after surgery by numeric rating scale (NRS) score. A rescue analgesia by was given if NRS score was >4 or on patient request. Results: No differences in operative time, complications and post-operative stay, no complications related to TAP-block technique were found. Post-operative pain scores (determined by NRS) were found to be significantly different between groups. Group A patients showed a significant reduction in NRS score at 6, 24 and 48 h (P < 0.005) and in the number of patients requiring further analgesic drugs administration (P < 0.005) compared to Group B patients. Conclusions: Laparoscopic-guided TAP-block can be considered safe and effective in the management of post-operative pain and in the reduction of analgesic need in patients undergoing laparoscopic repair of diastasis recti and ventral hernias. The non-randomised nature of the study and the lack of a consistent series of patients require further evaluations.

Multicenter retrospective cohort Italian study on elective laparoscopic cholecystectomy performed by the surgical residents.

PURPOSE: This retrospective multicenter cohort study aimed to evaluate the clinical outcomes (mortality rate, operative time, complications) of elective laparoscopic cholecystectomy (LC) when performed by a surgical resident in comparison to experienced consultant in the backdrop of Italian academic centers. METHODS: Retrospective review of all patients undergoing elective LC between January 2016 and January 2022 at six teaching hospitals across Italy was performed. Cases were identified using the Current Procedural Terminology (CPT) code 5123 (LC without cholangiogram). All cases of emergency surgery, ASA score > 3, or when cholecystectomy was performed with another surgical procedure, were excluded. All suitable cases were divided into 2 groups based on primary surgeon: consultant or senior resident. Main outcome was complication rates (intraoperative and peri/postoperative); secondary outcomes included operative time, the length of stay, and the rate of conversion to open. RESULTS: A total of 2331 cases (1425 females) were included, of which, consultants performed 1683 LCs (72%), while the residents performed 648 (28%) surgeries. The groups were statistically comparable regarding demographics, history of previous abdominal surgery, operative time, or intraoperative complications. The rate of conversion to open cholecystectomy was 1.42% for consultant and none for resident (p = 0.02). A statistically significant difference was observed between groups regarding the average length of stay (2.2 ± 3 vs 1.6 ± 1.3 days p = 0.03). Similarly, postoperative complications (1.7% vs 0.5%) resulted in statistically significant (p = 0.02) favoring resident group. CONCLUSIONS: Our study demonstrates that in selected patients, senior residents can safely perform LC when supervised by senior staff surgeons.

Laparoscopic-Guided Ropivacaine Trocar-Site Infiltration Can Improve Post-Operative Pain Control after Laparoscopic Adrenalectomy.

BACKGROUND: There is no consensus on pain control in patients undergoing laparoscopy; nowadays, conventional therapy may be improved by transversus abdominis plane block. The aim of this evaluation is to investigate the role of laparoscopic-assisted trocar-site ropivacaine infiltration during adrenalectomy in pain control. METHODS: This is a retrospective evaluation of a prospectively maintained database including patients undergoing adrenalectomy. Patients were divided into 2 groups: Group A patients received laparoscopic-assisted trocar-site infiltration of 7.5 mg/mL ropivacaine and Group B patients did not receive any infiltration. All patients received a 24-hour infusion of 20 mg morphine; pain was checked at 6, 24, and 48 hours after surgery by Visual Analogue Scale (VAS) score. A rescue analgesia by was given if VAS score was > 4 or on patient request. RESULTS: No differences in operative time, complications, and post-operative stay and no complications related to trocar-site infiltration were found. 6-hour and 48-hour VAS scores were not found to be significantly different between groups, even if a slight decrease in VAS score in Group A was reported. Group A showed significant reduction in VAS score at 24 hours (2.44 +/- .41 vs 3.01 +/- .78, P < .005) and in the number of patients requiring further analgesic drugs administration (40.6% vs 57.8%, P < .005). CONCLUSIONS: Laparoscopic-guided trocar-site ropivacaine infiltration can be considered safe and effective in the management of post-operative pain and in the reduction of analgesic need in patients undergoing laparoscopic adrenalectomy. The retrospective nature of the study and the lack of a consistent series of patients require further evaluations.

Printable Hydrogels Based on Alginate and Halloysite Nanotubes.

The design of hydrogels for the controlled release of active species is an attractive challenge. In this work, we prepared hybrid hydrogels composed of halloysite nanotubes as the inorganic component, and alginate as the organic counterpart. The reported procedure allowed us to provide the resulting materials with a peculiar wire-like shape. Both optical and scanning electron microscopy were used to characterize the morphological properties of the hydrogel wires, whose diameters were ca. 0.19 and 0.47 mm, respectively. The possibility to be exploited as drug delivery systems was carried out by loading the nanoclay with salicylic acid and by studying the release profiles. Thermogravimetric experiments showed that the amount of encapsulated drug was 4.35 wt%, and the salicylic acid was thermally stabilized after the loading into the nanotubes, as observed by the shift of the degradation peak in the differential thermograms from 193 to 267 °C. The kinetics investigation was conducted using UV-Vis spectrophotometry, and it exhibited the profound effects of both the morphology and dimensions on the release of the drugs. In particular, the release of 50% of the payload occurred in 6 and 10 h for the filiform hydrogels, and it was slower compared to the bare drug-loaded halloysite, which occurred in 2 h. Finally, an induction period of 2 h was observed in the release profile from the thicker sample.

Chitosan Functionalized with Carboxyl Groups as a Recyclable Biomaterial for the Adsorption of Cu (II) and Zn (II) Ions in Aqueous Media.

The modification of chitosan represents a challenging task in obtaining biopolymeric materials with enhanced removal capacity for heavy metals. In the present work, the adsorption characteristics of chitosan modified with carboxyl groups (CTS-CAA) towards copper (II) and zinc (II) ions have been tested. The efficacy of the synthesis of CTS-CAA has been evaluated by studying various properties of the modified chitosan. Specifically, the functionalized chitosan has been characterized by using several techniques, including thermal analyses (differential scanning calorimetry and thermogravimetry), spectroscopies (FT-IR, XRD), elemental analysis, and scanning electron microscopy. The kinetics and the adsorption isotherms of CTS-CAA towards both Cu (II) and Zn (II) have been determined in the aqueous solvent under variable pH. The obtained results have been analyzed by using different adsorption models. In addition, the experiments have been conducted at variable temperatures to explore the thermodynamics of the adsorption process. The regeneration of CTS-CAA has been investigated by studying the desorption process using different eluents. This paper reports an efficient protocol to synthesize chitosan-based material perspective as regenerative adsorbents for heavy metals.

Thermal and Mechanical Characterization of Yarn Samples from Flemish Tapestry of the Sixteenth Century.

We propose a physico-chemical approach for theharacterization of the conservation condition of yarns from a Flemish tapestry of the sixteenth century. The aging effect on the yarns' performance was evaluated by comparison with commercial materials. Water uptake experiments highlighted the aptitude of yarns toward water sorption and their increased hydrophilicity upon aging. Thermogravimetric analysis can be considered a fast approach for the fiber identification and assessment on the material life-time. The dynamic mechanical analysis provided direct evidence on the yarns, conservation state and their performance under different mechanical stresses. The proposed characterization path can be relevant for stating the condition of the tapestry and for designing a conservation protocol for the preservation of the artwork.

Effect of Polymer Length on the Adsorption onto Aluminogermanate Imogolite Nanotubes.

This study evidences the adsorption of model nonionic polymers onto aluminogermanate imogolite nanotubes, attractive porous nanofillers with potential molecular loading and release applications. We resolve the underlying mechanisms between nanotubes and polyethylene glycols with different molecular weights by means of nanoisothermal titration calorimetry. The analysis of the results provides a direct thermodynamic characterization, allowing us to propose a detailed description of the energetics involved in the formation of polymer/imogolite complexes. The affinity toward the nanotube surface is enthalpy-driven and strongly depends on the polymer chain length, which significantly affects the polymer configuration and the flow properties of the resulting complexes, probed by small-angle neutron scattering and rheology, respectively. These findings open new avenues for the rational design of these hybrid mixtures for advanced applications.

Understanding the Effects of Crosslinking and Reinforcement Agents on the Performance and Durability of Biopolymer Films for Cultural Heritage Protection.

In the last two decades, the naturally occurring polysaccharides, such as chitosan and pectin, have gained great attention having potential applications in different sectors, from biomedical to new generation packaging. Currently, the chitosan and pectic have been proposed as suitable materials also for the formulation of films and coatings for cultural heritage protection, as well as packaging films. Therefore, the formulation of biopolymer films, considering only naturally occurring polymers and additives, is a current challenging trend. This work reports on the formulation of chitosan (CS), pectin (PC), and chitosan:pectin (CS:PC) films, also containing natural crosslinking and reinforcement agents, such as citric acid (CA) and halloysite nanotubes (HNT), through the solvent casting technique. The produced films are characterized through water contact angle measurements, infrared and UV-visible spectroscopy and tensile test, while the durability of the CS:PC films is evaluated subjecting the film to accelerated UVB exposure and monitoring the photo-oxidation degradation in time though infrared spectroscopy. All obtained results suggest that both crosslinking and reinforcement agents have beneficial effects on the wettability, rigidity, and photo-oxidation resistance of biopolymer films. Therefore, these biopolymer films, also containing naturally occurring additives, have good properties and performance and they are suitable as coverage films for cultural heritage protection.

Conversion of Organic Dyes into Pigments: Extraction of Flavonoids from Blackberries (Rubus ulmifolius) and Stabilization.

The blackberry's color is composed mainly of natural dyes called anthocyanins. Their color is red-purple, and they can be used as a natural colorant. Anthocyanins are flavonoids, which are products of plants, and their colors range from orange and red to various shades of blue, purple and green, according to pH. In this study, the chemical composition of an extract obtained from blackberries was defined by LC-ESI/LTQOrbitrap/MS in positive and negative ionization mode. Furthermore, we investigated the adsorption process of blackberry extract using several inorganic fillers, such as metakaolin, silica, Lipari pumice, white pozzolan and alumina. The pigments exhibit different colors as a function of their interactions with the fillers. The analysis of the absorption data allowed the estimation of the maximum adsorbing capacity of each individual filler tested. Through thermogravimetric measurements (TGA), the thermal stability and the real adsorption of the organic extract were determined.

Prehospital Hemorrhage Assessment Criteria: A Concise Review.

OBJECTIVE: Early assessment of the clinical status of trauma patients is crucial for guiding the treatment strategy, and it requires a rapid and systematic approach. The aim of this report is to critically review the assessment parameters currently used in the prehospital setting to quantify blood loss in trauma. DATA SOURCES: Studies regarding hemorrhagic shock in trauma were pooled from PubMed, EMBASE, and Cochrane databases using key words such as "hemorrhagic shock," "vital signs evaluation," "trauma," "blood loss," and "emergency medical service," alone or combined. STUDY SELECTION: Articles published since 2009 in English and Italian were considered eligible if containing data on assessment parameters in blood loss in adults. DATA EXTRACTION: Sixteen articles matching the inclusion criteria were considered in our study. DATA SYNTHESIS: Current prehospital assessment measures lack precise correlation with blood loss. CONCLUSIONS: Traditional assessment parameters such as heart rate, systolic blood pressure, shock index, and Glasgow Coma Scale score often lag in providing accurate blood loss assessment. The current literature supports the need for a noninvasive, continuously monitored assessment parameter to identify early shock in the prehospital setting.

Halloysite Nanotubes: Interfacial Properties and Applications in Cultural Heritage.

The peculiar surfaces of halloysite nanotubes and their biocompatibility are attracting the interest of researchers based on the wide range of attainable applications. The large aspect ratio of this nanotubular material ensures promising properties as a reinforcing agent in polymeric matrixes, such as cellulose and its derivatives, that entail strengthening due to, for instance, aging-induced degradation. The halloysite cavity has a suitable size for hosting a large variety of active species such as deacidifying (calcium hydroxide) and flame retardant agents (fluorinated surfactants) for a controlled and sustained release relevant to the conservation of cultural heritage. Additionally, anionic surfactants can be selectively adsorbed at the inner surface generating inorganic micelles able to solubilize hydrophobic species in a controlled cleaning protocol. We briefly discuss how the natural halloysite nanotubes can be supportive in various conservation processes of cultural heritage and present an outlook for future perspectives.

Effect of the supramolecular interactions on the nanostructure of halloysite/biopolymer hybrids: a comprehensive study by SANS, fluorescence correlation spectroscopy and electric birefringence.

The structural properties of halloysite/biopolymer aqueous mixtures were firstly investigated by means of combining different techniques, including small-angle neutron scattering (SANS), electric birefringence (EBR) and fluorescence correlation spectroscopy (FCS). Among the biopolymers, non-ionic hydroxypropylcellulose and polyelectrolytes (anionic alginate and cationic chitosan) were selected. On this basis, the specific supramolecular interactions were correlated to the structural behavior of the halloysite/biopolymer mixtures. SANS data were analyzed in order to investigate the influence of the biopolymer adsorption on the halloysite gyration radius. In addition, a morphological description of the biopolymer-coated halloysite nanotubes (HNTs) was obtained by the simulation of SANS curves. EBR experiments evidenced that the orientation dynamics of the nanotubes in the electric field is influenced by the specific interactions with the polymers. Namely, both variations of the polymer charge and/or wrapping mechanisms strongly affected the HNT alignment process and, consequently, the rotational mobility of the nanotubes. FCS measurements with fluorescently labeled biopolymers allowed us to study the aqueous dynamic behavior of ionic biopolymers after their adsorption onto the HNT surfaces. The combination of EBR and FCS results revealed that the adsorption process reduces the mobility in water of both components. These effects are strongly enhanced by HNT/polyelectrolyte electrostatic interactions and wrapping processes occurring in the halloysite/chitosan mixture. The attained findings can be useful for designing halloysite/polymer hybrids with controlled structural properties.