Atomic force microscopy as a biophysical tool for nanoscale forensic investigations

A comprehensive review on application of atomic force microscopy in Forensic science

The primary objective of forensic investigation of a case is to recognize, identify, locate, and examine the evidence. Microscopy is a technique that provides crucial information for resolving a case or advancing the investigation process by analyzing the evidence obtained from a crime scene. It is often used in conjunction with suitable analytical techniques. Various microscopes are employed; scanning probe microscopes are available in diverse forensic analyses and studies. Among these, the atomic force microscope (AFM) is the most commonly used scanning probe technology, offering a unique morphological and physico-chemical perspective for analyzing multiple pieces of evidence in forensic investigations. Notably, it is a non-destructive technique capable of operating in liquid or air without complex sample preparation. The article delves into a detailed exploration of the applications of AFM in the realms of nanomechanical forensics and nanoscale characterization of forensically significant samples.

Regulation of Nanoliposome Rigidity and Bioavailability of Oligomeric Proanthocyanidin with Phytosterols Containing Different C3 Branches

The rigidity of nanoliposomes significantly influences their physical stability and in vitro and in vivo behaviors (e.g., cellular uptake, blood circulation, biodistribution, etc.). This study aimed to quantify the rigidity of the nanoliposomes composed of phytosterol with varying C3 branches and phospholipids (DPPC, DOPC) using atomic force microscopy. Young's modulus, determined by the Shell model, effectively differentiated between mechanical differences in nanoliposomes with varying components and component structure and phase states. FTIR results indicated that P-SG exhibited the highest Young's modulus (175.98 ± 10.53 MPa) due to the hydrogen bond between the glucose residue of steryl glycosides (SGs) and the phospholipid polar head. However, the rigidity of DOPC nanoliposomes was not significantly different due to the unsaturated bond. The addition of oligomeric proanthocyanidin (OPC) did not change the order of rigidity among the nanoliposomes, with P-SG-OPC having the highest Young's modulus (126.27 ± 2.06 MPa). In the simulated gastrointestinal tract experiment, P-SG-OPC exhibited the greatest stability, with minimal particle aggregation. Cellular uptake experiments revealed that DPPC nanoliposomes with high rigidity had optimal endocytosis, while DOPC nanoliposome uptake was independent of rigidity. In melanin production inhibition tests, the inhibitory effect correlated directly with Young's modulus and P-SG-OPC had the best inhibitory effect on melanin generation. Our findings in this study provide valuable insights into the design and optimization of nanoliposomes for the efficient delivery of active substances, offering potential solutions for improving the efficacy of drug delivery systems.

Tunable microfluidic chip for single-cell deformation study

Microfluidic phenotyping methods have been of vital importance for cellular characterization, especially for evaluating single cells. In order to study the deformability of a single cell, we devised and tested a tunable microfluidic chip-based method. A pneumatic polymer polydimethylsiloxane (PDMS) membrane was designed and fabricated abutting a single-cell trapping structure, so the cell could be squeezed controllably in a lateral direction. Cell contour changes under increasing pressure were recorded, enabling the deformation degree of different types of single cell to be analyzed and compared using computer vision. This provides a new perspective for studying mechanical properties of cells at the single cell level.

Forensic botany: who?, how?, where?, when?

Plants are a good source of biological forensic evidence; this is due to their ubiquity, their ability to collect reference material, and their sensitivity to environmental changes. However, in many countries, botanical evidence is recognised as being scientifically. Botanical evidence is not mostly used for perpertration, instead it tends to serve as circumstantial evidence. Plant materials constitute the basis, among others, for linking a suspect or object to a crime scene or a victim, confirming or not confirming an alibi, determining the post-mortem interval, and determining the origin of food/object. Forensic botany entails field work, knowledge of plants, understanding ecosystem processes, and a basis understaning of geoscience. In this study, experiments with mammal cadavers were conducted to determine the occurence of an event. The simplest criterion characterising botanical evidence is its size. Therefore, macroremains include whole plants or their larger fragments (e.g. tree bark, leaves, seeds, prickles, and thorns), whereas microscopic evidence includes palynomorphs (spores and pollen grains), diatoms, and tissues. Botanical methods allow for an analysis to be repeated multiple times and the test material is easy to collect in the field. Forensic botany can be supplemented with molecular analyses, which, although specific and sensitive, still require validation.

Insight into Drug Loading Regulated Micellar Rigidity by Nuclear Magnetic Resonance

The rigidity of polymeric micelles plays an important role in their biological behaviors. However, how drug loading affects the rigidity of polymeric micelles remains elusive. Herein, the indomethacin (IMC)-loaded Pluronic F127 micelle is used as a model system to illustrate the impact of drug loading on the rigidity and biological behaviors of polymeric micelles. Against expectations, micelles with moderate drug loading show higher cellular uptake and more severe cytotoxicity as compared to both high and low drug loading counterparts. Extensive one- and two-dimensional nuclear magnetic resonance (NMR) measurements are employed to reveal that the higher drug loading induces stronger interaction between IMC and hydrophilic block to boost the micellar rigidity; consequently, the moderate drug loading imparts micelles with appropriate rigidity for satisfactory cellular uptake and cytotoxicity. In summary, NMR spectroscopy is an important tool to gain insight into drug loading regulated micellar rigidity, which is helpful to understand their biological behaviors.

The Synthesis, Characterization and Applications of Polyhydroxyalkanoates (PHAs) and PHA-Based Nanoparticles

Polyhydroxyalkanoates (PHAs) are storage granules found in bacteria that are essentially hydroxy fatty acid polyesters. PHA molecules appear in variety of structures, and amongst all types of PHAs, polyhydroxybutyrate (PHB) is used in versatile fields as it is a biodegradable, biocompatible, and ecologically safe thermoplastic. The unique physicochemical characteristics of these PHAs have made them applicable in nanotechnology, tissue engineering, and other biomedical applications. In this review, the optimization, extraction, and characterization of PHAs are described. Their production and application in nanotechnology are also portrayed in this review, and the precise and various production methods of PHA-based nanoparticles, such as emulsion solvent diffusion, nanoprecipitation, and dialysis are discussed. The characterization techniques such as UV-Vis, FTIR, SEM, Zeta Potential, and XRD are also elaborated.