gistfile1.cs

 public static readonly string CHAR_UNICODE_FORMAT = "&#{0};";
        
        public static string EncodeUnicodeChars(this string srcString)
        {
            if (srcString == null)
            {
                throw new ArgumentNullException("srcString");
            }
            
            return srcString.Aggregate(new StringBuilder(),
                                                              (sb, 
                                                                currrentChar) => 
                                                                                {                                                                                    
                                                                                    sb.AppendFormat(CHAR_UNICODE_FORMAT , ((int)currrentChar).ToString());
                                                                                       
                                                                                    return sb;
                                                                                },
                                                                sb => sb.ToString());


            
            
        }